Java中的淡入淡出Android动画 [英] Fade In Fade Out Android Animation in Java

问题描述

我想要一个 ImageView 的 2 秒动画，该动画花费 1000 毫秒淡入，然后 1000 毫秒淡出.

I want to have a 2 second animation of an ImageView that spends 1000ms fading in and then 1000ms fading out.

这是我目前在 ImageView 构造函数中的内容:

Here's what I have so far in my ImageView constructor:

Animation fadeIn = new AlphaAnimation(0, 1);
fadeIn.setDuration(1000);

Animation fadeOut = new AlphaAnimation(1, 0);
fadeOut.setStartOffset(1000);
fadeOut.setDuration(1000);

AnimationSet animation = new AnimationSet(true);
animation.addAnimation(fadeIn);
animation.addAnimation(fadeOut);
this.setAnimation(animation);

当我运行那个动画时，没有出现.但是，当我删除其中一个 alpha 动画时，行为会按预期工作.

When I run that animation, nothing shows up. However, when I remove one of the alpha animations, the behavior works as expected.

我已经尝试过的事情:

• setFillBefore、setFillAfter 和 setFillEnabled 的各种可能组合.
• 将 LinearInterpolator 添加到 AnimationSet.

• Every conceivable combination of setFillBefore, setFillAfter, and setFillEnabled.
• Adding a LinearInterpolator to the AnimationSet.

推荐答案

解决了我自己的问题.该解决方案最终基于插值器.

Figured out my own problem. The solution ended up being based in interpolators.

Animation fadeIn = new AlphaAnimation(0, 1);
fadeIn.setInterpolator(new DecelerateInterpolator()); //add this
fadeIn.setDuration(1000);

Animation fadeOut = new AlphaAnimation(1, 0);
fadeOut.setInterpolator(new AccelerateInterpolator()); //and this
fadeOut.setStartOffset(1000);
fadeOut.setDuration(1000);

AnimationSet animation = new AnimationSet(false); //change to false
animation.addAnimation(fadeIn);
animation.addAnimation(fadeOut);
this.setAnimation(animation);

val fadeIn = AlphaAnimation(0f, 1f)
fadeIn.interpolator = DecelerateInterpolator() //add this
fadeIn.duration = 1000

val fadeOut = AlphaAnimation(1f, 0f)
fadeOut.interpolator = AccelerateInterpolator() //and this
fadeOut.startOffset = 1000
fadeOut.duration = 1000

val animation = AnimationSet(false) //change to false
animation.addAnimation(fadeIn)
animation.addAnimation(fadeOut)
this.setAnimation(animation)

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