Add double tap callback for divider bar

Add a callback in split layout to notify registered listener when users
double tapped the divider bar. Use this callback to switch side stage
position.

Bug: 176061049
Test: atest SplitLayoutTests
Test: manual check stage position changed when double tapped divider bar
Change-Id: Id3929b01a194b8eb0838cc892156bbbe48dc8690

libs/WindowManager/Shell/src/com/android/wm/shell/common/split/DividerView.java

@@ -21,6 +21,7 @@ import static android.view.WindowManager.LayoutParams.FLAG_SLIPPERY;
 
 import android.content.Context;
 import android.util.AttributeSet;
+import android.view.GestureDetector;
 import android.view.MotionEvent;
 import android.view.SurfaceControlViewHost;
 import android.view.VelocityTracker;
@@ -54,6 +55,7 @@ public class DividerView extends FrameLayout implements View.OnTouchListener {
     private VelocityTracker mVelocityTracker;
     private boolean mMoving;
     private int mStartPos;
+    private GestureDetector mDoubleTapDetector;
 
     public DividerView(@NonNull Context context) {
         super(context);
@@ -88,6 +90,7 @@ public class DividerView extends FrameLayout implements View.OnTouchListener {
         mBackground = findViewById(R.id.docked_divider_background);
         mTouchElevation = getResources().getDimensionPixelSize(
                 R.dimen.docked_stack_divider_lift_elevation);
+        mDoubleTapDetector = new GestureDetector(getContext(), new DoubleTapListener());
         setOnTouchListener(this);
     }
 
@@ -136,6 +139,8 @@ public class DividerView extends FrameLayout implements View.OnTouchListener {
                 mSplitLayout.snapToTarget(position, snapTarget);
                 break;
         }
+
+        mDoubleTapDetector.onTouchEvent(event);
         return true;
     }
 
@@ -200,4 +205,14 @@ public class DividerView extends FrameLayout implements View.OnTouchListener {
     private boolean isLandscape() {
         return getResources().getConfiguration().orientation == ORIENTATION_LANDSCAPE;
     }
+
+    private class DoubleTapListener extends GestureDetector.SimpleOnGestureListener {
+        @Override
+        public boolean onDoubleTap(MotionEvent e) {
+            if (mSplitLayout != null) {
+                mSplitLayout.onDoubleTappedDivider();
+            }
+            return false;
+        }
+    }
 }

libs/WindowManager/Shell/src/com/android/wm/shell/common/split/SplitLayout.java

@@ -201,6 +201,10 @@ public class SplitLayout {
         }
     }
 
+    void onDoubleTappedDivider() {
+        mLayoutChangeListener.onDoubleTappedDivider();
+    }
+
     /**
      * Returns {@link DividerSnapAlgorithm.SnapTarget} which matches passing position and velocity.
      */
@@ -249,9 +253,15 @@ public class SplitLayout {
     public interface LayoutChangeListener {
         /** Calls when dismissing split. */
         void onSnappedToDismiss(boolean snappedToEnd);
+
         /** Calls when the bounds is changing due to animation or dragging divider bar. */
         void onBoundsChanging(SplitLayout layout);
+
         /** Calls when the target bounds changed. */
         void onBoundsChanged(SplitLayout layout);
+
+        /** Calls when user double tapped on the divider bar. */
+        default void onDoubleTappedDivider() {
+        }
     }
 }

libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java

@@ -270,6 +270,12 @@ class StageCoordinator implements SplitLayout.LayoutChangeListener,
 
     }
 
+    @Override
+    public void onDoubleTappedDivider() {
+        setSideStagePosition(mSideStagePosition == SIDE_STAGE_POSITION_TOP_OR_LEFT
+                ? SIDE_STAGE_POSITION_BOTTOM_OR_RIGHT : SIDE_STAGE_POSITION_TOP_OR_LEFT);
+    }
+
     @Override
     public void onBoundsChanged(SplitLayout layout) {
         final SurfaceControl dividerLeash = mSplitLayout.getDividerLeash();

libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/common/split/SplitLayoutTests.java

@@ -82,6 +82,12 @@ public class SplitLayoutTests extends ShellTestCase {
         verify(mLayoutChangeListener).onBoundsChanged(any(SplitLayout.class));
     }
 
+    @Test
+    public void testOnDoubleTappedDivider() {
+        mSplitLayout.onDoubleTappedDivider();
+        verify(mLayoutChangeListener).onDoubleTappedDivider();
+    }
+
     @Test
     @UiThreadTest
     public void testSnapToDismissTarget() {