Add API to specify background color for animations

To be used for new task transtion animations
(go/android-new-task-motion) to set a background color behind the
animations instead of showing the wallpaper.

Test: atest FlickerTests:TaskTransitionTest
Bug: 199507257
Change-Id: I7fabfdcaf90be63c11eb3b18d65259c620570cab

core/java/android/view/animation/Animation.java

@@ -19,6 +19,7 @@ package android.view.animation;
 import android.annotation.AnimRes;
 import android.annotation.ColorInt;
 import android.annotation.InterpolatorRes;
+import android.app.ActivityThread;
 import android.compat.annotation.UnsupportedAppUsage;
 import android.content.Context;
 import android.content.res.TypedArray;
@@ -258,8 +259,6 @@ public abstract class Animation implements Cloneable {
 
         setZAdjustment(a.getInt(com.android.internal.R.styleable.Animation_zAdjustment, ZORDER_NORMAL));
 
-        setBackgroundColor(a.getInt(com.android.internal.R.styleable.Animation_background, 0));
-
         setDetachWallpaper(
                 a.getBoolean(com.android.internal.R.styleable.Animation_detachWallpaper, false));
         setShowWallpaper(
@@ -271,6 +270,15 @@ public abstract class Animation implements Cloneable {
 
         a.recycle();
 
+        Context uiContext = ActivityThread.currentActivityThread().getSystemUiContext();
+        TypedArray uiStyledAttrs = uiContext
+                .obtainStyledAttributes(attrs, com.android.internal.R.styleable.Animation);
+
+        setBackgroundColor(
+                uiStyledAttrs.getColor(com.android.internal.R.styleable.Animation_background, 0));
+
+        uiStyledAttrs.recycle();
+
         if (resID > 0) {
             setInterpolator(context, resID);
         }
@@ -632,16 +640,15 @@ public abstract class Animation implements Cloneable {
     }
 
     /**
-     * Set background behind animation.
+     * Set background behind an animation.
      *
-     * @param bg The background color.  If 0, no background.  Currently must
-     * be black, with any desired alpha level.
+     * @param bg The background color. If 0, no background.
      *
      * @deprecated None of window animations are running with background color.
      */
     @Deprecated
     public void setBackgroundColor(@ColorInt int bg) {
-        // The background color is not needed any more, do nothing.
+        mBackgroundColor = bg;
     }
 
     /**
@@ -803,7 +810,7 @@ public abstract class Animation implements Cloneable {
     @Deprecated
     @ColorInt
     public int getBackgroundColor() {
-        return 0;
+        return mBackgroundColor;
     }
 
     /**

core/res/res/values/attrs.xml

@@ -6822,9 +6822,8 @@
                  content for the duration of the animation. -->
             <enum name="bottom" value="-1" />
         </attr>
-        <!-- Special background behind animation.  Only for use with window
-             animations.  Can only be a color, and only black.  If 0, the
-             default, there is no background. -->
+        <!-- Special background behind animation. Only for use with task animations.
+             If 0, the default, there is no background. -->
         <attr name="background" />
         <!-- Special option for window animations: if this window is on top
              of a wallpaper, don't animate the wallpaper with it. -->
@@ -7737,7 +7736,7 @@
 
         <!-- Name of a method on the Context used to inflate the menu that will be
              called when the item is clicked.
-             {@deprecated Menu actually traverses the Context hierarchy looking for the 
+             {@deprecated Menu actually traverses the Context hierarchy looking for the
              relevant method, which is fragile (an intermediate ContextWrapper adding a
              same-named method would change behavior) and restricts bytecode optimizers
              such as R8. Instead, use MenuItem.setOnMenuItemClickListener.} -->

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

@@ -16,6 +16,7 @@
 
 package com.android.server.wm;
 
+import android.annotation.ColorInt;
 import android.util.proto.ProtoOutputStream;
 import android.view.SurfaceControl;
 import android.view.SurfaceControl.Transaction;
@@ -106,4 +107,14 @@ interface AnimationAdapter {
     default boolean shouldDeferAnimationFinish(Runnable endDeferFinishCallback) {
         return false;
     }
+
+    /**
+     * Gets the background color to show behind an animation.
+     *
+     * @return The background color to show behind an animation (0 for no background color).
+     */
+    @ColorInt
+    default int getBackgroundColor() {
+        return 0;
+    }
 }

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

@@ -19,6 +19,7 @@ package com.android.server.wm;
 import static com.android.server.wm.AnimationAdapterProto.LOCAL;
 import static com.android.server.wm.LocalAnimationAdapterProto.ANIMATION_SPEC;
 
+import android.annotation.ColorInt;
 import android.os.SystemClock;
 import android.util.proto.ProtoOutputStream;
 import android.view.SurfaceControl;
@@ -71,6 +72,12 @@ class LocalAnimationAdapter implements AnimationAdapter {
         return mSpec.calculateStatusBarTransitionStartTime();
     }
 
+    @Override
+    @ColorInt
+    public int getBackgroundColor() {
+        return mSpec.getBackgroundColor();
+    }
+
     @Override
     public void dump(PrintWriter pw, String prefix) {
         mSpec.dump(pw, prefix);
@@ -149,5 +156,9 @@ class LocalAnimationAdapter implements AnimationAdapter {
         }
 
         void dumpDebugInner(ProtoOutputStream proto);
+
+        default int getBackgroundColor() {
+            return 0;
+        }
     }
 }

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

@@ -21,6 +21,7 @@ import static com.android.server.wm.AnimationSpecProto.WINDOW;
 import static com.android.server.wm.WindowAnimationSpecProto.ANIMATION;
 import static com.android.server.wm.WindowStateAnimator.ROOT_TASK_CLIP_NONE;
 
+import android.annotation.ColorInt;
 import android.graphics.Point;
 import android.graphics.Rect;
 import android.os.SystemClock;
@@ -84,6 +85,12 @@ public class WindowAnimationSpec implements AnimationSpec {
         return mAnimation.computeDurationHint();
     }
 
+    @Override
+    @ColorInt
+    public int getBackgroundColor() {
+        return mAnimation.getBackgroundColor();
+    }
+
     @Override
     public void apply(Transaction t, SurfaceControl leash, long currentPlayTime) {
         final TmpValues tmp = mThreadLocalTmps.get();