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
17package com.android.gallery3d.anim;
18
19import com.android.gallery3d.common.Utils;
20import com.android.gallery3d.ui.GLCanvas;
21
22public class AlphaAnimation extends CanvasAnimation {
23    private final float mStartAlpha;
24    private final float mEndAlpha;
25    private float mCurrentAlpha;
26
27    public AlphaAnimation(float from, float to) {
28        mStartAlpha = from;
29        mEndAlpha = to;
30        mCurrentAlpha = from;
31    }
32
33    @Override
34    public void apply(GLCanvas canvas) {
35        canvas.multiplyAlpha(mCurrentAlpha);
36    }
37
38    @Override
39    public int getCanvasSaveFlags() {
40        return GLCanvas.SAVE_FLAG_ALPHA;
41    }
42
43    @Override
44    protected void onCalculate(float progress) {
45        mCurrentAlpha = Utils.clamp(mStartAlpha
46                + (mEndAlpha - mStartAlpha) * progress, 0f, 1f);
47    }
48}
49