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