[Paint Preview] Decouple *Controller classes from Mediator

Break cyclic dependency of PlayerFrameMediator with
- PlayerFrameScaleController
- PlayerFrameScrollController

BitmapState is tightly coupled to PlayerFrameMediator with good reason
so a cyclic dependency there is somewhat unavoidable.

This is achieved by having PlayerFrameCoordinator instantiate
everything and then introducing a new class that handles dispatch of
gestures. A helper for scaling is also added to break the two-way
interdependence that existed in the mediator.

Bug: 1099722
Change-Id: I13b258d973a5ff81cdf75505f59aabb02d66a6c6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2295751
Commit-Queue: Calder Kitagawa <ckitagawa@chromium.org>
Reviewed-by: Mehran Mahmoudi <mahmoudi@chromium.org>
Reviewed-by: Fred Mello <fredmello@chromium.org>
Cr-Commit-Position: refs/heads/master@{#789996}

components/paint_preview/player/android/BUILD.gn

@@ -61,6 +61,7 @@ android_library("java") {
     "java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameBitmapStateController.java",
     "java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameCoordinator.java",
     "java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameGestureDetector.java",
+    "java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameGestureDetectorDelegate.java",
     "java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameMediator.java",
     "java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameMediatorDelegate.java",
     "java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameProperties.java",

components/paint_preview/player/android/java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameCoordinator.java

@@ -6,6 +6,7 @@ package org.chromium.components.paintpreview.player.frame;
 
 import android.content.Context;
 import android.graphics.Rect;
+import android.util.Size;
 import android.view.View;
 import android.view.ViewConfiguration;
 import android.widget.OverScroller;
@@ -37,12 +38,24 @@ public class PlayerFrameCoordinator {
         PropertyModel model = new PropertyModel.Builder(PlayerFrameProperties.ALL_KEYS).build();
         OverScroller scroller = new OverScroller(context);
         scroller.setFriction(ViewConfiguration.getScrollFriction() / 2);
-        mMediator = new PlayerFrameMediator(model, compositorDelegate, new PlayerFrameViewport(),
-                scroller, gestureHandler, frameGuid, contentWidth, contentHeight, initialScrollX,
-                initialScrollY);
-        mView = new PlayerFrameView(context, canDetectZoom, mMediator);
+
+        mMediator = new PlayerFrameMediator(model, compositorDelegate, gestureHandler, frameGuid,
+                new Size(contentWidth, contentHeight), initialScrollX, initialScrollY);
+
+        PlayerFrameScaleController scaleController = null;
+        if (canDetectZoom) {
+            scaleController =
+                    new PlayerFrameScaleController(model.get(PlayerFrameProperties.SCALE_MATRIX),
+                            mMediator, gestureHandler::onScale);
+        }
+        PlayerFrameScrollController scrollController = new PlayerFrameScrollController(
+                scroller, mMediator, gestureHandler::onScroll, gestureHandler::onFling);
+        PlayerFrameGestureDetectorDelegate gestureDelegate = new PlayerFrameGestureDetectorDelegate(
+                scaleController, scrollController, mMediator);
+
+        mView = new PlayerFrameView(context, canDetectZoom, mMediator, gestureDelegate);
         if (overscrollHandler != null) {
-            mMediator.setOverscrollHandler(overscrollHandler);
+            scrollController.setOverscrollHandler(overscrollHandler);
         }
         PropertyModelChangeProcessor.create(model, mView, PlayerFrameViewBinder::bind);
     }

components/paint_preview/player/android/java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameGestureDetector.java

@@ -11,14 +11,14 @@ import android.view.ScaleGestureDetector;
 
 /**
  * Detects scroll, fling, and scale gestures on calls to {@link #onTouchEvent} and reports back to
- * the provided {@link PlayerFrameViewDelegate}.
+ * the provided {@link PlayerFrameGestureDetectorDelegate}.
  */
 class PlayerFrameGestureDetector
         implements GestureDetector.OnGestureListener, ScaleGestureDetector.OnScaleGestureListener {
     private GestureDetector mGestureDetector;
     private ScaleGestureDetector mScaleGestureDetector;
     private boolean mCanDetectZoom;
-    private PlayerFrameViewDelegate mPlayerFrameViewDelegate;
+    private PlayerFrameGestureDetectorDelegate mDelegate;
     private PlayerFrameGestureDetector mParentGestureDetector;
     /**
      * Last horizontal scroll distance that was detected by this {@link PlayerFrameGestureDetector}
@@ -36,14 +36,14 @@ class PlayerFrameGestureDetector
      * {@link ScaleGestureDetector}.
      * @param canDetectZoom Whether this {@link PlayerFrameGestureDetector} should detect scale
      * gestures.
-     * @param playerFrameViewDelegate The delegate used when desired gestured are detected.
+     * @param delegate The delegate used when desired gestured are detected.
      */
-    PlayerFrameGestureDetector(Context context, boolean canDetectZoom,
-            PlayerFrameViewDelegate playerFrameViewDelegate) {
+    PlayerFrameGestureDetector(
+            Context context, boolean canDetectZoom, PlayerFrameGestureDetectorDelegate delegate) {
         mGestureDetector = new GestureDetector(context, this);
         mScaleGestureDetector = new ScaleGestureDetector(context, this);
         mCanDetectZoom = canDetectZoom;
-        mPlayerFrameViewDelegate = playerFrameViewDelegate;
+        mDelegate = delegate;
     }
 
     /**
@@ -65,7 +65,7 @@ class PlayerFrameGestureDetector
         }
 
         if (event.getAction() == MotionEvent.ACTION_UP) {
-            mPlayerFrameViewDelegate.onRelease();
+            mDelegate.onRelease();
             // Propagate the release to the parent, this won't trigger any unexpected behavior as
             // this is only an UP event.
             if (mParentGestureDetector != null) {
@@ -85,13 +85,13 @@ class PlayerFrameGestureDetector
 
     @Override
     public boolean onSingleTapUp(MotionEvent e) {
-        mPlayerFrameViewDelegate.onTap((int) e.getX(), (int) e.getY());
+        mDelegate.onTap((int) e.getX(), (int) e.getY());
         return true;
     }
 
     @Override
     public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
-        if (mPlayerFrameViewDelegate.scrollBy(distanceX, distanceY)) {
+        if (mDelegate.scrollBy(distanceX, distanceY)) {
             mLastParentScrollX = 0f;
             mLastParentScrollY = 0f;
             return true;
@@ -116,12 +116,12 @@ class PlayerFrameGestureDetector
 
     @Override
     public void onLongPress(MotionEvent e) {
-        mPlayerFrameViewDelegate.onLongPress((int) e.getX(), (int) e.getY());
+        mDelegate.onLongPress((int) e.getX(), (int) e.getY());
     }
 
     @Override
     public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
-        if (mPlayerFrameViewDelegate.onFling(velocityX, velocityY)) return true;
+        if (mDelegate.onFling(velocityX, velocityY)) return true;
 
         if (mParentGestureDetector != null) {
             return mParentGestureDetector.onFling(e1, e2, velocityX, velocityY);
@@ -132,7 +132,7 @@ class PlayerFrameGestureDetector
     @Override
     public boolean onScale(ScaleGestureDetector detector) {
         assert mCanDetectZoom;
-        return mPlayerFrameViewDelegate.scaleBy(
+        return mDelegate.scaleBy(
                 detector.getScaleFactor(), detector.getFocusX(), detector.getFocusY());
     }
 
@@ -145,7 +145,7 @@ class PlayerFrameGestureDetector
     @Override
     public void onScaleEnd(ScaleGestureDetector detector) {
         assert mCanDetectZoom;
-        mPlayerFrameViewDelegate.scaleFinished(
+        mDelegate.scaleFinished(
                 detector.getScaleFactor(), detector.getFocusX(), detector.getFocusY());
     }
 }

components/paint_preview/player/android/java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameGestureDetectorDelegate.java

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.components.paintpreview.player.frame;
+
+/**
+ * Dispatches gesture events to the correct controllers.
+ */
+public class PlayerFrameGestureDetectorDelegate {
+    private final PlayerFrameScaleController mScaleController;
+    private final PlayerFrameScrollController mScrollController;
+    private final PlayerFrameViewDelegate mViewDelegate;
+
+    PlayerFrameGestureDetectorDelegate(PlayerFrameScaleController scaleController,
+            PlayerFrameScrollController scrollController, PlayerFrameViewDelegate viewDelegate) {
+        mScaleController = scaleController;
+        mScrollController = scrollController;
+        mViewDelegate = viewDelegate;
+    }
+
+    /**
+     * Called when a scroll gesture is performed.
+     * @param distanceX Horizontal scroll values in pixels.
+     * @param distanceY Vertical scroll values in pixels.
+     * @return Whether this scroll event was consumed.
+     */
+    boolean scrollBy(float distanceX, float distanceY) {
+        return mScrollController.scrollBy(distanceX, distanceY);
+    }
+
+    /**
+     * Called when a fling gesture is performed.
+     * @param velocityX Horizontal velocity value in pixels.
+     * @param velocityY Vertical velocity value in pixels.
+     * @return Whether this fling was consumed.
+     */
+    boolean onFling(float velocityX, float velocityY) {
+        return mScrollController.onFling(velocityX, velocityY);
+    }
+
+    /**
+     * Called when a gesture is released.
+     */
+    void onRelease() {
+        mScrollController.onRelease();
+    }
+
+    /**
+     * Called when a scale gesture is performed.
+     * @return Whether this scale event was consumed.
+     */
+    boolean scaleBy(float scaleFactor, float focalPointX, float focalPointY) {
+        return mScaleController.scaleBy(scaleFactor, focalPointX, focalPointY);
+    }
+
+    /**
+     * Called when a scale gesture is finished.
+     * @return Whether this scale event was consumed.
+     */
+    boolean scaleFinished(float scaleFactor, float focalPointX, float focalPointY) {
+        return mScaleController.scaleFinished(scaleFactor, focalPointX, focalPointY);
+    }
+
+    /**
+     * Called when a single tap gesture is performed.
+     * @param x X coordinate of the point clicked.
+     * @param y Y coordinate of the point clicked.
+     */
+    void onTap(int x, int y) {
+        mViewDelegate.onTap(x, y);
+    }
+
+    /**
+     * Called when a long press gesture is performed.
+     * @param x X coordinate of the point clicked.
+     * @param y Y coordinate of the point clicked.
+     */
+    void onLongPress(int x, int y) {
+        mViewDelegate.onLongPress(x, y);
+    }
+}

components/paint_preview/player/android/java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameMediator.java

@@ -9,12 +9,10 @@ import android.graphics.Matrix;
 import android.graphics.Rect;
 import android.util.Size;
 import android.view.View;
-import android.widget.OverScroller;
 
 import androidx.annotation.VisibleForTesting;
 
 import org.chromium.base.UnguessableToken;
-import org.chromium.components.paintpreview.player.OverscrollHandler;
 import org.chromium.components.paintpreview.player.PlayerCompositorDelegate;
 import org.chromium.components.paintpreview.player.PlayerGestureListener;
 import org.chromium.ui.modelutil.PropertyModel;
@@ -64,36 +62,29 @@ class PlayerFrameMediator implements PlayerFrameViewDelegate, PlayerFrameMediato
     /** The viewport of this frame. */
     private final PlayerFrameViewport mViewport;
 
+    private float mInitialScaleFactor;
     /** Handles scaling of bitmaps. */
-    private final Matrix mBitmapScaleMatrix = new Matrix();
-
-    /** Handles scrolling. */
-    private final PlayerFrameScrollController mScrollController;
-    /** Handles scaling. */
-    private final PlayerFrameScaleController mScaleController;
+    private final Matrix mBitmapScaleMatrix;
 
     private final PlayerFrameBitmapStateController mBitmapStateController;
 
     private PlayerGestureListener mGestureListener;
 
     PlayerFrameMediator(PropertyModel model, PlayerCompositorDelegate compositorDelegate,
-            PlayerFrameViewport viewport, OverScroller scroller,
-            PlayerGestureListener gestureListener, UnguessableToken frameGuid, int contentWidth,
-            int contentHeight, int initialScrollX, int initialScrollY) {
+            PlayerGestureListener gestureListener, UnguessableToken frameGuid, Size contentSize,
+            int initialScrollX, int initialScrollY) {
+        mBitmapScaleMatrix = new Matrix();
         mModel = model;
         mModel.set(PlayerFrameProperties.SCALE_MATRIX, mBitmapScaleMatrix);
 
         mCompositorDelegate = compositorDelegate;
-        mViewport = viewport;
+        mGestureListener = gestureListener;
+        mViewport = new PlayerFrameViewport();
+        mInitialScaleFactor = 0f;
         mGuid = frameGuid;
-        mContentSize = new Size(contentWidth, contentHeight);
+        mContentSize = contentSize;
         mBitmapStateController = new PlayerFrameBitmapStateController(
                 mGuid, mViewport, mContentSize, mCompositorDelegate, this);
-        mScrollController = new PlayerFrameScrollController(scroller, mViewport, mContentSize, this,
-                gestureListener::onScroll, gestureListener::onFling);
-        mScaleController = new PlayerFrameScaleController(
-                mViewport, mContentSize, mBitmapScaleMatrix, this, gestureListener::onScale);
-        mGestureListener = gestureListener;
         mViewport.offset(initialScrollX, initialScrollY);
         mViewport.setScale(0f);
     }
@@ -143,15 +134,6 @@ class PlayerFrameMediator implements PlayerFrameViewDelegate, PlayerFrameMediato
         setBitmapScaleMatrix(matrix, scaleFactor);
     }
 
-    /**
-     * Sets the overscroll-to-refresh handler on the {@link mScrollController}. This cannot be
-     * created at construction of this object as it needs to be created on top of the view
-     * hierarchy to show the animation.
-     */
-    void setOverscrollHandler(OverscrollHandler overscrollHandler) {
-        mScrollController.setOverscrollHandler(overscrollHandler);
-    }
-
     // PlayerFrameViewDelegate
 
     @Override
@@ -163,35 +145,10 @@ class PlayerFrameMediator implements PlayerFrameViewDelegate, PlayerFrameMediato
         }
 
         // Set initial scale so that content width fits within the layout dimensions.
-        mScaleController.calculateInitialScaleFactor(width);
+        adjustInitialScaleFactor(width);
         final float scaleFactor = mViewport.getScale();
-        updateViewportSize(width, height,
-                (scaleFactor == 0f) ? mScaleController.getInitialScaleFactor() : scaleFactor);
-    }
-
-    @Override
-    public boolean scrollBy(float distanceX, float distanceY) {
-        return mScrollController.scrollBy(distanceX, distanceY);
-    }
-
-    @Override
-    public boolean onFling(float velocityX, float velocityY) {
-        return mScrollController.onFling(velocityX, velocityY);
-    }
-
-    @Override
-    public void onRelease() {
-        mScrollController.onRelease();
-    }
-
-    @Override
-    public boolean scaleBy(float scaleFactor, float focalPointX, float focalPointY) {
-        return mScaleController.scaleBy(scaleFactor, focalPointX, focalPointY);
-    }
-
-    @Override
-    public boolean scaleFinished(float scaleFactor, float focalPointX, float focalPointY) {
-        return mScaleController.scaleFinished(scaleFactor, focalPointX, focalPointY);
+        updateViewportSize(
+                width, height, (scaleFactor == 0f) ? getInitialScaleFactor() : scaleFactor);
     }
 
     @Override
@@ -212,6 +169,21 @@ class PlayerFrameMediator implements PlayerFrameViewDelegate, PlayerFrameMediato
 
     // PlayerFrameMediatorDelegate
 
+    @Override
+    public PlayerFrameViewport getViewport() {
+        return mViewport;
+    }
+
+    @Override
+    public Size getContentSize() {
+        return mContentSize;
+    }
+
+    @Override
+    public float getInitialScaleFactor() {
+        return mInitialScaleFactor;
+    }
+
     @Override
     public void onStartScaling() {
         mBitmapStateController.invalidateLoadingBitmaps();
@@ -342,10 +314,9 @@ class PlayerFrameMediator implements PlayerFrameViewDelegate, PlayerFrameMediato
 
     @VisibleForTesting
     void forceRedraw() {
-        mScaleController.calculateInitialScaleFactor(mViewport.getWidth());
+        adjustInitialScaleFactor(mViewport.getWidth());
         final float scaleFactor = mViewport.getScale();
-        mViewport.setScale(
-                (scaleFactor == 0f) ? mScaleController.getInitialScaleFactor() : scaleFactor);
+        mViewport.setScale((scaleFactor == 0f) ? getInitialScaleFactor() : scaleFactor);
         updateVisuals(true);
         for (int i = 0; i < mSubFrameViews.size(); i++) {
             if (mSubFrameViews.get(i).getVisibility() != View.VISIBLE) continue;
@@ -360,4 +331,12 @@ class PlayerFrameMediator implements PlayerFrameViewDelegate, PlayerFrameMediato
                 (int) (((float) inRect.right) * scaleFactor),
                 (int) (((float) inRect.bottom) * scaleFactor));
     }
+
+    /**
+     * Calculates the initial scale factor for a given viewport width.
+     * @param width The viewport width.
+     */
+    private void adjustInitialScaleFactor(float width) {
+        mInitialScaleFactor = width / ((float) mContentSize.getWidth());
+    }
 }

components/paint_preview/player/android/java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameMediatorDelegate.java

@@ -7,11 +7,27 @@ package org.chromium.components.paintpreview.player.frame;
 import android.graphics.Bitmap;
 import android.graphics.Matrix;
 import android.graphics.Rect;
+import android.util.Size;
 
 /**
  * API of the PlayerFrameMediator to helper classes.
  */
 public interface PlayerFrameMediatorDelegate {
+    /**
+     * Gets the visual viewport of the player.
+     */
+    public PlayerFrameViewport getViewport();
+
+    /**
+     * Gets the size of the content shown in the mediator.
+     */
+    public Size getContentSize();
+
+    /**
+     * Gets the initial scale factor at the last computed viewport width.
+     */
+    public float getInitialScaleFactor();
+
     /**
      * Triggers an update of the visual contents of the PlayerFrameView. This fetches updates the
      * model and fetches any new bitmaps asynchronously.

components/paint_preview/player/android/java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameScaleController.java

@@ -18,7 +18,6 @@ import org.chromium.base.Callback;
 public class PlayerFrameScaleController {
     private static final float MAX_SCALE_FACTOR = 5f;
 
-    private float mInitialScaleFactor;
     private float mUncommittedScaleFactor;
 
     /** References to shared state. */
@@ -29,31 +28,17 @@ public class PlayerFrameScaleController {
     private final PlayerFrameMediatorDelegate mMediatorDelegate;
     private final Callback<Boolean> mOnScaleListener;
 
-    PlayerFrameScaleController(PlayerFrameViewport viewport, Size contentSize,
-            Matrix bitmapScaleMatrix, PlayerFrameMediatorDelegate mediatorDelegate,
+    PlayerFrameScaleController(Matrix bitmapScaleMatrix,
+            PlayerFrameMediatorDelegate mediatorDelegate,
             @Nullable Callback<Boolean> onScaleListener) {
-        mViewport = viewport;
-        mContentSize = contentSize;
+        mUncommittedScaleFactor = 0f;
+        mViewport = mediatorDelegate.getViewport();
+        mContentSize = mediatorDelegate.getContentSize();
         mBitmapScaleMatrix = bitmapScaleMatrix;
         mMediatorDelegate = mediatorDelegate;
         mOnScaleListener = onScaleListener;
     }
 
-    /**
-     * Calculates the initial scale factor for a given viewport width.
-     * @param width The viewport width.
-     */
-    void calculateInitialScaleFactor(float width) {
-        mInitialScaleFactor = width / ((float) mContentSize.getWidth());
-    }
-
-    /**
-     * Gets the initial scale factor at the last computed viewport width.
-     */
-    float getInitialScaleFactor() {
-        return mInitialScaleFactor;
-    }
-
     /**
      * How scale for the paint preview player works.
      *
@@ -92,22 +77,23 @@ public class PlayerFrameScaleController {
         }
         // Don't scale outside of the acceptable range. The value is still accumulated such that the
         // continuous gesture feels smooth.
+        final float initialScaleFactor = mMediatorDelegate.getInitialScaleFactor();
         final float lastUncommittedScaleFactor = mUncommittedScaleFactor;
         mUncommittedScaleFactor *= scaleFactor;
         // Compute a corrected and bounded scale factor when close to the max/min scale.
-        if (mUncommittedScaleFactor < mInitialScaleFactor
-                && lastUncommittedScaleFactor > mInitialScaleFactor) {
-            scaleFactor = mInitialScaleFactor / lastUncommittedScaleFactor;
+        if (mUncommittedScaleFactor < initialScaleFactor
+                && lastUncommittedScaleFactor > initialScaleFactor) {
+            scaleFactor = initialScaleFactor / lastUncommittedScaleFactor;
         } else if (mUncommittedScaleFactor > MAX_SCALE_FACTOR
                 && lastUncommittedScaleFactor < MAX_SCALE_FACTOR) {
             scaleFactor = MAX_SCALE_FACTOR / lastUncommittedScaleFactor;
-        } else if (mUncommittedScaleFactor > mInitialScaleFactor
-                && lastUncommittedScaleFactor < mInitialScaleFactor) {
-            scaleFactor = mUncommittedScaleFactor / mInitialScaleFactor;
+        } else if (mUncommittedScaleFactor > initialScaleFactor
+                && lastUncommittedScaleFactor < initialScaleFactor) {
+            scaleFactor = mUncommittedScaleFactor / initialScaleFactor;
         } else if (mUncommittedScaleFactor < MAX_SCALE_FACTOR
                 && lastUncommittedScaleFactor > MAX_SCALE_FACTOR) {
             scaleFactor = mUncommittedScaleFactor / MAX_SCALE_FACTOR;
-        } else if (mUncommittedScaleFactor < mInitialScaleFactor
+        } else if (mUncommittedScaleFactor < initialScaleFactor
                 || lastUncommittedScaleFactor > MAX_SCALE_FACTOR) {
             return true;
         }

components/paint_preview/player/android/java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameScrollController.java

@@ -32,12 +32,11 @@ public class PlayerFrameScrollController {
     private final Runnable mOnScrollListener;
     private final Runnable mOnFlingListener;
 
-    PlayerFrameScrollController(OverScroller scroller, PlayerFrameViewport viewport,
-            Size contentSize, PlayerFrameMediatorDelegate mediatorDelegate,
+    PlayerFrameScrollController(OverScroller scroller, PlayerFrameMediatorDelegate mediatorDelegate,
             @Nullable Runnable onScrollListener, @Nullable Runnable onFlingListener) {
         mScroller = scroller;
-        mViewport = viewport;
-        mContentSize = contentSize;
+        mViewport = mediatorDelegate.getViewport();
+        mContentSize = mediatorDelegate.getContentSize();
         mMediatorDelegate = mediatorDelegate;
         mOnScrollListener = onScrollListener;
         mOnFlingListener = onFlingListener;

components/paint_preview/player/android/java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameView.java

@@ -38,13 +38,14 @@ class PlayerFrameView extends FrameLayout {
      * @param playerFrameViewDelegate The interface used for forwarding events.
      */
     PlayerFrameView(@NonNull Context context, boolean canDetectZoom,
-            PlayerFrameViewDelegate playerFrameViewDelegate) {
+            PlayerFrameViewDelegate playerFrameViewDelegate,
+            PlayerFrameGestureDetectorDelegate gestureDetectorDelegate) {
         super(context);
         setWillNotDraw(false);
         mDelegate = playerFrameViewDelegate;
         mBitmapPainter = new PlayerFrameBitmapPainter(this::invalidate);
         mGestureDetector =
-                new PlayerFrameGestureDetector(context, canDetectZoom, playerFrameViewDelegate);
+                new PlayerFrameGestureDetector(context, canDetectZoom, gestureDetectorDelegate);
     }
 
     PlayerFrameGestureDetector getGestureDetector() {

components/paint_preview/player/android/java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameViewDelegate.java

@@ -13,26 +13,6 @@ interface PlayerFrameViewDelegate {
      */
     void setLayoutDimensions(int width, int height);
 
-    /**
-     * Called when a scroll gesture is performed.
-     * @param distanceX Horizontal scroll values in pixels.
-     * @param distanceY Vertical scroll values in pixels.
-     * @return Whether this scroll event was consumed.
-     */
-    boolean scrollBy(float distanceX, float distanceY);
-
-    /**
-     * Called when a scale gesture is performed.
-     * @return Whether this scale event was consumed.
-     */
-    boolean scaleBy(float scaleFactor, float focalPointX, float focalPointY);
-
-    /**
-     * Called when a scale gesture is finished.
-     * @return Whether this scale event was consumed.
-     */
-    boolean scaleFinished(float scaleFactor, float focalPointX, float focalPointY);
-
     /**
      * Called when a single tap gesture is performed.
      * @param x X coordinate of the point clicked.
@@ -46,17 +26,4 @@ interface PlayerFrameViewDelegate {
      * @param y Y coordinate of the point clicked.
      */
     void onLongPress(int x, int y);
-
-    /**
-     * Called when a fling gesture is performed.
-     * @param velocityX Horizontal velocity value in pixels.
-     * @param velocityY Vertical velocity value in pixels.
-     * @return Whether this fling was consumed.
-     */
-    boolean onFling(float velocityX, float velocityY);
-
-    /**
-     * Called when a gesture is released.
-     */
-    void onRelease();
 }

components/paint_preview/player/android/junit/src/org/chromium/components/paintpreview/player/frame/PlayerFrameScaleControllerTest.java

@@ -7,6 +7,7 @@ package org.chromium.components.paintpreview.player.frame;
 import static org.mockito.ArgumentMatchers.argThat;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.inOrder;
+import static org.mockito.Mockito.when;
 
 import android.graphics.Matrix;
 import android.util.Size;
@@ -59,29 +60,16 @@ public class PlayerFrameScaleControllerTest {
         Callback<Boolean> mScaleListener = (Boolean didFinish) -> mDidScale = true;
         mViewport = new PlayerFrameViewport();
         mBitmapScaleMatrix = new Matrix();
-        mScaleController =
-                new PlayerFrameScaleController(mViewport, new Size(CONTENT_WIDTH, CONTENT_HEIGHT),
-                        mBitmapScaleMatrix, mMediatorDelegateMock, mScaleListener);
-        mScaleController.calculateInitialScaleFactor(CONTENT_WIDTH);
-        mViewport.setScale(mScaleController.getInitialScaleFactor());
+        Size contentSize = new Size(CONTENT_WIDTH, CONTENT_HEIGHT);
+        when(mMediatorDelegateMock.getViewport()).thenReturn(mViewport);
+        when(mMediatorDelegateMock.getContentSize()).thenReturn(contentSize);
+        when(mMediatorDelegateMock.getInitialScaleFactor()).thenReturn(1f);
+        mScaleController = new PlayerFrameScaleController(
+                mBitmapScaleMatrix, mMediatorDelegateMock, mScaleListener);
+        mViewport.setScale(1f);
         mViewport.setSize(100, 100);
     }
 
-    /**
-     * Tests calculating and getting the initial scale factor.
-     */
-    @Test
-    public void testInitialScaleFactor() {
-        mScaleController.calculateInitialScaleFactor(CONTENT_WIDTH);
-        Assert.assertEquals(1f, mScaleController.getInitialScaleFactor(), TOLERANCE);
-
-        mScaleController.calculateInitialScaleFactor(250);
-        Assert.assertEquals(0.5f, mScaleController.getInitialScaleFactor(), TOLERANCE);
-
-        mScaleController.calculateInitialScaleFactor(1000);
-        Assert.assertEquals(2f, mScaleController.getInitialScaleFactor(), TOLERANCE);
-    }
-
     /**
      * Tests the limits of scaling.
      */

components/paint_preview/player/android/junit/src/org/chromium/components/paintpreview/player/frame/PlayerFrameScrollControllerTest.java

@@ -56,9 +56,11 @@ public class PlayerFrameScrollControllerTest {
         Runnable mOnScrollListener = () -> mDidScroll = true;
         Runnable mOnFlingListener = () -> mDidFling = true;
         mViewport = new PlayerFrameViewport();
-        mScrollController = new PlayerFrameScrollController(mScroller, mViewport,
-                new Size(CONTENT_WIDTH, CONTENT_HEIGHT), mMediatorDelegateMock, mOnScrollListener,
-                mOnFlingListener);
+        when(mMediatorDelegateMock.getViewport()).thenReturn(mViewport);
+        when(mMediatorDelegateMock.getContentSize())
+                .thenReturn(new Size(CONTENT_WIDTH, CONTENT_HEIGHT));
+        mScrollController = new PlayerFrameScrollController(
+                mScroller, mMediatorDelegateMock, mOnScrollListener, mOnFlingListener);
     }
 
     /**