Improve threading, add CameraOptions.supports() (#13)

* abstract WorkerHandler class, cleanup

* Start and stop in our thread

* Simplify Camera1 threading

* Add CameraOptions.supports() shorthands

* Improve supports() shorthands

* Rearrange orientation callbacks

cameraview/src/main/java/com/otaliastudios/cameraview/Camera1.java

@@ -11,6 +11,7 @@ import android.os.Build;
 import android.os.Handler;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
+import android.support.annotation.WorkerThread;
 import android.util.Log;
 import android.view.SurfaceHolder;
 
@@ -26,24 +27,31 @@ class Camera1 extends CameraController {
 
     private static final String TAG = Camera1.class.getSimpleName();
 
-    private static final int DELAY_MILLIS_BEFORE_RESETTING_FOCUS = 3000;
-
     private int mCameraId;
     private Camera mCamera;
-    private ExtraProperties mExtraProperties;
-    private CameraOptions mOptions;
-    private Size mPreviewSize;
-    private Size mCaptureSize;
     private MediaRecorder mMediaRecorder;
     private File mVideoFile;
 
-    private int mDisplayOffset;
-    private int mDeviceOrientation;
     private int mSensorOffset;
 
     private Location mLocation;
 
-    private Handler mFocusHandler = new Handler();
+    private final int mPostFocusResetDelay = 3000;
+    private Runnable mPostFocusResetRunnable = new Runnable() {
+        @Override
+        public void run() {
+            if (!isCameraOpened()) return;
+            mCamera.cancelAutoFocus();
+            synchronized (mLock) {
+                Camera.Parameters params = mCamera.getParameters();
+                params.setFocusAreas(null);
+                params.setMeteringAreas(null);
+                applyDefaultFocus(params); // Revert to internal focus.
+                mCamera.setParameters(params);
+            }
+        }
+    };
+
     private Mapper mMapper = new Mapper.Mapper1();
     private boolean mIsSetup = false;
     private boolean mIsCapturingImage = false;
@@ -129,9 +137,10 @@ class Camera1 extends CameraController {
     }
 
 
+    @WorkerThread
     @Override
-    void start() {
-        if (isCameraOpened()) stop();
+    void onStart() {
+        if (isCameraOpened()) onStop();
         if (collectCameraId()) {
             mCamera = Camera.open(mCameraId);
 
@@ -155,10 +164,10 @@ class Camera1 extends CameraController {
         }
     }
 
-
+    @WorkerThread
     @Override
-    void stop() {
-        mFocusHandler.removeCallbacksAndMessages(null);
+    void onStop() {
+        mHandler.get().removeCallbacks(mPostFocusResetRunnable);
         if (isCameraOpened()) {
             if (mIsCapturingVideo) endVideo();
             mCamera.stopPreview();
@@ -187,17 +196,6 @@ class Camera1 extends CameraController {
         return false;
     }
 
-    @Override
-    void onDisplayOffset(int displayOrientation) {
-        // I doubt this will ever change.
-        this.mDisplayOffset = displayOrientation;
-    }
-
-    @Override
-    void onDeviceOrientation(int deviceOrientation) {
-        this.mDeviceOrientation = deviceOrientation;
-    }
-
 
     @Override
     void setSessionType(SessionType sessionType) {
@@ -260,7 +258,7 @@ class Camera1 extends CameraController {
     }
 
     private boolean mergeWhiteBalance(Camera.Parameters params, WhiteBalance oldWhiteBalance) {
-        if (mOptions.getSupportedWhiteBalance().contains(mWhiteBalance)) {
+        if (mOptions.supports(mWhiteBalance)) {
             params.setWhiteBalance((String) mMapper.map(mWhiteBalance));
             return true;
         }
@@ -281,7 +279,7 @@ class Camera1 extends CameraController {
     }
 
     private boolean mergeHdr(Camera.Parameters params, Hdr oldHdr) {
-        if (mOptions.getSupportedHdr().contains(mHdr)) {
+        if (mOptions.supports(mHdr)) {
             params.setSceneMode((String) mMapper.map(mHdr));
             return true;
         }
@@ -303,7 +301,7 @@ class Camera1 extends CameraController {
 
 
     private boolean mergeFlash(Camera.Parameters params, Flash oldFlash) {
-        if (mOptions.getSupportedFlash().contains(mFlash)) {
+        if (mOptions.supports(mFlash)) {
             params.setFlashMode((String) mMapper.map(mFlash));
             return true;
         }
@@ -390,9 +388,15 @@ class Camera1 extends CameraController {
         mCamera.takePicture(null, null, null,
                 new Camera.PictureCallback() {
                     @Override
-                    public void onPictureTaken(byte[] data, Camera camera) {
+                    public void onPictureTaken(byte[] data, final Camera camera) {
                         mIsCapturingImage = false;
-                        camera.startPreview(); // This is needed, read somewhere in the docs.
+                        mHandler.post(new Runnable() {
+                            @Override
+                            public void run() {
+                                // This is needed, read somewhere in the docs.
+                                camera.startPreview();
+                            }
+                        });
                         mCameraCallbacks.processImage(data, consistentWithView, exifFlip);
                     }
                 });
@@ -443,16 +447,6 @@ class Camera1 extends CameraController {
         return true;
     }
 
-    @Override
-    Size getCaptureSize() {
-        return mCaptureSize;
-    }
-
-    @Override
-    Size getPreviewSize() {
-        return mPreviewSize;
-    }
-
     @Override
     boolean shouldFlipSizes() {
         return mSensorOffset % 180 != 0;
@@ -463,17 +457,6 @@ class Camera1 extends CameraController {
         return mCamera != null;
     }
 
-    @Nullable
-    @Override
-    ExtraProperties getExtraProperties() {
-        return mExtraProperties;
-    }
-
-    @Nullable
-    @Override
-    CameraOptions getCameraOptions() {
-        return mOptions;
-    }
 
     // Internal:
 
@@ -715,7 +698,8 @@ class Camera1 extends CameraController {
                 public void onAutoFocus(boolean success, Camera camera) {
                     // TODO lock auto exposure and white balance for a while
                     mCameraCallbacks.dispatchOnFocusEnd(gesture, success, p);
-                    postResetFocus();
+                    mHandler.get().removeCallbacks(mPostFocusResetRunnable);
+                    mHandler.get().postDelayed(mPostFocusResetRunnable, mPostFocusResetDelay);
                 }
             });
         }
@@ -723,25 +707,6 @@ class Camera1 extends CameraController {
     }
 
 
-    private void postResetFocus() {
-        mFocusHandler.removeCallbacksAndMessages(null);
-        mFocusHandler.postDelayed(new Runnable() {
-            @Override
-            public void run() {
-                if (!isCameraOpened()) return;
-                mCamera.cancelAutoFocus();
-                synchronized (mLock) {
-                    Camera.Parameters params = mCamera.getParameters();
-                    params.setFocusAreas(null);
-                    params.setMeteringAreas(null);
-                    applyDefaultFocus(params); // Revert to internal focus.
-                    mCamera.setParameters(params);
-                }
-            }
-        }, DELAY_MILLIS_BEFORE_RESETTING_FOCUS);
-    }
-
-
     private List<Camera.Area> computeMeteringAreas(double viewClickX, double viewClickY) {
         // Event came in view coordinates. We must rotate to sensor coordinates.
         // First, rescale to the -1000 ... 1000 range.

cameraview/src/main/java/com/otaliastudios/cameraview/Camera2.java

@@ -12,6 +12,7 @@ import android.hardware.camera2.params.StreamConfigurationMap;
 import android.location.Location;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
+import android.support.annotation.WorkerThread;
 import android.util.Log;
 
 import java.io.File;
@@ -29,8 +30,6 @@ class Camera2 extends CameraController {
 
     private String mCameraId;
 
-    private Size mCaptureSize;
-    private Size mPreviewSize;
 
     private Mapper mMapper = new Mapper.Mapper2();
     private final HashMap<String, ExtraProperties> mExtraPropertiesMap = new HashMap<>();
@@ -79,13 +78,15 @@ class Camera2 extends CameraController {
 
     // CameraImpl:
 
+    @WorkerThread
     @Override
-    void start() {
+    void onStart() {
 
     }
 
+    @WorkerThread
     @Override
-    void stop() {
+    void onStop() {
 
     }
 
@@ -186,57 +187,7 @@ class Camera2 extends CameraController {
         return false;
     }
 
-    @Override
-    Size getCaptureSize() {
-        if (mCaptureSize == null && mCameraCharacteristics != null) {
-            TreeSet<Size> sizes = new TreeSet<>();
-            sizes.addAll(getAvailableCaptureResolutions());
-
-            /* TreeSet<AspectRatio> aspectRatios = new CommonAspectRatioFilter(
-                    getAvailablePreviewResolutions(),
-                    getAvailableCaptureResolutions()
-            ).filter();
-            AspectRatio targetRatio = aspectRatios.size() > 0 ? aspectRatios.last() : null;
-
-            Iterator<Size> descendingSizes = sizes.descendingIterator();
-            Size size;
-            while (descendingSizes.hasNext() && mCaptureSize == null) {
-                size = descendingSizes.next();
-                if (targetRatio == null || targetRatio.matches(size)) {
-                    mCaptureSize = size;
-                    break;
-                }
-            } */
-        }
 
-        return mCaptureSize;
-    }
-
-    @Override
-    Size getPreviewSize() {
-        if (mPreviewSize == null && mCameraCharacteristics != null) {
-            TreeSet<Size> sizes = new TreeSet<>();
-            sizes.addAll(getAvailablePreviewResolutions());
-
-            /* TreeSet<AspectRatio> aspectRatios = new CommonAspectRatioFilter(
-                    getAvailablePreviewResolutions(),
-                    getAvailableCaptureResolutions()
-            ).filter();
-            AspectRatio targetRatio = aspectRatios.size() > 0 ? aspectRatios.last() : null;
-
-            Iterator<Size> descendingSizes = sizes.descendingIterator();
-            Size size;
-            while (descendingSizes.hasNext() && mPreviewSize == null) {
-                size = descendingSizes.next();
-                if (targetRatio == null || targetRatio.matches(size)) {
-                    mPreviewSize = size;
-                    break;
-                }
-            } */
-        }
-
-        return mPreviewSize;
-    }
 
     @Override
     boolean shouldFlipSizes() {
@@ -253,22 +204,9 @@ class Camera2 extends CameraController {
         return true;
     }
 
-    @Nullable
-    @Override
-    ExtraProperties getExtraProperties() {
-        if (mCamera == null) {
-            return null;
-        }
-        return mExtraPropertiesMap.get(mCamera.getId());
-    }
-    // Internal
 
+    // Internal
 
-    @Nullable
-    @Override
-    CameraOptions getCameraOptions() {
-        return null;
-    }
 
     private List<Size> getAvailableCaptureResolutions() {
         List<Size> output = new ArrayList<>();

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

@@ -4,6 +4,7 @@ import android.graphics.PointF;
 import android.location.Location;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
+import android.support.annotation.WorkerThread;
 
 import java.io.File;
 
@@ -19,47 +20,153 @@ abstract class CameraController implements Preview.SurfaceCallback {
     protected SessionType mSessionType;
     protected Hdr mHdr;
 
+    protected Size mCaptureSize;
+    protected Size mPreviewSize;
+
+    protected ExtraProperties mExtraProperties;
+    protected CameraOptions mOptions;
+
+    protected int mDisplayOffset;
+    protected int mDeviceOrientation;
+
+    protected WorkerHandler mHandler;
+
     CameraController(CameraView.CameraCallbacks callback, Preview preview) {
         mCameraCallbacks = callback;
         mPreview = preview;
         mPreview.setSurfaceCallback(this);
+        mHandler = new WorkerHandler("CameraViewController");
+    }
+
+    //region Start&Stop
+
+    // Starts the preview asynchronously.
+    final void start() {
+        mHandler.post(new Runnable() {
+            @Override
+            public void run() {
+                onStart();
+            }
+        });
     }
 
-    abstract void start();
-    abstract void stop();
+    // Stops the preview asynchronously.
+    final void stop() {
+        mHandler.post(new Runnable() {
+            @Override
+            public void run() {
+                onStop();
+            }
+        });
+    }
+
+    // Starts the preview.
+    @WorkerThread
+    abstract void onStart();
+
+    // Stops the preview.
+    @WorkerThread
+    abstract void onStop();
+
+    //endregion
 
-    abstract void onDisplayOffset(int displayOrientation);
-    abstract void onDeviceOrientation(int deviceOrientation);
+    //region Rotation callbacks
+
+    void onDisplayOffset(int displayOrientation) {
+        // I doubt this will ever change.
+        mDisplayOffset = displayOrientation;
+    }
+
+    void onDeviceOrientation(int deviceOrientation) {
+        mDeviceOrientation = deviceOrientation;
+    }
+
+    //endregion
+
+    //region Abstract setParameters
 
     abstract boolean setZoom(float zoom);
+
     abstract boolean setExposureCorrection(float EVvalue);
+
     abstract void setFacing(Facing facing);
+
     abstract void setFlash(Flash flash);
+
     abstract void setWhiteBalance(WhiteBalance whiteBalance);
+
     abstract void setVideoQuality(VideoQuality videoQuality);
+
     abstract void setSessionType(SessionType sessionType);
+
     abstract void setHdr(Hdr hdr);
+
     abstract void setLocation(Location location);
 
+    //endregion
+
+    //region APIs
+
     abstract boolean capturePicture();
+
     abstract boolean captureSnapshot();
+
     abstract boolean startVideo(@NonNull File file);
+
     abstract boolean endVideo();
 
-    abstract Size getCaptureSize();
-    abstract Size getPreviewSize();
+
     abstract boolean shouldFlipSizes(); // Wheter the Sizes should be flipped to match the view orientation.
+
     abstract boolean isCameraOpened();
 
     abstract boolean startAutoFocus(@Nullable Gesture gesture, PointF point);
 
-    @Nullable abstract ExtraProperties getExtraProperties();
-    @Nullable abstract CameraOptions getCameraOptions();
+    //endregion
+
+    //region final getters
+
+    @Nullable
+    final ExtraProperties getExtraProperties() {
+        return mExtraProperties;
+    }
+
+    @Nullable
+    final CameraOptions getCameraOptions() {
+        return mOptions;
+    }
+
+    final Facing getFacing() {
+        return mFacing;
+    }
+
+    final Flash getFlash() {
+        return mFlash;
+    }
+
+    final WhiteBalance getWhiteBalance() {
+        return mWhiteBalance;
+    }
+
+    final VideoQuality getVideoQuality() {
+        return mVideoQuality;
+    }
+
+    final SessionType getSessionType() {
+        return mSessionType;
+    }
+
+    final Hdr getHdr() {
+        return mHdr;
+    }
+
+    final Size getCaptureSize() {
+        return mCaptureSize;
+    }
+
+    final Size getPreviewSize() {
+        return mPreviewSize;
+    }
 
-    final Facing getFacing() { return mFacing; }
-    final Flash getFlash() { return mFlash; }
-    final WhiteBalance getWhiteBalance() { return mWhiteBalance; }
-    final VideoQuality getVideoQuality() { return mVideoQuality; }
-    final SessionType getSessionType() { return mSessionType; }
-    final Hdr getHdr() { return mHdr; }
+    //endregion
 }

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

@@ -88,6 +88,74 @@ public class CameraOptions {
     CameraOptions(CameraCharacteristics params) {}
 
 
+    /**
+     * Shorthand for getSupportedFacing().contains(value).
+     *
+     * @param facing value
+     * @return whether it's supported
+     */
+    public boolean supports(Facing facing) {
+        return getSupportedFacing().contains(facing);
+    }
+
+
+    /**
+     * Shorthand for getSupportedFlash().contains(value).
+     *
+     * @param flash value
+     * @return whether it's supported
+     */
+    public boolean supports(Flash flash) {
+        return getSupportedFlash().contains(flash);
+    }
+
+
+    /**
+     * Shorthand for getSupportedWhiteBalance().contains(value).
+     *
+     * @param whiteBalance value
+     * @return whether it's supported
+     */
+    public boolean supports(WhiteBalance whiteBalance) {
+        return getSupportedWhiteBalance().contains(whiteBalance);
+    }
+
+
+    /**
+     * Shorthand for getSupportedHdr().contains(value).
+     *
+     * @param hdr value
+     * @return whether it's supported
+     */
+    public boolean supports(Hdr hdr) {
+        return getSupportedHdr().contains(hdr);
+    }
+
+
+    /**
+     * Shorthand for other methods in this class,
+     * e.g. supports(GestureAction.ZOOM) == isZoomSupported().
+     *
+     * @param action value to be checked
+     * @return whether it's supported
+     */
+    public boolean supports(GestureAction action) {
+        switch (action) {
+            case FOCUS:
+            case FOCUS_WITH_MARKER:
+                return isAutoFocusSupported();
+            case CAPTURE:
+            case NONE:
+                return true;
+            case ZOOM:
+                return isZoomSupported();
+            case EXPOSURE_CORRECTION:
+                return isExposureCorrectionSupported();
+        }
+        return false;
+    }
+
+
     /**
      * Set of supported facing values.
      *

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

@@ -1,7 +1,6 @@
 package com.otaliastudios.cameraview;
 
 import android.Manifest;
-import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
 import android.app.Activity;
 import android.content.Context;
@@ -48,31 +47,20 @@ public class CameraView extends FrameLayout {
     private final static int DEFAULT_JPEG_QUALITY = 100;
     private final static boolean DEFAULT_CROP_OUTPUT = false;
 
-    private Handler mWorkerHandler;
-
-    private Handler getWorkerHandler() {
-        synchronized (this) {
-            if (mWorkerHandler == null) {
-                HandlerThread workerThread = new HandlerThread("CameraViewWorker");
-                workerThread.setDaemon(true);
-                workerThread.start();
-                mWorkerHandler = new Handler(workerThread.getLooper());
-            }
-        }
-        return mWorkerHandler;
-    }
-
-    private void run(Runnable runnable) {
-        getWorkerHandler().post(runnable);
-    }
-
+    // Self managed parameters
     private int mJpegQuality;
     private boolean mCropOutput;
+    private float mZoomValue;
+    private float mExposureCorrectionValue;
+    private HashMap<Gesture, GestureAction> mGestureMap = new HashMap<>(4);
+
+    // Components
     private CameraCallbacks mCameraCallbacks;
     private OrientationHelper mOrientationHelper;
     private CameraController mCameraController;
     private Preview mPreviewImpl;
 
+    // Views
     private GridLinesLayout mGridLinesLayout;
     private PinchGestureLayout mPinchGestureLayout;
     private TapGestureLayout mTapGestureLayout;
@@ -80,10 +68,9 @@ public class CameraView extends FrameLayout {
     private boolean mIsStarted;
     private boolean mKeepScreenOn;
 
-    private float mZoomValue;
-    private float mExposureCorrectionValue;
-
-    private HashMap<Gesture, GestureAction> mGestureMap = new HashMap<>(4);
+    // Threading
+    private Handler mUiHandler;
+    private WorkerHandler mWorkerHandler;
 
     public CameraView(@NonNull Context context) {
         super(context, null);
@@ -120,9 +107,14 @@ public class CameraView extends FrameLayout {
         GestureAction scrollVerticalGesture = GestureAction.fromValue(a.getInteger(R.styleable.CameraView_cameraGestureScrollVertical, GestureAction.DEFAULT_SCROLL_VERTICAL.value()));
         a.recycle();
 
+        // Components
         mCameraCallbacks = new CameraCallbacks();
         mPreviewImpl = new TextureViewPreview(context, this);
         mCameraController = new Camera1(mCameraCallbacks, mPreviewImpl);
+        mUiHandler = new Handler(Looper.getMainLooper());
+        mWorkerHandler = new WorkerHandler("CameraViewWorker");
+
+        // Views
         mGridLinesLayout = new GridLinesLayout(context);
         mPinchGestureLayout = new PinchGestureLayout(context);
         mTapGestureLayout = new TapGestureLayout(context);
@@ -134,11 +126,11 @@ public class CameraView extends FrameLayout {
 
         mIsStarted = false;
 
-        // Self managed
+        // Apply self managed
         setCropOutput(cropOutput);
         setJpegQuality(jpegQuality);
 
-        // Camera controller params
+        // Apply camera controller params
         setFacing(facing);
         setFlash(flash);
         setSessionType(sessionType);
@@ -146,7 +138,7 @@ public class CameraView extends FrameLayout {
         setWhiteBalance(whiteBalance);
         setGrid(grid);
 
-        // Gestures
+        // Apply gestures
         mapGesture(Gesture.TAP, tapGesture);
         // mapGesture(Gesture.DOUBLE_TAP, doubleTapGesture);
         mapGesture(Gesture.LONG_TAP, longTapGesture);
@@ -155,34 +147,7 @@ public class CameraView extends FrameLayout {
         mapGesture(Gesture.SCROLL_VERTICAL, scrollVerticalGesture);
 
         if (!isInEditMode()) {
-            mOrientationHelper = new OrientationHelper(context) {
-
-                private Integer mDisplayOffset;
-                private Integer mDeviceOrientation;
-
-                @Override
-                public void onDisplayOffsetChanged(int displayOffset) {
-                    mCameraController.onDisplayOffset(displayOffset);
-                    mPreviewImpl.onDisplayOffset(displayOffset);
-                    mDisplayOffset = displayOffset;
-                    send();
-                }
-
-                @Override
-                protected void onDeviceOrientationChanged(int deviceOrientation) {
-                    mCameraController.onDeviceOrientation(deviceOrientation);
-                    mPreviewImpl.onDeviceOrientation(deviceOrientation);
-                    mDeviceOrientation = deviceOrientation;
-                    send();
-                }
-
-                private void send() {
-                    if (mDeviceOrientation == null) return;
-                    if (mDisplayOffset == null) return;
-                    int value = (mDeviceOrientation + mDisplayOffset) % 360;
-                    mCameraCallbacks.dispatchOnOrientationChanged(value);
-                }
-            };
+            mOrientationHelper = new OrientationHelper(context, mCameraCallbacks);
         }
     }
 
@@ -497,12 +462,7 @@ public class CameraView extends FrameLayout {
 
         if (checkPermissions(getSessionType())) {
             mIsStarted = true;
-            run(new Runnable() {
-                @Override
-                public void run() {
-                    mCameraController.start();
-                }
-            });
+            mCameraController.start();
         }
     }
 
@@ -584,9 +544,8 @@ public class CameraView extends FrameLayout {
     }
 
     public void destroy() {
+        // TODO: this is not strictly needed
         mCameraCallbacks.clearListeners(); // Release inner listener.
-        // This might be useless, but no time to think about it now.
-        mWorkerHandler = null;
     }
 
     //endregion
@@ -788,12 +747,7 @@ public class CameraView extends FrameLayout {
      * @param facing a facing value.
      */
     public void setFacing(final Facing facing) {
-        run(new Runnable() {
-            @Override
-            public void run() {
-                mCameraController.setFacing(facing);
-            }
-        });
+        mCameraController.setFacing(facing);
     }
 
 
@@ -1212,20 +1166,21 @@ public class CameraView extends FrameLayout {
         }
     }
 
-    class CameraCallbacks {
 
-        private ArrayList<CameraListener> mListeners;
-        private Handler uiHandler;
+    class CameraCallbacks implements OrientationHelper.Callbacks {
 
+        // Outer listeners
+        private ArrayList<CameraListener> mListeners = new ArrayList<>(2);
 
-        CameraCallbacks() {
-            mListeners = new ArrayList<>(2);
-            uiHandler = new Handler(Looper.getMainLooper());
-        }
+        // Orientation TODO: move this logic into OrientationHelper
+        private Integer mDisplayOffset;
+        private Integer mDeviceOrientation;
+
+        CameraCallbacks() {}
 
 
         public void dispatchOnCameraOpened(final CameraOptions options) {
-            uiHandler.post(new Runnable() {
+            mUiHandler.post(new Runnable() {
                 @Override
                 public void run() {
                     for (CameraListener listener : mListeners) {
@@ -1237,7 +1192,7 @@ public class CameraView extends FrameLayout {
 
 
         public void dispatchOnCameraClosed() {
-            uiHandler.post(new Runnable() {
+            mUiHandler.post(new Runnable() {
                 @Override
                 public void run() {
                     for (CameraListener listener : mListeners) {
@@ -1253,7 +1208,7 @@ public class CameraView extends FrameLayout {
             // Request a layout pass for onMeasure() to do its stuff.
             // Potentially this will change CameraView size, which changes Surface size,
             // which triggers a new Preview size. But hopefully it will converge.
-            uiHandler.post(new Runnable() {
+            mUiHandler.post(new Runnable() {
                 @Override
                 public void run() {
                     requestLayout();
@@ -1280,7 +1235,7 @@ public class CameraView extends FrameLayout {
          *                         because it was taken with the front camera.
          */
         public void processImage(final byte[] jpeg, final boolean consistentWithView, final boolean flipHorizontally) {
-            getWorkerHandler().post(new Runnable() {
+            mWorkerHandler.post(new Runnable() {
                 @Override
                 public void run() {
                     byte[] jpeg2 = jpeg;
@@ -1300,25 +1255,30 @@ public class CameraView extends FrameLayout {
         }
 
 
-        public void processSnapshot(YuvImage yuv, boolean consistentWithView, boolean flipHorizontally) {
-            byte[] jpeg;
-            if (mCropOutput && mPreviewImpl.isCropping()) {
-                int w = consistentWithView ? getWidth() : getHeight();
-                int h = consistentWithView ? getHeight() : getWidth();
-                AspectRatio targetRatio = AspectRatio.of(w, h);
-                jpeg = CropHelper.cropToJpeg(yuv, targetRatio, mJpegQuality);
-            } else {
-                ByteArrayOutputStream out = new ByteArrayOutputStream();
-                yuv.compressToJpeg(new Rect(0, 0, yuv.getWidth(), yuv.getHeight()), mJpegQuality, out);
-                jpeg = out.toByteArray();
-            }
-            dispatchOnPictureTaken(jpeg);
+        public void processSnapshot(final YuvImage yuv, final boolean consistentWithView, boolean flipHorizontally) {
+            mWorkerHandler.post(new Runnable() {
+                @Override
+                public void run() {
+                    byte[] jpeg;
+                    if (mCropOutput && mPreviewImpl.isCropping()) {
+                        int w = consistentWithView ? getWidth() : getHeight();
+                        int h = consistentWithView ? getHeight() : getWidth();
+                        AspectRatio targetRatio = AspectRatio.of(w, h);
+                        jpeg = CropHelper.cropToJpeg(yuv, targetRatio, mJpegQuality);
+                    } else {
+                        ByteArrayOutputStream out = new ByteArrayOutputStream();
+                        yuv.compressToJpeg(new Rect(0, 0, yuv.getWidth(), yuv.getHeight()), mJpegQuality, out);
+                        jpeg = out.toByteArray();
+                    }
+                    dispatchOnPictureTaken(jpeg);
+                }
+            });
         }
 
 
         private void dispatchOnPictureTaken(byte[] jpeg) {
             final byte[] data = jpeg;
-            uiHandler.post(new Runnable() {
+            mUiHandler.post(new Runnable() {
                 @Override
                 public void run() {
                     for (CameraListener listener : mListeners) {
@@ -1330,7 +1290,7 @@ public class CameraView extends FrameLayout {
 
 
         public void dispatchOnVideoTaken(final File video) {
-            uiHandler.post(new Runnable() {
+            mUiHandler.post(new Runnable() {
                 @Override
                 public void run() {
                     for (CameraListener listener : mListeners) {
@@ -1342,7 +1302,7 @@ public class CameraView extends FrameLayout {
 
 
         public void dispatchOnFocusStart(@Nullable final Gesture gesture, final PointF point) {
-            uiHandler.post(new Runnable() {
+            mUiHandler.post(new Runnable() {
                 @Override
                 public void run() {
                     if (gesture != null && mGestureMap.get(gesture) == GestureAction.FOCUS_WITH_MARKER) {
@@ -1359,7 +1319,7 @@ public class CameraView extends FrameLayout {
 
         public void dispatchOnFocusEnd(@Nullable final Gesture gesture, final boolean success,
                                        final PointF point) {
-            uiHandler.post(new Runnable() {
+            mUiHandler.post(new Runnable() {
                 @Override
                 public void run() {
                     if (success && mUseSounds) {
@@ -1378,9 +1338,29 @@ public class CameraView extends FrameLayout {
             });
         }
 
+        @Override
+        public void onDisplayOffsetChanged(int displayOffset) {
+            mCameraController.onDisplayOffset(displayOffset);
+            mDisplayOffset = displayOffset;
+            if (mDeviceOrientation != null) {
+                int value = (mDeviceOrientation + mDisplayOffset) % 360;
+                dispatchOnOrientationChanged(value);
+            }
+        }
+
+        @Override
+        public void onDeviceOrientationChanged(int deviceOrientation) {
+            mCameraController.onDeviceOrientation(deviceOrientation);
+            mDeviceOrientation = deviceOrientation;
+            if (mDisplayOffset != null) {
+                int value = (mDeviceOrientation + mDisplayOffset) % 360;
+                dispatchOnOrientationChanged(value);
+            }
+        }
+
 
-        public void dispatchOnOrientationChanged(final int value) {
-            uiHandler.post(new Runnable() {
+        private void dispatchOnOrientationChanged(final int value) {
+            mUiHandler.post(new Runnable() {
                 @Override
                 public void run() {
                     for (CameraListener listener : mListeners) {
@@ -1392,7 +1372,7 @@ public class CameraView extends FrameLayout {
 
 
         public void dispatchOnZoomChanged(final float newValue, final PointF[] fingers) {
-            uiHandler.post(new Runnable() {
+            mUiHandler.post(new Runnable() {
                 @Override
                 public void run() {
                     for (CameraListener listener : mListeners) {
@@ -1406,7 +1386,7 @@ public class CameraView extends FrameLayout {
         public void dispatchOnExposureCorrectionChanged(final float newValue,
                                                         final float[] bounds,
                                                         final PointF[] fingers) {
-            uiHandler.post(new Runnable() {
+            mUiHandler.post(new Runnable() {
                 @Override
                 public void run() {
                     for (CameraListener listener : mListeners) {

cameraview/src/main/utils/com/otaliastudios/cameraview/OrientationHelper.java

@@ -2,14 +2,13 @@ package com.otaliastudios.cameraview;
 
 import android.content.Context;
 import android.hardware.SensorManager;
+import android.support.annotation.NonNull;
 import android.util.SparseIntArray;
 import android.view.Display;
 import android.view.OrientationEventListener;
 import android.view.Surface;
 
-abstract class OrientationHelper {
-
-    private final OrientationEventListener mOrientationEventListener;
+class OrientationHelper {
 
     private static final SparseIntArray DISPLAY_ORIENTATIONS = new SparseIntArray();
     static {
@@ -19,13 +18,20 @@ abstract class OrientationHelper {
         DISPLAY_ORIENTATIONS.put(Surface.ROTATION_270, 270);
     }
 
+    private final OrientationEventListener mListener;
+    private final Callbacks mCallbacks;
     private Display mDisplay;
-
     private int mLastKnownDisplayOffset = -1;
     private int mLastOrientation = -1;
 
-    OrientationHelper(Context context) {
-        mOrientationEventListener = new OrientationEventListener(context, SensorManager.SENSOR_DELAY_NORMAL) {
+    interface Callbacks {
+        void onDisplayOffsetChanged(int displayOffset);
+        void onDeviceOrientationChanged(int deviceOrientation);
+    }
+
+    OrientationHelper(Context context, @NonNull Callbacks callbacks) {
+        mCallbacks = callbacks;
+        mListener = new OrientationEventListener(context, SensorManager.SENSOR_DELAY_NORMAL) {
 
             @Override
             public void onOrientationChanged(int orientation) {
@@ -44,7 +50,7 @@ abstract class OrientationHelper {
 
                 if (or != mLastOrientation) {
                     mLastOrientation = or;
-                    onDeviceOrientationChanged(mLastOrientation);
+                    mCallbacks.onDeviceOrientationChanged(mLastOrientation);
                 }
 
                 // Let's see if display rotation has changed.. but how could it ever change...??
@@ -53,7 +59,7 @@ abstract class OrientationHelper {
                     final int offset = mDisplay.getRotation();
                     if (mLastKnownDisplayOffset != offset) {
                         mLastKnownDisplayOffset = offset;
-                        onDisplayOffsetChanged(DISPLAY_ORIENTATIONS.get(offset));
+                        mCallbacks.onDisplayOffsetChanged(DISPLAY_ORIENTATIONS.get(offset));
                     }
                 }
             }
@@ -63,18 +69,13 @@ abstract class OrientationHelper {
 
     void enable(Display display) {
         mDisplay = display;
-        mOrientationEventListener.enable();
+        mListener.enable();
         mLastKnownDisplayOffset = DISPLAY_ORIENTATIONS.get(display.getRotation());
-        onDisplayOffsetChanged(mLastKnownDisplayOffset);
+        mCallbacks.onDisplayOffsetChanged(mLastKnownDisplayOffset);
     }
 
     void disable() {
-        mOrientationEventListener.disable();
+        mListener.disable();
         mDisplay = null;
     }
-
-    protected abstract void onDisplayOffsetChanged(int displayOffset);
-
-    protected abstract void onDeviceOrientationChanged(int deviceOrientation);
-
 }

cameraview/src/main/utils/com/otaliastudios/cameraview/WorkerHandler.java

@@ -0,0 +1,30 @@
+package com.otaliastudios.cameraview;
+
+import android.os.Handler;
+import android.os.HandlerThread;
+
+/**
+ * Class holding a background handler.
+ * Using setDaemon right now but a better approach would be to have
+ * start() and stop() callbacks here. TODO
+ */
+class WorkerHandler {
+
+    private HandlerThread mThread;
+    private Handler mHandler;
+
+    public WorkerHandler(String name) {
+        mThread = new HandlerThread(name);
+        mThread.setDaemon(true);
+        mThread.start();
+        mHandler = new Handler(mThread.getLooper());
+    }
+
+    public Handler get() {
+        return mHandler;
+    }
+
+    public void post(Runnable runnable) {
+        mHandler.post(runnable);
+    }
+}

cameraview/src/main/views/com/otaliastudios/cameraview/Preview.java

@@ -33,8 +33,6 @@ abstract class Preview {
     abstract View getView();
     abstract Class getOutputClass();
     abstract boolean isReady();
-    protected void onDisplayOffset(int displayOrientation) {}
-    protected void onDeviceOrientation(int deviceOrientation) {}
     SurfaceHolder getSurfaceHolder() {
         return null;
     }