Reduce memory usage for drawing app theme snapshot.

Since the content of the app theme snapshot is mostly a monochrome
image, drawing it in a smaller size should be a reasonable solution
to prevent memory waste.

Flag: com.android.window.flags.reduce_task_snapshot_memory_usage
Bug: 238206323
Test: verify the memory usage of app theme snapshot become much
smaller, and there is no obvious difference on recents animation.

Change-Id: Ibc74938adbf323e4bf703135db17aaf8f7433f72

1 files changed, 13 insertions, 5 deletions

diff --git a/services/core/java/com/android/server/wm/AbsAppSnapshotController.java b/services/core/java/com/android/server/wm/AbsAppSnapshotController.java
index a731bf7c64b3..70fc6bace868 100644
--- a/services/core/java/com/android/server/wm/AbsAppSnapshotController.java
+++ b/services/core/java/com/android/server/wm/AbsAppSnapshotController.java
@@ -82,6 +82,7 @@ abstract class AbsAppSnapshotController<TYPE extends WindowContainer,
      */
     @VisibleForTesting
     static final int SNAPSHOT_MODE_NONE = 2;
+    static final float THEME_SNAPSHOT_MIN_Length = 128.0f;
 
     protected final WindowManagerService mService;
     protected final float mHighResSnapshotScale;
@@ -436,14 +437,21 @@ abstract class AbsAppSnapshotController<TYPE extends WindowContainer,
         final Rect taskBounds = source.getBounds();
         final InsetsState insetsState = mainWindow.getInsetsStateWithVisibilityOverride();
         final Rect systemBarInsets = getSystemBarInsets(mainWindow.getFrame(), insetsState);
+        final int taskWidth = taskBounds.width();
+        final int taskHeight = taskBounds.height();
+        float scale = mHighResSnapshotScale;
+        if (Flags.reduceTaskSnapshotMemoryUsage()) {
+            final int minLength = Math.min(taskWidth, taskHeight);
+            if (THEME_SNAPSHOT_MIN_Length < minLength) {
+                scale = Math.min(THEME_SNAPSHOT_MIN_Length / minLength, scale);
+            }
+        }
         final SnapshotDrawerUtils.SystemBarBackgroundPainter
                 decorPainter = new SnapshotDrawerUtils.SystemBarBackgroundPainter(attrs.flags,
                 attrs.privateFlags, attrs.insetsFlags.appearance, taskDescription,
-                mHighResSnapshotScale, mainWindow.getRequestedVisibleTypes());
-        final int taskWidth = taskBounds.width();
-        final int taskHeight = taskBounds.height();
-        final int width = (int) (taskWidth * mHighResSnapshotScale);
-        final int height = (int) (taskHeight * mHighResSnapshotScale);
+                scale, mainWindow.getRequestedVisibleTypes());
+        final int width = (int) (taskWidth * scale);
+        final int height = (int) (taskHeight * scale);
         final RenderNode node = RenderNode.create("SnapshotController", null);
         node.setLeftTopRightBottom(0, 0, width, height);
         node.setClipToBounds(false);