Circle Crop Effect on Bitmap. Designed specifically for Android ImageViews.

CircleCrop

/**
 * Returns a Bitmap object with a circle crop effect.
 * This can be used in an ImageView and it  must use
 * "centerCrop" on its scaleType to achieve desired output.
 * <p>
 * Reference: {@link} http://stackoverflow.com/a/14051472/2497859
 *
 * @param bitmap The bitmap that we're going to "circle crop"
 * @return  Bitmap with a circle crop overlay
 * @see     android.graphics.Bitmap
 */
private static Bitmap getCircleCroppedBitmap(Bitmap bitmap) {
    // use scaleType="centerCrop" on the ImageView to generate desire output
    Bitmap output = null;
    try {
        output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(output);
    
        final int color = 0xff424242;
        final Paint paint = new Paint();
        final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
    
        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        if(bitmap.getWidth() < bitmap.getHeight() ) { 
            // Bitmap is in portrait
            canvas.drawCircle(bitmap.getWidth() / 2, bitmap.getHeight() / 2, 
                    bitmap.getWidth() / 2, paint);
        } else{ 
            // Bitmap is in landscape or has a 1:1 aspect ratio
            canvas.drawCircle(bitmap.getWidth() / 2, bitmap.getHeight() / 2,
                    bitmap.getHeight() / 2, paint);
        }
        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
        canvas.drawBitmap(bitmap, rect, rect, paint);
    } catch (Exception e){
        Log.e(TAG, "getCircleCroppedBitmap " + e);
    }
    
    return output;
}