RippleButton.gif
基本思路是自定义控件继承至Button，记录手势抬起坐标，利用RadialGradient实现效果
代码语言：javascript复制 private Paint ripplePaint = new Paint();
private RadialGradient radialGradient;
//递增的半径
private float radius = -1;
private float currentX;
private float currentY;在onTouchEvent事件中记录手指抬起的坐标
代码语言：javascript复制 @Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_UP:
//记录手抬起的点
currentX = event.getX();
currentY = event.getY();
radius = 1;
//通知重绘
postInvalidate();
break;
}
return super.onTouchEvent(event);
}onDraw方法中实现效果
代码语言：javascript复制 @Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if (radius > 0 && radius < getMeasuredWidth()) {
radialGradient = new RadialGradient(currentX, currentY, radius, Color.TRANSPARENT, Color.GREEN, Shader.TileMode.CLAMP);
ripplePaint.setShader(radialGradient);
canvas.drawCircle(currentX, currentY, radius, ripplePaint);
postInvalidateDelayed(10);
radius = 10;
} else {
radius = -1;
}
}
