android通过Canvas和Paint截取无锯齿圆形图片

/**
* 根据原图和变长绘制圆形图片
*
* @param source
* @param min
* @return
*/
public static Bitmap createCircleImage(Bitmap source, int min) {
Paint paint = new Paint();
//        paint.setStyle(Paint.Style.STROKE);
//        paint.setFlags(Paint.ANTI_ALIAS_FLAG);
paint.setAntiAlias(true);
paint.setFilterBitmap(true);
Bitmap target = Bitmap.createBitmap(min, min, source.getConfig());
/**
* 产生一个同样大小的画布
*/
Canvas canvas = new Canvas(target);

/**
* 首先绘制圆形
*/
canvas.drawCircle(min / 2, min / 2, min / 2, paint);
/**
* 使用SRC_IN
*/
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));

/**
* 给Canvas加上抗锯齿标志
*/
canvas.setDrawFilter(new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG));

/**
* 绘制图片
*/
canvas.drawBitmap(source, 0, 0, paint);
return target;
}