Swap z-order of tasks for default wallpaper-open animation

the defaulthandler's wallpaper-open animation reverses the
normal closing/opening task dynamic: normally we animate OPEN
as the opening-task appearing over closing; however, for the
wallpaper-open case (which presumably assumes that the "opening"
task is a 3p launcher), we actually animate the closing task
closing over the opening-task. This requires the z-order to be
swapped.

Bug: 279680678
Test: use 3p launcher and 3-button nav. open an app. press "home"
      button.
Change-Id: I37362c1ade5ee786ed93b0544d37b6b38a549f04

1 files changed, 17 insertions, 0 deletions

diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/transition/DefaultTransitionHandler.java b/libs/WindowManager/Shell/src/com/android/wm/shell/transition/DefaultTransitionHandler.java
index 21dca95d056a..6a2468a7eaa2 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/transition/DefaultTransitionHandler.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/transition/DefaultTransitionHandler.java
@@ -435,6 +435,23 @@ public class DefaultTransitionHandler implements Transitions.TransitionHandler {
                         backgroundColorForTransition =
                                 uiContext.getColor(R.color.overview_background);
                     }
+                    if (wallpaperTransit == WALLPAPER_TRANSITION_OPEN
+                            && TransitionUtil.isOpeningType(info.getType())) {
+                        // Need to flip the z-order of opening/closing because the WALLPAPER_OPEN
+                        // always animates the closing task over the opening one while
+                        // traditionally, an OPEN transition animates the opening over the closing.
+
+                        // See Transitions#setupAnimHierarchy for details about these variables.
+                        final int numChanges = info.getChanges().size();
+                        final int zSplitLine = numChanges + 1;
+                        if (TransitionUtil.isOpeningType(mode)) {
+                            final int layer = zSplitLine - i;
+                            startTransaction.setLayer(change.getLeash(), layer);
+                        } else if (TransitionUtil.isClosingType(mode)) {
+                            final int layer = zSplitLine + numChanges - i;
+                            startTransaction.setLayer(change.getLeash(), layer);
+                        }
+                    }
                 }
 
                 final float cornerRadius;