Question

I’m trying to round corners of a bitmap using this code below. The problem is that no matter what I set the paint’s color to, e.g. Color.TRANSPARENT , it is always black. How can I actually clip the corners of a bitmap, not just color them black?

Thanks!

    public static Bitmap roundCorners(Bitmap src, int radius) {
    //Create a *mutable* location, and a canvas to draw into it
    int width = src.getWidth();
    int height = src.getHeight();
    Bitmap result = Bitmap.createBitmap(width, height, Config.ARGB_8888);
    Canvas canvas = new Canvas(result);
    Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    RectF rect = new RectF(0, 0, width, height);
    Shader bitmapShader = new BitmapShader(src, TileMode.CLAMP, TileMode.CLAMP);
    paint.setColor(0xFF000000);
    paint.setShader(bitmapShader);
    canvas.drawRoundRect(rect, radius, radius, paint);
    return result;
}

Answer 1

There’s an easier method that works in one pass. Just draw a rounded rect but set a BitmapShader on the Paint. This will fill the rounded rect with your bitmap. No need to change the xfermode or to call drawBitmap.