content: /*
   * Copyright (C) 2019 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 com.android.server.wm.utils;
  
  import android.graphics.Rect;
  import android.graphics.Region;
  import android.graphics.RegionIterator;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.function.Consumer;
  
  /**
   * Utility methods to handle Regions.
   */
  public class RegionUtils {
  
      private RegionUtils() {}
  
  
      /**
       * Converts a list of rects into a {@code Region}.
       *
       * @param rects the list of rects to convert
       * @param outRegion the Region to set to the list of rects
       */
      public static void rectListToRegion(List<Rect> rects, Region outRegion) {
          outRegion.setEmpty();
          final int n = rects.size();
          for (int i = 0; i < n; i++) {
              outRegion.union(rects.get(i));
          }
      }
  
      /**
       * Applies actions on each rect contained within a {@code Region}.
       *
       * Order is bottom to top, then right to left.
       *
       * @param region the given region.
       * @param rectConsumer the action holder.
       */
      public static void forEachRectReverse(Region region, Consumer<Rect> rectConsumer) {
          final RegionIterator it = new RegionIterator(region);
          final ArrayList<Rect> rects = new ArrayList<>();
          final Rect rect = new Rect();
          while (it.next(rect)) {
              rects.add(new Rect(rect));
          }
          // TODO: instead of creating an array and reversing it, expose the reverse iterator through
          //       JNI.
          Collections.reverse(rects);
          rects.forEach(rectConsumer);
      }
  }
  