Support backgrounds during animations in shell

This is required for the go/t-activity-transitions where we want to allow apps to fade to a clear background color and fade back in from the background to another activity

Test: atest FlickerTests
Bug: 202844659
Change-Id: Iea18a8e7d32a63da55ab3430c47f903da5cff807

core/java/android/window/TransitionInfo.java

@@ -36,6 +36,7 @@ import static android.view.WindowManager.TransitionFlags;
 import static android.view.WindowManager.TransitionType;
 import static android.view.WindowManager.transitTypeToString;
 
+import android.annotation.ColorInt;
 import android.annotation.IntDef;
 import android.annotation.NonNull;
 import android.annotation.Nullable;
@@ -366,6 +367,7 @@ public final class TransitionInfo implements Parcelable {
         private int mStartRotation = ROTATION_UNDEFINED;
         private int mEndRotation = ROTATION_UNDEFINED;
         private int mRotationAnimation = ROTATION_ANIMATION_UNSPECIFIED;
+        private @ColorInt int mBackgroundColor;
 
         public Change(@Nullable WindowContainerToken container, @NonNull SurfaceControl leash) {
             mContainer = container;
@@ -387,6 +389,7 @@ public final class TransitionInfo implements Parcelable {
             mStartRotation = in.readInt();
             mEndRotation = in.readInt();
             mRotationAnimation = in.readInt();
+            mBackgroundColor = in.readInt();
         }
 
         /** Sets the parent of this change's container. The parent must be a participant or null. */
@@ -446,6 +449,11 @@ public final class TransitionInfo implements Parcelable {
             mRotationAnimation = anim;
         }
 
+        /** Sets the background color of this change's container. */
+        public void setBackgroundColor(@ColorInt int backgroundColor) {
+            mBackgroundColor = backgroundColor;
+        }
+
         /** @return the container that is changing. May be null if non-remotable (eg. activity) */
         @Nullable
         public WindowContainerToken getContainer() {
@@ -526,6 +534,12 @@ public final class TransitionInfo implements Parcelable {
             return mRotationAnimation;
         }
 
+        /** @return get the background color of this change's container. */
+        @ColorInt
+        public int getBackgroundColor() {
+            return mBackgroundColor;
+        }
+
         /** @hide */
         @Override
         public void writeToParcel(@NonNull Parcel dest, int flags) {
@@ -542,6 +556,7 @@ public final class TransitionInfo implements Parcelable {
             dest.writeInt(mStartRotation);
             dest.writeInt(mEndRotation);
             dest.writeInt(mRotationAnimation);
+            dest.writeInt(mBackgroundColor);
         }
 
         @NonNull

libs/WindowManager/Shell/src/com/android/wm/shell/transition/DefaultTransitionHandler.java

@@ -291,8 +291,7 @@ public class DefaultTransitionHandler implements Transitions.TransitionHandler {
             finishCallback.onTransitionFinished(null /* wct */, null /* wctCB */);
         };
 
-        boolean requireBackgroundForTransition = false;
-
+        @ColorInt int backgroundColorForTransition = 0;
         final int wallpaperTransit = getWallpaperTransitType(info);
         for (int i = info.getChanges().size() - 1; i >= 0; --i) {
             final TransitionInfo.Change change = info.getChanges().get(i);
@@ -352,8 +351,19 @@ public class DefaultTransitionHandler implements Transitions.TransitionHandler {
 
             Animation a = loadAnimation(info, change, wallpaperTransit);
             if (a != null) {
-                if (changeRequiresBackground(info, change)) {
-                    requireBackgroundForTransition = true;
+                if (isTask) {
+                    final @TransitionType int type = info.getType();
+                    final boolean isOpenOrCloseTransition = type == TRANSIT_OPEN
+                            || type == TRANSIT_CLOSE
+                            || type == TRANSIT_TO_FRONT
+                            || type == TRANSIT_TO_BACK;
+                    if (isOpenOrCloseTransition) {
+                        // Use the overview background as the background for the animation
+                        final Context uiContext = ActivityThread.currentActivityThread()
+                                .getSystemUiContext();
+                        backgroundColorForTransition =
+                                uiContext.getColor(R.color.overview_background);
+                    }
                 }
 
                 float cornerRadius = 0;
@@ -365,6 +375,15 @@ public class DefaultTransitionHandler implements Transitions.TransitionHandler {
                             ScreenDecorationsUtils.getWindowCornerRadius(displayContext);
                 }
 
+                if (a.getShowBackground()) {
+                    // use the window's background color if provided as the background color for the
+                    // animation - the top most window with a valid background color and
+                    // showBackground set takes precedence.
+                    if (change.getBackgroundColor() != 0) {
+                        backgroundColorForTransition = change.getBackgroundColor();
+                    }
+                }
+
                 startSurfaceAnimation(animations, a, change.getLeash(), onAnimFinish,
                         mTransactionPool, mMainExecutor, mAnimExecutor, null /* position */,
                         cornerRadius, change.getEndAbsBounds());
@@ -376,8 +395,9 @@ public class DefaultTransitionHandler implements Transitions.TransitionHandler {
             }
         }
 
-        if (requireBackgroundForTransition) {
-            addBackgroundToTransition(info.getRootLeash(), startTransaction, finishTransaction);
+        if (backgroundColorForTransition != 0) {
+            addBackgroundToTransition(info.getRootLeash(), backgroundColorForTransition,
+                    startTransaction, finishTransaction);
         }
 
         startTransaction.apply();
@@ -388,24 +408,13 @@ public class DefaultTransitionHandler implements Transitions.TransitionHandler {
         return true;
     }
 
-    private boolean changeRequiresBackground(TransitionInfo info,
-            TransitionInfo.Change change) {
-        final boolean isTask = change.getTaskInfo() != null;
-        final @TransitionType int type = info.getType();
-        final boolean isOpenOrCloseTransition = type == TRANSIT_OPEN || type == TRANSIT_CLOSE
-                || type == TRANSIT_TO_FRONT || type == TRANSIT_TO_BACK;
-        return isTask && isOpenOrCloseTransition;
-    }
-
     private void addBackgroundToTransition(
             @NonNull SurfaceControl rootLeash,
+            @ColorInt int color,
             @NonNull SurfaceControl.Transaction startTransaction,
             @NonNull SurfaceControl.Transaction finishTransaction
     ) {
-        final Context uiContext = ActivityThread.currentActivityThread().getSystemUiContext();
-        final @ColorInt int overviewBackgroundColor =
-                uiContext.getColor(R.color.overview_background);
-        final Color bgColor = Color.valueOf(overviewBackgroundColor);
+        final Color bgColor = Color.valueOf(color);
         final float[] colorArray = new float[] { bgColor.red(), bgColor.green(), bgColor.blue() };
 
         final SurfaceControl animationBackgroundSurface = new SurfaceControl.Builder()

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

@@ -79,6 +79,7 @@ import android.window.RemoteTransition;
 import android.window.TransitionInfo;
 
 import com.android.internal.annotations.VisibleForTesting;
+import com.android.internal.graphics.ColorUtils;
 import com.android.internal.protolog.ProtoLogGroup;
 import com.android.internal.protolog.common.ProtoLog;
 import com.android.internal.util.function.pooled.PooledLambda;
@@ -1271,6 +1272,14 @@ class Transition extends Binder implements BLASTSyncEngine.TransactionReadyListe
                 change.setAllowEnterPip(topMostActivity != null
                         && topMostActivity.checkEnterPictureInPictureAppOpsState());
             }
+            final ActivityRecord activityRecord = target.asActivityRecord();
+            if (activityRecord != null) {
+                final Task arTask = activityRecord.getTask();
+                final int backgroundColor = ColorUtils.setAlphaComponent(
+                        arTask.getTaskDescription().getBackgroundColor(), 255);
+                change.setBackgroundColor(backgroundColor);
+            }
+
             out.addChange(change);
         }