Android Bitmap圆角

	 public Bitmap transform(Bitmap source) {
	        int size = Math.min(source.getWidth(), source.getHeight());

	        int x = (source.getWidth() - size) / 2;
	        int y = (source.getHeight() - size) / 2;

	        Bitmap squaredBitmap = Bitmap.createBitmap(source, x, y, size, size);
	        if (squaredBitmap != source) {
	            source.recycle();
	        }

	        Bitmap bitmap = Bitmap.createBitmap(size, size, source.getConfig());

	        Canvas canvas = new Canvas(bitmap);
	        Paint paint = new Paint();
	        BitmapShader shader = new BitmapShader(squaredBitmap, BitmapShader.TileMode.CLAMP, BitmapShader.TileMode.CLAMP);
	        paint.setShader(shader);
	        paint.setAntiAlias(true);

	        float r = size/2f;
	        canvas.drawCircle(r, r, r, paint);

	        squaredBitmap.recycle();
	        return bitmap;
	    }