Add discrete granularity to pinch and scroll events (#170)

* Add discrete granularity to pinch and scroll events

* Better tests

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

@@ -206,6 +206,7 @@ public class CameraViewTest extends BaseTest {
     @Test
     public void testGestureAction_zoom() {
         mockController.mockStarted(true);
+        mockController.mZoomChanged = false;
         MotionEvent event = MotionEvent.obtain(0L, 0L, 0, 0f, 0f, 0);
         ui(new Runnable() {
             @Override
@@ -214,10 +215,18 @@ public class CameraViewTest extends BaseTest {
                     public boolean onTouchEvent(MotionEvent event) { return true; }
                 };
                 cameraView.mPinchGestureLayout.setGestureType(Gesture.PINCH);
+                cameraView.mapGesture(Gesture.PINCH, GestureAction.ZOOM);
+
             }
         });
-        mockController.mZoomChanged = false;
-        cameraView.mapGesture(Gesture.PINCH, GestureAction.ZOOM);
+
+        // If factor is 0, we return the same value. The controller should not be notified.
+        cameraView.mPinchGestureLayout.mFactor = 0f;
+        cameraView.dispatchTouchEvent(event);
+        assertFalse(mockController.mZoomChanged);
+
+        // For larger factors, the value is scaled. The controller should be notified.
+        cameraView.mPinchGestureLayout.mFactor = 1f;
         cameraView.dispatchTouchEvent(event);
         assertTrue(mockController.mZoomChanged);
     }
@@ -230,7 +239,7 @@ public class CameraViewTest extends BaseTest {
         when(o.getExposureCorrectionMaxValue()).thenReturn(10f);
         mockController.setMockCameraOptions(o);
         mockController.mockStarted(true);
-
+        mockController.mExposureCorrectionChanged = false;
         MotionEvent event = MotionEvent.obtain(0L, 0L, 0, 0f, 0f, 0);
         ui(new Runnable() {
             @Override
@@ -239,10 +248,17 @@ public class CameraViewTest extends BaseTest {
                     public boolean onTouchEvent(MotionEvent event) { return true; }
                 };
                 cameraView.mScrollGestureLayout.setGestureType(Gesture.SCROLL_HORIZONTAL);
+                cameraView.mapGesture(Gesture.SCROLL_HORIZONTAL, GestureAction.EXPOSURE_CORRECTION);
             }
         });
-        mockController.mExposureCorrectionChanged = false;
-        cameraView.mapGesture(Gesture.SCROLL_HORIZONTAL, GestureAction.EXPOSURE_CORRECTION);
+
+        // If factor is 0, we return the same value. The controller should not be notified.
+        cameraView.mScrollGestureLayout.mFactor = 0f;
+        cameraView.dispatchTouchEvent(event);
+        assertFalse(mockController.mExposureCorrectionChanged);
+
+        // For larger factors, the value is scaled. The controller should be notified.
+        cameraView.mScrollGestureLayout.mFactor = 1f;
         cameraView.dispatchTouchEvent(event);
         assertTrue(mockController.mExposureCorrectionChanged);
     }

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

@@ -505,7 +505,9 @@ public class CameraView extends FrameLayout {
             case ZOOM:
                 oldValue = mCameraController.getZoomValue();
                 newValue = source.scaleValue(oldValue, 0, 1);
-                mCameraController.setZoom(newValue, points, true);
+                if (newValue != oldValue) {
+                    mCameraController.setZoom(newValue, points, true);
+                }
                 break;
 
             case EXPOSURE_CORRECTION:
@@ -513,8 +515,10 @@ public class CameraView extends FrameLayout {
                 float minValue = options.getExposureCorrectionMinValue();
                 float maxValue = options.getExposureCorrectionMaxValue();
                 newValue = source.scaleValue(oldValue, minValue, maxValue);
-                float[] bounds = new float[]{minValue, maxValue};
-                mCameraController.setExposureCorrection(newValue, bounds, points, true);
+                if (newValue != oldValue) {
+                    float[] bounds = new float[]{minValue, maxValue};
+                    mCameraController.setExposureCorrection(newValue, bounds, points, true);
+                }
                 break;
         }
     }

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

@@ -7,12 +7,12 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.FrameLayout;
 
-/**
- * Using Views to address the need to draw stuff, but think about it.
- * Simple classes could be enough.
- */
 abstract class GestureLayout extends FrameLayout {
 
+    // The number of possible values between minValue and maxValue, for the scaleValue method.
+    // We could make this non-static (e.g. larger granularity for exposure correction).
+    private final static int GRANULARITY = 50;
+
     protected boolean mEnabled;
     protected Gesture mType;
     protected PointF[] mPoints;
@@ -48,5 +48,22 @@ abstract class GestureLayout extends FrameLayout {
         return mPoints;
     }
 
+    // Implementors should call capValue at the end.
     public abstract float scaleValue(float currValue, float minValue, float maxValue);
+
+    // Checks for newValue to be between minValue and maxValue,
+    // and checks that it is 'far enough' from the oldValue, in order
+    // to reduce useless updates.
+    protected static float capValue(float oldValue, float newValue, float minValue, float maxValue) {
+        if (newValue < minValue) newValue = minValue;
+        if (newValue > maxValue) newValue = maxValue;
+
+        float distance = (maxValue - minValue) / (float) GRANULARITY;
+        float half = distance / 2;
+        if (newValue >= oldValue - half && newValue <= oldValue + half) {
+            // Too close! Return the oldValue.
+            return oldValue;
+        }
+        return newValue;
+    }
 }

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

@@ -3,12 +3,8 @@ package com.otaliastudios.cameraview;
 import android.content.Context;
 import android.graphics.PointF;
 import android.os.Build;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
-import android.util.AttributeSet;
 import android.view.MotionEvent;
 import android.view.ScaleGestureDetector;
-import android.view.View;
 
 class PinchGestureLayout extends GestureLayout {
 
@@ -16,7 +12,7 @@ class PinchGestureLayout extends GestureLayout {
 
     ScaleGestureDetector mDetector;
     private boolean mNotify;
-    private float mAdditionFactor = 0;
+    /* tests */ float mFactor = 0;
 
 
     public PinchGestureLayout(Context context) {
@@ -32,7 +28,7 @@ class PinchGestureLayout extends GestureLayout {
             @Override
             public boolean onScale(ScaleGestureDetector detector) {
                 mNotify = true;
-                mAdditionFactor = ((detector.getScaleFactor() - 1) * ADD_SENSITIVITY);
+                mFactor = ((detector.getScaleFactor() - 1) * ADD_SENSITIVITY);
                 return true;
             }
         });
@@ -75,7 +71,7 @@ class PinchGestureLayout extends GestureLayout {
 
     @Override
     public float scaleValue(float currValue, float minValue, float maxValue) {
-        float add = mAdditionFactor;
+        float add = mFactor;
         // ^ This works well if minValue = 0, maxValue = 1.
         // Account for the different range:
         add *= (maxValue - minValue);
@@ -87,10 +83,6 @@ class PinchGestureLayout extends GestureLayout {
         } else if (add < 0) {
             add *= (currValue - minValue);
         } Nope, I don't like this, it slows everything down. */
-
-        float newValue = currValue + add;
-        if (newValue < minValue) newValue = minValue;
-        if (newValue > maxValue) newValue = maxValue;
-        return newValue;
+        return capValue(currValue, currValue + add, minValue, maxValue);
     }
 }

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

@@ -1,16 +1,9 @@
 package com.otaliastudios.cameraview;
 
-import android.animation.Animator;
-import android.animation.AnimatorListenerAdapter;
 import android.content.Context;
 import android.graphics.PointF;
-import android.util.Log;
 import android.view.GestureDetector;
-import android.view.LayoutInflater;
 import android.view.MotionEvent;
-import android.view.View;
-import android.widget.FrameLayout;
-import android.widget.ImageView;
 
 class ScrollGestureLayout extends GestureLayout {
 
@@ -19,7 +12,7 @@ class ScrollGestureLayout extends GestureLayout {
 
     private GestureDetector mDetector;
     private boolean mNotify;
-    private float mDistance;
+    /* tests */ float mFactor;
 
 
     public ScrollGestureLayout(Context context) {
@@ -47,8 +40,8 @@ class ScrollGestureLayout extends GestureLayout {
                     horizontal = mType == Gesture.SCROLL_HORIZONTAL;
                 }
                 mPoints[1].set(e2.getX(), e2.getY());
-                mDistance = horizontal ? (distanceX / getWidth()) : (distanceY / getHeight());
-                mDistance = horizontal ? -mDistance : mDistance; // When vertical, up = positive
+                mFactor = horizontal ? (distanceX / getWidth()) : (distanceY / getHeight());
+                mFactor = horizontal ? -mFactor : mFactor; // When vertical, up = positive
                 mNotify = true;
                 return true;
             }
@@ -80,21 +73,14 @@ class ScrollGestureLayout extends GestureLayout {
 
     @Override
     public float scaleValue(float currValue, float minValue, float maxValue) {
-        float delta = mDistance; // -1 ... 1
+        float delta = mFactor; // -1 ... 1
 
         // ^ This works well if minValue = 0, maxValue = 1.
         // Account for the different range:
         delta *= (maxValue - minValue); // -(max-min) ... (max-min)
+        delta *= 2; // Add some sensitivity.
 
-        // Add some sensitivity.
-        delta *= 2;
-
-        // Cap
-        float newValue = currValue + delta;
-        if (newValue < minValue) newValue = minValue;
-        if (newValue > maxValue) newValue = maxValue;
-        LOG.i("curr="+currValue, "min="+minValue, "max="+maxValue, "out="+newValue);
-        return newValue;
+        return capValue(currValue, currValue + delta, minValue, maxValue);
     }
 
 }