/**
* 在圆形外面加一个圆环
*/
- (void)yuanHuan{
//0.加载图片
UIImage *image = [UIImage imageNamed:@"AppIcon1024"];
//图片的宽度
CGFloat imageWH = image.size.width;
//设置圆环的宽度
CGFloat border = 1;
//大圆形的宽度高度
CGFloat ovalWH = imageWH + 2 * border;
//1、开启位图上下文
UIGraphicsBeginImageContextWithOptions(CGSizeMake(ovalWH, ovalWH), NO, 0);
//2、画大圆
UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0, 0, ovalWH, ovalWH)];
[[UIColor redColor] set];
[path fill];
//3、设置裁剪区（小圆）
UIBezierPath *clipPath = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(border, border, imageWH, imageWH)];
[clipPath addClip];
//4、绘制图片
[image drawAtPoint:CGPointMake(border, border)];
//5、获取图片
UIImage *clipImage = UIGraphicsGetImageFromCurrentImageContext();
//6、关闭上下文
UIGraphicsEndImageContext();
self.imageView.image = clipImage;
}
/**
* 裁剪一个原型图片
*/
- (void)yuan{
//获取图片
UIImage *image = [UIImage imageNamed:@"AppIcon1024"];
//1.开启位图上下文，跟图片尺寸大小一样
//NO:不透明 0：scale不缩放
UIGraphicsBeginImageContextWithOptions(image.size, NO, 0);
//2.设置图形裁剪区域，正切图片
//2.1创建一个圆形路径
UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0, 0, image.size.width, image.size.width)];
//2.2把路径设置裁剪区
[path addClip];
//3.绘制图片
[image drawAtPoint:CGPointMake(0, 0)];
//4.从上下文中获取图片
UIImage *clipImage = UIGraphicsGetImageFromCurrentImageContext();
//5.关闭上下文
UIGraphicsEndImageContext();
_imageView.image = clipImage;
}