Use activity-exit animation for translucent-only close

This is parity w/ legacy. Many translucent tasks are designed
with the expectation of sliding-down for closing animation.

Bug: 282655010
Test: launch a translucent task (in 3 button nav) and press
      home button.
Change-Id: I9b04f5534742a9b853d870cff48a1f4eda4d97f2

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

@@ -326,6 +326,7 @@ public class DefaultTransitionHandler implements Transitions.TransitionHandler {
         final int wallpaperTransit = getWallpaperTransitType(info);
         boolean isDisplayRotationAnimationStarted = false;
         final boolean isDreamTransition = isDreamTransition(info);
+        final boolean isOnlyTranslucent = isOnlyTranslucent(info);
 
         for (int i = info.getChanges().size() - 1; i >= 0; --i) {
             final TransitionInfo.Change change = info.getChanges().get(i);
@@ -451,6 +452,17 @@ public class DefaultTransitionHandler implements Transitions.TransitionHandler {
                             final int layer = zSplitLine + numChanges - i;
                             startTransaction.setLayer(change.getLeash(), layer);
                         }
+                    } else if (isOnlyTranslucent && TransitionUtil.isOpeningType(info.getType())
+                                && TransitionUtil.isClosingType(mode)) {
+                        // If there is a closing translucent task in an OPENING transition, we will
+                        // actually select a CLOSING animation, so move the closing task into
+                        // the animating part of the z-order.
+
+                        // See Transitions#setupAnimHierarchy for details about these variables.
+                        final int numChanges = info.getChanges().size();
+                        final int zSplitLine = numChanges + 1;
+                        final int layer = zSplitLine + numChanges - i;
+                        startTransaction.setLayer(change.getLeash(), layer);
                     }
                 }
 
@@ -542,6 +554,29 @@ public class DefaultTransitionHandler implements Transitions.TransitionHandler {
         return false;
     }
 
+    /**
+     * Does `info` only contain translucent visibility changes (CHANGEs are ignored). We select
+     * different animations and z-orders for these
+     */
+    private static boolean isOnlyTranslucent(@NonNull TransitionInfo info) {
+        int translucentOpen = 0;
+        int translucentClose = 0;
+        for (int i = info.getChanges().size() - 1; i >= 0; --i) {
+            final TransitionInfo.Change change = info.getChanges().get(i);
+            if (change.getMode() == TRANSIT_CHANGE) continue;
+            if (change.hasFlags(FLAG_TRANSLUCENT)) {
+                if (TransitionUtil.isOpeningType(change.getMode())) {
+                    translucentOpen += 1;
+                } else {
+                    translucentClose += 1;
+                }
+            } else {
+                return false;
+            }
+        }
+        return (translucentOpen + translucentClose) > 0;
+    }
+
     @Override
     public void mergeAnimation(@NonNull IBinder transition, @NonNull TransitionInfo info,
             @NonNull SurfaceControl.Transaction t, @NonNull IBinder mergeTarget,

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

@@ -102,10 +102,11 @@ public class TransitionAnimationHelper {
             // We will translucent open animation for translucent activities and tasks. Choose
             // WindowAnimation_activityOpenEnterAnimation and set translucent here, then
             // TransitionAnimation loads appropriate animation later.
-            if ((changeFlags & FLAG_TRANSLUCENT) != 0 && enter) {
-                translucent = true;
-            }
-            if (isTask && !translucent) {
+            translucent = (changeFlags & FLAG_TRANSLUCENT) != 0;
+            if (isTask && translucent && !enter) {
+                // For closing translucent tasks, use the activity close animation
+                animAttr = R.styleable.WindowAnimation_activityCloseExitAnimation;
+            } else if (isTask && !translucent) {
                 animAttr = enter
                         ? R.styleable.WindowAnimation_taskOpenEnterAnimation
                         : R.styleable.WindowAnimation_taskOpenExitAnimation;

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

@@ -567,8 +567,8 @@ public class Transitions implements RemoteCallable<Transitions>,
                     layer = zSplitLine + numChanges - i;
                 }
             } else { // CHANGE or other
-                if (isClosing) {
-                    // Put below CLOSE mode.
+                if (isClosing || TransitionUtil.isOrderOnly(change)) {
+                    // Put below CLOSE mode (in the "static" section).
                     layer = zSplitLine - i;
                 } else {
                     // Put above CLOSE mode.