自定义动画之自定义HSVEvaluator(颜色渐变)

// 自定义 HslEvaluator

private class HsvEvaluator implements TypeEvaluator<Integer> {
   float[] startHsv = new float[3];
   float[] endHsv = new float[3];
   float[] outHsv = new float[3];
   
   @Override
   public Integer evaluate(float fraction, Integer startValue, Integer endValue) {
       // 把 ARGB 转换成 HSV
       Color.colorToHSV(startValue, startHsv);
       Color.colorToHSV(endValue, endHsv);
       
       // 计算当前动画完成度（fraction）所对应的颜色值
       if (endHsv[0] - startHsv[0] > 180) {
           endHsv[0] -= 360;
       } else if (endHsv[0] - startHsv[0] < -180) {
           endHsv[0] += 360;
       }
       outHsv[0] = startHsv[0] + (endHsv[0] - startHsv[0]) * fraction;
       if (outHsv[0] > 360) {
           outHsv[0] -= 360;
       } else if (outHsv[0] < 0) {
           outHsv[0] += 360;
       }
       outHsv[1] = startHsv[1] + (endHsv[1] - startHsv[1]) * fraction;
       outHsv[2] = startHsv[2] + (endHsv[2] - startHsv[2]) * fraction;
       // 计算当前动画完成度（fraction）所对应的透明度
       int alpha = startValue >> 24 + (int) ((endValue >> 24 - startValue >> 24) * fraction);

       // 把 HSV 转换回 ARGB 返回
       return Color.HSVToColor(alpha, outHsv);
   }
}

ObjectAnimator animator = ObjectAnimator.ofInt(view, "color", 0xff00ff00);
// 使用自定义的 HslEvaluator
animator.setEvaluator(new HsvEvaluator());
animator.start();

出处http://mp.weixin.qq.com/s/k0nfDfktf3CcGnFR9nY_GQ