Android：创建圆形图像不适用于大照片

Question

我使用以下代码创建圆形ImageView：

Class RoundedImageView：

public class RoundedImageView {
    public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, int pixels) {

        Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), 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());
        final RectF rectF = new RectF(rect);
        final float roundPx = pixels;

        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);

        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(bitmap, rect, rect, paint);

        return output;
    }
}

我用它：

Bitmap bitmap = ((BitmapDrawable)viewHolder.imageUser.getDrawable()).getBitmap();
                        Bitmap bpRounded = RoundedImageView.getRoundedCornerBitmap(bitmap, 2000);
                        viewHolder.imageUser.setImageBitmap(bpRounded);

对于某些照片，效果不佳：

你知道问题出在哪里吗？