Fix Fade transition interrupt.

Bug 26963113

When a Fade transition is interrupted and reversed, the
View started the animation from the beginning. This change
captures the previous transitionAlpha and starts the animation
from the previous alpha state.

Change-Id: I801fe9ade6af4cf8446838e231bdc71841668a18
(cherry picked from commit 3cf9fa3db0231d035142c27992818d8f7827ac3e)

3 files changed, 223 insertions, 17 deletions

diff --git a/core/java/android/transition/Fade.java b/core/java/android/transition/Fade.java
index 287c69608b8b..b2e8d3351028 100644
--- a/core/java/android/transition/Fade.java
+++ b/core/java/android/transition/Fade.java
@@ -57,9 +57,9 @@ import android.view.ViewGroup;
  * tag <code>fade</code>, along with the standard
  * attributes of {@link android.R.styleable#Fade} and
  * {@link android.R.styleable#Transition}.</p>
-
  */
 public class Fade extends Visibility {
+    static final String PROPNAME_TRANSITION_ALPHA = "android:fade:transitionAlpha";
 
     private static boolean DBG = Transition.DBG && false;
 
@@ -105,6 +105,13 @@ public class Fade extends Visibility {
         setMode(fadingMode);
     }
 
+    @Override
+    public void captureStartValues(TransitionValues transitionValues) {
+        super.captureStartValues(transitionValues);
+        transitionValues.values.put(PROPNAME_TRANSITION_ALPHA,
+                transitionValues.view.getTransitionAlpha());
+    }
+
     /**
      * Utility method to handle creating and running the Animator.
      */
@@ -119,7 +126,6 @@ public class Fade extends Visibility {
         }
         final FadeAnimatorListener listener = new FadeAnimatorListener(view);
         anim.addListener(listener);
-        anim.addPauseListener(listener);
         addListener(new TransitionListenerAdapter() {
             @Override
             public void onTransitionEnd(Transition transition) {
@@ -138,18 +144,28 @@ public class Fade extends Visibility {
             Log.d(LOG_TAG, "Fade.onAppear: startView, startVis, endView, endVis = " +
                     startView + ", " + view);
         }
-        return createAnimation(view, 0, 1);
+        float startAlpha = 0;
+        if (startValues != null) {
+            startAlpha = (Float) startValues.values.get(PROPNAME_TRANSITION_ALPHA);
+            if (startAlpha == 1) {
+                startAlpha = 0;
+            }
+        }
+        return createAnimation(view, startAlpha, 1);
     }
 
     @Override
     public Animator onDisappear(ViewGroup sceneRoot, final View view, TransitionValues startValues,
             TransitionValues endValues) {
-        return createAnimation(view, 1, 0);
+        float startAlpha = 1;
+        if (startValues != null) {
+            startAlpha = (Float) startValues.values.get(PROPNAME_TRANSITION_ALPHA);
+        }
+        return createAnimation(view, startAlpha, 0);
     }
 
     private static class FadeAnimatorListener extends AnimatorListenerAdapter {
         private final View mView;
-        private float mPausedAlpha = -1;
         private boolean mLayerTypeChanged = false;
 
         public FadeAnimatorListener(View view) {
@@ -171,16 +187,5 @@ public class Fade extends Visibility {
                 mView.setLayerType(View.LAYER_TYPE_NONE, null);
             }
         }
-
-        @Override
-        public void onAnimationPause(Animator animator) {
-            mPausedAlpha = mView.getTransitionAlpha();
-            mView.setTransitionAlpha(1);
-        }
-
-        @Override
-        public void onAnimationResume(Animator animator) {
-            mView.setTransitionAlpha(mPausedAlpha);
-        }
     }
 }
diff --git a/core/tests/coretests/res/layout/animator_set_squares.xml b/core/tests/coretests/res/layout/animator_set_squares.xml
index 23e6eea06a2b..6888248f5b13 100644
--- a/core/tests/coretests/res/layout/animator_set_squares.xml
+++ b/core/tests/coretests/res/layout/animator_set_squares.xml
@@ -4,7 +4,8 @@
     android:layout_width="fill_parent"
     android:layout_height="fill_parent"
     android:background="@android:color/white"
-    android:orientation="horizontal">
+    android:orientation="horizontal"
+    android:id="@+id/container">
     <View
         android:layout_width="50dp"
         android:layout_height="50dp"
diff --git a/core/tests/coretests/src/android/transition/FadeTransitionTest.java b/core/tests/coretests/src/android/transition/FadeTransitionTest.java
new file mode 100644
index 000000000000..dc6042311095
--- /dev/null
+++ b/core/tests/coretests/src/android/transition/FadeTransitionTest.java
@@ -0,0 +1,200 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.transition;
+
+import android.animation.AnimatorSetActivity;
+import android.app.Activity;
+import android.test.ActivityInstrumentationTestCase2;
+import android.test.suitebuilder.annotation.SmallTest;
+import android.transition.Transition.TransitionListener;
+import android.transition.Transition.TransitionListenerAdapter;
+import android.view.View;
+import android.view.ViewGroup;
+
+import com.android.frameworks.coretests.R;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
+import static android.support.test.espresso.Espresso.onView;
+
+public class FadeTransitionTest extends ActivityInstrumentationTestCase2<AnimatorSetActivity> {
+    Activity mActivity;
+    public FadeTransitionTest() {
+        super(AnimatorSetActivity.class);
+    }
+
+    @Override
+    protected void setUp() throws Exception {
+        mActivity = getActivity();
+    }
+
+    @SmallTest
+    public void testFadeOutAndIn() throws Throwable {
+        View square1 = mActivity.findViewById(R.id.square1);
+        Fade fadeOut = new Fade(Fade.MODE_OUT);
+        TransitionLatch latch = setVisibilityInTransition(fadeOut, R.id.square1, View.INVISIBLE);
+        assertTrue(latch.startLatch.await(200, TimeUnit.MILLISECONDS));
+        assertEquals(View.VISIBLE, square1.getVisibility());
+        Thread.sleep(100);
+        assertFalse(square1.getTransitionAlpha() == 0 || square1.getTransitionAlpha() == 1);
+        assertTrue(latch.endLatch.await(400, TimeUnit.MILLISECONDS));
+        assertEquals(1.0f, square1.getTransitionAlpha());
+        assertEquals(View.INVISIBLE, square1.getVisibility());
+
+        Fade fadeIn = new Fade(Fade.MODE_IN);
+        latch = setVisibilityInTransition(fadeIn, R.id.square1, View.VISIBLE);
+        assertTrue(latch.startLatch.await(200, TimeUnit.MILLISECONDS));
+        assertEquals(View.VISIBLE, square1.getVisibility());
+        Thread.sleep(100);
+        final float transitionAlpha = square1.getTransitionAlpha();
+        assertTrue("expecting transitionAlpha to be between 0 and 1. Was " + transitionAlpha,
+                transitionAlpha > 0 && transitionAlpha < 1);
+        assertTrue(latch.endLatch.await(400, TimeUnit.MILLISECONDS));
+        assertEquals(1.0f, square1.getTransitionAlpha());
+        assertEquals(View.VISIBLE, square1.getVisibility());
+    }
+
+    @SmallTest
+    public void testFadeOutInterrupt() throws Throwable {
+        View square1 = mActivity.findViewById(R.id.square1);
+        Fade fadeOut = new Fade(Fade.MODE_OUT);
+        FadeValueCheck fadeOutValueCheck = new FadeValueCheck(square1);
+        fadeOut.addListener(fadeOutValueCheck);
+        TransitionLatch outLatch = setVisibilityInTransition(fadeOut, R.id.square1, View.INVISIBLE);
+        assertTrue(outLatch.startLatch.await(200, TimeUnit.MILLISECONDS));
+        Thread.sleep(100);
+
+        Fade fadeIn = new Fade(Fade.MODE_IN);
+        FadeValueCheck fadeInValueCheck = new FadeValueCheck(square1);
+        fadeIn.addListener(fadeInValueCheck);
+        TransitionLatch inLatch = setVisibilityInTransition(fadeIn, R.id.square1, View.VISIBLE);
+        assertTrue(inLatch.startLatch.await(200, TimeUnit.MILLISECONDS));
+
+        assertEquals(fadeOutValueCheck.pauseTransitionAlpha, fadeInValueCheck.startTransitionAlpha);
+        assertTrue("expecting transitionAlpha to be between 0 and 1. Was " +
+                fadeOutValueCheck.pauseTransitionAlpha,
+                fadeOutValueCheck.pauseTransitionAlpha > 0 &&
+                        fadeOutValueCheck.pauseTransitionAlpha < 1);
+
+        assertTrue(inLatch.endLatch.await(400, TimeUnit.MILLISECONDS));
+        assertEquals(1.0f, square1.getTransitionAlpha());
+        assertEquals(View.VISIBLE, square1.getVisibility());
+    }
+
+    @SmallTest
+    public void testFadeInInterrupt() throws Throwable {
+        final View square1 = mActivity.findViewById(R.id.square1);
+        runTestOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                square1.setVisibility(View.INVISIBLE);
+            }
+        });
+        Fade fadeIn = new Fade(Fade.MODE_IN);
+        FadeValueCheck fadeInValueCheck = new FadeValueCheck(square1);
+        fadeIn.addListener(fadeInValueCheck);
+        TransitionLatch inLatch = setVisibilityInTransition(fadeIn, R.id.square1, View.VISIBLE);
+        assertTrue(inLatch.startLatch.await(200, TimeUnit.MILLISECONDS));
+        Thread.sleep(100);
+
+        Fade fadeOut = new Fade(Fade.MODE_OUT);
+        FadeValueCheck fadeOutValueCheck = new FadeValueCheck(square1);
+        fadeOut.addListener(fadeOutValueCheck);
+        TransitionLatch outLatch = setVisibilityInTransition(fadeOut, R.id.square1, View.INVISIBLE);
+        assertTrue(outLatch.startLatch.await(200, TimeUnit.MILLISECONDS));
+
+        assertEquals(fadeOutValueCheck.pauseTransitionAlpha, fadeInValueCheck.startTransitionAlpha);
+        assertTrue("expecting transitionAlpha to be between 0 and 1. Was " +
+                        fadeInValueCheck.pauseTransitionAlpha,
+                fadeInValueCheck.pauseTransitionAlpha > 0 &&
+                        fadeInValueCheck.pauseTransitionAlpha < 1);
+
+        assertTrue(outLatch.endLatch.await(400, TimeUnit.MILLISECONDS));
+        assertEquals(1.0f, square1.getTransitionAlpha());
+        assertEquals(View.INVISIBLE, square1.getVisibility());
+    }
+
+    public TransitionLatch setVisibilityInTransition(final Transition transition, int viewId,
+            final int visibility) throws Throwable {
+        final ViewGroup sceneRoot = (ViewGroup) mActivity.findViewById(R.id.container);
+        final View view = sceneRoot.findViewById(viewId);
+        TransitionLatch latch = new TransitionLatch();
+        transition.addListener(latch);
+        runTestOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                TransitionManager.beginDelayedTransition(sceneRoot, transition);
+                view.setVisibility(visibility);
+            }
+        });
+        return latch;
+    }
+
+    public static class TransitionLatch implements TransitionListener {
+        public CountDownLatch startLatch = new CountDownLatch(1);
+        public CountDownLatch endLatch = new CountDownLatch(1);
+        public CountDownLatch cancelLatch = new CountDownLatch(1);
+        public CountDownLatch pauseLatch = new CountDownLatch(1);
+        public CountDownLatch resumeLatch = new CountDownLatch(1);
+
+        @Override
+        public void onTransitionStart(Transition transition) {
+            startLatch.countDown();
+        }
+
+        @Override
+        public void onTransitionEnd(Transition transition) {
+            endLatch.countDown();
+            transition.removeListener(this);
+        }
+
+        @Override
+        public void onTransitionCancel(Transition transition) {
+            cancelLatch.countDown();
+        }
+
+        @Override
+        public void onTransitionPause(Transition transition) {
+            pauseLatch.countDown();
+        }
+
+        @Override
+        public void onTransitionResume(Transition transition) {
+            resumeLatch.countDown();
+        }
+    }
+
+    private static class FadeValueCheck extends TransitionListenerAdapter {
+        public float startTransitionAlpha;
+        public float pauseTransitionAlpha;
+        private final View mView;
+
+        public FadeValueCheck(View view) {
+            mView = view;
+        }
+        @Override
+        public void onTransitionStart(Transition transition) {
+            startTransitionAlpha = mView.getTransitionAlpha();
+        }
+
+        @Override
+        public void onTransitionPause(Transition transition) {
+            pauseTransitionAlpha = mView.getTransitionAlpha();
+        }
+    }
+}