1 /* 2 * Copyright (C) 2018 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.launcher3.util; 18 19 import android.util.Property; 20 import android.view.View; 21 22 /** 23 * Utility class to handle separating a single value as a factor of multiple values 24 */ 25 public class MultiValueAlpha { 26 27 public static final Property<AlphaProperty, Float> VALUE = 28 new Property<AlphaProperty, Float>(Float.TYPE, "value") { 29 30 @Override 31 public Float get(AlphaProperty alphaProperty) { 32 return alphaProperty.mValue; 33 } 34 35 @Override 36 public void set(AlphaProperty object, Float value) { 37 object.setValue(value); 38 } 39 }; 40 41 private final View mView; 42 private final AlphaProperty[] mMyProperties; 43 44 private int mValidMask; 45 MultiValueAlpha(View view, int size)46 public MultiValueAlpha(View view, int size) { 47 mView = view; 48 mMyProperties = new AlphaProperty[size]; 49 50 mValidMask = 0; 51 for (int i = 0; i < size; i++) { 52 int myMask = 1 << i; 53 mValidMask |= myMask; 54 mMyProperties[i] = new AlphaProperty(myMask); 55 } 56 } 57 getProperty(int index)58 public AlphaProperty getProperty(int index) { 59 return mMyProperties[index]; 60 } 61 62 public class AlphaProperty { 63 64 private final int mMyMask; 65 66 private float mValue = 1; 67 // Factor of all other alpha channels, only valid if mMyMask is present in mValidMask. 68 private float mOthers = 1; 69 AlphaProperty(int myMask)70 AlphaProperty(int myMask) { 71 mMyMask = myMask; 72 } 73 setValue(float value)74 public void setValue(float value) { 75 if (mValue == value) { 76 return; 77 } 78 79 if ((mValidMask & mMyMask) == 0) { 80 // Our cache value is not correct, recompute it. 81 mOthers = 1; 82 for (AlphaProperty prop : mMyProperties) { 83 if (prop != this) { 84 mOthers *= prop.mValue; 85 } 86 } 87 } 88 89 // Since we have changed our value, all other caches except our own need to be 90 // recomputed. Change mValidMask to indicate the new valid caches (only our own). 91 mValidMask = mMyMask; 92 mValue = value; 93 94 mView.setAlpha(mOthers * mValue); 95 } 96 getValue()97 public float getValue() { 98 return mValue; 99 } 100 } 101 } 102