content: /*
   * Copyright (C) 2018 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.launcher3.util;
  
  import android.util.Property;
  import android.view.View;
  
  import java.util.Arrays;
  
  /**
   * Utility class to handle separating a single value as a factor of multiple values
   */
  public class MultiValueAlpha {
  
      public static final Property<AlphaProperty, Float> VALUE =
              new Property<AlphaProperty, Float>(Float.TYPE, "value") {
  
                  @Override
                  public Float get(AlphaProperty alphaProperty) {
                      return alphaProperty.mValue;
                  }
  
                  @Override
                  public void set(AlphaProperty object, Float value) {
                      object.setValue(value);
                  }
              };
  
      private final View mView;
      private final AlphaProperty[] mMyProperties;
  
      private int mValidMask;
  
      public MultiValueAlpha(View view, int size) {
          mView = view;
          mMyProperties = new AlphaProperty[size];
  
          mValidMask = 0;
          for (int i = 0; i < size; i++) {
              int myMask = 1 << i;
              mValidMask |= myMask;
              mMyProperties[i] = new AlphaProperty(myMask);
          }
      }
  
      @Override
      public String toString() {
          return Arrays.toString(mMyProperties);
      }
  
      public AlphaProperty getProperty(int index) {
          return mMyProperties[index];
      }
  
      public class AlphaProperty {
  
          private final int mMyMask;
  
          private float mValue = 1;
          // Factor of all other alpha channels, only valid if mMyMask is present in mValidMask.
          private float mOthers = 1;
  
          AlphaProperty(int myMask) {
              mMyMask = myMask;
          }
  
          public void setValue(float value) {
              if (mValue == value) {
                  return;
              }
  
              if ((mValidMask & mMyMask) == 0) {
                  // Our cache value is not correct, recompute it.
                  mOthers = 1;
                  for (AlphaProperty prop : mMyProperties) {
                      if (prop != this) {
                          mOthers *= prop.mValue;
                      }
                  }
              }
  
              // Since we have changed our value, all other caches except our own need to be
              // recomputed. Change mValidMask to indicate the new valid caches (only our own).
              mValidMask = mMyMask;
              mValue = value;
  
              mView.setAlpha(mOthers * mValue);
          }
  
          public float getValue() {
              return mValue;
          }
  
          @Override
          public String toString() {
              return Float.toString(mValue);
          }
      }
  }
  