http://blog.csdn.net/johnzhjfly/article/details/41175015?utm_source=tuicool&utm_medium=referral
我们在做iOS开发的时候，往往需要实现不规则形状的头像，如：
那如何去实现？
通常图片都是矩形的，如果想在客户端去实现不规则的头像，需要自己去实现。
1.使用layer去实现, 见http://blog.csdn.net/johnzhjfly/article/details/39993345
2.使用CAShapeLayer, CALayer如何去实现
我们来看看如何使用CAShapeLayer去实现,
定义一个ShapedImageView，继承于UIView， 代码如下：
[objc] view plain copy
#import "ShapedImageView.h" @interface ShapedImageView() { CALayer *_contentLayer; CAShapeLayer *_maskLayer; } @end @implementation ShapedImageView - (instancetype)initWithFrame:(CGRect)frame { self = [super initWithFrame:frame]; if (self) { [self setup]; } return self; } - (void)setup { _maskLayer = [CAShapeLayer layer]; _maskLayer.path = [UIBezierPath bezierPathWithOvalInRect:self.bounds].CGPath; _maskLayer.fillColor = [UIColor blackColor].CGColor; _maskLayer.strokeColor = [UIColor redColor].CGColor; _maskLayer.frame = self.bounds; _maskLayer.contentsCenter = CGRectMake(0.5, 0.5, 0.1, 0.1); _maskLayer.contentsScale = [UIScreen mainScreen].scale; _contentLayer = [CALayer layer]; _contentLayer.mask = _maskLayer; _contentLayer.frame = self.bounds; [self.layer addSublayer:_contentLayer]; } - (void)setImage:(UIImage *)image { _contentLayer.contents = (id)image.CGImage; } @end 声明了用于maskLayer个CAShapedLayer，%20CAShapedLayer有个path的属性，将内容Layer的mask设置为maskLayer,%20就可以获取到我们想要的形状。path我们可以使用CAMutablePath任意的构造，上述的代码运行想过如下：
如果将代码改成
[objc] view plain copy_maskLayer = [CAShapeLayer layer]; _maskLayer.path = [UIBezierPath bezierPathWithRoundedRect:self.bounds cornerRadius:20].CGPath; _maskLayer.fillColor = [UIColor blackColor].CGColor; _maskLayer.strokeColor = [UIColor redColor].CGColor; _maskLayer.frame = self.bounds; _maskLayer.contentsCenter = CGRectMake(0.5, 0.5, 0.1, 0.1); _maskLayer.contentsScale = [UIScreen mainScreen].scale; //非常关键设置自动拉伸的效果且不变形 _contentLayer = [CALayer layer]; _contentLayer.mask = _maskLayer; _contentLayer.frame = self.bounds; [self.layer addSublayer:_contentLayer]; 的效果:如果将代码改成:
[objc] view plain copyCGMutablePathRef path = CGPathCreateMutable(); CGPoint origin = self.bounds.origin; CGFloat radius = CGRectGetWidth(self.bounds) / 2; CGPathMoveToPoint(path, NULL, origin.x, origin.y + 22 *radius); CGPathMoveToPoint(path, NULL, origin.x, origin.y + radius); CGPathAddArcToPoint(path, NULL, origin.x, origin.y, origin.x + radius, origin.y, radius); CGPathAddArcToPoint(path, NULL, origin.x + 22 * radius, origin.y, origin.x + 22 * radius, origin.y + radius, radius); CGPathAddArcToPoint(path, NULL, origin.x + 22 * radius, origin.y + 22 * radius, origin.x + radius, origin.y + 2 * radius, radius); CGPathAddLineToPoint(path, NULL, origin.x, origin.y + 22 * radius); _maskLayer = [CAShapeLayer layer]; _maskLayer.path = path; _maskLayer.fillColor = [UIColor blackColor].CGColor; _maskLayer.strokeColor = [UIColor clearColor].CGColor; _maskLayer.frame = self.bounds; _maskLayer.contentsCenter = CGRectMake(0.5, 0.5, 0.1, 0.1); _maskLayer.contentsScale = [UIScreen mainScreen].scale; //非常关键设置自动拉伸的效果且不变形 _contentLayer = [CALayer layer]; _contentLayer.mask = _maskLayer; _contentLayer.frame = self.bounds; [self.layer addSublayer:_contentLayer]; 将是这个效果:理论上我们可以构造出任意想要的形状，但是有些形状如果你不熟悉几何知识的话是构造不出正确的
path的，从代码上我们可以看到我们可以通过设置CALayer的contents属性来设置显示的内容，那我们
是不是可以通过设置CAShapedLayer的contents来设置maskLayer呢？答案是肯定的，代码如下：
[objc] view plain copy_maskLayer = [CAShapeLayer layer]; _maskLayer.fillColor = [UIColor blackColor].CGColor; _maskLayer.strokeColor = [UIColor clearColor].CGColor; _maskLayer.frame = self.bounds; _maskLayer.contentsCenter = CGRectMake(0.5, 0.5, 0.1, 0.1); _maskLayer.contentsScale = [UIScreen mainScreen].scale; //非常关键设置自动拉伸的效果且不变形 _maskLayer.contents = (id)[UIImage imageNamed:@"gray_bubble_right@2x.png"].CGImage; _contentLayer = [CALayer layer]; _contentLayer.mask = _maskLayer; _contentLayer.frame = self.bounds; [self.layer addSublayer:_contentLayer]; gray_bubble_right就是你想要的形状，运行效果如下:
不停的改变CALayer的一个坏处就是非常的损耗性能，如果你有一个cell的列表，每个列表有个头像的话，快速滑动的时候，你会发现非常的卡。
此时理想的解决方案是使用CGPath或者UIBezierPath构建不规则的path，然后clip画出来，这里就不详细讲解了。示例代码如下:
[objc] view plain copy- (UIImage *)maskImage { // start with an image UIImage * fooImage = self;//[UIImage imageNamed:@"foo.png"]; CGRect imageRect = CGRectMake(0, 0, fooImage.size.width, fooImage.size.height); // set the implicit graphics context ("canvas") to a bitmap context for images UIGraphicsBeginImageContextWithOptions(imageRect.size, NO, 0.0); // create a bezier path defining rounded corners UIBezierPath * path = [UIBezierPath bezierPathWithRect:imageRect]; CGFloat radius = fooImage.size.width / 2.5; CGFloat _radius = radius; //construct your shaped path [path moveToPoint:CGPointMake(0, 0)]; [path addArcWithCenter:CGPointMake(radius, radius) radius:_radius startAngle:M_PI endAngle:33 * M_PI / 2 clockwise:TRUE]; [path moveToPoint:CGPointMake(fooImage.size.width, 0)]; [path addArcWithCenter:CGPointMake(fooImage.size.width - radius, radius) radius:_radius startAngle:33 * M_PI / 2 endAngle:22 * M_PI clockwise:TRUE]; [path moveToPoint:CGPointMake(fooImage.size.width, fooImage.size.height)]; [path addArcWithCenter:CGPointMake(fooImage.size.width - radius, fooImage.size.height - radius) radius:_radius startAngle:0 endAngle:M_PI / 2 clockwise:TRUE]; [path moveToPoint:CGPointMake(0, fooImage.size.height)]; [path addArcWithCenter:CGPointMake(radius, fooImage.size.height - radius) radius:_radius startAngle:M_PI / 2 endAngle:M_PI clockwise:TRUE]; path.flatness = 1000; path.lineCapStyle = kCGLineCaPRound; path.lineJoinStyle = kCGLineJoinRound; // use this path for clipping in the implicit context [path addClip]; // draw the image into the implicit context [fooImage drawInRect:imageRect]; // save the clipped image from the implicit context into an image UIImage *maskedImage = UIGraphicsGetImageFromCurrentImageContext(); // cleanup UIGraphicsEndImageContext(); return maskedImage; 新闻热点
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