Don't scale on double tap if there is movement before an up event

Change-Id: I60fc2025def88ac9b7b55ba52c93569f7cfd8f45

1 files changed, 65 insertions, 15 deletions

diff --git a/src/com/android/ex/photo/views/PhotoView.java b/src/com/android/ex/photo/views/PhotoView.java
index 0bc704e..a2e7107 100644
--- a/src/com/android/ex/photo/views/PhotoView.java
+++ b/src/com/android/ex/photo/views/PhotoView.java
@@ -34,6 +34,7 @@ import android.view.GestureDetector.OnDoubleTapListener;
 import android.view.MotionEvent;
 import android.view.ScaleGestureDetector;
 import android.view.View;
+import android.view.ViewConfiguration;
 
 import com.android.ex.photo.R;
 import com.android.ex.photo.fragments.PhotoViewFragment.HorizontallyScrollable;
@@ -59,6 +60,12 @@ public class PhotoView extends View implements OnGestureListener,
     /** The width & height of the bitmap returned by {@link #getCroppedPhoto()} */
     private final static float CROPPED_SIZE = 256.0f;
 
+    /**
+     * Touch slop used to determine if this double tap is valid for starting a scale or should be
+     * ignored.
+     */
+    private static int sTouchSlopSquare;
+
     /** If {@code true}, the static values have been initialized */
     private static boolean sInitialized;
 
@@ -154,6 +161,19 @@ public class PhotoView extends View implements OnGestureListener,
     /** Array to store a copy of the matrix values */
     private float[] mValues = new float[9];
 
+    /**
+     * Track whether a double tap event occurred.
+     */
+    private boolean mDoubleTapOccurred;
+
+    /**
+     * X and Y coordinates for the current down event. Since mDoubleTapOccurred only contains the
+     * information that there was a double tap event, use these to get the secondary tap
+     * information to determine if a user has moved beyond touch slop.
+     */
+    private float mDownFocusX;
+    private float mDownFocusY;
+
     public PhotoView(Context context) {
         super(context);
         initialize();
@@ -194,25 +214,50 @@ public class PhotoView extends View implements OnGestureListener,
 
     @Override
     public boolean onDoubleTap(MotionEvent e) {
-        if (mDoubleTapToZoomEnabled && mTransformsEnabled) {
-            if (!mDoubleTapDebounce) {
-                float currentScale = getScale();
-                float targetScale = currentScale * DOUBLE_TAP_SCALE_FACTOR;
-
-                // Ensure the target scale is within our bounds
-                targetScale = Math.max(mMinScale, targetScale);
-                targetScale = Math.min(mMaxScale, targetScale);
-
-                mScaleRunnable.start(currentScale, targetScale, e.getX(), e.getY());
-            }
-            mDoubleTapDebounce = false;
-        }
-        return true;
+        mDoubleTapOccurred = true;
+        return false;
     }
 
     @Override
     public boolean onDoubleTapEvent(MotionEvent e) {
-        return true;
+        final int action = e.getAction();
+        boolean handled = false;
+
+        switch (action) {
+            case MotionEvent.ACTION_DOWN:
+                mDownFocusX = e.getX();
+                mDownFocusY = e.getY();
+                break;
+            case MotionEvent.ACTION_UP:
+                if (mDoubleTapToZoomEnabled && mTransformsEnabled && mDoubleTapOccurred) {
+                    if (!mDoubleTapDebounce) {
+                        float currentScale = getScale();
+                        float targetScale = currentScale * DOUBLE_TAP_SCALE_FACTOR;
+
+                        // Ensure the target scale is within our bounds
+                        targetScale = Math.max(mMinScale, targetScale);
+                        targetScale = Math.min(mMaxScale, targetScale);
+
+                        mScaleRunnable.start(currentScale, targetScale, e.getX(), e.getY());
+                    }
+                    mDoubleTapDebounce = false;
+                }
+                handled = true;
+                mDoubleTapOccurred = false;
+                break;
+            case MotionEvent.ACTION_MOVE:
+                if (mDoubleTapOccurred) {
+                    final int deltaX = (int) (e.getX() - mDownFocusX);
+                    final int deltaY = (int) (e.getY() - mDownFocusY);
+                    int distance = (deltaX * deltaX) + (deltaY * deltaY);
+                    if (distance > sTouchSlopSquare) {
+                        mDoubleTapOccurred = false;
+                    }
+                }
+                break;
+
+        }
+        return handled;
     }
 
     @Override
@@ -379,6 +424,7 @@ public class PhotoView extends View implements OnGestureListener,
         mRotateRunnable = null;
         setOnClickListener(null);
         mExternalClickListener = null;
+        mDoubleTapOccurred = false;
     }
 
     /**
@@ -933,6 +979,10 @@ public class PhotoView extends View implements OnGestureListener,
             sCropPaint.setColor(resources.getColor(R.color.photo_crop_highlight_color));
             sCropPaint.setStyle(Style.STROKE);
             sCropPaint.setStrokeWidth(resources.getDimension(R.dimen.photo_crop_stroke_width));
+
+            final ViewConfiguration configuration = ViewConfiguration.get(context);
+            final int touchSlop = configuration.getScaledTouchSlop();
+            sTouchSlopSquare = touchSlop * touchSlop;
         }
 
         mGestureDetector = new GestureDetectorCompat(context, this, null);