iphone中的圆形相框效果

[问答小助手]

原问题来自于CSDN问答频道，更多解决方案见：http://ask.csdn.net/questions/1908

想用下面的代码实现一个圆形相框：

CGContextRef context = CGBitmapContextCreate(NULL, self.bounds.size.width, self.bounds.size.height, 8, 4 * self.bounds.size.width, CGColorSpaceCreateDeviceRGB(), kCGImageAlphaPremultipliedFirst);
CGContextAddArc(context, 1024/2, 768/2, size, 0, 6.3, 0);
CGContextClosePath(context);
CGContextClip(context);
CGContextDrawImage(context, self.bounds, imageView.image.CGImage);
CGImageRef imageMasked = CGBitmapContextCreateImage(context);
CGContextRelease(context);
UIImage *newImage = [UIImage imageWithCGImage:imageMasked];
CGImageRelease(imageMasked);

[imageView setImage:newImage];
UIGraphicsEndImageContext();

在设置size--，圆形区域就会缩小，但是设置size++的时候，就没有反应。
不知道怎么呢？




解决方案：

你的代码修改成这样就可以了

- (IBAction)minus:(id)sender {
    self.radius = @([self.radius floatValue]+10.0f);
    [self redrawImage];
}

- (IBAction)plus:(id)sender {
    self.radius = @([self.radius floatValue]-10.0f);
    [self redrawImage];
}

-(void)redrawImage
{
    //set the original image first
    [_imageView setImage:[UIImage imageNamed:@"your image goes here"]];

    CGFloat size = [self.radius floatValue];
    CGContextRef context = CGBitmapContextCreate(NULL, self.view.bounds.size.width, self.view.bounds.size.height, 8, 4 * self.view.bounds.size.width, CGColorSpaceCreateDeviceRGB(), kCGImageAlphaPremultipliedFirst);
    CGContextAddArc(context, 320/2, 460/2, size, 0, 2*M_PI, 0);
    CGContextClosePath(context);
    CGContextClip(context);
    CGContextDrawImage(context, self.view.bounds, _imageView.image.CGImage);
    CGImageRef imageMasked = CGBitmapContextCreateImage(context);
    CGContextRelease(context);
    UIImage *newImage = [UIImage imageWithCGImage:imageMasked];
    CGImageRelease(imageMasked);

    [_imageView setImage:newImage];
    UIGraphicsEndImageContext();
}

[zyr987503101]

看不懂，悲催的。。。。

[furlxy]

用不着这么麻烦

#import <QuartzCore/QuartzCore.h>
// ...
[image.layer setCornerRadius:17];
[image.layer setMasksToBounds:TRUE];

[u010202722]

[isaced]

不错哦！！！

[zxqw3366]

[_过去已空白]

无满意结贴，来接分的

[xhang21a]

楼主牛啊，学习了

[u010229958]

顶，楼主牛人，膜拜

[sosoben]

引用 5 楼 u010133114 的回复:

这是C的吗，还是C++的

Objective C 上百度google一下吧

[qq823869568]

[whq_0413]

CALayer *l = [img_HeaderIcon layer]; //获取ImageView的层 [l setMasksToBounds:YES]; [l setCornerRadius:15.0]; 这三行代码就能搞定。img_HeaderIcon是你想把哪个UIIMageView来变成圆形的，15.0是根据图片的大小来改变的角度，so easy!

[SiamPig]

引用 47 楼 furlxy 的回复:

用不着这么麻烦

#import <QuartzCore/QuartzCore.h>
// ...
[image.layer setCornerRadius:17];
[image.layer setMasksToBounds:TRUE];

这个方法起始挺好的，不需要那么麻烦的

[gxingmin]

也可以这样实现圆形相框

#import <QuartzCore/QuartzCore.h>

imageView.layer.cornerRadius = imageView.frame.size.width/2;
imageView.layer.masksToBounds = YES;

[creso]

- (void)drawRect:(CGRect)rect
{
    // Drawing code
    
    if (self.image != nil && ![self.image isEqual:[NSNull null]]) {

        CGRect imgRect = originalFrame;//originalBounds;
        imgRect.origin = CGPointMake(shadowWidth * 2, shadowWidth * 2);
        CGContextRef context = UIGraphicsGetCurrentContext();
        
        UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, [CYInfo screenScale]);
        CGContextRef imgContext = UIGraphicsGetCurrentContext();
        CGPathRef clippingPath = [UIBezierPath bezierPathWithArcCenter:CGPointMake(imgRect.size.width / 2, imgRect.size.height / 2) radius:self.cornerRadius - 2 startAngle:0.0 endAngle:360 clockwise:YES].CGPath;  //bezierPathWithRoundedRect:imgRect cornerRadius:self.cornerRadius].CGPath;
        CGContextAddPath(imgContext, clippingPath);
        CGContextClip(imgContext);
        [image drawInRect:imgRect];
        UIImage *currentContextImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        
        if (shadowWidth > 0.0) {
            CGContextSetShadowWithColor(context, shadowOffset, shadowBlur, self.shadowColor.CGColor);
        }
        [currentContextImage drawInRect:self.bounds];
    }
}

[wwwang89123]

( ^_^ )不错嘛

[junfeng531]

很不错啊不错加油

[NULL]

[image.layer setCornerRadius:17]; [image.layer setMasksToBounds:TRUE]; 这两句就可以了

[xia61972612]

好屌！我完全看不懂

[zhuobattle]

[凛然。]

每次都需要重新绘制就好了