3 files changed, 102 insertions, 31 deletions
diff --git a/core/java/android/app/EnterTransitionCoordinator.java b/core/java/android/app/EnterTransitionCoordinator.java
index c053c83..e84a8da 100644
--- a/core/java/android/app/EnterTransitionCoordinator.java
+++ b/core/java/android/app/EnterTransitionCoordinator.java
@@ -18,6 +18,7 @@ package android.app;
 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
 import android.animation.ObjectAnimator;
+import android.app.SharedElementCallback.OnSharedElementsReadyListener;
 import android.graphics.drawable.Drawable;
 import android.os.Bundle;
 import android.os.ResultReceiver;
@@ -140,13 +141,13 @@ class EnterTransitionCoordinator extends ActivityTransitionCoordinator {
         } else {
             decor.getViewTreeObserver()
                     .addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
-                @Override
-                public boolean onPreDraw() {
-                    decor.getViewTreeObserver().removeOnPreDrawListener(this);
-                    viewsReady(sharedElements);
-                    return true;
-                }
-            });
+                        @Override
+                        public boolean onPreDraw() {
+                            decor.getViewTreeObserver().removeOnPreDrawListener(this);
+                            viewsReady(sharedElements);
+                            return true;
+                        }
+                    });
         }
     }
 
@@ -383,23 +384,33 @@ class EnterTransitionCoordinator extends ActivityTransitionCoordinator {
         }
         final Bundle sharedElementState = mSharedElementsBundle;
         mSharedElementsBundle = null;
-        final View decorView = getDecor();
-        if (decorView != null) {
-            decorView.getViewTreeObserver()
-                    .addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
-                        @Override
-                        public boolean onPreDraw() {
-                            decorView.getViewTreeObserver().removeOnPreDrawListener(this);
-                            startTransition(new Runnable() {
+        OnSharedElementsReadyListener listener = new OnSharedElementsReadyListener() {
+            @Override
+            public void onSharedElementsReady() {
+                final View decorView = getDecor();
+                if (decorView != null) {
+                    decorView.getViewTreeObserver()
+                            .addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
                                 @Override
-                                public void run() {
-                                    startSharedElementTransition(sharedElementState);
+                                public boolean onPreDraw() {
+                                    decorView.getViewTreeObserver().removeOnPreDrawListener(this);
+                                    startTransition(new Runnable() {
+                                        @Override
+                                        public void run() {
+                                            startSharedElementTransition(sharedElementState);
+                                        }
+                                    });
+                                    return false;
                                 }
                             });
-                            return false;
-                        }
-                    });
-            decorView.invalidate();
+                    decorView.invalidate();
+                }
+            }
+        };
+        if (mListener == null) {
+            listener.onSharedElementsReady();
+        } else {
+            mListener.onSharedElementsArrived(mSharedElementNames, mSharedElements, listener);
         }
     }
 
diff --git a/core/java/android/app/ExitTransitionCoordinator.java b/core/java/android/app/ExitTransitionCoordinator.java
index dd3df47..169952a 100644
--- a/core/java/android/app/ExitTransitionCoordinator.java
+++ b/core/java/android/app/ExitTransitionCoordinator.java
@@ -18,6 +18,7 @@ package android.app;
 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
 import android.animation.ObjectAnimator;
+import android.app.SharedElementCallback.OnSharedElementsReadyListener;
 import android.content.Intent;
 import android.graphics.Color;
 import android.graphics.Matrix;
@@ -27,6 +28,7 @@ import android.graphics.drawable.Drawable;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Message;
+import android.os.ResultReceiver;
 import android.transition.Transition;
 import android.transition.TransitionManager;
 import android.view.View;
@@ -408,18 +410,38 @@ class ExitTransitionCoordinator extends ActivityTransitionCoordinator {
             if (!mSharedElementNotified) {
                 mSharedElementNotified = true;
                 delayCancel();
-                mResultReceiver.send(MSG_TAKE_SHARED_ELEMENTS, mSharedElementBundle);
-            }
-            if (!mExitNotified && mExitComplete) {
-                mExitNotified = true;
-                mResultReceiver.send(MSG_EXIT_TRANSITION_COMPLETE, null);
-                mResultReceiver = null; // done talking
-                ViewGroup decorView = getDecor();
-                if (!mIsReturning && decorView != null) {
-                    decorView.suppressLayout(false);
+                if (mListener == null) {
+                    mResultReceiver.send(MSG_TAKE_SHARED_ELEMENTS, mSharedElementBundle);
+                    notifyExitComplete();
+                } else {
+                    final ResultReceiver resultReceiver = mResultReceiver;
+                    final Bundle sharedElementBundle = mSharedElementBundle;
+                    mListener.onSharedElementsArrived(mSharedElementNames, mSharedElements,
+                            new OnSharedElementsReadyListener() {
+                                @Override
+                                public void onSharedElementsReady() {
+                                    resultReceiver.send(MSG_TAKE_SHARED_ELEMENTS,
+                                            sharedElementBundle);
+                                    notifyExitComplete();
+                                }
+                            });
                 }
-                finishIfNecessary();
+            } else {
+                notifyExitComplete();
+            }
+        }
+    }
+
+    private void notifyExitComplete() {
+        if (!mExitNotified && mExitComplete) {
+            mExitNotified = true;
+            mResultReceiver.send(MSG_EXIT_TRANSITION_COMPLETE, null);
+            mResultReceiver = null; // done talking
+            ViewGroup decorView = getDecor();
+            if (!mIsReturning && decorView != null) {
+                decorView.suppressLayout(false);
             }
+            finishIfNecessary();
         }
     }
 
diff --git a/core/java/android/app/SharedElementCallback.java b/core/java/android/app/SharedElementCallback.java
index 6ac2401..e58b7fb 100644
--- a/core/java/android/app/SharedElementCallback.java
+++ b/core/java/android/app/SharedElementCallback.java
@@ -221,4 +221,42 @@ public abstract class SharedElementCallback {
         }
         return view;
     }
+
+    /**
+     * Called during an Activity Transition when the shared elements have arrived at the
+     * final location and are ready to be transferred. This method is called for both the
+     * source and destination Activities.
+     * <p>
+     * When the shared elements are ready to be transferred,
+     * {@link OnSharedElementsReadyListener#onSharedElementsReady()}
+     * must be called to trigger the transfer.
+     * <p>
+     * The default behavior is to trigger the transfer immediately.
+     *
+     * @param sharedElementNames The names of the shared elements that are being transferred..
+     * @param sharedElements The shared elements that are part of the View hierarchy.
+     * @param listener The listener to call when the shared elements are ready to be hidden
+     *                 in the source Activity or shown in the destination Activity.
+     */
+    public void onSharedElementsArrived(List<String> sharedElementNames,
+            List<View> sharedElements, OnSharedElementsReadyListener listener) {
+        listener.onSharedElementsReady();
+    }
+
+    /**
+     * Listener to be called after {@link
+     * SharedElementCallback#onSharedElementsArrived(List, List, OnSharedElementsReadyListener)}
+     * when the shared elements are ready to be hidden in the source Activity and shown in the
+     * destination Activity.
+     */
+    public interface OnSharedElementsReadyListener {
+
+        /**
+         * Call this method during or after the OnSharedElementsReadyListener has been received
+         * in {@link SharedElementCallback#onSharedElementsArrived(List, List,
+         * OnSharedElementsReadyListener)} to indicate that the shared elements are ready to be
+         * hidden in the source and shown in the destination Activity.
+         */
+        void onSharedElementsReady();
+    }
 }