Android裁剪图片为圆形

public Bitmap getCircleBitmap(){

//需要裁剪的源图片

Bitmap resBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);

int targetWidth,targetHeight,radius;

//新图片的长和宽，为正方形（取两者中小的）

targetHeight = targetWidth=Math.max(resBitmap.getWidth(), resBitmap.getHeight());

//图片的半径

radius = targetHeight/4;

//create a new Bitmap

Bitmap outBitmap = Bitmap.createBitmap(targetWidth, targetHeight, Config.ARGB_8888);

Canvas canvas = new Canvas(outBitmap);

Paint paint = new Paint();

final int color = 0xff424242;

paint.setColor(color);

//以中心点为圆心，radius为半径画一个圆

canvas.drawCircle(targetHeight/2, targetHeight/2, radius, paint);

//设置两张图片交互时的方式为SRC_IN

paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));

canvas.drawBitmap(resBitmap, 0, 0, paint);

return outBitmap;

}