90 lines
2.7 KiB
Java
90 lines
2.7 KiB
Java
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/*
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* Copyright (C) 2006 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 android.view.animation;
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import android.content.Context;
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import android.content.res.TypedArray;
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import android.util.AttributeSet;
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/**
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* An animation that controls the alpha level of an object.
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* Useful for fading things in and out. This animation ends up
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* changing the alpha property of a {@link Transformation}
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*
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*/
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public class AlphaAnimation extends Animation {
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private float mFromAlpha;
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private float mToAlpha;
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/**
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* Constructor used when an AlphaAnimation is loaded from a resource.
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*
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* @param context Application context to use
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* @param attrs Attribute set from which to read values
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*/
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public AlphaAnimation(Context context, AttributeSet attrs) {
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super(context, attrs);
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TypedArray a =
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context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.AlphaAnimation);
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mFromAlpha = a.getFloat(com.android.internal.R.styleable.AlphaAnimation_fromAlpha, 1.0f);
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mToAlpha = a.getFloat(com.android.internal.R.styleable.AlphaAnimation_toAlpha, 1.0f);
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a.recycle();
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}
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/**
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* Constructor to use when building an AlphaAnimation from code
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*
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* @param fromAlpha Starting alpha value for the animation, where 1.0 means
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* fully opaque and 0.0 means fully transparent.
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* @param toAlpha Ending alpha value for the animation.
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*/
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public AlphaAnimation(float fromAlpha, float toAlpha) {
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mFromAlpha = fromAlpha;
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mToAlpha = toAlpha;
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}
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/**
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* Changes the alpha property of the supplied {@link Transformation}
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*/
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@Override
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protected void applyTransformation(float interpolatedTime, Transformation t) {
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final float alpha = mFromAlpha;
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t.setAlpha(alpha + ((mToAlpha - alpha) * interpolatedTime));
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}
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@Override
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public boolean willChangeTransformationMatrix() {
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return false;
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}
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@Override
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public boolean willChangeBounds() {
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return false;
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}
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/**
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* @hide
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*/
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@Override
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public boolean hasAlpha() {
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return true;
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}
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}
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