1 /*
2  * Copyright (C) 2010 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.gallery3d.anim;
18 
19 import com.android.gallery3d.common.Utils;
20 import com.android.gallery3d.glrenderer.GLCanvas;
21 
22 public class AlphaAnimation extends CanvasAnimation {
23     private final float mStartAlpha;
24     private final float mEndAlpha;
25     private float mCurrentAlpha;
26 
AlphaAnimation(float from, float to)27     public AlphaAnimation(float from, float to) {
28         mStartAlpha = from;
29         mEndAlpha = to;
30         mCurrentAlpha = from;
31     }
32 
33     @Override
apply(GLCanvas canvas)34     public void apply(GLCanvas canvas) {
35         canvas.multiplyAlpha(mCurrentAlpha);
36     }
37 
38     @Override
getCanvasSaveFlags()39     public int getCanvasSaveFlags() {
40         return GLCanvas.SAVE_FLAG_ALPHA;
41     }
42 
43     @Override
onCalculate(float progress)44     protected void onCalculate(float progress) {
45         mCurrentAlpha = Utils.clamp(mStartAlpha
46                 + (mEndAlpha - mStartAlpha) * progress, 0f, 1f);
47     }
48 }
49