Android 利用属性动画结合贝塞尔曲线方程编写好看的动画.

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研究一下贝塞尔曲线.

/*** 贝塞尔方程*/private class BeizerEvaluator implements TypeEvaluator<PointF> {private PointF point1;private PointF point2;private PointF pointF;public BeizerEvaluator(PointF point1, PointF point2) {this.point1 = point1;this.point2 = point2;}@Overridepublic PointF evaluate(float time, PointF start, PointF end) {float timeLeft = 1.0f - time;pointF = new PointF();//结果PointF point0 = start;//起点PointF point3 = end;//终点pointF.x = timeLeft * timeLeft * timeLeft * (point0.x)+ 3 * timeLeft * timeLeft * time * (point1.x)+ 3 * timeLeft * time * time * (point2.x)+ time * time * time * (point3.x);pointF.y = timeLeft * timeLeft * timeLeft * (point0.y)+ 3 * timeLeft * timeLeft * time * (point1.y)+ 3 * timeLeft * time * time * (point2.y)+ time * time * time * (point3.y);return pointF;}}

//初始化一个BezierEvaluatorBeizerEvaluator evaluator = new BeizerEvaluator(getPointF(1), getPointF(2));ValueAnimator animator = ValueAnimator.ofObject(evaluator, new PointF(rand.nextInt(getWidth()), 0), new PointF(rand.nextInt(getWidth()), mHeight - dHeight));//随机animator.addUpdateListener(new BezierListenr(tag));animator.setInterpolator(interpolators[rand.nextInt(3)]);animator.setTarget(tag);animator.setDuration(3000);

然后在需要更新的时候去Update设置imageVIew的路径:

private class BezierListenr implements ValueAnimator.AnimatorUpdateListener {private View target;public BezierListenr(View target) {this.target = target;}@Overridepublic void onAnimationUpdate(ValueAnimator animation) {PointF pointF = (PointF) animation.getAnimatedValue();ViewHelper.setX(target, pointF.x);ViewHelper.setY(target, pointF.y);ViewHelper.setAlpha(target, 1 - animation.getAnimatedFraction());}}

GitHub:https://github.com/q422013/BezierFlower

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