content: /*
   * Copyright (c) 2020. André Mion
   *
   * 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 com.andremion.louvre.util.transition;
  
  import androidx.annotation.NonNull;
  import androidx.core.app.SharedElementCallback;
  import androidx.core.view.ViewCompat;
  import android.view.View;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  import java.util.Map;
  
  /**
   * Some hacks pulled from https://github.com/googlesamples/android-unsplash
   */
  public class MediaSharedElementCallback extends SharedElementCallback {
  
      private final List<View> mSharedElementViews;
  
      public MediaSharedElementCallback() {
          mSharedElementViews = new ArrayList<>();
      }
  
      public void setSharedElementViews(@NonNull View... sharedElementViews) {
          mSharedElementViews.clear();
          mSharedElementViews.addAll(Arrays.asList(sharedElementViews));
      }
  
      @Override
      public void onMapSharedElements(List<String> names, Map<String, View> sharedElements) {
          if (!mSharedElementViews.isEmpty()) {
              removeObsoleteElements(names, sharedElements, mapObsoleteElements(names));
              for (View sharedElementView : mSharedElementViews) {
                  String transitionName = ViewCompat.getTransitionName(sharedElementView);
                  names.add(transitionName);
                  sharedElements.put(transitionName, sharedElementView);
              }
          }
      }
  
      @Override
      public void onSharedElementEnd(List<String> sharedElementNames,
                                     List<View> sharedElements,
                                     List<View> sharedElementSnapshots) {
          for (View sharedElementView : mSharedElementViews) {
              forceSharedElementLayout(sharedElementView);
          }
      }
  
      /**
       * Maps all views that don't start with "android" namespace.
       *
       * @param names All shared element names.
       * @return The obsolete shared element names.
       */
      @NonNull
      private List<String> mapObsoleteElements(List<String> names) {
          List<String> elementsToRemove = new ArrayList<>(names.size());
          for (String name : names) {
              if (name.startsWith("android")) continue;
              elementsToRemove.add(name);
          }
          return elementsToRemove;
      }
  
      /**
       * Removes obsolete elements from names and shared elements.
       *
       * @param names            Shared element names.
       * @param sharedElements   Shared elements.
       * @param elementsToRemove The elements that should be removed.
       */
      private void removeObsoleteElements(List<String> names,
                                          Map<String, View> sharedElements,
                                          List<String> elementsToRemove) {
          if (elementsToRemove.size() > 0) {
              names.removeAll(elementsToRemove);
              for (String elementToRemove : elementsToRemove) {
                  sharedElements.remove(elementToRemove);
              }
          }
      }
  
      private void forceSharedElementLayout(View view) {
          int widthSpec = View.MeasureSpec.makeMeasureSpec(view.getWidth(),
                  View.MeasureSpec.EXACTLY);
          int heightSpec = View.MeasureSpec.makeMeasureSpec(view.getHeight(),
                  View.MeasureSpec.EXACTLY);
          view.measure(widthSpec, heightSpec);
          view.layout(view.getLeft(), view.getTop(), view.getRight(), view.getBottom());
      }
  
  }
  