Make internals more open (#494)

* Simplify GestureLayouts, now simple classes

* Reorder CameraEngine members

* Refactor CameraPreviews

* Reorder Camera1Engine

* Fix tests

* New angle classes, fix snapshot rotation

* Small changes

* Add AnglesTest

cameraview/src/androidTest/java/com/otaliastudios/cameraview/CameraViewCallbacksTest.java

@@ -195,7 +195,7 @@ public class CameraViewCallbacksTest extends BaseTest {
     @Test
     public void testDispatchOnFocusStart() {
         // Enable tap gesture.
-        // Can't mock package protected. camera.mTapGestureLayout = mock(TapGestureLayout.class);
+        // Can't mock package protected. camera.mTapGestureFinder = mock(TapGestureLayout.class);
         camera.mapGesture(Gesture.TAP, GestureAction.AUTO_FOCUS);
         AutoFocusMarker marker = mock(AutoFocusMarker.class);
         MarkerLayout markerLayout = mock(MarkerLayout.class);
@@ -215,7 +215,7 @@ public class CameraViewCallbacksTest extends BaseTest {
     @Test
     public void testDispatchOnFocusEnd() {
         // Enable tap gesture.
-        // Can't mock package protected. camera.mTapGestureLayout = mock(TapGestureLayout.class);
+        // Can't mock package protected. camera.mTapGestureFinder = mock(TapGestureLayout.class);
         camera.mapGesture(Gesture.TAP, GestureAction.AUTO_FOCUS);
         AutoFocusMarker marker = mock(AutoFocusMarker.class);
         camera.setAutoFocusMarker(marker);
@@ -229,7 +229,7 @@ public class CameraViewCallbacksTest extends BaseTest {
         verify(listener, times(1)).onAutoFocusEnd(success, point);
         verify(marker, times(1)).onAutoFocusEnd(AutoFocusTrigger.GESTURE, success, point);
 
-        // Can't mock package protected. verify(camera.mTapGestureLayout, times(1)).onAutoFocusEnd(success);
+        // Can't mock package protected. verify(camera.mTapGestureFinder, times(1)).onAutoFocusEnd(success);
     }
 
     @Test

cameraview/src/androidTest/java/com/otaliastudios/cameraview/CameraViewTest.java

@@ -28,9 +28,9 @@ import com.otaliastudios.cameraview.controls.Mode;
 import com.otaliastudios.cameraview.controls.VideoCodec;
 import com.otaliastudios.cameraview.controls.WhiteBalance;
 import com.otaliastudios.cameraview.gesture.GestureParser;
-import com.otaliastudios.cameraview.gesture.PinchGestureLayout;
+import com.otaliastudios.cameraview.gesture.PinchGestureFinder;
-import com.otaliastudios.cameraview.gesture.ScrollGestureLayout;
+import com.otaliastudios.cameraview.gesture.ScrollGestureFinder;
-import com.otaliastudios.cameraview.gesture.TapGestureLayout;
+import com.otaliastudios.cameraview.gesture.TapGestureFinder;
 import com.otaliastudios.cameraview.engine.MockCameraEngine;
 import com.otaliastudios.cameraview.internal.utils.Op;
 import com.otaliastudios.cameraview.markers.AutoFocusMarker;
@@ -201,21 +201,21 @@ public class CameraViewTest extends BaseTest {
 
         // PinchGestureLayout
         cameraView.mapGesture(Gesture.PINCH, GestureAction.ZOOM);
-        assertTrue(cameraView.mPinchGestureLayout.isActive());
+        assertTrue(cameraView.mPinchGestureFinder.isActive());
         cameraView.clearGesture(Gesture.PINCH);
-        assertFalse(cameraView.mPinchGestureLayout.isActive());
+        assertFalse(cameraView.mPinchGestureFinder.isActive());
 
         // TapGestureLayout
         cameraView.mapGesture(Gesture.TAP, GestureAction.TAKE_PICTURE);
-        assertTrue(cameraView.mTapGestureLayout.isActive());
+        assertTrue(cameraView.mTapGestureFinder.isActive());
         cameraView.clearGesture(Gesture.TAP);
-        assertFalse(cameraView.mPinchGestureLayout.isActive());
+        assertFalse(cameraView.mPinchGestureFinder.isActive());
 
         // ScrollGestureLayout
         cameraView.mapGesture(Gesture.SCROLL_HORIZONTAL, GestureAction.ZOOM);
-        assertTrue(cameraView.mScrollGestureLayout.isActive());
+        assertTrue(cameraView.mScrollGestureFinder.isActive());
         cameraView.clearGesture(Gesture.SCROLL_HORIZONTAL);
-        assertFalse(cameraView.mScrollGestureLayout.isActive());
+        assertFalse(cameraView.mScrollGestureFinder.isActive());
     }
 
     //endregion
@@ -231,7 +231,7 @@ public class CameraViewTest extends BaseTest {
         ui(new Runnable() {
             @Override
             public void run() {
-                cameraView.mTapGestureLayout = new TapGestureLayout(cameraView.getContext()) {
+                cameraView.mTapGestureFinder = new TapGestureFinder(cameraView.mCameraCallbacks) {
                     protected boolean handleTouchEvent(@NonNull MotionEvent event) {
                         setGesture(Gesture.TAP);
                         return true;
@@ -253,7 +253,7 @@ public class CameraViewTest extends BaseTest {
         ui(new Runnable() {
             @Override
             public void run() {
-                cameraView.mTapGestureLayout = new TapGestureLayout(cameraView.getContext()) {
+                cameraView.mTapGestureFinder = new TapGestureFinder(cameraView.mCameraCallbacks) {
                     protected boolean handleTouchEvent(@NonNull MotionEvent event) {
                         setGesture(Gesture.TAP);
                         return true;
@@ -280,7 +280,7 @@ public class CameraViewTest extends BaseTest {
         ui(new Runnable() {
             @Override
             public void run() {
-                cameraView.mPinchGestureLayout = new PinchGestureLayout(cameraView.getContext()) {
+                cameraView.mPinchGestureFinder = new PinchGestureFinder(cameraView.mCameraCallbacks) {
                     @Override
                     protected boolean handleTouchEvent(@NonNull MotionEvent event) {
                         setGesture(Gesture.PINCH);
@@ -321,7 +321,7 @@ public class CameraViewTest extends BaseTest {
         ui(new Runnable() {
             @Override
             public void run() {
-                cameraView.mScrollGestureLayout = new ScrollGestureLayout(cameraView.getContext()) {
+                cameraView.mScrollGestureFinder = new ScrollGestureFinder(cameraView.mCameraCallbacks) {
                     @Override
                     protected boolean handleTouchEvent(@NonNull MotionEvent event) {
                         setGesture(Gesture.SCROLL_HORIZONTAL);
@@ -626,7 +626,7 @@ public class CameraViewTest extends BaseTest {
     public void testPreviewStreamSizeSelector() {
         SizeSelector source = SizeSelectors.minHeight(50);
         cameraView.setPreviewStreamSize(source);
-        SizeSelector result = mockController.getInternalPreviewStreamSizeSelector();
+        SizeSelector result = mockController.getPreviewStreamSizeSelector();
         assertNotNull(result);
         assertEquals(result, source);
     }
@@ -635,7 +635,7 @@ public class CameraViewTest extends BaseTest {
     public void testPictureSizeSelector() {
         SizeSelector source = SizeSelectors.minHeight(50);
         cameraView.setPictureSize(source);
-        SizeSelector result = mockController.getInternalPictureSizeSelector();
+        SizeSelector result = mockController.getPictureSizeSelector();
         assertNotNull(result);
         assertEquals(result, source);
     }
@@ -644,7 +644,7 @@ public class CameraViewTest extends BaseTest {
     public void testVideoSizeSelector() {
         SizeSelector source = SizeSelectors.minHeight(50);
         cameraView.setVideoSize(source);
-        SizeSelector result = mockController.getInternalVideoSizeSelector();
+        SizeSelector result = mockController.getVideoSizeSelector();
         assertNotNull(result);
         assertEquals(result, source);
     }

cameraview/src/androidTest/java/com/otaliastudios/cameraview/engine/MockCameraEngine.java

@@ -87,27 +87,6 @@ public class MockCameraEngine extends CameraEngine {
         mEngineStep.setState(started ? STATE_STARTED : STATE_STOPPED);
     }
 
-    public int getSnapshotMaxWidth() {
-        return mSnapshotMaxWidth;
-    }
-
-    public int getSnapshotMaxHeight() {
-        return mSnapshotMaxHeight;
-    }
-
-    public SizeSelector getInternalPreviewStreamSizeSelector() {
-        return super.getPreviewStreamSizeSelector();
-    }
-
-    public SizeSelector getInternalPictureSizeSelector() {
-        return super.getPictureSizeSelector();
-    }
-
-    public SizeSelector getInternalVideoSizeSelector() {
-        return super.getVideoSizeSelector();
-    }
-
-
     @Override
     public void setZoom(float zoom, @Nullable PointF[] points, boolean notify) {
         mZoomValue = zoom;
@@ -194,32 +173,8 @@ public class MockCameraEngine extends CameraEngine {
 
     }
 
-    @Override
-    public void setHasFrameProcessors(boolean hasFrameProcessors) {
-
-    }
-
     @Override
     protected boolean collectCameraInfo(@NonNull Facing facing) {
         return true;
     }
-
-    /*
-
-    @Override
-    public void setFacing(@NonNull Facing facing) {
-        mFacing = facing;
-    }
-
-    @Override
-    public void setMode(@NonNull Mode mode) {
-        mMode = mode;
-    }
-
-    @Override
-    public void setAudio(@NonNull Audio audio) {
-        mAudio = audio;
-    }
-
-    */
 }

cameraview/src/androidTest/java/com/otaliastudios/cameraview/gesture/GestureFinderTest.java

@@ -4,11 +4,14 @@ package com.otaliastudios.cameraview.gesture;
 import android.annotation.TargetApi;
 import android.content.Context;
 
+import androidx.annotation.NonNull;
 import androidx.test.espresso.ViewInteraction;
 import androidx.test.espresso.matcher.RootMatchers;
 import androidx.test.rule.ActivityTestRule;
 import android.view.MotionEvent;
 import android.view.View;
+import android.view.ViewGroup;
+import android.widget.FrameLayout;
 
 import com.otaliastudios.cameraview.BaseTest;
 import com.otaliastudios.cameraview.TestActivity;
@@ -21,17 +24,19 @@ import org.junit.Rule;
 import static androidx.test.espresso.Espresso.onView;
 
 @TargetApi(17)
-public abstract class GestureLayoutTest<T extends GestureLayout> extends BaseTest {
+public abstract class GestureFinderTest<T extends GestureFinder> extends BaseTest {
 
-    protected abstract T create(Context context);
+    protected abstract T createFinder(@NonNull GestureFinder.Controller controller);
 
     @Rule
     public ActivityTestRule<TestActivity> rule = new ActivityTestRule<>(TestActivity.class);
 
     @SuppressWarnings("WeakerAccess")
-    protected T layout;
+    protected T finder;
     @SuppressWarnings("WeakerAccess")
-    protected Op<Gesture> touch;
+    protected Op<Gesture> touchOp;
+    @SuppressWarnings("WeakerAccess")
+    protected ViewGroup layout;
 
     @Before
     public void setUp() {
@@ -39,16 +44,17 @@ public abstract class GestureLayoutTest<T extends GestureLayout> extends BaseTes
             @Override
             public void run() {
                 TestActivity a = rule.getActivity();
-                layout = create(a);
+                layout = new FrameLayout(a);
-                layout.setActive(true);
+                finder = createFinder(new Controller());
+                finder.setActive(true);
                 a.inflate(layout);
 
-                touch = new Op<>();
+                touchOp = new Op<>();
                 layout.setOnTouchListener(new View.OnTouchListener() {
                     @Override
                     public boolean onTouch(View view, MotionEvent motionEvent) {
-                        boolean found = layout.onTouchEvent(motionEvent);
+                        boolean found = finder.onTouchEvent(motionEvent);
-                        if (found) touch.end(layout.getGesture());
+                        if (found) touchOp.end(finder.getGesture());
                         return true;
                     }
                 });
@@ -62,4 +68,23 @@ public abstract class GestureLayoutTest<T extends GestureLayout> extends BaseTes
                 .inRoot(RootMatchers.withDecorView(
                         Matchers.is(rule.getActivity().getWindow().getDecorView())));
     }
+
+    private class Controller implements GestureFinder.Controller {
+
+        @NonNull
+        @Override
+        public Context getContext() {
+            return layout.getContext();
+        }
+
+        @Override
+        public int getWidth() {
+            return layout.getWidth();
+        }
+
+        @Override
+        public int getHeight() {
+            return layout.getHeight();
+        }
+    }
 }

cameraview/src/androidTest/java/com/otaliastudios/cameraview/gesture/PinchGestureFinderTest.java

@@ -3,10 +3,7 @@ package com.otaliastudios.cameraview.gesture;
 
 import android.content.Context;
 
-import com.otaliastudios.cameraview.gesture.Gesture;
+import androidx.annotation.NonNull;
-import com.otaliastudios.cameraview.gesture.GestureLayoutTest;
-import com.otaliastudios.cameraview.gesture.PinchGestureLayout;
-
 import androidx.test.espresso.ViewAction;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import androidx.test.filters.SmallTest;
@@ -22,21 +19,21 @@ import static org.junit.Assert.assertTrue;
 
 @RunWith(AndroidJUnit4.class)
 @SmallTest
-public class PinchGestureLayoutTest extends GestureLayoutTest<PinchGestureLayout> {
+public class PinchGestureFinderTest extends GestureFinderTest<PinchGestureFinder> {
 
     @Override
-    protected PinchGestureLayout create(Context context) {
+    protected PinchGestureFinder createFinder(@NonNull GestureFinder.Controller controller) {
-        return new PinchGestureLayout(context);
+        return new PinchGestureFinder(controller);
     }
 
     @Test
     public void testDefaults() {
-        assertEquals(layout.getGesture(), Gesture.PINCH);
+        assertEquals(finder.getGesture(), Gesture.PINCH);
-        assertEquals(layout.getPoints().length, 2);
+        assertEquals(finder.getPoints().length, 2);
-        assertEquals(layout.getPoints()[0].x, 0, 0);
+        assertEquals(finder.getPoints()[0].x, 0, 0);
-        assertEquals(layout.getPoints()[0].y, 0, 0);
+        assertEquals(finder.getPoints()[0].y, 0, 0);
-        assertEquals(layout.getPoints()[1].x, 0, 0);
+        assertEquals(finder.getPoints()[1].x, 0, 0);
-        assertEquals(layout.getPoints()[1].y, 0, 0);
+        assertEquals(finder.getPoints()[1].y, 0, 0);
     }
 
     // TODO: test pinch open
@@ -51,15 +48,15 @@ public class PinchGestureLayoutTest extends GestureLayoutTest<PinchGestureLayout
     }
 
     private void testPinch(ViewAction action, boolean increasing) {
-        touch.listen();
+        touchOp.listen();
-        touch.start();
+        touchOp.start();
         onLayout().perform(action);
-        Gesture found = touch.await(10000);
+        Gesture found = touchOp.await(10000);
         assertNotNull(found);
 
         // How will this move  our parameter?
         float curr = 0.5f, min = 0f, max = 1f;
-        float newValue = layout.computeValue(curr, min, max);
+        float newValue = finder.computeValue(curr, min, max);
         if (increasing) {
             assertTrue(newValue > curr);
             assertTrue(newValue <= max);

cameraview/src/androidTest/java/com/otaliastudios/cameraview/gesture/ScrollGestureFinderTest.java

@@ -3,10 +3,7 @@ package com.otaliastudios.cameraview.gesture;
 
 import android.content.Context;
 
-import com.otaliastudios.cameraview.gesture.Gesture;
+import androidx.annotation.NonNull;
-import com.otaliastudios.cameraview.gesture.GestureLayoutTest;
-import com.otaliastudios.cameraview.gesture.ScrollGestureLayout;
-
 import androidx.test.espresso.ViewAction;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import androidx.test.filters.SmallTest;
@@ -27,43 +24,43 @@ import static org.junit.Assert.assertTrue;
 
 @RunWith(AndroidJUnit4.class)
 @SmallTest
-public class ScrollGestureLayoutTest extends GestureLayoutTest<ScrollGestureLayout> {
+public class ScrollGestureFinderTest extends GestureFinderTest<ScrollGestureFinder> {
 
     @Override
-    protected ScrollGestureLayout create(Context context) {
+    protected ScrollGestureFinder createFinder(@NonNull GestureFinder.Controller controller) {
-        return new ScrollGestureLayout(context);
+        return new ScrollGestureFinder(controller);
     }
 
     @Test
     public void testDefaults() {
-        assertNull(layout.getGesture());
+        assertNull(finder.getGesture());
-        assertEquals(layout.getPoints().length, 2);
+        assertEquals(finder.getPoints().length, 2);
-        assertEquals(layout.getPoints()[0].x, 0, 0);
+        assertEquals(finder.getPoints()[0].x, 0, 0);
-        assertEquals(layout.getPoints()[0].y, 0, 0);
+        assertEquals(finder.getPoints()[0].y, 0, 0);
-        assertEquals(layout.getPoints()[1].x, 0, 0);
+        assertEquals(finder.getPoints()[1].x, 0, 0);
-        assertEquals(layout.getPoints()[1].y, 0, 0);
+        assertEquals(finder.getPoints()[1].y, 0, 0);
     }
 
     @Test
     public void testScrollDisabled() {
-        layout.setActive(false);
+        finder.setActive(false);
-        touch.listen();
+        touchOp.listen();
-        touch.start();
+        touchOp.start();
         onLayout().perform(swipeUp());
-        Gesture found = touch.await(500);
+        Gesture found = touchOp.await(500);
         assertNull(found);
     }
 
     private void testScroll(ViewAction scroll, Gesture expected, boolean increasing) {
-        touch.listen();
+        touchOp.listen();
-        touch.start();
+        touchOp.start();
         onLayout().perform(scroll);
-        Gesture found = touch.await(500);
+        Gesture found = touchOp.await(500);
         assertEquals(found, expected);
 
         // How will this move our parameter?
         float curr = 0.5f, min = 0f, max = 1f;
-        float newValue = layout.computeValue(curr, min, max);
+        float newValue = finder.computeValue(curr, min, max);
         if (increasing) {
             assertTrue(newValue >= curr);
             assertTrue(newValue <= max);

cameraview/src/androidTest/java/com/otaliastudios/cameraview/gesture/TapGestureFinderTest.java

@@ -2,6 +2,8 @@ package com.otaliastudios.cameraview.gesture;
 
 
 import android.content.Context;
+
+import androidx.annotation.NonNull;
 import androidx.test.espresso.action.GeneralClickAction;
 import androidx.test.espresso.action.GeneralLocation;
 import androidx.test.espresso.action.Press;
@@ -11,9 +13,6 @@ import androidx.test.filters.SmallTest;
 import android.view.InputDevice;
 import android.view.MotionEvent;
 
-import com.otaliastudios.cameraview.gesture.Gesture;
-import com.otaliastudios.cameraview.gesture.GestureLayoutTest;
-import com.otaliastudios.cameraview.gesture.TapGestureLayout;
 import com.otaliastudios.cameraview.size.Size;
 
 import org.junit.Test;
@@ -24,59 +23,59 @@ import static org.junit.Assert.*;
 
 @RunWith(AndroidJUnit4.class)
 @SmallTest
-public class TapGestureLayoutTest extends GestureLayoutTest<TapGestureLayout> {
+public class TapGestureFinderTest extends GestureFinderTest<TapGestureFinder> {
 
     @Override
-    protected TapGestureLayout create(Context context) {
+    protected TapGestureFinder createFinder(@NonNull GestureFinder.Controller controller) {
-        return new TapGestureLayout(context);
+        return new TapGestureFinder(controller);
     }
 
     @Test
     public void testDefaults() {
-        assertNull(layout.getGesture());
+        assertNull(finder.getGesture());
-        assertEquals(layout.getPoints().length, 1);
+        assertEquals(finder.getPoints().length, 1);
-        assertEquals(layout.getPoints()[0].x, 0, 0);
+        assertEquals(finder.getPoints()[0].x, 0, 0);
-        assertEquals(layout.getPoints()[0].y, 0, 0);
+        assertEquals(finder.getPoints()[0].y, 0, 0);
     }
 
     @Test
     public void testTap() {
-        touch.listen();
+        touchOp.listen();
-        touch.start();
+        touchOp.start();
         GeneralClickAction a = new GeneralClickAction(
                 Tap.SINGLE, GeneralLocation.CENTER, Press.FINGER,
                 InputDevice.SOURCE_UNKNOWN, MotionEvent.BUTTON_PRIMARY);
         onLayout().perform(a);
-        Gesture found = touch.await(500);
+        Gesture found = touchOp.await(500);
 
         assertEquals(found, Gesture.TAP);
         Size size = rule.getActivity().getContentSize();
-        assertEquals(layout.getPoints()[0].x, (size.getWidth() / 2f), 1f);
+        assertEquals(finder.getPoints()[0].x, (size.getWidth() / 2f), 1f);
-        assertEquals(layout.getPoints()[0].y, (size.getHeight() / 2f), 1f);
+        assertEquals(finder.getPoints()[0].y, (size.getHeight() / 2f), 1f);
     }
 
     @Test
     public void testTapWhileDisabled() {
-        layout.setActive(false);
+        finder.setActive(false);
-        touch.listen();
+        touchOp.listen();
-        touch.start();
+        touchOp.start();
         onLayout().perform(click());
-        Gesture found = touch.await(500);
+        Gesture found = touchOp.await(500);
         assertNull(found);
     }
 
     @Test
     public void testLongTap() {
-        touch.listen();
+        touchOp.listen();
-        touch.start();
+        touchOp.start();
         GeneralClickAction a = new GeneralClickAction(
                 Tap.LONG, GeneralLocation.CENTER, Press.FINGER,
                 InputDevice.SOURCE_UNKNOWN, MotionEvent.BUTTON_PRIMARY);
         onLayout().perform(a);
-        Gesture found = touch.await(500);
+        Gesture found = touchOp.await(500);
         assertEquals(found, Gesture.LONG_TAP);
         Size size = rule.getActivity().getContentSize();
-        assertEquals(layout.getPoints()[0].x, (size.getWidth() / 2f), 1f);
+        assertEquals(finder.getPoints()[0].x, (size.getWidth() / 2f), 1f);
-        assertEquals(layout.getPoints()[0].y, (size.getHeight() / 2f), 1f);
+        assertEquals(finder.getPoints()[0].y, (size.getHeight() / 2f), 1f);
     }
 }

cameraview/src/androidTest/java/com/otaliastudios/cameraview/preview/CameraPreviewTest.java

@@ -27,7 +27,7 @@ public abstract class CameraPreviewTest extends BaseTest {
 
     private final static long DELAY = 4000;
 
-    protected abstract CameraPreview createPreview(Context context, ViewGroup parent, CameraPreview.SurfaceCallback callback);
+    protected abstract CameraPreview createPreview(Context context, ViewGroup parent);
 
     @Rule
     public ActivityTestRule<TestActivity> rule = new ActivityTestRule<>(TestActivity.class);
@@ -69,7 +69,8 @@ public abstract class CameraPreviewTest extends BaseTest {
                     }
                 }).when(callback).onSurfaceDestroyed();
 
-                preview = createPreview(a, a.getContentView(), callback);
+                preview = createPreview(a, a.getContentView());
+                preview.setSurfaceCallback(callback);
             }
         });
     }

cameraview/src/androidTest/java/com/otaliastudios/cameraview/preview/GlCameraPreviewTest.java

@@ -14,8 +14,8 @@ import org.junit.runner.RunWith;
 public class GlCameraPreviewTest extends CameraPreviewTest {
 
     @Override
-    protected CameraPreview createPreview(Context context, ViewGroup parent, CameraPreview.SurfaceCallback callback) {
+    protected CameraPreview createPreview(Context context, ViewGroup parent) {
-        return new GlCameraPreview(context, parent, callback);
+        return new GlCameraPreview(context, parent);
     }
 
     @Override

cameraview/src/androidTest/java/com/otaliastudios/cameraview/preview/MockCameraPreview.java

@@ -12,7 +12,7 @@ import com.otaliastudios.cameraview.preview.CameraPreview;
 public class MockCameraPreview extends CameraPreview<View, Void> {
 
     public MockCameraPreview(Context context, ViewGroup parent) {
-        super(context, parent, null);
+        super(context, parent);
     }
 
     @Override

cameraview/src/androidTest/java/com/otaliastudios/cameraview/preview/SurfaceCameraPreviewTest.java

@@ -18,8 +18,8 @@ import org.junit.runner.RunWith;
 public class SurfaceCameraPreviewTest extends CameraPreviewTest {
 
     @Override
-    protected CameraPreview createPreview(Context context, ViewGroup parent, CameraPreview.SurfaceCallback callback) {
+    protected CameraPreview createPreview(Context context, ViewGroup parent) {
-        return new SurfaceCameraPreview(context, parent, callback);
+        return new SurfaceCameraPreview(context, parent);
     }
 
     @Override

cameraview/src/androidTest/java/com/otaliastudios/cameraview/preview/TextureCameraPreviewTest.java

@@ -18,8 +18,8 @@ import org.junit.runner.RunWith;
 public class TextureCameraPreviewTest extends CameraPreviewTest {
 
     @Override
-    protected CameraPreview createPreview(Context context, ViewGroup parent, CameraPreview.SurfaceCallback callback) {
+    protected CameraPreview createPreview(Context context, ViewGroup parent) {
-        return new TextureCameraPreview(context, parent, callback);
+        return new TextureCameraPreview(context, parent);
     }
 
     @Override

cameraview/src/main/java/com/otaliastudios/cameraview/CameraView.java

@@ -37,6 +37,7 @@ import com.otaliastudios.cameraview.controls.Engine;
 import com.otaliastudios.cameraview.controls.Facing;
 import com.otaliastudios.cameraview.controls.Flash;
 import com.otaliastudios.cameraview.engine.Camera2Engine;
+import com.otaliastudios.cameraview.engine.offset.Reference;
 import com.otaliastudios.cameraview.markers.MarkerLayout;
 import com.otaliastudios.cameraview.engine.Camera1Engine;
 import com.otaliastudios.cameraview.engine.CameraEngine;
@@ -50,11 +51,11 @@ import com.otaliastudios.cameraview.controls.Mode;
 import com.otaliastudios.cameraview.controls.Preview;
 import com.otaliastudios.cameraview.controls.VideoCodec;
 import com.otaliastudios.cameraview.controls.WhiteBalance;
-import com.otaliastudios.cameraview.gesture.GestureLayout;
+import com.otaliastudios.cameraview.gesture.GestureFinder;
 import com.otaliastudios.cameraview.gesture.GestureParser;
-import com.otaliastudios.cameraview.gesture.PinchGestureLayout;
+import com.otaliastudios.cameraview.gesture.PinchGestureFinder;
-import com.otaliastudios.cameraview.gesture.ScrollGestureLayout;
+import com.otaliastudios.cameraview.gesture.ScrollGestureFinder;
-import com.otaliastudios.cameraview.gesture.TapGestureLayout;
+import com.otaliastudios.cameraview.gesture.TapGestureFinder;
 import com.otaliastudios.cameraview.internal.GridLinesLayout;
 import com.otaliastudios.cameraview.internal.utils.CropHelper;
 import com.otaliastudios.cameraview.internal.utils.OrientationHelper;
@@ -115,11 +116,13 @@ public class CameraView extends FrameLayout implements LifecycleObserver {
     @VisibleForTesting List<FrameProcessor> mFrameProcessors = new CopyOnWriteArrayList<>();
     private Lifecycle mLifecycle;
 
+    // Gestures
+    @VisibleForTesting PinchGestureFinder mPinchGestureFinder;
+    @VisibleForTesting TapGestureFinder mTapGestureFinder;
+    @VisibleForTesting ScrollGestureFinder mScrollGestureFinder;
+
     // Views
     GridLinesLayout mGridLinesLayout;
-    PinchGestureLayout mPinchGestureLayout;
-    TapGestureLayout mTapGestureLayout;
-    ScrollGestureLayout mScrollGestureLayout;
     MarkerLayout mMarkerLayout;
     private boolean mKeepScreenOn;
     @SuppressWarnings({"FieldCanBeLocal", "unused"})
@@ -173,16 +176,15 @@ public class CameraView extends FrameLayout implements LifecycleObserver {
         mUiHandler = new Handler(Looper.getMainLooper());
         mFrameProcessorsHandler = WorkerHandler.get("FrameProcessorsWorker");
 
+        // Gestures
+        mPinchGestureFinder = new PinchGestureFinder(mCameraCallbacks);
+        mTapGestureFinder = new TapGestureFinder(mCameraCallbacks);
+        mScrollGestureFinder = new ScrollGestureFinder(mCameraCallbacks);
+
         // Views
         mGridLinesLayout = new GridLinesLayout(context);
-        mPinchGestureLayout = new PinchGestureLayout(context);
-        mTapGestureLayout = new TapGestureLayout(context);
-        mScrollGestureLayout = new ScrollGestureLayout(context);
         mMarkerLayout = new MarkerLayout(context);
         addView(mGridLinesLayout);
-        addView(mPinchGestureLayout);
-        addView(mTapGestureLayout);
-        addView(mScrollGestureLayout);
         addView(mMarkerLayout);
 
         // Create the engine
@@ -225,6 +227,26 @@ public class CameraView extends FrameLayout implements LifecycleObserver {
         }
     }
 
+    /**
+     * Engine is instantiated on creation and anytime
+     * {@link #setEngine(Engine)} is called.
+     */
+    private void doInstantiateEngine() {
+        mCameraEngine = instantiateCameraEngine(mEngine, mCameraCallbacks);
+    }
+
+    /**
+     * Preview is instantiated {@link #onAttachedToWindow()}, because
+     * we want to know if we're hardware accelerated or not.
+     * However, in tests, we might want to create the preview right after constructor.
+     */
+    @VisibleForTesting
+    void doInstantiatePreview() {
+        mCameraPreview = instantiatePreview(mPreview, getContext(), this);
+        mCameraEngine.setPreview(mCameraPreview);
+    }
+
+
     /**
      * Instantiates the camera engine.
      *
@@ -255,30 +277,20 @@ public class CameraView extends FrameLayout implements LifecycleObserver {
         LOG.w("preview:", "isHardwareAccelerated:", isHardwareAccelerated());
         switch (preview) {
             case SURFACE:
-                return new SurfaceCameraPreview(context, container, null);
+                return new SurfaceCameraPreview(context, container);
             case TEXTURE: {
                 if (isHardwareAccelerated()) {
                     // TextureView is not supported without hardware acceleration.
-                    return new TextureCameraPreview(context, container, null);
+                    return new TextureCameraPreview(context, container);
                 }
             }
             case GL_SURFACE: default: {
                 mPreview = Preview.GL_SURFACE;
-                return new GlCameraPreview(context, container, null);
+                return new GlCameraPreview(context, container);
             }
         }
     }
 
-    @VisibleForTesting
-    void doInstantiatePreview() {
-        mCameraPreview = instantiatePreview(mPreview, getContext(), this);
-        mCameraEngine.setPreview(mCameraPreview);
-    }
-
-    private void doInstantiateEngine() {
-        mCameraEngine = instantiateCameraEngine(mEngine, mCameraCallbacks);
-    }
-
     @Override
     protected void onAttachedToWindow() {
         super.onAttachedToWindow();
@@ -331,7 +343,7 @@ public class CameraView extends FrameLayout implements LifecycleObserver {
      */
     @Override
     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
-        Size previewSize = mCameraEngine.getPreviewStreamSize(CameraEngine.REF_VIEW);
+        Size previewSize = mCameraEngine.getPreviewStreamSize(Reference.VIEW);
         if (previewSize == null) {
             LOG.w("onMeasure:", "surface is not ready. Calling default behavior.");
             super.onMeasure(widthMeasureSpec, heightMeasureSpec);
@@ -474,19 +486,19 @@ public class CameraView extends FrameLayout implements LifecycleObserver {
             mGestureMap.put(gesture, action);
             switch (gesture) {
                 case PINCH:
-                    mPinchGestureLayout.setActive(mGestureMap.get(Gesture.PINCH) != none);
+                    mPinchGestureFinder.setActive(mGestureMap.get(Gesture.PINCH) != none);
                     break;
                 case TAP:
                 // case DOUBLE_TAP:
                 case LONG_TAP:
-                    mTapGestureLayout.setActive(
+                    mTapGestureFinder.setActive(
                             mGestureMap.get(Gesture.TAP) != none ||
                             // mGestureMap.get(Gesture.DOUBLE_TAP) != none ||
                             mGestureMap.get(Gesture.LONG_TAP) != none);
                     break;
                 case SCROLL_HORIZONTAL:
                 case SCROLL_VERTICAL:
-                    mScrollGestureLayout.setActive(
+                    mScrollGestureFinder.setActive(
                             mGestureMap.get(Gesture.SCROLL_HORIZONTAL) != none ||
                             mGestureMap.get(Gesture.SCROLL_VERTICAL) != none);
                     break;
@@ -534,15 +546,15 @@ public class CameraView extends FrameLayout implements LifecycleObserver {
         // Pass to our own GestureLayouts
         CameraOptions options = mCameraEngine.getCameraOptions(); // Non null
         if (options == null) throw new IllegalStateException("Options should not be null here.");
-        if (mPinchGestureLayout.onTouchEvent(event)) {
+        if (mPinchGestureFinder.onTouchEvent(event)) {
             LOG.i("onTouchEvent", "pinch!");
-            onGesture(mPinchGestureLayout, options);
+            onGesture(mPinchGestureFinder, options);
-        } else if (mScrollGestureLayout.onTouchEvent(event)) {
+        } else if (mScrollGestureFinder.onTouchEvent(event)) {
             LOG.i("onTouchEvent", "scroll!");
-            onGesture(mScrollGestureLayout, options);
+            onGesture(mScrollGestureFinder, options);
-        } else if (mTapGestureLayout.onTouchEvent(event)) {
+        } else if (mTapGestureFinder.onTouchEvent(event)) {
             LOG.i("onTouchEvent", "tap!");
-            onGesture(mTapGestureLayout, options);
+            onGesture(mTapGestureFinder, options);
         }
         return true;
     }
@@ -551,7 +563,7 @@ public class CameraView extends FrameLayout implements LifecycleObserver {
     // Some gesture layout detected a gesture. It's not known at this moment:
     // (1) if it was mapped to some action (we check here)
     // (2) if it's supported by the camera (CameraEngine checks)
-    private void onGesture(GestureLayout source, @NonNull CameraOptions options) {
+    private void onGesture(GestureFinder source, @NonNull CameraOptions options) {
         Gesture gesture = source.getGesture();
         GestureAction action = mGestureMap.get(gesture);
         PointF[] points = source.getPoints();
@@ -1538,12 +1550,12 @@ public class CameraView extends FrameLayout implements LifecycleObserver {
 
         // Get the preview size and crop according to the current view size.
         // It's better to do calculations in the REF_VIEW reference, and then flip if needed.
-        Size preview = mCameraEngine.getUncroppedSnapshotSize(CameraEngine.REF_VIEW);
+        Size preview = mCameraEngine.getUncroppedSnapshotSize(Reference.VIEW);
         if (preview == null) return null; // Should never happen.
         AspectRatio viewRatio = AspectRatio.of(getWidth(), getHeight());
         Rect crop = CropHelper.computeCrop(preview, viewRatio);
         Size cropSize = new Size(crop.width(), crop.height());
-        if (mCameraEngine.flip(CameraEngine.REF_VIEW, CameraEngine.REF_OUTPUT)) {
+        if (mCameraEngine.getAngles().flip(Reference.VIEW, Reference.OUTPUT)) {
             return cropSize.flip();
         } else {
             return cropSize;
@@ -1562,7 +1574,7 @@ public class CameraView extends FrameLayout implements LifecycleObserver {
      */
     @Nullable
     public Size getPictureSize() {
-        return mCameraEngine.getPictureSize(CameraEngine.REF_OUTPUT);
+        return mCameraEngine.getPictureSize(Reference.OUTPUT);
     }
 
 
@@ -1577,7 +1589,7 @@ public class CameraView extends FrameLayout implements LifecycleObserver {
      */
     @Nullable
     public Size getVideoSize() {
-        return mCameraEngine.getVideoSize(CameraEngine.REF_OUTPUT);
+        return mCameraEngine.getVideoSize(Reference.OUTPUT);
     }
 
 
@@ -1732,7 +1744,10 @@ public class CameraView extends FrameLayout implements LifecycleObserver {
     //region Callbacks and dispatching
 
     @VisibleForTesting
-    class CameraCallbacks implements CameraEngine.Callback, OrientationHelper.Callback {
+    class CameraCallbacks implements
+            CameraEngine.Callback,
+            OrientationHelper.Callback,
+            GestureFinder.Controller {
 
         private CameraLogger mLogger = CameraLogger.create(CameraCallbacks.class.getSimpleName());
 
@@ -1742,6 +1757,16 @@ public class CameraView extends FrameLayout implements LifecycleObserver {
             return CameraView.this.getContext();
         }
 
+        @Override
+        public int getWidth() {
+            return CameraView.this.getWidth();
+        }
+
+        @Override
+        public int getHeight() {
+            return CameraView.this.getHeight();
+        }
+
         @Override
         public void dispatchOnCameraOpened(final CameraOptions options) {
             mLogger.i("dispatchOnCameraOpened", options);
@@ -1786,7 +1811,6 @@ public class CameraView extends FrameLayout implements LifecycleObserver {
         @Override
         public void onShutter(boolean shouldPlaySound) {
             if (shouldPlaySound && mPlaySounds) {
-                //noinspection all
                 playSound(MediaActionSound.SHUTTER_CLICK);
             }
         }
@@ -1847,7 +1871,6 @@ public class CameraView extends FrameLayout implements LifecycleObserver {
                 @Override
                 public void run() {
                     if (success && mPlaySounds) {
-                        //noinspection all
                         playSound(MediaActionSound.FOCUS_COMPLETE);
                     }
 

cameraview/src/main/java/com/otaliastudios/cameraview/engine/Camera1Engine.java

@@ -14,7 +14,6 @@ import androidx.annotation.Nullable;
 import androidx.annotation.VisibleForTesting;
 import androidx.annotation.WorkerThread;
 
-import android.util.Log;
 import android.view.SurfaceHolder;
 
 import com.google.android.gms.tasks.Task;
@@ -23,6 +22,8 @@ import com.otaliastudios.cameraview.CameraException;
 import com.otaliastudios.cameraview.CameraLogger;
 import com.otaliastudios.cameraview.CameraOptions;
 import com.otaliastudios.cameraview.controls.Engine;
+import com.otaliastudios.cameraview.engine.offset.Axis;
+import com.otaliastudios.cameraview.engine.offset.Reference;
 import com.otaliastudios.cameraview.frame.Frame;
 import com.otaliastudios.cameraview.PictureResult;
 import com.otaliastudios.cameraview.VideoResult;
@@ -34,7 +35,6 @@ import com.otaliastudios.cameraview.controls.Hdr;
 import com.otaliastudios.cameraview.controls.Mode;
 import com.otaliastudios.cameraview.controls.WhiteBalance;
 import com.otaliastudios.cameraview.internal.utils.CropHelper;
-import com.otaliastudios.cameraview.internal.utils.Op;
 import com.otaliastudios.cameraview.picture.Full1PictureRecorder;
 import com.otaliastudios.cameraview.picture.Snapshot1PictureRecorder;
 import com.otaliastudios.cameraview.picture.SnapshotGlPictureRecorder;
@@ -57,52 +57,84 @@ public class Camera1Engine extends CameraEngine implements
 
     private static final String TAG = Camera1Engine.class.getSimpleName();
     private static final CameraLogger LOG = CameraLogger.create(TAG);
+
+    private static final int PREVIEW_FORMAT = ImageFormat.NV21;
     @VisibleForTesting static final int AUTOFOCUS_END_DELAY_MILLIS = 2500;
 
     private Camera mCamera;
     @VisibleForTesting int mCameraId;
-    private int mPreviewStreamFormat;
-
-
     private Runnable mFocusEndRunnable;
-    private final Runnable mFocusResetRunnable = new Runnable() {
-        @Override
-        public void run() {
-            if (!isCameraAvailable()) return;
-            mCamera.cancelAutoFocus();
-            Camera.Parameters params = mCamera.getParameters();
-            int maxAF = params.getMaxNumFocusAreas();
-            int maxAE = params.getMaxNumMeteringAreas();
-            if (maxAF > 0) params.setFocusAreas(null);
-            if (maxAE > 0) params.setMeteringAreas(null);
-            applyDefaultFocus(params); // Revert to internal focus.
-            mCamera.setParameters(params);
-        }
-    };
 
     public Camera1Engine(@NonNull Callback callback) {
         super(callback);
         mMapper = Mapper.get(Engine.CAMERA1);
     }
 
-    private boolean isCameraAvailable() {
+    //region Utilities
-        return getEngineState() == STATE_STARTED;
+
+    @Override
+    public void onError(int error, Camera camera) {
+        if (error == Camera.CAMERA_ERROR_SERVER_DIED) {
+            // Looks like this is recoverable.
+            LOG.w("Recoverable error inside the onError callback.", "CAMERA_ERROR_SERVER_DIED");
+            restart();
+            return;
         }
 
-    private void schedule(@Nullable final Op<Void> op, final boolean ensureAvailable, final Runnable action) {
+        String message = LOG.e("Internal Camera1 error.", error);
-        mHandler.run(new Runnable() {
+        Exception runtime = new RuntimeException(message);
+        int reason;
+        switch (error) {
+            case Camera.CAMERA_ERROR_EVICTED: reason = CameraException.REASON_DISCONNECTED; break;
+            case Camera.CAMERA_ERROR_UNKNOWN: reason = CameraException.REASON_UNKNOWN; break;
+            default: reason = CameraException.REASON_UNKNOWN;
+        }
+        throw new CameraException(runtime, reason);
+    }
+
+    //endregion
+
+    //region Protected APIs
+
+    @NonNull
     @Override
-            public void run() {
+    protected List<Size> getPreviewStreamAvailableSizes() {
-                if (ensureAvailable && !isCameraAvailable()) {
+        List<Camera.Size> sizes = mCamera.getParameters().getSupportedPreviewSizes();
-                    if (op != null) op.end(null);
+        List<Size> result = new ArrayList<>(sizes.size());
-                } else {
+        for (Camera.Size size : sizes) {
-                    action.run();
+            Size add = new Size(size.width, size.height);
-                    if (op != null) op.end(null);
+            if (!result.contains(add)) result.add(add);
         }
+        LOG.i("getPreviewStreamAvailableSizes:", result);
+        return result;
     }
-        });
+
+    @WorkerThread
+    @Override
+    protected void onPreviewStreamSizeChanged() {
+        restartPreview();
+    }
+
+    @Override
+    protected boolean collectCameraInfo(@NonNull Facing facing) {
+        int internalFacing = mMapper.map(facing);
+        LOG.i("collectCameraInfo", "Facing:", facing, "Internal:", internalFacing, "Cameras:", Camera.getNumberOfCameras());
+        Camera.CameraInfo cameraInfo = new Camera.CameraInfo();
+        for (int i = 0, count = Camera.getNumberOfCameras(); i < count; i++) {
+            Camera.getCameraInfo(i, cameraInfo);
+            if (cameraInfo.facing == internalFacing) {
+                setSensorOffset(facing, cameraInfo.orientation);
+                mCameraId = i;
+                return true;
+            }
+        }
+        return false;
     }
 
+    //endregion
+
+    //region Start
+
     @NonNull
     @WorkerThread
     @Override
@@ -118,16 +150,10 @@ public class Camera1Engine extends CameraEngine implements
         // Set parameters that might have been set before the camera was opened.
         LOG.i("onStartEngine:", "Applying default parameters.");
         Camera.Parameters params = mCamera.getParameters();
-        mCameraOptions = new CameraOptions(params, flip(REF_SENSOR, REF_VIEW));
+        mCameraOptions = new CameraOptions(params, getAngles().flip(Reference.SENSOR, Reference.VIEW));
-        applyDefaultFocus(params);
+        applyAllParameters(params);
-        applyFlash(params, Flash.OFF);
-        applyLocation(params, null);
-        applyWhiteBalance(params, WhiteBalance.AUTO);
-        applyHdr(params, Hdr.OFF);
-        applyPlaySounds(mPlaySounds);
-        params.setRecordingHint(mMode == Mode.VIDEO);
         mCamera.setParameters(params);
-        mCamera.setDisplayOrientation(offset(REF_SENSOR, REF_VIEW)); // <- not allowed during preview
+        mCamera.setDisplayOrientation(getAngles().offset(Reference.SENSOR, Reference.VIEW, Axis.ABSOLUTE)); // <- not allowed during preview
         LOG.i("onStartEngine:", "Ended");
         return Tasks.forResult(null);
     }
@@ -161,17 +187,17 @@ public class Camera1Engine extends CameraEngine implements
         LOG.i("onStartPreview", "Dispatching onCameraPreviewStreamSizeChanged.");
         mCallback.onCameraPreviewStreamSizeChanged();
 
-        Size previewSize = getPreviewStreamSize(REF_VIEW);
+        Size previewSize = getPreviewStreamSize(Reference.VIEW);
         if (previewSize == null) {
             throw new IllegalStateException("previewStreamSize should not be null at this point.");
         }
         mPreview.setStreamSize(previewSize.getWidth(), previewSize.getHeight());
 
         Camera.Parameters params = mCamera.getParameters();
-        mPreviewStreamFormat = params.getPreviewFormat();
+        params.setPreviewFormat(ImageFormat.NV21); // should be the default, but let's make sure, since YuvImage will only support this & a few others
-        params.setPreviewSize(mPreviewStreamSize.getWidth(), mPreviewStreamSize.getHeight()); // <- not allowed during preview
+        params.setPreviewSize(mPreviewStreamSize.getWidth(), mPreviewStreamSize.getHeight()); // not allowed during preview
-        if (mMode == Mode.PICTURE) {
+        if (getMode() == Mode.PICTURE) {
-            params.setPictureSize(mCaptureSize.getWidth(), mCaptureSize.getHeight()); // <- allowed
+            params.setPictureSize(mCaptureSize.getWidth(), mCaptureSize.getHeight()); // allowed during preview
         } else {
             // mCaptureSize in this case is a video size. The available video sizes are not necessarily
             // a subset of the picture sizes, so we can't use the mCaptureSize value: it might crash.
@@ -184,7 +210,7 @@ public class Camera1Engine extends CameraEngine implements
 
         mCamera.setPreviewCallbackWithBuffer(null); // Release anything left
         mCamera.setPreviewCallbackWithBuffer(this); // Add ourselves
-        getFrameManager().setUp(ImageFormat.getBitsPerPixel(mPreviewStreamFormat), mPreviewStreamSize);
+        getFrameManager().setUp(ImageFormat.getBitsPerPixel(PREVIEW_FORMAT), mPreviewStreamSize);
 
         LOG.i("onStartPreview", "Starting preview with startPreview().");
         try {
@@ -197,6 +223,10 @@ public class Camera1Engine extends CameraEngine implements
         return Tasks.forResult(null);
     }
 
+    //endregion
+
+    //region Stop
+
     @NonNull
     @Override
     protected Task<Void> onStopPreview() {
@@ -205,7 +235,6 @@ public class Camera1Engine extends CameraEngine implements
             mVideoRecorder = null;
         }
         mPictureRecorder = null;
-        mPreviewStreamFormat = 0;
         getFrameManager().release();
         mCamera.setPreviewCallbackWithBuffer(null); // Release anything left
         try {
@@ -216,7 +245,6 @@ public class Camera1Engine extends CameraEngine implements
         return Tasks.forResult(null);
     }
 
-
     @NonNull
     @Override
     protected Task<Void> onStopBind() {
@@ -263,77 +291,172 @@ public class Camera1Engine extends CameraEngine implements
         return Tasks.forResult(null);
     }
 
+    //endregion
+
+    //region Pictures
+
     @WorkerThread
     @Override
-    protected void onPreviewStreamSizeChanged() {
+    protected void onTakePicture(@NonNull PictureResult.Stub stub) {
-        restartPreview();
+        stub.rotation = getAngles().offset(Reference.SENSOR, Reference.OUTPUT, Axis.RELATIVE_TO_SENSOR);
+        stub.size = getPictureSize(Reference.OUTPUT);
+        mPictureRecorder = new Full1PictureRecorder(stub, Camera1Engine.this, mCamera);
+        mPictureRecorder.take();
     }
 
+    @WorkerThread
     @Override
-    protected boolean collectCameraInfo(@NonNull Facing facing) {
+    protected void onTakePictureSnapshot(@NonNull PictureResult.Stub stub, @NonNull AspectRatio viewAspectRatio) {
-        int internalFacing = mMapper.map(facing);
+        stub.size = getUncroppedSnapshotSize(Reference.OUTPUT); // Not the real size: it will be cropped to match the view ratio
-        LOG.i("collectCameraInfo", "Facing:", facing, "Internal:", internalFacing, "Cameras:", Camera.getNumberOfCameras());
+        stub.rotation = getAngles().offset(Reference.SENSOR, Reference.OUTPUT, Axis.RELATIVE_TO_SENSOR); // Actually it will be rotated and set to 0.
-        Camera.CameraInfo cameraInfo = new Camera.CameraInfo();
+        AspectRatio outputRatio = getAngles().flip(Reference.OUTPUT, Reference.VIEW) ? viewAspectRatio.flip() : viewAspectRatio;
-        for (int i = 0, count = Camera.getNumberOfCameras(); i < count; i++) {
+
-            Camera.getCameraInfo(i, cameraInfo);
+        if (mPreview instanceof GlCameraPreview && Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
-            if (cameraInfo.facing == internalFacing) {
+            mPictureRecorder = new SnapshotGlPictureRecorder(stub, this, (GlCameraPreview) mPreview, outputRatio);
-                mSensorOffset = cameraInfo.orientation;
+        } else {
-                mCameraId = i;
+            mPictureRecorder = new Snapshot1PictureRecorder(stub, this, mCamera, outputRatio);
-                return true;
-            }
         }
-        return false;
+        mPictureRecorder.take();
     }
 
+    //endregion
+
+    //region Videos
+
     @Override
-    public void setHasFrameProcessors(boolean hasFrameProcessors) {
+    protected void onTakeVideo(@NonNull VideoResult.Stub stub) {
-        mHasFrameProcessors = hasFrameProcessors;
+        stub.rotation = getAngles().offset(Reference.SENSOR, Reference.OUTPUT, Axis.RELATIVE_TO_SENSOR);
+        stub.size = getAngles().flip(Reference.SENSOR, Reference.OUTPUT) ? mCaptureSize.flip() : mCaptureSize;
+        // Unlock the camera and start recording.
+        try {
+            mCamera.unlock();
+        } catch (Exception e) {
+            // If this failed, we are unlikely able to record the video.
+            // Dispatch an error.
+            onVideoResult(null, e);
+            return;
+        }
+        mVideoRecorder = new Full1VideoRecorder(Camera1Engine.this, mCamera, mCameraId);
+        mVideoRecorder.start(stub);
     }
 
-    @NonNull
+    @SuppressLint("NewApi")
+    @WorkerThread
     @Override
-    protected FrameManager instantiateFrameManager() {
+    protected void onTakeVideoSnapshot(@NonNull VideoResult.Stub stub, @NonNull AspectRatio viewAspectRatio) {
-        return new FrameManager(2, this);
+        if (!(mPreview instanceof GlCameraPreview)) {
+            throw new IllegalStateException("Video snapshots are only supported with GlCameraPreview.");
         }
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR2) {
+            throw new IllegalStateException("Video snapshots are only supported starting from API 18.");
+        }
+        GlCameraPreview glPreview = (GlCameraPreview) mPreview;
 
-    @Override
+        // Output size is easy:
-    public void onBufferAvailable(@NonNull byte[] buffer) {
+        Size outputSize = getUncroppedSnapshotSize(Reference.OUTPUT);
-        // TODO: sync with handler?
+        if (outputSize == null) {
-        if (isCameraAvailable()) {
+            throw new IllegalStateException("outputSize should not be null.");
-            mCamera.addCallbackBuffer(buffer);
         }
+        AspectRatio outputRatio = getAngles().flip(Reference.OUTPUT, Reference.VIEW) ? viewAspectRatio.flip() : viewAspectRatio;
+        Rect outputCrop = CropHelper.computeCrop(outputSize, outputRatio);
+        outputSize = new Size(outputCrop.width(), outputCrop.height());
+        stub.size = outputSize;
+        stub.rotation = getAngles().offset(Reference.VIEW, Reference.OUTPUT, Axis.ABSOLUTE);
+
+        // Start.
+        mVideoRecorder = new SnapshotVideoRecorder(Camera1Engine.this, glPreview);
+        mVideoRecorder.start(stub);
     }
 
     @Override
-    public void onError(int error, Camera camera) {
+    public void onVideoResult(@Nullable VideoResult.Stub result, @Nullable Exception exception) {
-        if (error == Camera.CAMERA_ERROR_SERVER_DIED) {
+        super.onVideoResult(result, exception);
-            // Looks like this is recoverable.
+        if (result == null) {
-            LOG.w("Recoverable error inside the onError callback.", "CAMERA_ERROR_SERVER_DIED");
+            // Something went wrong, lock the camera again.
-            restart();
+            mCamera.lock();
+        }
+    }
+
+    //endregion
+
+    //region Parameters
+
+    private void applyAllParameters(@NonNull Camera.Parameters params) {
+        params.setRecordingHint(getMode() == Mode.VIDEO);
+        applyDefaultFocus(params);
+        applyFlash(params, Flash.OFF);
+        applyLocation(params, null);
+        applyWhiteBalance(params, WhiteBalance.AUTO);
+        applyHdr(params, Hdr.OFF);
+        applyZoom(params, 0F);
+        applyExposureCorrection(params, 0F);
+        applyPlaySounds(mPlaySounds);
+    }
+
+    private void applyDefaultFocus(@NonNull Camera.Parameters params) {
+        List<String> modes = params.getSupportedFocusModes();
+
+        if (getMode() == Mode.VIDEO &&
+                modes.contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO)) {
+            params.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO);
             return;
         }
 
-        String message = LOG.e("Internal Camera1 error.", error);
+        if (modes.contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE)) {
-        Exception runtime = new RuntimeException(message);
+            params.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
-        int reason;
+            return;
-        switch (error) {
-            case Camera.CAMERA_ERROR_EVICTED: reason = CameraException.REASON_DISCONNECTED; break;
-            case Camera.CAMERA_ERROR_UNKNOWN: reason = CameraException.REASON_UNKNOWN; break;
-            default: reason = CameraException.REASON_UNKNOWN;
         }
-        throw new CameraException(runtime, reason);
+
+        if (modes.contains(Camera.Parameters.FOCUS_MODE_INFINITY)) {
+            params.setFocusMode(Camera.Parameters.FOCUS_MODE_INFINITY);
+            return;
+        }
+
+        if (modes.contains(Camera.Parameters.FOCUS_MODE_FIXED)) {
+            params.setFocusMode(Camera.Parameters.FOCUS_MODE_FIXED);
+            //noinspection UnnecessaryReturnStatement
+            return;
+        }
+    }
+
+    @Override
+    public void setFlash(@NonNull Flash flash) {
+        final Flash old = mFlash;
+        mFlash = flash;
+        mHandler.run(new Runnable() {
+            @Override
+            public void run() {
+                if (getEngineState() == STATE_STARTED) {
+                    Camera.Parameters params = mCamera.getParameters();
+                    if (applyFlash(params, old)) mCamera.setParameters(params);
+                }
+                mFlashOp.end(null);
+            }
+        });
+    }
+
+    private boolean applyFlash(@NonNull Camera.Parameters params, @NonNull Flash oldFlash) {
+        if (mCameraOptions.supports(mFlash)) {
+            params.setFlashMode((String) mMapper.map(mFlash));
+            return true;
+        }
+        mFlash = oldFlash;
+        return false;
     }
 
     @Override
     public void setLocation(@Nullable Location location) {
         final Location oldLocation = mLocation;
         mLocation = location;
-        schedule(mLocationOp, true, new Runnable() {
+        mHandler.run(new Runnable() {
             @Override
             public void run() {
+                if (getEngineState() == STATE_STARTED) {
                     Camera.Parameters params = mCamera.getParameters();
                     if (applyLocation(params, oldLocation)) mCamera.setParameters(params);
                 }
+                mLocationOp.end(null);
+            }
         });
     }
 
@@ -353,12 +476,15 @@ public class Camera1Engine extends CameraEngine implements
     public void setWhiteBalance(@NonNull WhiteBalance whiteBalance) {
         final WhiteBalance old = mWhiteBalance;
         mWhiteBalance = whiteBalance;
-        schedule(mWhiteBalanceOp, true, new Runnable() {
+        mHandler.run(new Runnable() {
             @Override
             public void run() {
+                if (getEngineState() == STATE_STARTED) {
                     Camera.Parameters params = mCamera.getParameters();
                     if (applyWhiteBalance(params, old)) mCamera.setParameters(params);
                 }
+                mWhiteBalanceOp.end(null);
+            }
         });
     }
 
@@ -375,12 +501,15 @@ public class Camera1Engine extends CameraEngine implements
     public void setHdr(@NonNull Hdr hdr) {
         final Hdr old = mHdr;
         mHdr = hdr;
-        schedule(mHdrOp, true, new Runnable() {
+        mHandler.run(new Runnable() {
             @Override
             public void run() {
+                if (getEngineState() == STATE_STARTED) {
                     Camera.Parameters params = mCamera.getParameters();
                     if (applyHdr(params, old)) mCamera.setParameters(params);
                 }
+                mHdrOp.end(null);
+            }
         });
     }
 
@@ -393,268 +522,149 @@ public class Camera1Engine extends CameraEngine implements
         return false;
     }
 
-    @SuppressWarnings("UnusedReturnValue")
-    @TargetApi(17)
-    private boolean applyPlaySounds(boolean oldPlaySound) {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
-            Camera.CameraInfo info = new Camera.CameraInfo();
-            Camera.getCameraInfo(mCameraId, info);
-            if (info.canDisableShutterSound) {
-                try {
-                    // this method is documented to throw on some occasions. #377
-                    return mCamera.enableShutterSound(mPlaySounds);
-                } catch (RuntimeException exception) {
-                    return false;
-                }
-            }
-        }
-        if (mPlaySounds) {
-            return true;
-        }
-        mPlaySounds = oldPlaySound;
-        return false;
-    }
-
     @Override
-    public void setFlash(@NonNull Flash flash) {
+    public void setZoom(final float zoom, @Nullable final PointF[] points, final boolean notify) {
-        final Flash old = mFlash;
+        final float old = mZoomValue;
-        mFlash = flash;
+        mZoomValue = zoom;
-        schedule(mFlashOp, true, new Runnable() {
+        mHandler.run(new Runnable() {
             @Override
             public void run() {
+                if (getEngineState() == STATE_STARTED) {
                     Camera.Parameters params = mCamera.getParameters();
-                if (applyFlash(params, old)) mCamera.setParameters(params);
+                    if (applyZoom(params, old)) {
+                        mCamera.setParameters(params);
+                        if (notify) {
+                            mCallback.dispatchOnZoomChanged(mZoomValue, points);
+                        }
+                    }
+                }
+                mZoomOp.end(null);
             }
         });
     }
 
-
+    private boolean applyZoom(@NonNull Camera.Parameters params, float oldZoom) {
-    private boolean applyFlash(@NonNull Camera.Parameters params, @NonNull Flash oldFlash) {
+        if (mCameraOptions.isZoomSupported()) {
-        if (mCameraOptions.supports(mFlash)) {
+            float max = params.getMaxZoom();
-            params.setFlashMode((String) mMapper.map(mFlash));
+            params.setZoom((int) (mZoomValue * max));
+            mCamera.setParameters(params);
             return true;
         }
-        mFlash = oldFlash;
+        mZoomValue = oldZoom;
         return false;
     }
 
-
+    @Override
-    // Choose the best default focus, based on session type.
+    public void setExposureCorrection(final float EVvalue, @NonNull final float[] bounds,
-    private void applyDefaultFocus(@NonNull Camera.Parameters params) {
+                                      @Nullable final PointF[] points, final boolean notify) {
-        List<String> modes = params.getSupportedFocusModes();
+        final float old = mExposureCorrectionValue;
-
+        mExposureCorrectionValue = EVvalue;
-        if (mMode == Mode.VIDEO &&
+        mHandler.run(new Runnable() {
-                modes.contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO)) {
+            @Override
-            params.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO);
+            public void run() {
-            return;
+                if (getEngineState() == STATE_STARTED) {
-        }
+                    Camera.Parameters params = mCamera.getParameters();
-
+                    if (applyExposureCorrection(params, old)) {
-        if (modes.contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE)) {
+                        mCamera.setParameters(params);
-            params.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
+                        if (notify) {
-            return;
+                            mCallback.dispatchOnExposureCorrectionChanged(mExposureCorrectionValue, bounds, points);
                         }
-
-        if (modes.contains(Camera.Parameters.FOCUS_MODE_INFINITY)) {
-            params.setFocusMode(Camera.Parameters.FOCUS_MODE_INFINITY);
-            return;
                     }
-
-        if (modes.contains(Camera.Parameters.FOCUS_MODE_FIXED)) {
-            params.setFocusMode(Camera.Parameters.FOCUS_MODE_FIXED);
-            //noinspection UnnecessaryReturnStatement
-            return;
                 }
+                mExposureCorrectionOp.end(null);
             }
-
+        });
-    // -----------------
-    // Picture recording stuff.
-
-    @WorkerThread
-    @Override
-    protected void onTakePicture(@NonNull PictureResult.Stub stub) {
-        stub.rotation = offset(REF_SENSOR, REF_OUTPUT);
-        stub.size = getPictureSize(REF_OUTPUT);
-        mPictureRecorder = new Full1PictureRecorder(stub, Camera1Engine.this, mCamera);
-        mPictureRecorder.take();
     }
 
-    @WorkerThread
+    private boolean applyExposureCorrection(@NonNull Camera.Parameters params, float oldExposureCorrection) {
-    @Override
+        if (mCameraOptions.isExposureCorrectionSupported()) {
-    protected void onTakePictureSnapshot(@NonNull PictureResult.Stub stub, @NonNull AspectRatio viewAspectRatio) {
+            // Just make sure we're inside boundaries.
-        stub.size = getUncroppedSnapshotSize(REF_OUTPUT); // Not the real size: it will be cropped to match the view ratio
+            float max = mCameraOptions.getExposureCorrectionMaxValue();
-        stub.rotation = offset(REF_SENSOR, REF_OUTPUT); // Actually it will be rotated and set to 0.
+            float min = mCameraOptions.getExposureCorrectionMinValue();
-        AspectRatio outputRatio = flip(REF_OUTPUT, REF_VIEW) ? viewAspectRatio.flip() : viewAspectRatio;
+            float val = mExposureCorrectionValue;
-
+            val = val < min ? min : val > max ? max : val; // cap
-        if (mPreview instanceof GlCameraPreview && Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
+            mExposureCorrectionValue = val;
-            mPictureRecorder = new SnapshotGlPictureRecorder(stub, this, (GlCameraPreview) mPreview, outputRatio);
+            // Apply.
-        } else {
+            int indexValue = (int) (mExposureCorrectionValue / params.getExposureCompensationStep());
-            mPictureRecorder = new Snapshot1PictureRecorder(stub, this, mCamera, outputRatio);
+            params.setExposureCompensation(indexValue);
-        }
+            return true;
-        mPictureRecorder.take();
         }
-
+        mExposureCorrectionValue = oldExposureCorrection;
-    @Override
+        return false;
-    public void onPreviewFrame(@NonNull byte[] data, Camera camera) {
-        Frame frame = getFrameManager().getFrame(data,
-                System.currentTimeMillis(),
-                offset(REF_SENSOR, REF_OUTPUT),
-                mPreviewStreamSize,
-                mPreviewStreamFormat);
-        mCallback.dispatchFrame(frame);
     }
 
-    // -----------------
-    // Video recording stuff.
-
     @Override
-    public void onVideoResult(@Nullable VideoResult.Stub result, @Nullable Exception exception) {
+    public void setPlaySounds(boolean playSounds) {
-        super.onVideoResult(result, exception);
+        final boolean old = mPlaySounds;
-        if (result == null) {
+        mPlaySounds = playSounds;
-            // Something went wrong, lock the camera again.
+        mHandler.run(new Runnable() {
-            mCamera.lock();
-        }
-    }
-
             @Override
-    protected void onTakeVideo(@NonNull VideoResult.Stub stub) {
+            public void run() {
-        stub.rotation = offset(REF_SENSOR, REF_OUTPUT);
+                if (getEngineState() == STATE_STARTED) {
-        stub.size = flip(REF_SENSOR, REF_OUTPUT) ? mCaptureSize.flip() : mCaptureSize;
+                    applyPlaySounds(old);
-        // Unlock the camera and start recording.
-        try {
-            mCamera.unlock();
-        } catch (Exception e) {
-            // If this failed, we are unlikely able to record the video.
-            // Dispatch an error.
-            onVideoResult(null, e);
-            return;
                 }
-        if (!(mVideoRecorder instanceof Full1VideoRecorder)) {
+                mPlaySoundsOp.end(null);
-            mVideoRecorder = new Full1VideoRecorder(Camera1Engine.this, mCamera, mCameraId);
             }
-        mVideoRecorder.start(stub);
+        });
     }
 
-    @SuppressLint("NewApi")
+    @SuppressWarnings("UnusedReturnValue")
-    @WorkerThread
+    @TargetApi(17)
-    @Override
+    private boolean applyPlaySounds(boolean oldPlaySound) {
-    protected void onTakeVideoSnapshot(@NonNull VideoResult.Stub stub, @NonNull AspectRatio viewAspectRatio) {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
-        if (!(mPreview instanceof GlCameraPreview)) {
+            Camera.CameraInfo info = new Camera.CameraInfo();
-            throw new IllegalStateException("Video snapshots are only supported with GlCameraPreview.");
+            Camera.getCameraInfo(mCameraId, info);
+            if (info.canDisableShutterSound) {
+                try {
+                    // this method is documented to throw on some occasions. #377
+                    return mCamera.enableShutterSound(mPlaySounds);
+                } catch (RuntimeException exception) {
+                    return false;
                 }
-        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR2) {
-            throw new IllegalStateException("Video snapshots are only supported starting from API 18.");
             }
-        GlCameraPreview glPreview = (GlCameraPreview) mPreview;
-
-        // Size and rotation turned out to be extremely tricky. In case of Snapshot1PictureRecorder
-        // we use the preview size in REF_OUTPUT (cropped) and offset(REF_SENSOR, REF_OUTPUT) as rotation.
-        // These values mean that we expect input to be in the REF_SENSOR system.
-
-        // Here everything seems different. We would expect a difference because the two snapshot
-        // recorders have different mechanics (the picture one uses a SurfaceTexture with setBufferSize,
-        // the video one here uses the MediaCodec input surface which we can't control).
-
-        // The strangest thing is the fact that the correct angle seems to be the same for FRONT and
-        // BACK sensor, which means that our sensor correction actually screws things up. For this reason
-        // facing value is temporarily set to BACK.
-        Facing realFacing = mFacing;
-        mFacing = Facing.BACK;
-
-        // These are the angles that make it work on a Nexus5X, compared to the offset() results.
-        // For instance, SV means offset(REF_SENSOR, REF_VIEW). The rest should be clear.
-        //    CONFIG   | WANTED |   SV   |   VS   |   VO   |   OV   |   SO   |   OS   |
-        // ------------|--------|--------|--------|--------|--------|--------|--------|
-        //   Vertical  |   0    |   270  |   90   |   0    |   0    |   270  |   90   |
-        //     Left    |   270  |   270  |   90   |  270   |   90   |   180  |   180  |
-        //    Right    |   90   |   270  |   90   |   90   |   270  |    0   |    0   |
-        // Upside down |   180  |   270  |   90   |  180   |   180  |   90   |   270  |
-
-        // The VO is the only correct value. Things change when using FRONT camera, in which case,
-        // no value is actually correct, and the needed values are the same of BACK!
-        //    CONFIG   | WANTED |   SV   |   VS   |   VO   |   OV   |   SO   |   OS   |
-        // ------------|--------|--------|--------|--------|--------|--------|--------|
-        //   Vertical  |   0    |   90   |   270  |  180   |   180  |   270  |   90   |
-        //     Left    |   270  |   90   |   270  |  270   |   90   |    0   |    0   |
-        //    Right    |   90   |   90   |   270  |   90   |   270  |   180  |   180  |
-        // Upside down |   180  |   90   |   270  |   0    |    0   |   90   |   270  |
-
-        // Based on this we will use VO for everything. See if we get issues about distortion
-        // and maybe we can improve. The reason why this happen is beyond my understanding.
-
-        Size outputSize = getUncroppedSnapshotSize(REF_OUTPUT);
-        if (outputSize == null) {
-            throw new IllegalStateException("outputSize should not be null.");
         }
-        AspectRatio outputRatio = flip(REF_OUTPUT, REF_VIEW) ? viewAspectRatio.flip() : viewAspectRatio;
+        if (mPlaySounds) {
-        Rect outputCrop = CropHelper.computeCrop(outputSize, outputRatio);
+            return true;
-        outputSize = new Size(outputCrop.width(), outputCrop.height());
-        stub.size = outputSize;
-        stub.rotation = offset(REF_VIEW, REF_OUTPUT);
-
-        // Reset facing and start.
-        mFacing = realFacing;
-        if (!(mVideoRecorder instanceof SnapshotVideoRecorder)) {
-            mVideoRecorder = new SnapshotVideoRecorder(Camera1Engine.this, glPreview);
         }
-        mVideoRecorder.start(stub);
+        mPlaySounds = oldPlaySound;
+        return false;
     }
 
-    // -----------------
+    //endregion
-    // Zoom and simpler stuff.
 
+    //region Frame Processing
 
+    @NonNull
     @Override
-    public void setZoom(final float zoom, @Nullable final PointF[] points, final boolean notify) {
+    protected FrameManager instantiateFrameManager() {
-        schedule(mZoomOp, true, new Runnable() {
+        return new FrameManager(2, this);
-            @Override
-            public void run() {
-                if (!mCameraOptions.isZoomSupported()) return;
-
-                mZoomValue = zoom;
-                Camera.Parameters params = mCamera.getParameters();
-                float max = params.getMaxZoom();
-                params.setZoom((int) (zoom * max));
-                mCamera.setParameters(params);
-
-                if (notify) {
-                    mCallback.dispatchOnZoomChanged(zoom, points);
-                }
-            }
-        });
     }
 
     @Override
-    public void setExposureCorrection(final float EVvalue, @NonNull final float[] bounds,
+    public void onBufferAvailable(@NonNull byte[] buffer) {
-                               @Nullable final PointF[] points, final boolean notify) {
+        if (getEngineState() == STATE_STARTED) {
-        schedule(mExposureCorrectionOp, true, new Runnable() {
+            mCamera.addCallbackBuffer(buffer);
-            @Override
-            public void run() {
-                if (!mCameraOptions.isExposureCorrectionSupported()) return;
-
-                float value = EVvalue;
-                float max = mCameraOptions.getExposureCorrectionMaxValue();
-                float min = mCameraOptions.getExposureCorrectionMinValue();
-                value = value < min ? min : value > max ? max : value; // cap
-                mExposureCorrectionValue = value;
-                Camera.Parameters params = mCamera.getParameters();
-                int indexValue = (int) (value / params.getExposureCompensationStep());
-                params.setExposureCompensation(indexValue);
-                mCamera.setParameters(params);
-
-                if (notify) {
-                    mCallback.dispatchOnExposureCorrectionChanged(value, bounds, points);
         }
     }
-        });
+
+    @Override
+    public void onPreviewFrame(@NonNull byte[] data, Camera camera) {
+        Frame frame = getFrameManager().getFrame(data,
+                System.currentTimeMillis(),
+                getAngles().offset(Reference.SENSOR, Reference.OUTPUT, Axis.RELATIVE_TO_SENSOR),
+                mPreviewStreamSize,
+                PREVIEW_FORMAT);
+        mCallback.dispatchFrame(frame);
     }
 
-    // -----------------
+    //endregion
-    // Tap to focus stuff.
 
+    //region Auto Focus
 
     @Override
     public void startAutoFocus(@Nullable final Gesture gesture, @NonNull final PointF point) {
         // Must get width and height from the UI thread.
+        // TODO could take mPreview.surfaceSize like Camera2 does?
         int viewWidth = 0, viewHeight = 0;
         if (mPreview != null && mPreview.hasSurface()) {
             viewWidth = mPreview.getView().getWidth();
@@ -662,14 +672,15 @@ public class Camera1Engine extends CameraEngine implements
         }
         final int viewWidthF = viewWidth;
         final int viewHeightF = viewHeight;
-        // Schedule.
+        mHandler.run(new Runnable() {
-        schedule(null, true, new Runnable() {
             @Override
             public void run() {
+                if (getEngineState() < STATE_STARTED) return;
                 if (!mCameraOptions.isAutoFocusSupported()) return;
                 final PointF p = new PointF(point.x, point.y); // copy.
+                int offset = getAngles().offset(Reference.SENSOR, Reference.VIEW, Axis.ABSOLUTE);
                 List<Camera.Area> meteringAreas2 = computeMeteringAreas(p.x, p.y,
-                        viewWidthF, viewHeightF, offset(REF_SENSOR, REF_VIEW));
+                        viewWidthF, viewHeightF, offset);
                 List<Camera.Area> meteringAreas1 = meteringAreas2.subList(0, 1);
 
                 // At this point we are sure that camera supports auto focus... right? Look at CameraView.onTouchEvent().
@@ -688,10 +699,8 @@ public class Camera1Engine extends CameraEngine implements
                 mFocusEndRunnable = new Runnable() {
                     @Override
                     public void run() {
-                        if (isCameraAvailable()) {
                         mCallback.dispatchOnFocusEnd(gesture, false, p);
                     }
-                    }
                 };
                 mHandler.post(AUTOFOCUS_END_DELAY_MILLIS, mFocusEndRunnable);
 
@@ -717,6 +726,7 @@ public class Camera1Engine extends CameraEngine implements
                     // Let the mFocusEndRunnable do its job. (could remove it and quickly dispatch
                     // onFocusEnd here, but let's make it simpler).
                 }
+
             }
         });
     }
@@ -763,38 +773,21 @@ public class Camera1Engine extends CameraEngine implements
         return new Rect(left, top, right, bottom);
     }
 
-
+    private final Runnable mFocusResetRunnable = new Runnable() {
-    // -----------------
-    // Size stuff.
-
-    public final int getPreviewStreamFormat() {
-        return mPreviewStreamFormat;
-    }
-
-
-    @NonNull
-    @Override
-    protected List<Size> getPreviewStreamAvailableSizes() {
-        List<Camera.Size> sizes = mCamera.getParameters().getSupportedPreviewSizes();
-        List<Size> result = new ArrayList<>(sizes.size());
-        for (Camera.Size size : sizes) {
-            Size add = new Size(size.width, size.height);
-            if (!result.contains(add)) result.add(add);
-        }
-        LOG.i("getPreviewStreamAvailableSizes:", result);
-        return result;
-    }
-
-    @Override
-    public void setPlaySounds(boolean playSounds) {
-        final boolean old = mPlaySounds;
-        mPlaySounds = playSounds;
-        schedule(mPlaySoundsOp, true, new Runnable() {
         @Override
         public void run() {
-                applyPlaySounds(old);
+            if (getEngineState() < STATE_STARTED) return;
-            }
+            mCamera.cancelAutoFocus();
-        });
+            Camera.Parameters params = mCamera.getParameters();
+            int maxAF = params.getMaxNumFocusAreas();
+            int maxAE = params.getMaxNumMeteringAreas();
+            if (maxAF > 0) params.setFocusAreas(null);
+            if (maxAE > 0) params.setMeteringAreas(null);
+            applyDefaultFocus(params); // Revert to internal focus.
+            mCamera.setParameters(params);
         }
+    };
+
+    //endregion
 }
 

cameraview/src/main/java/com/otaliastudios/cameraview/engine/Camera2Engine.java

@@ -44,6 +44,8 @@ import com.otaliastudios.cameraview.controls.Flash;
 import com.otaliastudios.cameraview.controls.Hdr;
 import com.otaliastudios.cameraview.controls.Mode;
 import com.otaliastudios.cameraview.controls.WhiteBalance;
+import com.otaliastudios.cameraview.engine.offset.Axis;
+import com.otaliastudios.cameraview.engine.offset.Reference;
 import com.otaliastudios.cameraview.frame.Frame;
 import com.otaliastudios.cameraview.frame.FrameManager;
 import com.otaliastudios.cameraview.gesture.Gesture;
@@ -299,7 +301,8 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
                 CameraCharacteristics characteristics = mManager.getCameraCharacteristics(cameraId);
                 if (internalFacing == readCharacteristic(characteristics, CameraCharacteristics.LENS_FACING, -99)) {
                     mCameraId = cameraId;
-                    mSensorOffset = readCharacteristic(characteristics, CameraCharacteristics.SENSOR_ORIENTATION, 0);
+                    int sensorOffset = readCharacteristic(characteristics, CameraCharacteristics.SENSOR_ORIENTATION, 0);
+                    setSensorOffset(facing, sensorOffset);
                     return true;
                 }
             } catch (CameraAccessException ignore) {
@@ -330,7 +333,8 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
                     try {
                         LOG.i("createCamera:", "Applying default parameters.");
                         mCameraCharacteristics = mManager.getCameraCharacteristics(mCameraId);
-                        mCameraOptions = new CameraOptions(mManager, mCameraId, flip(REF_SENSOR, REF_VIEW));
+                        boolean flip = getAngles().flip(Reference.SENSOR, Reference.VIEW);
+                        mCameraOptions = new CameraOptions(mManager, mCameraId, flip);
                         createRepeatingRequestBuilder(CameraDevice.TEMPLATE_PREVIEW);
                     } catch (CameraAccessException e) {
                         task.trySetException(createCameraException(e));
@@ -406,7 +410,7 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
         outputSurfaces.add(mPreviewStreamSurface);
 
         // 2. VIDEO RECORDING
-        if (mMode == Mode.VIDEO) {
+        if (getMode() == Mode.VIDEO) {
             if (Full2VideoRecorder.SUPPORTS_PERSISTENT_SURFACE) {
                 mFullVideoPersistentSurface = MediaCodec.createPersistentInputSurface();
                 outputSurfaces.add(mFullVideoPersistentSurface);
@@ -422,7 +426,7 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
         }
 
         // 3. PICTURE RECORDING
-        if (mMode == Mode.PICTURE) {
+        if (getMode() == Mode.PICTURE) {
             mPictureReader = ImageReader.newInstance(
                     mCaptureSize.getWidth(),
                     mCaptureSize.getHeight(),
@@ -433,7 +437,7 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
         }
 
         // 4. FRAME PROCESSING
-        if (mHasFrameProcessors) {
+        if (hasFrameProcessors()) {
             // Choose the size.
             StreamConfigurationMap streamMap = mCameraCharacteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
             if (streamMap == null) throw new RuntimeException("StreamConfigurationMap is null. Should not happen.");
@@ -489,13 +493,13 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
         LOG.i("onStartPreview", "Dispatching onCameraPreviewStreamSizeChanged.");
         mCallback.onCameraPreviewStreamSizeChanged();
 
-        Size previewSizeForView = getPreviewStreamSize(REF_VIEW);
+        Size previewSizeForView = getPreviewStreamSize(Reference.VIEW);
         if (previewSizeForView == null) {
             throw new IllegalStateException("previewStreamSize should not be null at this point.");
         }
         mPreview.setStreamSize(previewSizeForView.getWidth(), previewSizeForView.getHeight());
-        mPreview.setDrawRotation(mDisplayOffset);
+        mPreview.setDrawRotation(getAngles().offset(Reference.BASE, Reference.VIEW, Axis.ABSOLUTE));
-        if (mHasFrameProcessors) {
+        if (hasFrameProcessors()) {
             getFrameManager().setUp(ImageFormat.getBitsPerPixel(FRAME_PROCESSING_FORMAT), mFrameProcessingSize);
         }
 
@@ -537,7 +541,7 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
             mVideoRecorder = null;
         }
         mPictureRecorder = null;
-        if (mHasFrameProcessors) {
+        if (hasFrameProcessors()) {
             getFrameManager().release();
         }
         try {
@@ -613,9 +617,9 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
     @WorkerThread
     @Override
     protected void onTakePictureSnapshot(@NonNull PictureResult.Stub stub, @NonNull AspectRatio viewAspectRatio) {
-        stub.size = getUncroppedSnapshotSize(REF_OUTPUT); // Not the real size: it will be cropped to match the view ratio
+        stub.size = getUncroppedSnapshotSize(Reference.OUTPUT); // Not the real size: it will be cropped to match the view ratio
-        stub.rotation = offset(REF_SENSOR, REF_OUTPUT); // Actually it will be rotated and set to 0.
+        stub.rotation = getAngles().offset(Reference.SENSOR, Reference.OUTPUT, Axis.RELATIVE_TO_SENSOR); // Actually it will be rotated and set to 0.
-        AspectRatio outputRatio = flip(REF_OUTPUT, REF_VIEW) ? viewAspectRatio.flip() : viewAspectRatio;
+        AspectRatio outputRatio = getAngles().flip(Reference.OUTPUT, Reference.VIEW) ? viewAspectRatio.flip() : viewAspectRatio;
         if (mPreview instanceof GlCameraPreview) {
             mPictureRecorder = new SnapshotGlPictureRecorder(stub, this, (GlCameraPreview) mPreview, outputRatio);
         } else {
@@ -626,8 +630,8 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
 
     @Override
     protected void onTakePicture(@NonNull PictureResult.Stub stub) {
-        stub.rotation = offset(REF_SENSOR, REF_OUTPUT);
+        stub.rotation = getAngles().offset(Reference.SENSOR, Reference.OUTPUT, Axis.RELATIVE_TO_SENSOR);
-        stub.size = getPictureSize(REF_OUTPUT);
+        stub.size = getPictureSize(Reference.OUTPUT);
         try {
             CaptureRequest.Builder builder = mCamera.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
             applyAllParameters(builder);
@@ -647,7 +651,6 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
     public void onPictureResult(@Nullable PictureResult.Stub result, @Nullable Exception error) {
         boolean fullPicture = mPictureRecorder instanceof Full2PictureRecorder;
         super.onPictureResult(result, error);
-        //noinspection StatementWithEmptyBody
         if (fullPicture && mPictureCaptureStopsPreview) {
             // See comments in Full2PictureRecorder.
             applyRepeatingRequestBuilder();
@@ -662,8 +665,8 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
     @Override
     protected void onTakeVideo(@NonNull VideoResult.Stub stub) {
         LOG.i("onTakeVideo", "called.");
-        stub.rotation = offset(REF_SENSOR, REF_OUTPUT);
+        stub.rotation = getAngles().offset(Reference.SENSOR, Reference.OUTPUT, Axis.RELATIVE_TO_SENSOR);
-        stub.size = flip(REF_SENSOR, REF_OUTPUT) ? mCaptureSize.flip() : mCaptureSize;
+        stub.size = getAngles().flip(Reference.SENSOR, Reference.OUTPUT) ? mCaptureSize.flip() : mCaptureSize;
         if (!Full2VideoRecorder.SUPPORTS_PERSISTENT_SURFACE) {
             // On API 21 and 22, we must restart the session at each time.
             // Save the pending data and restart the session.
@@ -676,9 +679,7 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
     }
 
     private void doTakeVideo(@NonNull final VideoResult.Stub stub) {
-        if (!(mVideoRecorder instanceof Full2VideoRecorder)) {
         mVideoRecorder = new Full2VideoRecorder(this, mCameraId, mFullVideoPersistentSurface);
-        }
         Full2VideoRecorder recorder = (Full2VideoRecorder) mVideoRecorder;
         try {
             createRepeatingRequestBuilder(CameraDevice.TEMPLATE_RECORD);
@@ -698,10 +699,6 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
         }
     }
 
-    /**
-     * See {@link CameraEngine#onTakeVideoSnapshot(VideoResult.Stub, AspectRatio)}
-     * to read about the size and rotation computation.
-     */
     @WorkerThread
     @Override
     protected void onTakeVideoSnapshot(@NonNull VideoResult.Stub stub, @NonNull AspectRatio viewAspectRatio) {
@@ -709,23 +706,20 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
             throw new IllegalStateException("Video snapshots are only supported with GlCameraPreview.");
         }
         GlCameraPreview glPreview = (GlCameraPreview) mPreview;
-        Facing realFacing = mFacing;
+
-        mFacing = Facing.BACK;
+        // Output size is easy:
-        Size outputSize = getUncroppedSnapshotSize(REF_OUTPUT);
+        Size outputSize = getUncroppedSnapshotSize(Reference.OUTPUT);
         if (outputSize == null) {
             throw new IllegalStateException("outputSize should not be null.");
         }
-        AspectRatio outputRatio = flip(REF_OUTPUT, REF_VIEW) ? viewAspectRatio.flip() : viewAspectRatio;
+        AspectRatio outputRatio = getAngles().flip(Reference.OUTPUT, Reference.VIEW) ? viewAspectRatio.flip() : viewAspectRatio;
         Rect outputCrop = CropHelper.computeCrop(outputSize, outputRatio);
         outputSize = new Size(outputCrop.width(), outputCrop.height());
         stub.size = outputSize;
-        stub.rotation = offset(REF_VIEW, REF_OUTPUT);
+        stub.rotation = getAngles().offset(Reference.VIEW, Reference.OUTPUT, Axis.ABSOLUTE);
 
-        // Reset facing and start.
+        // Start.
-        mFacing = realFacing;
-        if (!(mVideoRecorder instanceof SnapshotVideoRecorder)) {
         mVideoRecorder = new SnapshotVideoRecorder(this, glPreview);
-        }
         mVideoRecorder.start(stub);
     }
 
@@ -764,7 +758,7 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
         int[] modesArray = readCharacteristic(CameraCharacteristics.CONTROL_AF_AVAILABLE_MODES, new int[]{});
         List<Integer> modes = new ArrayList<>();
         for (int mode : modesArray) { modes.add(mode); }
-        if (mMode == Mode.VIDEO &&
+        if (getMode() == Mode.VIDEO &&
                 modes.contains(CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_VIDEO)) {
             builder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_VIDEO);
             return;
@@ -1053,7 +1047,7 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
         if (getEngineState() == STATE_STARTED) {
             Frame frame = getFrameManager().getFrame(data,
                     System.currentTimeMillis(),
-                    offset(REF_SENSOR, REF_OUTPUT),
+                    getAngles().offset(Reference.SENSOR, Reference.OUTPUT, Axis.RELATIVE_TO_SENSOR),
                     mFrameProcessingSize,
                     FRAME_PROCESSING_FORMAT);
             mCallback.dispatchFrame(frame);
@@ -1064,8 +1058,8 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
 
     @Override
     public void setHasFrameProcessors(final boolean hasFrameProcessors) {
+        super.setHasFrameProcessors(hasFrameProcessors);
         LOG.i("setHasFrameProcessors", "changed to", hasFrameProcessors, "posting.");
-        mHasFrameProcessors = hasFrameProcessors;
         mHandler.run(new Runnable() {
             @Override
             public void run() {
@@ -1102,12 +1096,11 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
                 // This is a good Q/A. https://stackoverflow.com/a/33181620/4288782
                 // At first, the point is relative to the View system and does not account our own cropping.
                 // Will keep updating these two below.
-                //noinspection UnnecessaryLocalVariable
                 PointF referencePoint = new PointF(point.x, point.y);
                 Size referenceSize /* = previewSurfaceSize */;
 
                 // 1. Account for cropping.
-                Size previewStreamSize = getPreviewStreamSize(REF_VIEW);
+                Size previewStreamSize = getPreviewStreamSize(Reference.VIEW);
                 Size previewSurfaceSize = mPreview.getSurfaceSize();
                 if (previewStreamSize == null) throw new IllegalStateException("getPreviewStreamSize should not be null at this point.");
                 AspectRatio previewStreamAspectRatio = AspectRatio.of(previewStreamSize);
@@ -1134,7 +1127,7 @@ public class Camera2Engine extends CameraEngine implements ImageReader.OnImageAv
 
                 // 3. Rotate to the stream coordinate system.
                 // Not elegant, but the sin/cos way was failing.
-                int angle = offset(REF_SENSOR, REF_VIEW);
+                int angle = getAngles().offset(Reference.SENSOR, Reference.VIEW, Axis.ABSOLUTE);
                 boolean flip = angle % 180 != 0;
                 float tempX = referencePoint.x; float tempY = referencePoint.y;
                 if (angle == 0) {

cameraview/src/main/java/com/otaliastudios/cameraview/engine/CameraEngine.java

@@ -1,9 +1,7 @@
 package com.otaliastudios.cameraview.engine;
 
 import android.content.Context;
-import android.graphics.Camera;
 import android.graphics.PointF;
-import android.hardware.camera2.CameraCharacteristics;
 import android.location.Location;
 
 
@@ -21,6 +19,8 @@ import com.otaliastudios.cameraview.CameraLogger;
 import com.otaliastudios.cameraview.CameraOptions;
 import com.otaliastudios.cameraview.PictureResult;
 import com.otaliastudios.cameraview.VideoResult;
+import com.otaliastudios.cameraview.engine.offset.Angles;
+import com.otaliastudios.cameraview.engine.offset.Reference;
 import com.otaliastudios.cameraview.frame.Frame;
 import com.otaliastudios.cameraview.frame.FrameManager;
 import com.otaliastudios.cameraview.internal.utils.Op;
@@ -84,7 +84,7 @@ import java.util.concurrent.TimeUnit;
  * - {@link #start()}: ASYNC - starts the engine (S2). When possible, at a later time, S3 and S4 are also performed.
  * - {@link #stop()}: ASYNC - stops everything: undoes S4, then S3, then S2.
  * - {@link #restart()}: ASYNC - completes a stop then a start.
- * - {@link #destroy()}: ASYNC - performs a {@link #stop()} that will go on no matter the exceptions, without throwing.
+ * - {@link #destroy()}: SYNC - performs a {@link #stop()} that will go on no matter the exceptions, without throwing.
  *                              Makes the engine unusable and clears resources.
  *
  * For example, we expose the engine (S2) state through {@link #getEngineState()}. It will be:
@@ -139,59 +139,52 @@ public abstract class CameraEngine implements
     private static final String TAG = CameraEngine.class.getSimpleName();
     private static final CameraLogger LOG = CameraLogger.create(TAG);
 
-    @SuppressWarnings("WeakerAccess")
+    @SuppressWarnings({"WeakerAccess", "unused"})
     public static final int STATE_STOPPING = CameraEngineStep.STATE_STOPPING;
     public static final int STATE_STOPPED = CameraEngineStep.STATE_STOPPED;
-    @SuppressWarnings("WeakerAccess")
+    @SuppressWarnings({"WeakerAccess", "unused"})
     public static final int STATE_STARTING = CameraEngineStep.STATE_STARTING;
     public static final int STATE_STARTED = CameraEngineStep.STATE_STARTED;
 
-    public static final int REF_SENSOR = 0;
+    // Need to be protected
-    public static final int REF_VIEW = 1;
+    @SuppressWarnings("WeakerAccess") protected WorkerHandler mHandler;
-    public static final int REF_OUTPUT = 2;
+    @SuppressWarnings("WeakerAccess") protected final Callback mCallback;
-
+    @SuppressWarnings("WeakerAccess") protected CameraPreview mPreview;
-    protected final Callback mCallback;
+    @SuppressWarnings("WeakerAccess") protected CameraOptions mCameraOptions;
-    private final FrameManager mFrameManager;
+    @SuppressWarnings("WeakerAccess") protected Mapper mMapper;
-    protected CameraPreview mPreview;
+    @SuppressWarnings("WeakerAccess") protected PictureRecorder mPictureRecorder;
-    protected WorkerHandler mHandler;
+    @SuppressWarnings("WeakerAccess") protected VideoRecorder mVideoRecorder;
+    @SuppressWarnings("WeakerAccess") protected Size mCaptureSize;
+    @SuppressWarnings("WeakerAccess") protected Size mPreviewStreamSize;
+    @SuppressWarnings("WeakerAccess") protected Flash mFlash;
+    @SuppressWarnings("WeakerAccess") protected WhiteBalance mWhiteBalance;
+    @SuppressWarnings("WeakerAccess") protected VideoCodec mVideoCodec;
+    @SuppressWarnings("WeakerAccess") protected Hdr mHdr;
+    @SuppressWarnings("WeakerAccess") protected Location mLocation;
+    @SuppressWarnings("WeakerAccess") protected float mZoomValue;
+    @SuppressWarnings("WeakerAccess") protected float mExposureCorrectionValue;
+    @SuppressWarnings("WeakerAccess") protected boolean mPlaySounds;
+
+    // Can be private
     @VisibleForTesting Handler mCrashHandler;
-
+    private final FrameManager mFrameManager;
-    protected Facing mFacing;
+    private final Angles mAngles;
-    protected Flash mFlash;
-    protected WhiteBalance mWhiteBalance;
-    protected VideoCodec mVideoCodec;
-    protected Mode mMode;
-    protected Hdr mHdr;
-    protected Location mLocation;
-    protected Audio mAudio;
-    protected float mZoomValue;
-    protected float mExposureCorrectionValue;
-    protected boolean mPlaySounds;
-    protected boolean mHasFrameProcessors;
-
     @Nullable private SizeSelector mPreviewStreamSizeSelector;
     private SizeSelector mPictureSizeSelector;
     private SizeSelector mVideoSizeSelector;
-
+    private Facing mFacing;
-    @VisibleForTesting int mSnapshotMaxWidth = Integer.MAX_VALUE; // in REF_VIEW for consistency with SizeSelectors
+    private Mode mMode;
-    @VisibleForTesting int mSnapshotMaxHeight = Integer.MAX_VALUE; // in REF_VIEW for consistency with SizeSelectors
+    private Audio mAudio;
-
+    private long mVideoMaxSize;
-    protected CameraOptions mCameraOptions;
+    private int mVideoMaxDuration;
-    protected Mapper mMapper;
+    private int mVideoBitRate;
-    protected PictureRecorder mPictureRecorder;
+    private int mAudioBitRate;
-    protected VideoRecorder mVideoRecorder;
+    private boolean mHasFrameProcessors;
-    protected long mVideoMaxSize;
+    private long mAutoFocusResetDelayMillis;
-    protected int mVideoMaxDuration;
+    private int mSnapshotMaxWidth = Integer.MAX_VALUE; // in REF_VIEW for consistency with SizeSelectors
-    protected int mVideoBitRate;
+    private int mSnapshotMaxHeight = Integer.MAX_VALUE; // in REF_VIEW for consistency with SizeSelectors
-    protected int mAudioBitRate;
+
-    protected Size mCaptureSize;
+    // Steps
-    protected Size mPreviewStreamSize;
-    protected long mAutoFocusResetDelayMillis;
-
-    protected int mSensorOffset;
-    protected int mDisplayOffset;
-    protected int mDeviceOrientation;
-
     private final CameraEngineStep.Callback mStepCallback = new CameraEngineStep.Callback() {
         @Override @NonNull public Executor getExecutor() { return mHandler.getExecutor(); }
         @Override public void handleException(@NonNull Exception exception) {
@@ -203,29 +196,23 @@ public abstract class CameraEngine implements
     private CameraEngineStep mPreviewStep = new CameraEngineStep("preview", mStepCallback);
     private CameraEngineStep mAllStep = new CameraEngineStep("all", mStepCallback);
 
-    // Used for testing.
+    // Ops used for testing.
-    @VisibleForTesting(otherwise = VisibleForTesting.PROTECTED)
-    Op<Void> mZoomOp = new Op<>();
-    @VisibleForTesting(otherwise = VisibleForTesting.PROTECTED)
-    Op<Void> mExposureCorrectionOp = new Op<>();
-    @VisibleForTesting(otherwise = VisibleForTesting.PROTECTED)
-    Op<Void> mFlashOp = new Op<>();
-    @VisibleForTesting(otherwise = VisibleForTesting.PROTECTED)
-    Op<Void> mWhiteBalanceOp = new Op<>();
-    @VisibleForTesting(otherwise = VisibleForTesting.PROTECTED)
-    Op<Void> mHdrOp = new Op<>();
-    @VisibleForTesting(otherwise = VisibleForTesting.PROTECTED)
-    Op<Void> mLocationOp = new Op<>();
     @VisibleForTesting Op<Void> mStartVideoOp = new Op<>();
-    @VisibleForTesting(otherwise = VisibleForTesting.PROTECTED)
+    @VisibleForTesting(otherwise = VisibleForTesting.PROTECTED) Op<Void> mZoomOp = new Op<>();
-    Op<Void> mPlaySoundsOp = new Op<>();
+    @VisibleForTesting(otherwise = VisibleForTesting.PROTECTED) Op<Void> mExposureCorrectionOp = new Op<>();
-
+    @VisibleForTesting(otherwise = VisibleForTesting.PROTECTED) Op<Void> mFlashOp = new Op<>();
-    protected CameraEngine(Callback callback) {
+    @VisibleForTesting(otherwise = VisibleForTesting.PROTECTED) Op<Void> mWhiteBalanceOp = new Op<>();
+    @VisibleForTesting(otherwise = VisibleForTesting.PROTECTED) Op<Void> mHdrOp = new Op<>();
+    @VisibleForTesting(otherwise = VisibleForTesting.PROTECTED) Op<Void> mLocationOp = new Op<>();
+    @VisibleForTesting(otherwise = VisibleForTesting.PROTECTED) Op<Void> mPlaySoundsOp = new Op<>();
+
+    protected CameraEngine(@NonNull Callback callback) {
         mCallback = callback;
         mCrashHandler = new Handler(Looper.getMainLooper());
         mHandler = WorkerHandler.get("CameraViewEngine");
         mHandler.getThread().setUncaughtExceptionHandler(new CrashExceptionHandler());
         mFrameManager = instantiateFrameManager();
+        mAngles = new Angles();
     }
 
     public void setPreview(@NonNull CameraPreview cameraPreview) {
@@ -320,7 +307,7 @@ public abstract class CameraEngine implements
         return mBindStep.getState();
     }
 
-    @SuppressWarnings("unused")
+    @SuppressWarnings({"unused", "WeakerAccess"})
     public final int getPreviewState() {
         return mPreviewStep.getState();
     }
@@ -580,7 +567,7 @@ public abstract class CameraEngine implements
      */
     @Override
     public final void onSurfaceAvailable() {
-        LOG.i("onSurfaceAvailable:", "Size is", getPreviewSurfaceSize(REF_VIEW));
+        LOG.i("onSurfaceAvailable:", "Size is", getPreviewSurfaceSize(Reference.VIEW));
         mHandler.run(new Runnable() {
             @Override
             public void run() {
@@ -597,7 +584,7 @@ public abstract class CameraEngine implements
 
     @Override
     public final void onSurfaceChanged() {
-        LOG.i("onSurfaceChanged:", "Size is", getPreviewSurfaceSize(REF_VIEW), "Posting.");
+        LOG.i("onSurfaceChanged:", "Size is", getPreviewSurfaceSize(Reference.VIEW), "Posting.");
         mHandler.run(new Runnable() {
             @Override
             public void run() {
@@ -658,7 +645,7 @@ public abstract class CameraEngine implements
      * that would cause deadlocks due to us awaiting for {@link #stop()} to return.
      */
     public void destroy() {
-        LOG.i("destroy:", "state:", getEngineStateName());
+        LOG.i("destroy:", "state:", getEngineStateName(), "thread:", Thread.currentThread());
         // Prevent CameraEngine leaks. Don't set to null, or exceptions
         // inside the standard stop() method might crash the main thread.
         mHandler.getThread().setUncaughtExceptionHandler(new NoOpExceptionHandler());
@@ -674,6 +661,7 @@ public abstract class CameraEngine implements
         try {
             boolean success = latch.await(3, TimeUnit.SECONDS);
             if (!success) {
+                // TODO seems like this is always the case?
                 LOG.e("Probably some deadlock in destroy.",
                         "Current thread:", Thread.currentThread(),
                         "Handler thread: ", mHandler.getThread());
@@ -790,60 +778,115 @@ public abstract class CameraEngine implements
 
     //endregion
 
-    //region final setters
+    //region Final setters and getters
+
+    @SuppressWarnings("WeakerAccess")
+    public final Angles getAngles() {
+        return mAngles;
+    }
+
+    @SuppressWarnings("WeakerAccess")
+    protected final void setSensorOffset(@NonNull Facing facing, int sensorOffset) {
+        mAngles.setSensorOffset(facing, sensorOffset);
+    }
 
     // This is called before start() and never again.
     public final void setDisplayOffset(int displayOffset) {
-        mDisplayOffset = displayOffset;
+        mAngles.setDisplayOffset(displayOffset);
     }
 
     // This can be called multiple times.
     public final void setDeviceOrientation(int deviceOrientation) {
-        mDeviceOrientation = deviceOrientation;
+        mAngles.setDeviceOrientation(deviceOrientation);
     }
 
     public final void setPreviewStreamSizeSelector(@Nullable SizeSelector selector) {
         mPreviewStreamSizeSelector = selector;
     }
 
+    @Nullable
+    public final SizeSelector getPreviewStreamSizeSelector() {
+        return mPreviewStreamSizeSelector;
+    }
+
     public final void setPictureSizeSelector(@NonNull SizeSelector selector) {
         mPictureSizeSelector = selector;
     }
 
+    @NonNull
+    public final SizeSelector getPictureSizeSelector() {
+        return mPictureSizeSelector;
+    }
+
     public final void setVideoSizeSelector(@NonNull SizeSelector selector) {
         mVideoSizeSelector = selector;
     }
 
+    @NonNull
+    public final SizeSelector getVideoSizeSelector() {
+        return mVideoSizeSelector;
+    }
+
     public final void setVideoMaxSize(long videoMaxSizeBytes) {
         mVideoMaxSize = videoMaxSizeBytes;
     }
 
+    public final long getVideoMaxSize() {
+        return mVideoMaxSize;
+    }
+
     public final void setVideoMaxDuration(int videoMaxDurationMillis) {
         mVideoMaxDuration = videoMaxDurationMillis;
     }
 
+    public final int getVideoMaxDuration() {
+        return mVideoMaxDuration;
+    }
+
     public final void setVideoCodec(@NonNull VideoCodec codec) {
         mVideoCodec = codec;
     }
 
+    public final VideoCodec getVideoCodec() {
+        return mVideoCodec;
+    }
+
     public final void setVideoBitRate(int videoBitRate) {
         mVideoBitRate = videoBitRate;
     }
 
+    public final int getVideoBitRate() {
+        return mVideoBitRate;
+    }
+
     public final void setAudioBitRate(int audioBitRate) {
         mAudioBitRate = audioBitRate;
     }
 
+    public final int getAudioBitRate() {
+        return mAudioBitRate;
+    }
+
     public final void setSnapshotMaxWidth(int maxWidth) {
         mSnapshotMaxWidth = maxWidth;
     }
 
+    public int getSnapshotMaxWidth() {
+        return mSnapshotMaxWidth;
+    }
+
     public final void setSnapshotMaxHeight(int maxHeight) {
         mSnapshotMaxHeight = maxHeight;
     }
 
+    public int getSnapshotMaxHeight() {
+        return mSnapshotMaxHeight;
+    }
+
     public final void setAutoFocusResetDelay(long delayMillis) { mAutoFocusResetDelayMillis = delayMillis; }
 
+    public final long getAutoFocusResetDelay() { return mAutoFocusResetDelayMillis; }
+
     /**
      * Sets a new facing value. This will restart the session (if there's any)
      * so that we can open the new facing camera.
@@ -867,6 +910,11 @@ public abstract class CameraEngine implements
         }
     }
 
+    @NonNull
+    public final Facing getFacing() {
+        return mFacing;
+    }
+
     /**
      * Sets a new audio value that will be used for video recordings.
      * @param audio desired audio
@@ -881,6 +929,11 @@ public abstract class CameraEngine implements
         }
     }
 
+    @NonNull
+    public final Audio getAudio() {
+        return mAudio;
+    }
+
     /**
      * Sets the desired mode (either picture or video).
      * @param mode desired mode.
@@ -899,6 +952,64 @@ public abstract class CameraEngine implements
         }
     }
 
+    @NonNull
+    public final Mode getMode() {
+        return mMode;
+    }
+
+    @NonNull
+    public final FrameManager getFrameManager() {
+        return mFrameManager;
+    }
+
+    @Nullable
+    public final CameraOptions getCameraOptions() {
+        return mCameraOptions;
+    }
+
+    @NonNull
+    public final Flash getFlash() {
+        return mFlash;
+    }
+
+    @NonNull
+    public final WhiteBalance getWhiteBalance() {
+        return mWhiteBalance;
+    }
+
+    @NonNull
+    public final Hdr getHdr() {
+        return mHdr;
+    }
+
+    @Nullable
+    public final Location getLocation() {
+        return mLocation;
+    }
+
+    public final float getZoomValue() {
+        return mZoomValue;
+    }
+
+    public final float getExposureCorrectionValue() {
+        return mExposureCorrectionValue;
+    }
+
+    @CallSuper
+    public void setHasFrameProcessors(boolean hasFrameProcessors) {
+        mHasFrameProcessors = hasFrameProcessors;
+    }
+
+    @SuppressWarnings("WeakerAccess")
+    public final boolean hasFrameProcessors() {
+        return mHasFrameProcessors;
+    }
+
+    @SuppressWarnings("WeakerAccess")
+    protected final boolean shouldResetAutoFocus() {
+        return mAutoFocusResetDelayMillis > 0 && mAutoFocusResetDelayMillis != Long.MAX_VALUE;
+    }
+
     //endregion
 
     //region Abstract setters and APIs
@@ -907,8 +1018,8 @@ public abstract class CameraEngine implements
      * Camera is about to be opened. Implementors should look into available cameras
      * and see if anyone matches the given {@link Facing value}.
      *
-     * If so, implementors should set {@link #mSensorOffset} and any other information
+     * If so, implementors should set {@link #setSensorOffset(Facing, int)} and any other information
-     * (like camera ID) needed to start teh engine.
+     * (like camera ID) needed to start the engine.
      *
      * @param facing the facing value
      * @return true if we have one
@@ -945,12 +1056,14 @@ public abstract class CameraEngine implements
 
     public abstract void setPlaySounds(boolean playSounds);
 
-    public abstract void setHasFrameProcessors(boolean hasFrameProcessors);
-
     //endregion
 
     //region picture and video control
 
+    public final boolean isTakingPicture() {
+        return mPictureRecorder != null;
+    }
+
     /* not final for tests */
     public void takePicture(final @NonNull PictureResult.Stub stub) {
         LOG.v("takePicture", "scheduling");
@@ -970,10 +1083,10 @@ public abstract class CameraEngine implements
                 onTakePicture(stub);
             }
         });
-    };
+    }
 
     /**
-     * The snapshot size is the {@link #getPreviewStreamSize(int)}, but cropped based on the
+     * The snapshot size is the {@link #getPreviewStreamSize(Reference)}, but cropped based on the
      * view/surface aspect ratio.
      * @param stub a picture stub
      * @param viewAspectRatio the view aspect ratio
@@ -990,9 +1103,6 @@ public abstract class CameraEngine implements
                 stub.isSnapshot = true;
                 stub.facing = mFacing;
                 // Leave the other parameters to subclasses.
-                LOG.v("takePictureSnapshot", "Rotations", "SV", offset(REF_SENSOR, REF_VIEW), "VS", offset(REF_VIEW, REF_SENSOR));
-                LOG.v("takePictureSnapshot", "Rotations", "SO", offset(REF_SENSOR, REF_OUTPUT), "OS", offset(REF_OUTPUT, REF_SENSOR));
-                LOG.v("takePictureSnapshot", "Rotations", "VO", offset(REF_VIEW, REF_OUTPUT), "OV", offset(REF_OUTPUT, REF_VIEW));
                 onTakePictureSnapshot(stub, viewAspectRatio);
             }
         });
@@ -1014,6 +1124,10 @@ public abstract class CameraEngine implements
         }
     }
 
+    public final boolean isTakingVideo() {
+        return mVideoRecorder != null && mVideoRecorder.isRecording();
+    }
+
     public final void takeVideo(final @NonNull VideoResult.Stub stub, final @NonNull File file) {
         LOG.v("takeVideo", "scheduling");
         mHandler.run(new Runnable() {
@@ -1110,187 +1224,31 @@ public abstract class CameraEngine implements
 
     //endregion
 
-    //region final getters
+    //region Size utilities
-
-    @NonNull
-    public final FrameManager getFrameManager() {
-        return mFrameManager;
-    }
-
-    @Nullable
-    public final CameraOptions getCameraOptions() {
-        return mCameraOptions;
-    }
-
-    @NonNull
-    public final Facing getFacing() {
-        return mFacing;
-    }
-
-    @NonNull
-    public final Flash getFlash() {
-        return mFlash;
-    }
-
-    @NonNull
-    public final WhiteBalance getWhiteBalance() {
-        return mWhiteBalance;
-    }
-
-    public final VideoCodec getVideoCodec() {
-        return mVideoCodec;
-    }
-
-    public final int getVideoBitRate() {
-        return mVideoBitRate;
-    }
-
-    public final long getVideoMaxSize() {
-        return mVideoMaxSize;
-    }
-
-    public final int getVideoMaxDuration() {
-        return mVideoMaxDuration;
-    }
-
-    @NonNull
-    public final Mode getMode() {
-        return mMode;
-    }
-
-    @NonNull
-    public final Hdr getHdr() {
-        return mHdr;
-    }
-
-    @Nullable
-    public final Location getLocation() {
-        return mLocation;
-    }
-
-    @NonNull
-    public final Audio getAudio() {
-        return mAudio;
-    }
-
-    public final int getAudioBitRate() {
-        return mAudioBitRate;
-    }
-
-    @SuppressWarnings("unused")
-    @Nullable
-    @VisibleForTesting
-    final SizeSelector getPreviewStreamSizeSelector() {
-        return mPreviewStreamSizeSelector;
-    }
-
-    @SuppressWarnings("unused")
-    @NonNull
-    public final SizeSelector getPictureSizeSelector() {
-        return mPictureSizeSelector;
-    }
-
-    @SuppressWarnings("unused")
-    @NonNull
-    public final SizeSelector getVideoSizeSelector() {
-        return mVideoSizeSelector;
-    }
-
-    public final float getZoomValue() {
-        return mZoomValue;
-    }
-
-    public final float getExposureCorrectionValue() {
-        return mExposureCorrectionValue;
-    }
-
-    public final boolean isTakingVideo() {
-        return mVideoRecorder != null && mVideoRecorder.isRecording();
-    }
-
-    public final boolean isTakingPicture() {
-        return mPictureRecorder != null;
-    }
-
-    public final long getAutoFocusResetDelay() { return mAutoFocusResetDelayMillis; }
-
-    public boolean getHasFrameProcessors() {
-        return mHasFrameProcessors;
-    }
-
-    //endregion
-
-    final boolean shouldResetAutoFocus() {
-        return mAutoFocusResetDelayMillis > 0 && mAutoFocusResetDelayMillis != Long.MAX_VALUE;
-    }
-
-    //region Orientation utils
-
-    private int computeSensorToViewOffset() {
-        if (mFacing == Facing.FRONT) {
-            return (360 - ((mSensorOffset + mDisplayOffset) % 360)) % 360;
-        } else {
-            return (mSensorOffset - mDisplayOffset + 360) % 360;
-        }
-    }
-
-    private int computeSensorToOutputOffset() {
-        if (mFacing == Facing.FRONT) {
-            return (mSensorOffset - mDeviceOrientation + 360) % 360;
-        } else {
-            return (mSensorOffset + mDeviceOrientation) % 360;
-        }
-    }
-
-    // o(S, V) - o(S, O)
-    // displayOffset - deviceOrientation
-
-    // Returns the offset between two reference systems.
-    @SuppressWarnings("WeakerAccess")
-    public final int offset(int fromReference, int toReference) {
-        if (fromReference == toReference) return 0;
-        // We only know how to compute offsets with respect to REF_SENSOR.
-        // That's why we separate the two cases.
-        if (fromReference == REF_SENSOR) {
-            return toReference == REF_VIEW ?
-                    computeSensorToViewOffset() :
-                    computeSensorToOutputOffset();
-        }
-        // Maybe the sensor is the other.
-        if (toReference == REF_SENSOR) {
-            return (-offset(toReference, fromReference) + 360) % 360;
-        }
-        // None of them is the sensor. Use a difference.
-        return (offset(REF_SENSOR, toReference) - offset(REF_SENSOR, fromReference) + 360) % 360;
-    }
-
-    public final boolean flip(int reference1, int reference2) {
-        return offset(reference1, reference2) % 180 != 0;
-    }
 
     @Nullable
-    public final Size getPictureSize(@SuppressWarnings("SameParameterValue") int reference) {
+    public final Size getPictureSize(@SuppressWarnings("SameParameterValue") @NonNull Reference reference) {
         if (mCaptureSize == null || mMode == Mode.VIDEO) return null;
-        return flip(REF_SENSOR, reference) ? mCaptureSize.flip() : mCaptureSize;
+        return getAngles().flip(Reference.SENSOR, reference) ? mCaptureSize.flip() : mCaptureSize;
     }
 
     @Nullable
-    public final Size getVideoSize(@SuppressWarnings("SameParameterValue") int reference) {
+    public final Size getVideoSize(@SuppressWarnings("SameParameterValue") @NonNull Reference reference) {
         if (mCaptureSize == null || mMode == Mode.PICTURE) return null;
-        return flip(REF_SENSOR, reference) ? mCaptureSize.flip() : mCaptureSize;
+        return getAngles().flip(Reference.SENSOR, reference) ? mCaptureSize.flip() : mCaptureSize;
     }
 
     @Nullable
-    public final Size getPreviewStreamSize(int reference) {
+    public final Size getPreviewStreamSize(@NonNull Reference reference) {
         if (mPreviewStreamSize == null) return null;
-        return flip(REF_SENSOR, reference) ? mPreviewStreamSize.flip() : mPreviewStreamSize;
+        return getAngles().flip(Reference.SENSOR, reference) ? mPreviewStreamSize.flip() : mPreviewStreamSize;
     }
 
     @SuppressWarnings("SameParameterValue")
     @Nullable
-    private Size getPreviewSurfaceSize(int reference) {
+    private Size getPreviewSurfaceSize(@NonNull Reference reference) {
         if (mPreview == null) return null;
-        return flip(REF_VIEW, reference) ? mPreview.getSurfaceSize().flip() : mPreview.getSurfaceSize();
+        return getAngles().flip(Reference.VIEW, reference) ? mPreview.getSurfaceSize().flip() : mPreview.getSurfaceSize();
     }
 
     /**
@@ -1314,10 +1272,10 @@ public abstract class CameraEngine implements
      * apply, despite the capturing mechanism being different.
      */
     @Nullable
-    public final Size getUncroppedSnapshotSize(int reference) {
+    public final Size getUncroppedSnapshotSize(@NonNull Reference reference) {
         Size baseSize = getPreviewStreamSize(reference);
         if (baseSize == null) return null;
-        boolean flip = flip(reference, REF_VIEW);
+        boolean flip = getAngles().flip(reference, Reference.VIEW);
         int maxWidth = flip ? mSnapshotMaxHeight : mSnapshotMaxWidth;
         int maxHeight = flip ? mSnapshotMaxWidth : mSnapshotMaxHeight;
         float baseRatio = AspectRatio.of(baseSize).toFloat();
@@ -1335,11 +1293,6 @@ public abstract class CameraEngine implements
         }
     }
 
-
-    //endregion
-
-    //region Size utils
-
     /**
      * This is called either on cameraView.start(), or when the underlying surface changes.
      * It is possible that in the first call the preview surface has not already computed its
@@ -1354,10 +1307,10 @@ public abstract class CameraEngine implements
     }
 
     @SuppressWarnings("WeakerAccess")
-    protected final Size computeCaptureSize(Mode mode) {
+    protected final Size computeCaptureSize(@NonNull Mode mode) {
         // We want to pass stuff into the REF_VIEW reference, not the sensor one.
         // This is already managed by CameraOptions, so we just flip again at the end.
-        boolean flip = flip(REF_SENSOR, REF_VIEW);
+        boolean flip = getAngles().flip(Reference.SENSOR, Reference.VIEW);
         SizeSelector selector;
         Collection<Size> sizes;
         if (mode == Mode.PICTURE) {
@@ -1393,7 +1346,7 @@ public abstract class CameraEngine implements
         @NonNull List<Size> previewSizes = getPreviewStreamAvailableSizes();
         // These sizes come in REF_SENSOR. Since there is an external selector involved,
         // we must convert all of them to REF_VIEW, then flip back when returning.
-        boolean flip = flip(REF_SENSOR, REF_VIEW);
+        boolean flip = getAngles().flip(Reference.SENSOR, Reference.VIEW);
         List<Size> sizes = new ArrayList<>(previewSizes.size());
         for (Size size : previewSizes) {
             sizes.add(flip ? size.flip() : size);
@@ -1401,7 +1354,7 @@ public abstract class CameraEngine implements
 
         // Create our own default selector, which will be used if the external mPreviewStreamSizeSelector
         // is null, or if it fails in finding a size.
-        Size targetMinSize = getPreviewSurfaceSize(REF_VIEW);
+        Size targetMinSize = getPreviewSurfaceSize(Reference.VIEW);
         if (targetMinSize == null) throw new IllegalStateException("targetMinSize should not be null here.");
         AspectRatio targetRatio = AspectRatio.of(mCaptureSize.getWidth(), mCaptureSize.getHeight());
         if (flip) targetRatio = targetRatio.flip();

cameraview/src/main/java/com/otaliastudios/cameraview/engine/offset/Angles.java

@@ -0,0 +1,121 @@
+package com.otaliastudios.cameraview.engine.offset;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.VisibleForTesting;
+
+import com.otaliastudios.cameraview.controls.Facing;
+
+/**
+ * Manages offsets between different {@link Reference} systems.
+ *
+ * These offsets are computed based on the {@link #setSensorOffset(Facing, int)},
+ * {@link #setDisplayOffset(int)} and {@link #setDeviceOrientation(int)} values that are coming
+ * from outside.
+ *
+ * When communicating with the sensor, {@link Axis#RELATIVE_TO_SENSOR} should probably be used.
+ * This means inverting the offset when using the front camera.
+ * This is often the case when calling offset(SENSOR, OUTPUT), for example when passing a JPEG
+ * rotation to the sensor. That is meant to be consumed as relative to the sensor plane.
+ *
+ * For all other usages, {@link Axis#ABSOLUTE} is probably a better choice.
+ */
+public class Angles {
+
+    private Facing mSensorFacing;
+    @VisibleForTesting int mSensorOffset = 0;
+    @VisibleForTesting int mDisplayOffset = 0;
+    @VisibleForTesting int mDeviceOrientation = 0;
+
+    /**
+     * We want to keep everything in the {@link Axis#ABSOLUTE} reference,
+     * so a front facing sensor offset must be inverted.
+     *
+     * @param sensorFacing sensor facing value
+     * @param sensorOffset sensor offset
+     */
+    public void setSensorOffset(@NonNull Facing sensorFacing, int sensorOffset) {
+        sanitizeInput(sensorOffset);
+        mSensorFacing = sensorFacing;
+        mSensorOffset = sensorOffset;
+        if (mSensorFacing == Facing.FRONT) {
+            mSensorOffset = sanitizeOutput(360 - mSensorOffset);
+        }
+    }
+
+    /**
+     * Sets the display offset.
+     * @param displayOffset the display offset
+     */
+    public void setDisplayOffset(int displayOffset) {
+        sanitizeInput(displayOffset);
+        mDisplayOffset = displayOffset;
+    }
+
+    /**
+     * Sets the device orientation.
+     * @param deviceOrientation the device orientation
+     */
+    public void setDeviceOrientation(int deviceOrientation) {
+        sanitizeInput(deviceOrientation);
+        mDeviceOrientation = deviceOrientation;
+    }
+
+    /**
+     * Returns the offset between two reference systems, computed along the given axis.
+     * @param from the source reference system
+     * @param to the destination reference system
+     * @param axis the axis
+     * @return the offset
+     */
+    public int offset(@NonNull Reference from, @NonNull Reference to, @NonNull Axis axis) {
+        int offset = absoluteOffset(from, to);
+        if (axis == Axis.RELATIVE_TO_SENSOR) {
+            if (mSensorFacing == Facing.FRONT) {
+                offset = sanitizeOutput(360 - offset);
+            }
+        }
+        return offset;
+    }
+
+    private int absoluteOffset(@NonNull Reference from, @NonNull Reference to) {
+        if (from == to) {
+            return 0;
+        } else if (to == Reference.BASE) {
+            return sanitizeOutput(360 - absoluteOffset(to, from));
+        } else if (from == Reference.BASE) {
+            switch (to) {
+                case VIEW: return sanitizeOutput(360 - mDisplayOffset);
+                case OUTPUT: return sanitizeOutput(mDeviceOrientation);
+                case SENSOR: return sanitizeOutput(360 - mSensorOffset);
+                default: throw new RuntimeException("Unknown reference: " + to);
+            }
+        } else {
+            return sanitizeOutput(
+                    absoluteOffset(Reference.BASE, to)
+                    - absoluteOffset(Reference.BASE, from));
+        }
+    }
+
+    /**
+     * Whether the two references systems are flipped.
+     * @param from source
+     * @param to destination
+     * @return true if flipped
+     */
+    public boolean flip(@NonNull Reference from, @NonNull Reference to) {
+        return offset(from, to, Axis.ABSOLUTE) % 180 != 0;
+    }
+
+    private void sanitizeInput(int value) {
+        if (value != 0
+                && value != 90
+                && value != 180
+                && value != 270) {
+            throw new IllegalStateException("This value is not sanitized: " + value);
+        }
+    }
+
+    private int sanitizeOutput(int value) {
+        return (value + 360) % 360;
+    }
+}

cameraview/src/main/java/com/otaliastudios/cameraview/engine/offset/Axis.java

@@ -0,0 +1,28 @@
+package com.otaliastudios.cameraview.engine.offset;
+
+/**
+ * The axis around which offsets are computed. We have two possibilities:
+ * - an axis going out of the device screen towards the user's face
+ * - an axis going out of the device screen towards the back
+ *
+ * We are mostly interested in the first one, but some APIs will require
+ * angles in the sensor reference, in which case, for front cameras, we are
+ * required to use {@link #RELATIVE_TO_SENSOR}.
+ */
+public enum Axis {
+
+    /**
+     * This rotation axis is the one going out of the device screen
+     * towards the user's face.
+     */
+    ABSOLUTE,
+
+    /**
+     * This rotation axis takes into account the current
+     * {@link com.otaliastudios.cameraview.controls.Facing} value.
+     *
+     * - for {@link com.otaliastudios.cameraview.controls.Facing#BACK}, this equals {@link #ABSOLUTE}
+     * - for {@link com.otaliastudios.cameraview.controls.Facing#FRONT}, this is inverted
+     */
+    RELATIVE_TO_SENSOR
+}

cameraview/src/main/java/com/otaliastudios/cameraview/engine/offset/Reference.java

@@ -0,0 +1,28 @@
+package com.otaliastudios.cameraview.engine.offset;
+
+public enum Reference {
+
+    /**
+     * The base reference system has its 'north' aligned with the device natural
+     * orientation.
+     */
+    BASE,
+
+    /**
+     * This reference system has its 'north' aligned with the camera sensor.
+     */
+    SENSOR,
+
+    /**
+     * This reference system has its 'north' aligned with the View hierarchy.
+     * This can be different than {@link #BASE} if the activity is allowed to rotate
+     * (or forced into a non natural position).
+     */
+    VIEW,
+
+    /**
+     * This reference system has its 'north' aligned with the output picture/video.
+     * This means that it takes into account the device orientation.
+     */
+    OUTPUT
+}

cameraview/src/main/java/com/otaliastudios/cameraview/gesture/GestureFinder.java

@@ -4,23 +4,30 @@ import android.content.Context;
 import android.graphics.PointF;
 import androidx.annotation.NonNull;
 import android.view.MotionEvent;
-import android.widget.FrameLayout;
 
 /**
- * Base class for gesture layouts, that is, layouts that will capture
+ * Base class for gesture finders.
- * gestures.
+ * Gesture finders are passed down touch events to detect gestures.
  */
-public abstract class GestureLayout extends FrameLayout {
+public abstract class GestureFinder {
+
+    public interface Controller {
+        @NonNull Context getContext();
+        int getWidth();
+        int getHeight();
+    }
 
     // The number of possible values between minValue and maxValue, for the getValue method.
     // We could make this non-static (e.g. larger granularity for exposure correction).
     private final static int GRANULARITY = 50;
+
     private boolean mActive;
     private Gesture mType;
     private PointF[] mPoints;
+    private Controller mController;
 
-    GestureLayout(@NonNull Context context, int points) {
+    GestureFinder(@NonNull Controller controller, int points) {
-        super(context);
+        mController = controller;
         mPoints = new PointF[points];
         for (int i = 0; i < points; i++) {
             mPoints[i] = new PointF(0, 0);
@@ -108,6 +115,7 @@ public abstract class GestureLayout extends FrameLayout {
      * @param which the array position
      * @return the point
      */
+    @SuppressWarnings("WeakerAccess")
     @NonNull
     protected final PointF getPoint(int which) {
         return mPoints[which];
@@ -156,4 +164,13 @@ public abstract class GestureLayout extends FrameLayout {
         }
         return newValue;
     }
+
+    /**
+     * Returns the controller for this finder.
+     * @return the controller
+     */
+    @NonNull
+    protected Controller getController() {
+        return mController;
+    }
 }

cameraview/src/main/java/com/otaliastudios/cameraview/gesture/PinchGestureFinder.java

@@ -1,26 +1,25 @@
 package com.otaliastudios.cameraview.gesture;
 
-import android.content.Context;
 import android.os.Build;
 import androidx.annotation.NonNull;
 import android.view.MotionEvent;
 import android.view.ScaleGestureDetector;
 
 /**
- * A {@link GestureLayout} that detects {@link Gesture#PINCH} gestures.
+ * A {@link GestureFinder} that detects {@link Gesture#PINCH} gestures.
  */
-public class PinchGestureLayout extends GestureLayout {
+public class PinchGestureFinder extends GestureFinder {
 
     private final static float ADD_SENSITIVITY = 2f;
 
-    ScaleGestureDetector mDetector;
+    private ScaleGestureDetector mDetector;
     private boolean mNotify;
     private float mFactor = 0;
 
-    public PinchGestureLayout(@NonNull Context context) {
+    public PinchGestureFinder(@NonNull Controller controller) {
-        super(context, 2);
+        super(controller, 2);
         setGesture(Gesture.PINCH);
-        mDetector = new ScaleGestureDetector(context, new ScaleGestureDetector.SimpleOnScaleGestureListener() {
+        mDetector = new ScaleGestureDetector(controller.getContext(), new ScaleGestureDetector.SimpleOnScaleGestureListener() {
             @Override
             public boolean onScale(ScaleGestureDetector detector) {
                 mNotify = true;

cameraview/src/main/java/com/otaliastudios/cameraview/gesture/ScrollGestureFinder.java

@@ -1,6 +1,5 @@
 package com.otaliastudios.cameraview.gesture;
 
-import android.content.Context;
 import androidx.annotation.NonNull;
 import android.view.GestureDetector;
 import android.view.MotionEvent;
@@ -8,21 +7,21 @@ import android.view.MotionEvent;
 import com.otaliastudios.cameraview.CameraLogger;
 
 /**
- * A {@link GestureLayout} that detects {@link Gesture#SCROLL_HORIZONTAL}
+ * A {@link GestureFinder} that detects {@link Gesture#SCROLL_HORIZONTAL}
  * and {@link Gesture#SCROLL_VERTICAL} gestures.
  */
-public class ScrollGestureLayout extends GestureLayout {
+public class ScrollGestureFinder extends GestureFinder {
 
-    private static final String TAG = ScrollGestureLayout.class.getSimpleName();
+    private static final String TAG = ScrollGestureFinder.class.getSimpleName();
     private static final CameraLogger LOG = CameraLogger.create(TAG);
 
     private GestureDetector mDetector;
     private boolean mNotify;
     private float mFactor;
 
-    public ScrollGestureLayout(@NonNull Context context) {
+    public ScrollGestureFinder(final @NonNull Controller controller) {
-        super(context, 2);
+        super(controller, 2);
-        mDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
+        mDetector = new GestureDetector(controller.getContext(), new GestureDetector.SimpleOnGestureListener() {
 
             @Override
             public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
@@ -40,7 +39,7 @@ public class ScrollGestureLayout extends GestureLayout {
                     horizontal = getGesture() == Gesture.SCROLL_HORIZONTAL;
                 }
                 getPoint(1).set(e2.getX(), e2.getY());
-                mFactor = horizontal ? (distanceX / getWidth()) : (distanceY / getHeight());
+                mFactor = horizontal ? (distanceX / controller.getWidth()) : (distanceY / controller.getHeight());
                 mFactor = horizontal ? -mFactor : mFactor; // When vertical, up = positive
                 mNotify = true;
                 return true;

cameraview/src/main/java/com/otaliastudios/cameraview/gesture/TapGestureFinder.java

@@ -1,32 +1,22 @@
 package com.otaliastudios.cameraview.gesture;
 
-import android.animation.Animator;
-import android.animation.AnimatorListenerAdapter;
-import android.content.Context;
-import android.graphics.PointF;
 import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
+
 import android.view.GestureDetector;
-import android.view.LayoutInflater;
 import android.view.MotionEvent;
-import android.view.View;
-import android.widget.FrameLayout;
-import android.widget.ImageView;
-
-import com.otaliastudios.cameraview.R;
 
 /**
- * A {@link GestureLayout} that detects {@link Gesture#TAP}
+ * A {@link GestureFinder} that detects {@link Gesture#TAP}
  * and {@link Gesture#LONG_TAP} gestures.
  */
-public class TapGestureLayout extends GestureLayout {
+public class TapGestureFinder extends GestureFinder {
 
     private GestureDetector mDetector;
     private boolean mNotify;
 
-    public TapGestureLayout(@NonNull Context context) {
+    public TapGestureFinder(@NonNull Controller controller) {
-        super(context, 1);
+        super(controller, 1);
-        mDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
+        mDetector = new GestureDetector(controller.getContext(), new GestureDetector.SimpleOnGestureListener() {
 
             @Override
             public boolean onSingleTapUp(MotionEvent e) {

cameraview/src/main/java/com/otaliastudios/cameraview/internal/egl/EglViewport.java

@@ -40,7 +40,7 @@ public class EglViewport extends EglElement {
     // Stuff from Drawable2d.FULL_RECTANGLE
     // A full square, extending from -1 to +1 in both dimensions.
     // When the model/view/projection matrix is identity, this will exactly cover the viewport.
-    private static final float FULL_RECTANGLE_COORDS[] = {
+    private static final float[] FULL_RECTANGLE_COORDS = {
             -1.0f, -1.0f,   // 0 bottom left
             1.0f, -1.0f,   // 1 bottom right
             -1.0f, 1.0f,   // 2 top left
@@ -49,7 +49,7 @@ public class EglViewport extends EglElement {
 
     // Stuff from Drawable2d.FULL_RECTANGLE
     // A full square, extending from -1 to +1 in both dimensions.
-    private static final float FULL_RECTANGLE_TEX_COORDS[] = {
+    private static final float[] FULL_RECTANGLE_TEX_COORDS = {
             0.0f, 0.0f,     // 0 bottom left
             1.0f, 0.0f,     // 1 bottom right
             0.0f, 1.0f,     // 2 top left

cameraview/src/main/java/com/otaliastudios/cameraview/picture/Snapshot1PictureRecorder.java

@@ -1,32 +1,18 @@
 package com.otaliastudios.cameraview.picture;
 
-import android.annotation.TargetApi;
-import android.graphics.Bitmap;
 import android.graphics.ImageFormat;
 import android.graphics.Rect;
-import android.graphics.SurfaceTexture;
 import android.graphics.YuvImage;
 import android.hardware.Camera;
-import android.opengl.EGL14;
-import android.opengl.EGLContext;
-import android.opengl.Matrix;
-import android.os.Build;
 
 import com.otaliastudios.cameraview.CameraLogger;
 import com.otaliastudios.cameraview.PictureResult;
-import com.otaliastudios.cameraview.controls.Facing;
 import com.otaliastudios.cameraview.engine.Camera1Engine;
 import com.otaliastudios.cameraview.engine.CameraEngine;
-import com.otaliastudios.cameraview.internal.egl.EglCore;
+import com.otaliastudios.cameraview.engine.offset.Reference;
-import com.otaliastudios.cameraview.internal.egl.EglViewport;
-import com.otaliastudios.cameraview.internal.egl.EglWindowSurface;
 import com.otaliastudios.cameraview.internal.utils.CropHelper;
 import com.otaliastudios.cameraview.internal.utils.RotationHelper;
 import com.otaliastudios.cameraview.internal.utils.WorkerHandler;
-import com.otaliastudios.cameraview.preview.CameraPreview;
-import com.otaliastudios.cameraview.preview.GlCameraPreview;
-import com.otaliastudios.cameraview.preview.RendererFrameCallback;
-import com.otaliastudios.cameraview.preview.RendererThread;
 import com.otaliastudios.cameraview.size.AspectRatio;
 import com.otaliastudios.cameraview.size.Size;
 
@@ -40,6 +26,7 @@ import java.io.ByteArrayOutputStream;
 public class Snapshot1PictureRecorder extends PictureRecorder {
 
     private static final String TAG = Snapshot1PictureRecorder.class.getSimpleName();
+    @SuppressWarnings("unused")
     private static final CameraLogger LOG = CameraLogger.create(TAG);
 
     private Camera1Engine mEngine1;
@@ -47,9 +34,6 @@ public class Snapshot1PictureRecorder extends PictureRecorder {
     private AspectRatio mOutputRatio;
     private int mFormat;
 
-    /**
-     * Camera1 constructor.
-     */
     public Snapshot1PictureRecorder(
             @NonNull PictureResult.Stub stub,
             @NonNull Camera1Engine engine,
@@ -59,7 +43,7 @@ public class Snapshot1PictureRecorder extends PictureRecorder {
         mEngine1 = engine;
         mCamera = camera;
         mOutputRatio = outputRatio;
-        mFormat = engine.getPreviewStreamFormat();
+        mFormat = camera.getParameters().getPreviewFormat();
     }
 
     @Override
@@ -74,7 +58,7 @@ public class Snapshot1PictureRecorder extends PictureRecorder {
                 // Adding EXIF to a byte array, unfortunately, is hard.
                 final int sensorToOutput = mResult.rotation;
                 final Size outputSize = mResult.size;
-                final Size previewStreamSize = mEngine1.getPreviewStreamSize(CameraEngine.REF_SENSOR);
+                final Size previewStreamSize = mEngine1.getPreviewStreamSize(Reference.SENSOR);
                 if (previewStreamSize == null) {
                     throw new IllegalStateException("Preview stream size should never be null here.");
                 }

cameraview/src/main/java/com/otaliastudios/cameraview/picture/SnapshotGlPictureRecorder.java

@@ -4,7 +4,6 @@ import android.annotation.TargetApi;
 import android.graphics.Bitmap;
 import android.graphics.Rect;
 import android.graphics.SurfaceTexture;
-import android.hardware.Camera;
 import android.opengl.EGL14;
 import android.opengl.EGLContext;
 import android.opengl.Matrix;
@@ -13,14 +12,13 @@ import android.os.Build;
 import com.otaliastudios.cameraview.CameraLogger;
 import com.otaliastudios.cameraview.PictureResult;
 import com.otaliastudios.cameraview.controls.Facing;
-import com.otaliastudios.cameraview.engine.Camera1Engine;
 import com.otaliastudios.cameraview.engine.CameraEngine;
+import com.otaliastudios.cameraview.engine.offset.Reference;
 import com.otaliastudios.cameraview.internal.egl.EglCore;
 import com.otaliastudios.cameraview.internal.egl.EglViewport;
 import com.otaliastudios.cameraview.internal.egl.EglWindowSurface;
 import com.otaliastudios.cameraview.internal.utils.CropHelper;
 import com.otaliastudios.cameraview.internal.utils.WorkerHandler;
-import com.otaliastudios.cameraview.preview.CameraPreview;
 import com.otaliastudios.cameraview.preview.GlCameraPreview;
 import com.otaliastudios.cameraview.preview.RendererFrameCallback;
 import com.otaliastudios.cameraview.preview.RendererThread;
@@ -107,7 +105,7 @@ public class SnapshotGlPictureRecorder extends PictureRecorder {
 
                         // Apply scale and crop:
                         // NOTE: scaleX and scaleY are in REF_VIEW, while our input appears to be in REF_SENSOR.
-                        boolean flip = mEngine.flip(CameraEngine.REF_VIEW, CameraEngine.REF_SENSOR);
+                        boolean flip = mEngine.getAngles().flip(Reference.VIEW, Reference.SENSOR);
                         float realScaleX = flip ? scaleY : scaleX;
                         float realScaleY = flip ? scaleX : scaleY;
                         float scaleTranslX = (1F - realScaleX) / 2F;

cameraview/src/main/java/com/otaliastudios/cameraview/preview/CameraPreview.java

@@ -67,11 +67,9 @@ public abstract class CameraPreview<T extends View, Output> {
      * Creates a new preview.
      * @param context a context
      * @param parent where to inflate our view
-     * @param callback the callback
      */
-    public CameraPreview(@NonNull Context context, @NonNull ViewGroup parent, @Nullable SurfaceCallback callback) {
+    public CameraPreview(@NonNull Context context, @NonNull ViewGroup parent) {
         mView = onCreateView(context, parent);
-        mSurfaceCallback = callback;
     }
 
     /**
@@ -79,10 +77,12 @@ public abstract class CameraPreview<T extends View, Output> {
      * @param callback a callback
      */
     public final void setSurfaceCallback(@Nullable SurfaceCallback callback) {
+        if (hasSurface() && mSurfaceCallback != null) {
+            mSurfaceCallback.onSurfaceDestroyed();
+        }
         mSurfaceCallback = callback;
-        // If surface already available, dispatch.
+        if (hasSurface() && mSurfaceCallback != null) {
-        if (mOutputSurfaceWidth != 0 || mOutputSurfaceHeight != 0) {
+            mSurfaceCallback.onSurfaceAvailable();
-            if (callback != null) callback.onSurfaceAvailable();
         }
     }
 

cameraview/src/main/java/com/otaliastudios/cameraview/preview/GlCameraPreview.java

@@ -57,7 +57,7 @@ import javax.microedition.khronos.opengles.GL10;
  * Callbacks are guaranteed to be called on the renderer thread, which means that we can fetch
  * the GL context that was created and is managed by the {@link GLSurfaceView}.
  */
-public class GlCameraPreview extends CameraPreview<GLSurfaceView, SurfaceTexture> implements GLSurfaceView.Renderer {
+public class GlCameraPreview extends CameraPreview<GLSurfaceView, SurfaceTexture> {
 
     private boolean mDispatched;
     private final float[] mTransformMatrix = new float[16];
@@ -69,32 +69,8 @@ public class GlCameraPreview extends CameraPreview<GLSurfaceView, SurfaceTexture
     @VisibleForTesting float mCropScaleY = 1F;
     private View mRootView;
 
-    /**
+    public GlCameraPreview(@NonNull Context context, @NonNull ViewGroup parent) {
-     * Method specific to the GL preview. Adds a {@link RendererFrameCallback}
+        super(context, parent);
-     * to receive renderer frame events.
-     * @param callback a callback
-     */
-    public void addRendererFrameCallback(@NonNull final RendererFrameCallback callback) {
-        getView().queueEvent(new Runnable() {
-            @Override
-            public void run() {
-                mRendererFrameCallbacks.add(callback);
-                if (mOutputTextureId != 0) callback.onRendererTextureCreated(mOutputTextureId);
-            }
-        });
-    }
-
-    /**
-     * Method specific to the GL preview. Removes a {@link RendererFrameCallback}
-     * that was previously added to receive renderer frame events.
-     * @param callback a callback
-     */
-    public void removeRendererFrameCallback(@NonNull final RendererFrameCallback callback) {
-        mRendererFrameCallbacks.remove(callback);
-    }
-
-    public GlCameraPreview(@NonNull Context context, @NonNull ViewGroup parent, @Nullable SurfaceCallback callback) {
-        super(context, parent, callback);
     }
 
     @NonNull
@@ -103,11 +79,8 @@ public class GlCameraPreview extends CameraPreview<GLSurfaceView, SurfaceTexture
         ViewGroup root = (ViewGroup) LayoutInflater.from(context).inflate(R.layout.cameraview_gl_view, parent, false);
         GLSurfaceView glView = root.findViewById(R.id.gl_surface_view);
         glView.setEGLContextClientVersion(2);
-        glView.setRenderer(this);
+        glView.setRenderer(instantiateRenderer());
         glView.setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);
-        // Tried these 2 to remove the black background, does not work.
-        // glView.getHolder().setFormat(PixelFormat.TRANSLUCENT);
-        // glView.setZOrderMediaOverlay(true);
         glView.getHolder().addCallback(new SurfaceHolder.Callback() {
             public void surfaceCreated(SurfaceHolder holder) {}
             public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { }
@@ -158,6 +131,11 @@ public class GlCameraPreview extends CameraPreview<GLSurfaceView, SurfaceTexture
         }
     }
 
+    /**
+     * The core renderer that performs the actual drawing operations.
+     */
+    public class Renderer implements GLSurfaceView.Renderer {
+
         @RendererThread
         @Override
         public void onSurfaceCreated(GL10 gl, EGLConfig config) {
@@ -184,7 +162,6 @@ public class GlCameraPreview extends CameraPreview<GLSurfaceView, SurfaceTexture
         }
 
         @RendererThread
-    @SuppressWarnings("StatementWithEmptyBody")
         @Override
         public void onSurfaceChanged(GL10 gl, final int width, final int height) {
             gl.glViewport(0, 0, width, height);
@@ -213,15 +190,14 @@ public class GlCameraPreview extends CameraPreview<GLSurfaceView, SurfaceTexture
             // See TextureCameraPreview.setDrawRotation() for info.
             if (mDrawRotation != 0) {
                 Matrix.translateM(mTransformMatrix, 0, 0.5F, 0.5F, 0);
-            Matrix.rotateM(mTransformMatrix, 0, -mDrawRotation, 0, 0, 1);
+                Matrix.rotateM(mTransformMatrix, 0, mDrawRotation, 0, 0, 1);
                 Matrix.translateM(mTransformMatrix, 0, -0.5F, -0.5F, 0);
             }
 
             if (isCropping()) {
-            // Scaling is easy. However:
+                // Scaling is easy, but we must also translate before:
                 // If the view is 10x1000 (very tall), it will show only the left strip of the preview (not the center one).
                 // If the view is 1000x10 (very large), it will show only the bottom strip of the preview (not the center one).
-            // So we must use Matrix.translateM, and it must happen before the crop.
                 float translX = (1F - mCropScaleX) / 2F;
                 float translY = (1F - mCropScaleY) / 2F;
                 Matrix.translateM(mTransformMatrix, 0, translX, translY, 0);
@@ -234,6 +210,7 @@ public class GlCameraPreview extends CameraPreview<GLSurfaceView, SurfaceTexture
                 callback.onRendererFrame(mInputSurfaceTexture, mCropScaleX, mCropScaleY);
             }
         }
+    }
 
     @NonNull
     @Override
@@ -262,7 +239,7 @@ public class GlCameraPreview extends CameraPreview<GLSurfaceView, SurfaceTexture
      *   platform when its window is positioned asynchronously.
      *
      * But to support older platforms, this seem to work - computing scale values and requesting a new frame,
-     * then drawing it with a scaled transformation matrix. See {@link #onDrawFrame(GL10)}.
+     * then drawing it with a scaled transformation matrix. See {@link Renderer#onDrawFrame(GL10)}.
      */
     @Override
     protected void crop(@NonNull Op<Void> op) {
@@ -285,4 +262,46 @@ public class GlCameraPreview extends CameraPreview<GLSurfaceView, SurfaceTexture
         }
         op.end(null);
     }
+
+    /**
+     * Method specific to the GL preview. Adds a {@link RendererFrameCallback}
+     * to receive renderer frame events.
+     * @param callback a callback
+     */
+    public void addRendererFrameCallback(@NonNull final RendererFrameCallback callback) {
+        getView().queueEvent(new Runnable() {
+            @Override
+            public void run() {
+                mRendererFrameCallbacks.add(callback);
+                if (mOutputTextureId != 0) callback.onRendererTextureCreated(mOutputTextureId);
+            }
+        });
+    }
+
+    /**
+     * Method specific to the GL preview. Removes a {@link RendererFrameCallback}
+     * that was previously added to receive renderer frame events.
+     * @param callback a callback
+     */
+    public void removeRendererFrameCallback(@NonNull final RendererFrameCallback callback) {
+        mRendererFrameCallbacks.remove(callback);
+    }
+
+    /**
+     * Returns the output GL texture id.
+     * @return the output GL texture id
+     */
+    @SuppressWarnings("unused")
+    protected int getTextureId() {
+        return mOutputTextureId;
+    }
+
+    /**
+     * Creates the renderer for this GL surface.
+     * @return the renderer for this GL surface
+     */
+    @NonNull
+    protected Renderer instantiateRenderer() {
+        return new Renderer();
+    }
 }

cameraview/src/main/java/com/otaliastudios/cameraview/preview/SurfaceCameraPreview.java

@@ -26,8 +26,8 @@ public class SurfaceCameraPreview extends CameraPreview<SurfaceView, SurfaceHold
     private boolean mDispatched;
     private View mRootView;
 
-    public SurfaceCameraPreview(@NonNull Context context, @NonNull ViewGroup parent, @Nullable SurfaceCallback callback) {
+    public SurfaceCameraPreview(@NonNull Context context, @NonNull ViewGroup parent) {
-        super(context, parent, callback);
+        super(context, parent);
     }
 
     @NonNull
@@ -37,7 +37,6 @@ public class SurfaceCameraPreview extends CameraPreview<SurfaceView, SurfaceHold
         parent.addView(root, 0);
         SurfaceView surfaceView = root.findViewById(R.id.surface_view);
         final SurfaceHolder holder = surfaceView.getHolder();
-        //noinspection deprecation
         holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
         holder.addCallback(new SurfaceHolder.Callback() {
 

cameraview/src/main/java/com/otaliastudios/cameraview/preview/TextureCameraPreview.java

@@ -30,8 +30,8 @@ public class TextureCameraPreview extends CameraPreview<TextureView, SurfaceText
 
     private View mRootView;
 
-    public TextureCameraPreview(@NonNull Context context, @NonNull ViewGroup parent, @Nullable SurfaceCallback callback) {
+    public TextureCameraPreview(@NonNull Context context, @NonNull ViewGroup parent) {
-        super(context, parent, callback);
+        super(context, parent);
     }
 
     @NonNull
@@ -140,7 +140,7 @@ public class TextureCameraPreview extends CameraPreview<TextureView, SurfaceText
                     float scaleX = (float) mOutputSurfaceHeight / mOutputSurfaceWidth;
                     matrix.postScale(scaleX, 1F / scaleX, outputCenterX, outputCenterY);
                 }
-                matrix.postRotate((float) -drawRotation, outputCenterX, outputCenterY);
+                matrix.postRotate((float) drawRotation, outputCenterX, outputCenterY);
                 getView().setTransform(matrix);
                 task.setResult(null);
             }

cameraview/src/main/java/com/otaliastudios/cameraview/video/SnapshotVideoRecorder.java

@@ -4,11 +4,11 @@ import android.graphics.SurfaceTexture;
 import android.opengl.EGL14;
 import android.os.Build;
 
-import com.otaliastudios.cameraview.CameraException;
 import com.otaliastudios.cameraview.CameraLogger;
 import com.otaliastudios.cameraview.VideoResult;
 import com.otaliastudios.cameraview.controls.Audio;
 import com.otaliastudios.cameraview.engine.CameraEngine;
+import com.otaliastudios.cameraview.engine.offset.Reference;
 import com.otaliastudios.cameraview.preview.GlCameraPreview;
 import com.otaliastudios.cameraview.preview.RendererFrameCallback;
 import com.otaliastudios.cameraview.preview.RendererThread;
@@ -58,7 +58,7 @@ public class SnapshotVideoRecorder extends VideoRecorder implements RendererFram
     @Override
     protected void onStart() {
         mPreview.addRendererFrameCallback(this);
-        mFlipped = mEngine.flip(CameraEngine.REF_SENSOR, CameraEngine.REF_VIEW);
+        mFlipped = mEngine.getAngles().flip(Reference.SENSOR, Reference.VIEW);
         mDesiredState = STATE_RECORDING;
     }
 
@@ -128,8 +128,11 @@ public class SnapshotVideoRecorder extends VideoRecorder implements RendererFram
             TextureMediaEncoder.TextureFrame textureFrame = textureEncoder.acquireFrame();
             textureFrame.timestamp = surfaceTexture.getTimestamp();
             surfaceTexture.getTransformMatrix(textureFrame.transform);
+            if (mEncoderEngine != null) {
+                // can happen on teardown
                 mEncoderEngine.notify(TextureMediaEncoder.FRAME_EVENT, textureFrame);
             }
+        }
 
         if (mCurrentState == STATE_RECORDING && mDesiredState == STATE_NOT_RECORDING) {
             LOG.i("Stopping the encoder engine.");

cameraview/src/test/java/com/otaliastudios/cameraview/engine/offset/AnglesTest.java

@@ -0,0 +1,80 @@
+package com.otaliastudios.cameraview.engine.offset;
+
+
+import com.otaliastudios.cameraview.controls.Facing;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class AnglesTest {
+
+    private Angles angles;
+
+    @Before
+    public void setUp() {
+        angles = new Angles();
+    }
+
+    @After
+    public void tearDown() {
+        angles = null;
+    }
+
+    @Test
+    public void testSetSensorOffset() {
+        angles.setSensorOffset(Facing.BACK, 90);
+        assertEquals(90, angles.mSensorOffset);
+        angles.setSensorOffset(Facing.FRONT, 90);
+        assertEquals(270, angles.mSensorOffset);
+    }
+
+    @Test
+    public void testSetDisplayOffset() {
+        angles.setDisplayOffset(90);
+        assertEquals(90, angles.mDisplayOffset);
+    }
+
+    @Test
+    public void testSetDeviceOrientation() {
+        angles.setDeviceOrientation(90);
+        assertEquals(90, angles.mDeviceOrientation);
+    }
+
+    @Test(expected = IllegalStateException.class)
+    public void testSetSensorOffset_throws() {
+        angles.setSensorOffset(Facing.BACK, 135);
+    }
+
+    @Test(expected = IllegalStateException.class)
+    public void testSetDisplayOffset_throws() {
+        angles.setDisplayOffset(135);
+    }
+
+    @Test(expected = IllegalStateException.class)
+    public void testSetDeviceOrientation_throws() {
+        angles.setDeviceOrientation(135);
+    }
+
+    @Test
+    public void testOffset_BaseToSensor() {
+        angles.setSensorOffset(Facing.BACK, 90);
+        assertEquals(270, angles.offset(Reference.BASE, Reference.SENSOR, Axis.RELATIVE_TO_SENSOR));
+        angles.setSensorOffset(Facing.FRONT, 270); // This is like setting 90
+        assertEquals(90, angles.offset(Reference.BASE, Reference.SENSOR, Axis.RELATIVE_TO_SENSOR));
+    }
+
+    @Test
+    public void testOffset_BaseToView() {
+        angles.setDisplayOffset(90);
+        assertEquals(270, angles.offset(Reference.BASE, Reference.VIEW, Axis.ABSOLUTE));
+    }
+
+    @Test
+    public void testOffset_BaseToOutput() {
+        angles.setDeviceOrientation(90);
+        assertEquals(90, angles.offset(Reference.BASE, Reference.OUTPUT, Axis.ABSOLUTE));
+    }
+}