Let the client compute the backdrop frame on its own

Since the new split-screen doesn't need the fullscreen backdrop frame.
The backdrop frame will always be the window frame. The server doesn't
need to send the backdrop frame to the client. The client just needs to
offset the backdrop frame to (0, 0).

This CL also moves the logic of calling onWindowSizeIsChanging to the
handler thread because it reads some fields which should only be
accessed on the handler thread. Otherwise, there might be race
conditions.

Bug: 161810301
Test: 1. Perform drag-resize and drag-move on a freeform app, and see if
         the layout is expected.
      2. Move the divider in the split-screen mode, and see if there is
         any abnormal.
Change-Id: Ie0058db0447260dd0561634179fc7721d965a9e2

2 files changed, 31 insertions, 48 deletions

diff --git a/core/java/android/view/ViewRootImpl.java b/core/java/android/view/ViewRootImpl.java
index d15b2a457bfb..5850715f9691 100644
--- a/core/java/android/view/ViewRootImpl.java
+++ b/core/java/android/view/ViewRootImpl.java
@@ -401,10 +401,8 @@ public final class ViewRootImpl implements ViewParent,
     private static boolean sAlwaysAssignFocus;
 
     /**
-     * This list must only be modified by the main thread, so a lock is only needed when changing
-     * the list or when accessing the list from a non-main thread.
+     * This list must only be modified by the main thread.
      */
-    @GuardedBy("mWindowCallbacks")
     final ArrayList<WindowCallbacks> mWindowCallbacks = new ArrayList<>();
     @UnsupportedAppUsage
     @UiContext
@@ -981,15 +979,11 @@ public final class ViewRootImpl implements ViewParent,
     }
 
     public void addWindowCallbacks(WindowCallbacks callback) {
-        synchronized (mWindowCallbacks) {
-            mWindowCallbacks.add(callback);
-        }
+        mWindowCallbacks.add(callback);
     }
 
     public void removeWindowCallbacks(WindowCallbacks callback) {
-        synchronized (mWindowCallbacks) {
-            mWindowCallbacks.remove(callback);
-        }
+        mWindowCallbacks.remove(callback);
     }
 
     public void reportDrawFinish() {
@@ -1711,15 +1705,19 @@ public final class ViewRootImpl implements ViewParent,
         final boolean forceNextWindowRelayout = args.argi1 != 0;
         final int displayId = args.argi3;
         final int resizeMode = args.argi5;
-        final Rect backdropFrame = frames.backdropFrame;
 
-        final boolean frameChanged = !mWinFrame.equals(frames.frame);
-        final boolean backdropFrameChanged = !mPendingBackDropFrame.equals(backdropFrame);
+        final Rect frame = frames.frame;
+        final Rect displayFrame = frames.displayFrame;
+        if (mTranslator != null) {
+            mTranslator.translateRectInScreenToAppWindow(frame);
+            mTranslator.translateRectInScreenToAppWindow(displayFrame);
+        }
+        final boolean frameChanged = !mWinFrame.equals(frame);
         final boolean configChanged = !mLastReportedMergedConfiguration.equals(mergedConfiguration);
         final boolean displayChanged = mDisplay.getDisplayId() != displayId;
         final boolean resizeModeChanged = mResizeMode != resizeMode;
-        if (msg == MSG_RESIZED && !frameChanged && !backdropFrameChanged && !configChanged
-                && !displayChanged && !resizeModeChanged && !forceNextWindowRelayout) {
+        if (msg == MSG_RESIZED && !frameChanged && !configChanged && !displayChanged
+                && !resizeModeChanged && !forceNextWindowRelayout) {
             return;
         }
 
@@ -1735,9 +1733,17 @@ public final class ViewRootImpl implements ViewParent,
             onMovedToDisplay(displayId, mLastConfigurationFromResources);
         }
 
-        setFrame(frames.frame);
-        mTmpFrames.displayFrame.set(frames.displayFrame);
-        mPendingBackDropFrame.set(backdropFrame);
+        setFrame(frame);
+        mTmpFrames.displayFrame.set(displayFrame);
+
+        if (mDragResizing && mUseMTRenderer) {
+            boolean fullscreen = frame.equals(mPendingBackDropFrame);
+            for (int i = mWindowCallbacks.size() - 1; i >= 0; i--) {
+                mWindowCallbacks.get(i).onWindowSizeIsChanging(mPendingBackDropFrame, fullscreen,
+                        mAttachInfo.mVisibleInsets, mAttachInfo.mStableInsets);
+            }
+        }
+
         mForceNextWindowRelayout = forceNextWindowRelayout;
         mPendingAlwaysConsumeSystemBars = args.argi2 != 0;
         mSyncSeqId = args.argi4;
@@ -5510,8 +5516,6 @@ public final class ViewRootImpl implements ViewParent,
                         mTmpFrames.frame.top = t;
                         mTmpFrames.frame.bottom = t + h;
                         setFrame(mTmpFrames.frame);
-
-                        mPendingBackDropFrame.set(mWinFrame);
                         maybeHandleWindowMove(mWinFrame);
                     }
                     break;
@@ -8006,7 +8010,6 @@ public final class ViewRootImpl implements ViewParent,
                     getConfiguration().windowConfiguration.getBounds());
         }
 
-        mPendingBackDropFrame.set(mTmpFrames.backdropFrame);
         if (mSurfaceControl.isValid()) {
             if (!useBLAST()) {
                 mSurface.copyFrom(mSurfaceControl);
@@ -8037,6 +8040,7 @@ public final class ViewRootImpl implements ViewParent,
 
         if (mTranslator != null) {
             mTranslator.translateRectInScreenToAppWindow(mTmpFrames.frame);
+            mTranslator.translateRectInScreenToAppWindow(mTmpFrames.displayFrame);
             mTranslator.translateInsetsStateInScreenToAppWindow(mTempInsets);
             mTranslator.translateSourceControlsInScreenToAppWindow(mTempControls);
         }
@@ -8081,6 +8085,13 @@ public final class ViewRootImpl implements ViewParent,
 
     private void setFrame(Rect frame) {
         mWinFrame.set(frame);
+
+        // Surface position is now inherited from parent, and BackdropFrameRenderer uses backdrop
+        // frame to position content. Thus, we just keep the size of backdrop frame, and remove the
+        // offset to avoid double offset from display origin.
+        mPendingBackDropFrame.set(frame);
+        mPendingBackDropFrame.offsetTo(0, 0);
+
         mInsetsController.onFrameChanged(mOverrideInsetsFrame != null ?
             mOverrideInsetsFrame : frame);
     }
@@ -8472,28 +8483,7 @@ public final class ViewRootImpl implements ViewParent,
     private void dispatchResized(ClientWindowFrames frames, boolean reportDraw,
             MergedConfiguration mergedConfiguration, boolean forceLayout,
             boolean alwaysConsumeSystemBars, int displayId, int seqId, int resizeMode) {
-        final Rect frame = frames.frame;
-        final Rect backDropFrame = frames.backdropFrame;
-        if (DEBUG_LAYOUT) Log.v(mTag, "Resizing " + this + ": frame=" + frame.toShortString()
-                + " reportDraw=" + reportDraw
-                + " backDropFrame=" + backDropFrame);
-
-        // Tell all listeners that we are resizing the window so that the chrome can get
-        // updated as fast as possible on a separate thread,
-        if (mDragResizing && mUseMTRenderer) {
-            boolean fullscreen = frame.equals(backDropFrame);
-            synchronized (mWindowCallbacks) {
-                for (int i = mWindowCallbacks.size() - 1; i >= 0; i--) {
-                    mWindowCallbacks.get(i).onWindowSizeIsChanging(backDropFrame, fullscreen,
-                            mAttachInfo.mVisibleInsets, mAttachInfo.mStableInsets);
-                }
-            }
-        }
-
         Message msg = mHandler.obtainMessage(reportDraw ? MSG_RESIZED_REPORT : MSG_RESIZED);
-        if (mTranslator != null) {
-            mTranslator.translateRectInScreenToAppWindow(frame);
-        }
         SomeArgs args = SomeArgs.obtain();
         final boolean sameProcessCall = (Binder.getCallingPid() == android.os.Process.myPid());
         args.arg1 = sameProcessCall ? new ClientWindowFrames(frames) : frames;
diff --git a/core/java/android/window/ClientWindowFrames.java b/core/java/android/window/ClientWindowFrames.java
index 5b915cc22ec5..51f3fe2551ad 100644
--- a/core/java/android/window/ClientWindowFrames.java
+++ b/core/java/android/window/ClientWindowFrames.java
@@ -40,9 +40,6 @@ public class ClientWindowFrames implements Parcelable {
      */
     public final @NonNull Rect parentFrame = new Rect();
 
-    /** The background area while the window is resizing. */
-    public final @NonNull Rect backdropFrame = new Rect();
-
     public boolean isParentFrameClippedByDisplayCutout;
 
     public ClientWindowFrames() {
@@ -52,7 +49,6 @@ public class ClientWindowFrames implements Parcelable {
         frame.set(other.frame);
         displayFrame.set(other.displayFrame);
         parentFrame.set(other.parentFrame);
-        backdropFrame.set(other.backdropFrame);
         isParentFrameClippedByDisplayCutout = other.isParentFrameClippedByDisplayCutout;
     }
 
@@ -65,7 +61,6 @@ public class ClientWindowFrames implements Parcelable {
         frame.readFromParcel(in);
         displayFrame.readFromParcel(in);
         parentFrame.readFromParcel(in);
-        backdropFrame.readFromParcel(in);
         isParentFrameClippedByDisplayCutout = in.readBoolean();
     }
 
@@ -74,7 +69,6 @@ public class ClientWindowFrames implements Parcelable {
         frame.writeToParcel(dest, flags);
         displayFrame.writeToParcel(dest, flags);
         parentFrame.writeToParcel(dest, flags);
-        backdropFrame.writeToParcel(dest, flags);
         dest.writeBoolean(isParentFrameClippedByDisplayCutout);
     }
 
@@ -84,7 +78,6 @@ public class ClientWindowFrames implements Parcelable {
         return "ClientWindowFrames{frame=" + frame.toShortString(sb)
                 + " display=" + displayFrame.toShortString(sb)
                 + " parentFrame=" + parentFrame.toShortString(sb)
-                + " backdrop=" + backdropFrame.toShortString(sb)
                 + " parentClippedByDisplayCutout=" + isParentFrameClippedByDisplayCutout + "}";
     }