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/*
* 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);
}
}
}
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