imageView创建圆形头像

public class MainActivity extends Activity {
        private ImageView image;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        image=(ImageView)findViewById(R.id.image);
        
        Bitmap bitmap=BitmapFactory.decodeResource(getResources(), R.drawable.bt);
      Bitmap output=toRoundCorner(bitmap, 15.0f);
        image.setImageBitmap(output);
    }  
    public static Bitmap toRoundCorner(Bitmap bitmap, float 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);  
        System.out.println("pixels+++++++"+pixels);
        
  
        return output;  
    }
}