public class RoundCornerImageView extends ImageView {

//這裡是上邊兩個角是圓角 ，總共八個引數，後面四個決定了下面兩個角的radius
     static final float[] f ={30f,30f,30f,30f,0f,0f,0f,0f};
    public RoundCornerImageView(Context context) {
        super(context);

    }
    public RoundCornerImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
    public RoundCornerImageView(Context context, AttributeSet attrs,
                                int defStyle) {
        super(context, attrs, defStyle);
    }
    @Override
    protected void onDraw(Canvas canvas) {
        Path clipPath = new Path();
        int w = this.getWidth();
        int h = this.getHeight();
        clipPath.addRoundRect(new RectF(0, 0, w, h), f , Path.Direction.CW);
        canvas.clipPath(clipPath);
        super.onDraw(canvas);
    }
}