Fix flicker when docking task

Bug: 28051193
Change-Id: I191c01f90c775a26fce6e6f73a0573a0be91a61f

services/core/java/com/android/server/wm/Task.java

@@ -595,6 +595,12 @@ class Task implements DimLayer.DimLayerUser {
                 if (win.mHasSurface && !resizingWindows.contains(win)) {
                     if (DEBUG_RESIZE) Slog.d(TAG, "resizeWindows: Resizing " + win);
                     resizingWindows.add(win);
+
+                    // If we are not drag resizing, force recreating of a new surface so updating
+                    // the content and positioning that surface will be in sync.
+                    if (!win.computeDragResizing()) {
+                        win.mResizedWhileNotDragResizing = true;
+                    }
                 }
                 if (win.isGoneForLayoutLw()) {
                     win.mResizedWhileGone = true;

services/core/java/com/android/server/wm/WindowManagerService.java

@@ -2935,8 +2935,9 @@ public class WindowManagerService extends IWindowManager.Stub
 
         // If we're starting a drag-resize, we'll be changing the surface size as well as
         // notifying the client to render to with an offset from the surface's top-left.
-        if (win.isDragResizeChanged()) {
+        if (win.isDragResizeChanged() || win.mResizedWhileNotDragResizing) {
             win.setDragResizing();
+            win.mResizedWhileNotDragResizing = false;
             // We can only change top level windows to the full-screen surface when
             // resizing (as we only have one full-screen surface). So there is no need
             // to preserve and destroy windows which are attached to another, they
@@ -9021,7 +9022,8 @@ public class WindowManagerService extends IWindowManager.Stub
                     || winAnimator.mSurfaceResized
                     || w.mOutsetsChanged
                     || configChanged
-                    || dragResizingChanged) {
+                    || dragResizingChanged
+                    || w.mResizedWhileNotDragResizing) {
                 if (DEBUG_RESIZE || DEBUG_ORIENTATION) {
                     Slog.v(TAG_WM, "Resize reasons for w=" + w + ": "
                             + " contentInsetsChanged=" + w.mContentInsetsChanged
@@ -9055,7 +9057,8 @@ public class WindowManagerService extends IWindowManager.Stub
                 // the display until this window has been redrawn; to do that,
                 // we need to go through the process of getting informed by the
                 // application when it has finished drawing.
-                if (w.mOrientationChanging || dragResizingChanged) {
+                if (w.mOrientationChanging || dragResizingChanged
+                        || w.mResizedWhileNotDragResizing) {
                     if (DEBUG_SURFACE_TRACE || DEBUG_ANIM || DEBUG_ORIENTATION || DEBUG_RESIZE) {
                         Slog.v(TAG_WM, "Orientation or resize start waiting for draw"
                                 + ", mDrawState=DRAW_PENDING in " + w

services/core/java/com/android/server/wm/WindowState.java

@@ -468,6 +468,13 @@ final class WindowState implements WindowManagerPolicy.WindowState {
      */
     boolean mResizedWhileGone = false;
 
+    /**
+     * Indicates whether we got resized but drag resizing flag was false. In this case, we also
+     * need to recreate the surface and defer surface bound updates in order to make sure the
+     * buffer contents and the positioning/size stay in sync.
+     */
+    boolean mResizedWhileNotDragResizing;
+
     WindowState(WindowManagerService service, Session s, IWindow c, WindowToken token,
            WindowState attachedWindow, int appOp, int seq, WindowManager.LayoutParams a,
            int viewVisibility, final DisplayContent displayContent) {

services/core/java/com/android/server/wm/WindowStateAnimator.java

@@ -1318,6 +1318,11 @@ class WindowStateAnimator {
         final WindowState w = mWin;
         final Task task = w.getTask();
 
+        // We got resized, so block all updates until we got the new surface.
+        if (w.mResizedWhileNotDragResizing) {
+            return;
+        }
+
         mTmpSize.set(w.mShownPosition.x, w.mShownPosition.y, 0, 0);
         calculateSurfaceBounds(w, w.getAttrs());