android 使图片显示 圆角

//获得圆角图片的方法   
public Bitmap getRoundedCornerBitmap(Bitmap bitmap,float roundPx){   
            
    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);   
     
    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;   
}