content: /*
   * Copyright (C) 2014 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.Animator;
  import android.animation.ObjectAnimator;
  import android.content.Context;
  import android.util.AttributeSet;
  import android.view.View;
  import android.view.ViewGroup;
  
  /**
   * This transition captures the scroll properties of targets before and after
   * the scene change and animates any changes.
   */
  public class ChangeScroll extends Transition {
  
      private static final String PROPNAME_SCROLL_X = "android:changeScroll:x";
      private static final String PROPNAME_SCROLL_Y = "android:changeScroll:y";
  
      private static final String[] PROPERTIES = {
              PROPNAME_SCROLL_X,
              PROPNAME_SCROLL_Y,
      };
  
      public ChangeScroll() {}
  
      public ChangeScroll(Context context, AttributeSet attrs) {
          super(context, attrs);
      }
  
      @Override
      public void captureStartValues(TransitionValues transitionValues) {
          captureValues(transitionValues);
      }
  
      @Override
      public void captureEndValues(TransitionValues transitionValues) {
          captureValues(transitionValues);
      }
  
      @Override
      public String[] getTransitionProperties() {
          return PROPERTIES;
      }
  
      private void captureValues(TransitionValues transitionValues) {
          transitionValues.values.put(PROPNAME_SCROLL_X, transitionValues.view.getScrollX());
          transitionValues.values.put(PROPNAME_SCROLL_Y, transitionValues.view.getScrollY());
      }
  
      @Override
      public Animator createAnimator(ViewGroup sceneRoot, TransitionValues startValues,
              TransitionValues endValues) {
          if (startValues == null || endValues == null) {
              return null;
          }
          final View view = endValues.view;
          int startX = (Integer) startValues.values.get(PROPNAME_SCROLL_X);
          int endX = (Integer) endValues.values.get(PROPNAME_SCROLL_X);
          int startY = (Integer) startValues.values.get(PROPNAME_SCROLL_Y);
          int endY = (Integer) endValues.values.get(PROPNAME_SCROLL_Y);
          Animator scrollXAnimator = null;
          Animator scrollYAnimator = null;
          if (startX != endX) {
              view.setScrollX(startX);
              scrollXAnimator = ObjectAnimator.ofInt(view, "scrollX", startX, endX);
          }
          if (startY != endY) {
              view.setScrollY(startY);
              scrollYAnimator = ObjectAnimator.ofInt(view, "scrollY", startY, endY);
          }
          return TransitionUtils.mergeAnimators(scrollXAnimator, scrollYAnimator);
      }
  }
  