/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.launcher3.util;
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import android.util.Property;
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import android.view.View;
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import java.util.Arrays;
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/**
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* Utility class to handle separating a single value as a factor of multiple values
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*/
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public class MultiValueAlpha {
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public static final Property<AlphaProperty, Float> VALUE =
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new Property<AlphaProperty, Float>(Float.TYPE, "value") {
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@Override
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public Float get(AlphaProperty alphaProperty) {
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return alphaProperty.mValue;
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}
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@Override
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public void set(AlphaProperty object, Float value) {
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object.setValue(value);
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}
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};
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private final View mView;
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private final AlphaProperty[] mMyProperties;
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private int mValidMask;
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public MultiValueAlpha(View view, int size) {
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mView = view;
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mMyProperties = new AlphaProperty[size];
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mValidMask = 0;
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for (int i = 0; i < size; i++) {
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int myMask = 1 << i;
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mValidMask |= myMask;
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mMyProperties[i] = new AlphaProperty(myMask);
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}
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}
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@Override
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public String toString() {
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return Arrays.toString(mMyProperties);
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}
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public AlphaProperty getProperty(int index) {
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return mMyProperties[index];
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}
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public class AlphaProperty {
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private final int mMyMask;
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private float mValue = 1;
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// Factor of all other alpha channels, only valid if mMyMask is present in mValidMask.
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private float mOthers = 1;
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AlphaProperty(int myMask) {
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mMyMask = myMask;
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}
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public void setValue(float value) {
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if (mValue == value) {
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return;
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}
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if ((mValidMask & mMyMask) == 0) {
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// Our cache value is not correct, recompute it.
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mOthers = 1;
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for (AlphaProperty prop : mMyProperties) {
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if (prop != this) {
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mOthers *= prop.mValue;
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}
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}
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}
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// Since we have changed our value, all other caches except our own need to be
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// recomputed. Change mValidMask to indicate the new valid caches (only our own).
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mValidMask = mMyMask;
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mValue = value;
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mView.setAlpha(mOthers * mValue);
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}
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public float getValue() {
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return mValue;
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}
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@Override
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public String toString() {
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return Float.toString(mValue);
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}
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}
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}
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