From b04b36eaadb2f3e56206d8ae157df06bb89f9866 Mon Sep 17 00:00:00 2001
From: Dake Gu <dake@google.com>
Date: Fri, 8 Aug 2014 11:22:30 -0700
Subject: [PATCH] Transition: remap if views in calling activity became invalid

In activity back,  the calling activity might have re-constructed
UI, the accepted views captured in calling activity  was detached
and no longer valid.  Re-query the calling activity for shared
element in such case.  If the app has reconstructed UI of calling
activity,  it is app's responsibility to assign same transition name
to new view where it desires to transition back to.

b/16853679

Change-Id: Ia6729c6082fbaf54c2ce17f695d5b8d66bd9187d
---
 .../android/app/ActivityTransitionState.java  |  5 ++---
 .../app/EnterTransitionCoordinator.java       | 19 +++++++++++++++++--
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/core/java/android/app/ActivityTransitionState.java b/core/java/android/app/ActivityTransitionState.java
index 4f556a8697f95..4f3b02c0a86e5 100644
--- a/core/java/android/app/ActivityTransitionState.java
+++ b/core/java/android/app/ActivityTransitionState.java
@@ -193,7 +193,8 @@ class ActivityTransitionState {
     private void startEnter() {
         if (mEnterActivityOptions.isReturning()) {
             if (mExitingToView != null) {
-                mEnterTransitionCoordinator.viewInstancesReady(mExitingFrom, mExitingToView);
+                mEnterTransitionCoordinator.viewInstancesReady(mExitingFrom, mExitingTo,
+                        mExitingToView);
             } else {
                 mEnterTransitionCoordinator.namedViewsReady(mExitingFrom, mExitingTo);
             }
@@ -248,8 +249,6 @@ class ActivityTransitionState {
                     mEnterTransitionCoordinator.cancelEnter();
                     mEnterTransitionCoordinator = null;
                 }
-                ArrayMap<String, View> sharedElements = new ArrayMap<String, View>();
-                activity.getWindow().getDecorView().findNamedViews(sharedElements);
 
                 ExitTransitionCoordinator exitCoordinator =
                         new ExitTransitionCoordinator(activity, mEnteringNames, null, null, true);
diff --git a/core/java/android/app/EnterTransitionCoordinator.java b/core/java/android/app/EnterTransitionCoordinator.java
index b5d362d79ac21..3f1eee1c268ce 100644
--- a/core/java/android/app/EnterTransitionCoordinator.java
+++ b/core/java/android/app/EnterTransitionCoordinator.java
@@ -24,6 +24,7 @@ import android.os.Bundle;
 import android.os.Handler;
 import android.os.Message;
 import android.os.ResultReceiver;
+import android.text.TextUtils;
 import android.transition.Transition;
 import android.transition.TransitionManager;
 import android.util.ArrayMap;
@@ -82,8 +83,22 @@ class EnterTransitionCoordinator extends ActivityTransitionCoordinator {
                 });
     }
 
-    public void viewInstancesReady(ArrayList<String> accepted, ArrayList<View> localViews) {
-        triggerViewsReady(mapSharedElements(accepted, localViews));
+    public void viewInstancesReady(ArrayList<String> accepted, ArrayList<String> localNames,
+            ArrayList<View> localViews) {
+        boolean remap = false;
+        for (int i = 0; i < localViews.size(); i++) {
+            View view = localViews.get(i);
+            if (!TextUtils.equals(view.getTransitionName(), localNames.get(i))
+                    || !view.isAttachedToWindow()) {
+                remap = true;
+                break;
+            }
+        }
+        if (remap) {
+            triggerViewsReady(mapNamedElements(accepted, localNames));
+        } else {
+            triggerViewsReady(mapSharedElements(accepted, localViews));
+        }
     }
 
     public void namedViewsReady(ArrayList<String> accepted, ArrayList<String> localNames) {