java - 如何在android中创建平滑的高度变化动画

Question

我想创建平滑的高度变化动画。下面，您可以看到我当前的实现。它可以工作，但并不像我预期的那样顺利。

import android.view.View;
import android.view.animation.Animation;
import android.view.animation.Transformation;

public class HeightAnimation extends Animation {
     private final int targetHeight;
     private final View view;
     private final int height;

     public HeightAnimation(View view, int targetHeight) {
         this.view = view;
         this.targetHeight = targetHeight;
         height = view.getHeight();
     }

     @Override
     protected void applyTransformation(float interpolatedTime, Transformation t) {
         view.getLayoutParams().height = (int) (height + (targetHeight - height) * interpolatedTime);
         view.requestLayout();
     }

     @Override
     public void initialize(int width, int height, int parentWidth,
                       int parentHeight) {
         super.initialize(width, height, parentWidth, parentHeight);
     }

     @Override
     public boolean willChangeBounds() {
         return true;
     }
 }

有没有人有更好的解决方案？也许有办法使用 ObjectAnimator？

Answer 1

我认为您应该使用 ObjectAnimator 来驱动它，而不是创建一个扩展 Animation 的类。

private void animateViewHeight(View view, int targetHeight) {
    ValueAnimator animator = ObjectAnimator.ofInt(view.getHeight(), targetHeight);

    animator.addUpdateListener(animation -> {
        LayoutParams params = view.getLayoutParams();
        params.height = (int) animation.getAnimatedValue();
        view.setLayoutParams(params);
    });

    animator.start();
}