PercentClipHelper.java 文件源码

private Bitmap createMask(int width, int height) {
    Bitmap mask = Bitmap.createBitmap(width, height, Bitmap.Config.ALPHA_8);
    Canvas canvas = new Canvas(mask);

    Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    paint.setAntiAlias(true);
    paint.setColor(Color.WHITE);
    canvas.drawRect(0, 0, width, height, paint);

    if (this.params.left + this.params.right >= 1) return mask;
    if (this.params.top + this.params.bottom >= 1) return mask;

    paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
    canvas.drawRect(
            width * this.params.left, height * this.params.top,
            width * (1f - this.params.right), height * (1f - this.params.bottom),
            paint);
    return mask;
}