java - ConstraintLayout 指南百分比动画

Question

我对使用 ConstraintLayout (java) 还很陌生。

我想要实现的是当小键盘作为幻灯片动画显示/隐藏时，我尝试过这样的事情:

Animation a = new Animation() {
    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        ConstraintLayout.LayoutParams lparams = (ConstraintLayout.LayoutParams) guideline.getLayoutParams();
        lparams.guidePercent = 0.5f;
        guideline.setLayoutParams(lparams);
    }
};
a.setDuration(3000);
a.setFillAfter(true);
guideline.startAnimation(a);

是的，指南(以及附加到它的相应 View )正在移动到屏幕的中心，但它并不像预期的那样平滑。有没有什么办法可以达到动画的流畅度？

如有任何建议，我们将不胜感激!

Answer 1

您可以使用ValueAnimator

Kotlin 示例。

    val guideline = findViewById<View>(R.id.guideline2) as Guideline
    val end = (guideline.layoutParams as ConstraintLayout.LayoutParams).guidePercent
    // get end percent. start at 0
    val valueAnimator = ValueAnimator.ofFloat(0f, end)
    valueAnimator.duration = 3000
    // set duration 
    valueAnimator.interpolator = AccelerateDecelerateInterpolator()
    // set interpolator and  updateListener to get the animated value
    valueAnimator.addUpdateListener { valueAnimator ->
        val lp = guideline.layoutParams as ConstraintLayout.LayoutParams
        // get the float value
        lp.guidePercent = valueAnimator.animatedValue as Float
        // update layout params
        guideline.layoutParams = lp
    }
    valueAnimator.start()

Java 版本

 final Guideline guideline = findViewById(R.id.guideline2) ;
 ConstraintLayout.LayoutParams lp = (ConstraintLayout.LayoutParams)guideline.getLayoutParams();
 float end =lp.guidePercent;
 ValueAnimator valueAnimator = ValueAnimator.ofFloat(0f, end);
 valueAnimator.setDuration(3000);
 valueAnimator.setInterpolator(new AccelerateDecelerateInterpolator());
 valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator valueAnimator) {
                ConstraintLayout.LayoutParams lp = (ConstraintLayout.LayoutParams)guideline.getLayoutParams();
                lp.guidePercent = valueAnimator.getAnimatedFraction();
                guideline.setLayoutParams(lp);

            }
 });