Question

我想设置无限颜色动画，这会将颜色从随机开始颜色变为随机结束颜色，然后从随机结束颜色变为下一个随机结束颜色等。我尝试设置此值动画师：

ValueAnimator valueAnimator = ValueAnimator.ofObject(new ArgbEvaluator(), randomColorStart, randomColorEnd);

然后尝试在randomColorStart方法上更新randomColorEnd和onAnimationRepeat()，但更新的值不会影响动画。我怎么能做到这一点？

Answer 1

我不知道这个解决方案是否最好。但是，它的确有效！

简而言之，我创建了ValueAnimator并将其重复模式设置为INFINITE。然后，我实施了Animator.AnimatorListener来覆盖onAnimationRepeat，这在持续时间结束时被调用。然后，在onAnimationRepeat内我生成下一个随机颜色。

    int nextColor; // class-scope variable
    int startColor; // class-scope variable

    final Random rnd = new Random();
    final float[] hsv = new float[3];
    final float[] from = new float[3];
    final float[] to = new float[3];

    //generate random initial color and next color
    startColor = Color.argb(255, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256));
    nextColor = Color.argb(255, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256));

    // to get nicer smooth transition I'm using HSV 
    Color.colorToHSV(startColor, from);
    Color.colorToHSV(nextColor, to);

    final ValueAnimator anim = ValueAnimator.ofInt(startColor, nextColor);
    // animate from the current color to the next color;

    anim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            hsv[0] = from[0] + (to[0] - from[0]) * animation.getAnimatedFraction();
            hsv[1] = from[1] + (to[1] - from[1]) * animation.getAnimatedFraction();
            hsv[2] = from[2] + (to[2] - from[2]) * animation.getAnimatedFraction();

            view.setBackgroundColor(Color.HSVToColor(hsv));
        }
    });


    anim.addListener(new Animator.AnimatorListener() {
        @Override
        public void onAnimationStart(Animator animation) {

        }

        @Override
        public void onAnimationEnd(Animator animation) {

        }

        @Override
        public void onAnimationCancel(Animator animation) {

        }

        @Override
        public void onAnimationRepeat(Animator animation) {
            // generate next random color
            startColor = Color.HSVToColor(to);
            nextColor = Color.argb(255, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256));

            Color.colorToHSV(startColor, from);
            Color.colorToHSV(nextColor, to);
        }
    });

    anim.setDuration(4000); // duration to change colors
    anim.setRepeatCount(ValueAnimator.INFINITE);
    anim.start();

是否可以在动画重复时更改ValueAnimator的开始/结束值？

1 个答案: