Fix the flaky AccessibilityMagnificationTest#testListener

The listner might invoked twice because we use vsync to
change the magnification spec. When the animation is running,
the posted tasks might executed after animation ended twice.

To fix, we update the source bounds only when it is indeed changed,
which also could reduce the redudant mirroing content operation when
the request is sent consecutively in a short time.

Bug: 214785717
Test: atest AccesibilityMagnificationTest \
      --retry-strategy ITERATIONS --max-testcase-run-count 20
Change-Id: I68962b189d8f39f587b717e8125a224e0f67a7e7

packages/SystemUI/src/com/android/systemui/accessibility/WindowMagnificationController.java

@@ -254,8 +254,8 @@ class WindowMagnificationController implements View.OnTouchListener, SurfaceHold
 
         mMirrorViewGeometryVsyncCallback =
                 l -> {
-                    if (isWindowVisible() && mMirrorSurface != null) {
-                        calculateSourceBounds(mMagnificationFrame, mScale);
+                    if (isWindowVisible() && mMirrorSurface != null && calculateSourceBounds(
+                            mMagnificationFrame, mScale)) {
                         // The final destination for the magnification surface should be at 0,0
                         // since the ViewRootImpl's position will change
                         mTmpRect.set(0, 0, mMagnificationFrame.width(),
@@ -350,6 +350,7 @@ class WindowMagnificationController implements View.OnTouchListener, SurfaceHold
             mMirrorWindowControl.destroyControl();
         }
         mMirrorViewBounds.setEmpty();
+        mSourceBounds.setEmpty();
         updateSystemUIStateIfNeeded();
         mContext.unregisterComponentCallbacks(this);
     }
@@ -728,8 +729,12 @@ class WindowMagnificationController implements View.OnTouchListener, SurfaceHold
     /**
      * Calculates the desired source bounds. This will be the area under from the center of  the
      * displayFrame, factoring in scale.
+     *
+     * @return {@code true} if the source bounds is changed.
      */
-    private void calculateSourceBounds(Rect displayFrame, float scale) {
+    private boolean calculateSourceBounds(Rect displayFrame, float scale) {
+        final Rect oldSourceBounds = mTmpRect;
+        oldSourceBounds.set(mSourceBounds);
         int halfWidth = displayFrame.width() / 2;
         int halfHeight = displayFrame.height() / 2;
         int left = displayFrame.left + (halfWidth - (int) (halfWidth / scale));
@@ -757,6 +762,7 @@ class WindowMagnificationController implements View.OnTouchListener, SurfaceHold
             mSourceBounds.offsetTo(mSourceBounds.left,
                     mWindowBounds.height() - mSourceBounds.height());
         }
+        return !mSourceBounds.equals(oldSourceBounds);
     }
 
     private void calculateMagnificationFrameBoundary() {
@@ -1079,7 +1085,7 @@ class WindowMagnificationController implements View.OnTouchListener, SurfaceHold
         pw.println("      mMagnificationFrame:"
                 + (isWindowVisible() ? mMagnificationFrame : "empty"));
         pw.println("      mSourceBounds:"
-                 + (isWindowVisible() ? mSourceBounds : "empty"));
+                 + (mSourceBounds.isEmpty() ? "empty" : mSourceBounds));
         pw.println("      mSystemGestureTop:" + mSystemGestureTop);
         pw.println("      mMagnificationFrameOffsetX:" + mMagnificationFrameOffsetX);
         pw.println("      mMagnificationFrameOffsetY:" + mMagnificationFrameOffsetY);

packages/SystemUI/tests/src/com/android/systemui/accessibility/WindowMagnificationControllerTest.java

@@ -172,17 +172,26 @@ public class WindowMagnificationControllerTest extends SysuiTestCase {
 
     @Test
     public void enableWindowMagnification_notifySourceBoundsChanged() {
-        mInstrumentation.runOnMainSync(() -> {
-            mWindowMagnificationController.enableWindowMagnification(Float.NaN, Float.NaN,
-                    Float.NaN, /* magnificationFrameOffsetRatioX= */ 0,
-                    /* magnificationFrameOffsetRatioY= */ 0, null);
-        });
+        mInstrumentation.runOnMainSync(
+                () -> mWindowMagnificationController.enableWindowMagnification(Float.NaN, Float.NaN,
+                        Float.NaN, /* magnificationFrameOffsetRatioX= */ 0,
+                /* magnificationFrameOffsetRatioY= */ 0, null));
 
         // Waits for the surface created
         verify(mWindowMagnifierCallback, timeout(LAYOUT_CHANGE_TIMEOUT_MS)).onSourceBoundsChanged(
                 (eq(mContext.getDisplayId())), any());
     }
 
+    @Test
+    public void enableWindowMagnification_disabled_notifySourceBoundsChanged() {
+        enableWindowMagnification_notifySourceBoundsChanged();
+        mInstrumentation.runOnMainSync(
+                () -> mWindowMagnificationController.deleteWindowMagnification(null));
+        Mockito.reset(mWindowMagnifierCallback);
+
+        enableWindowMagnification_notifySourceBoundsChanged();
+    }
+
     @Test
     public void enableWindowMagnification_withAnimation_schedulesFrame() {
         mInstrumentation.runOnMainSync(() -> {