Android水波纹效果按钮

aruba

发布于 2020-07-03 11:05:56

1.2K0

发布于 2020-07-03 11:05:56

文章被收录于专栏：android技术android技术

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

    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

    @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

    @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;
        }
    }