圆角图片的设置ios

一般图片圆角显示都是四个角都显示圆角，如果只有这个功能需求，采用常用的方法就可以了，也不用费那么多事情。但是在有些情况下需要只显示图片的2个圆角，就不太好实现了。

先看效果图 ，未做圆角转换的图片

做了4个角的圆角转换的图片

只做了下面2个圆角转换的图片

如何实现画四个方向的弧线呢？

先看看示意图

头文件

#import<Foundation/Foundation.h>

typedefenum{
UIImageRoundedCornerTopLeft=1,
UIImageRoundedCornerTopRight=1<<1,
UIImageRoundedCornerBottomRight=1<<2,
UIImageRoundedCornerBottomLeft=1<<3
}UIImageRoundedCorner;

@interfaceUIImage(Utility)

//+(void)addRoundedRectToPath(CGContextRefcontext,CGRectrect,floatradius,UIImageRoundedCornercornerMask);

-(UIImage*)roundedRectWith:(float)radiuscornerMask:(UIImageRoundedCorner)cornerMask;

@end

实现文件

#import"UIImage+Utility.h"

//UIKit坐标系统原点在左上角，y方向向下的（坐标系A），但在Quartz中坐标系原点在左下角，y方向向上的(坐标系B)。图片绘制也是颠倒的。
staticvoidaddRoundedRectToPath(CGContextRefcontext,CGRectrect,floatradius,UIImageRoundedCornercornerMask)
{
//原点在左下方，y方向向上。移动到线条2的起点。
CGContextMoveToPoint(context,rect.origin.x,rect.origin.y+radius);

//画出线条2,目前画线的起始点已经移动到线条2的结束地方了。
CGContextAddLineToPoint(context,rect.origin.x,rect.origin.y+rect.size.height-radius);

//如果左上角需要画圆角，画出一个弧线出来。
if(cornerMask&UIImageRoundedCornerTopLeft){

//已左上的正方形的右下脚为圆心，半径为radius，180度到90度画一个弧线，
CGContextAddArc(context,rect.origin.x+radius,rect.origin.y+rect.size.height-radius,
radius,M_PI,M_PI/2,1);
}

else{
//如果不需要画左上角的弧度。从线2终点，画到线3的终点，
CGContextAddLineToPoint(context,rect.origin.x,rect.origin.y+rect.size.height);

//线3终点，画到线4的起点
CGContextAddLineToPoint(context,rect.origin.x+radius,rect.origin.y+rect.size.height);
}

//画线4的起始，到线4的终点
CGContextAddLineToPoint(context,rect.origin.x+rect.size.width-radius,
rect.origin.y+rect.size.height);

//画右上角
if(cornerMask&UIImageRoundedCornerTopRight){
CGContextAddArc(context,rect.origin.x+rect.size.width-radius,
rect.origin.y+rect.size.height-radius,radius,M_PI/2,0.0f,1);
}
else{
CGContextAddLineToPoint(context,rect.origin.x+rect.size.width,rect.origin.y+rect.size.height);
CGContextAddLineToPoint(context,rect.origin.x+rect.size.width,rect.origin.y+rect.size.height-radius);
}

CGContextAddLineToPoint(context,rect.origin.x+rect.size.width,rect.origin.y+radius);

//画右下角弧线
if(cornerMask&UIImageRoundedCornerBottomRight){
CGContextAddArc(context,rect.origin.x+rect.size.width-radius,rect.origin.y+radius,
radius,0.0f,-M_PI/2,1);
}
else{
CGContextAddLineToPoint(context,rect.origin.x+rect.size.width,rect.origin.y);
CGContextAddLineToPoint(context,rect.origin.x+rect.size.width-radius,rect.origin.y);
}

CGContextAddLineToPoint(context,rect.origin.x+radius,rect.origin.y);

//画左下角弧线
if(cornerMask&UIImageRoundedCornerBottomLeft){
CGContextAddArc(context,rect.origin.x+radius,rect.origin.y+radius,radius,
-M_PI/2,M_PI,1);
}
else{
CGContextAddLineToPoint(context,rect.origin.x,rect.origin.y);
CGContextAddLineToPoint(context,rect.origin.x,rect.origin.y+radius);
}

CGContextClosePath(context);
}


@implementationUIImage(Utility)
-(UIImage*)roundedRectWith:(float)radiuscornerMask:(UIImageRoundedCorner)cornerMask
{
UIImageView*bkImageViewTmp=[[[UIImageViewalloc]initWithImage:self]autorelease];

intw=self.size.width;
inth=self.size.height;

CGColorSpaceRefcolorSpace=CGColorSpaceCreateDeviceRGB();
CGContextRefcontext=CGBitmapContextCreate(NULL,w,h,8,4*w,colorSpace,kCGImageAlphaPremultipliedFirst);

CGContextBeginPath(context);
addRoundedRectToPath(context,bkImageViewTmp.frame,radius,cornerMask);
CGContextClosePath(context);
CGContextClip(context);

CGContextDrawImage(context,CGRectMake(0,0,w,h),self.CGImage);

CGImageRefimageMasked=CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);

UIImage*newImage=[UIImageimageWithCGImage:imageMasked];

CGImageRelease(imageMasked);

returnnewImage;
}

@end

实现方法如下：

-(IBAction)showRectImage
{
UIImage*rectImage=[UIImageimageNamed:@"test.jpg"];
self.imageView.image=rectImage;
}

-(IBAction)showRoundImage
{
UIImage*rectImage=[UIImageimageNamed:@"test.jpg"];
UIImage*roundImage=[rectImageroundedRectWith:100
cornerMask:UIImageRoundedCornerBottomLeft|UIImageRoundedCornerBottomRight|UIImageRoundedCornerTopLeft|UIImageRoundedCornerTopRight];
self.imageView.image=roundImage;
}


-(IBAction)show2RoundImage
{
UIImage*rectImage=[UIImageimageNamed:@"test.jpg"];
UIImage*round2Image=[rectImageroundedRectWith:100
cornerMask:UIImageRoundedCornerBottomLeft|UIImageRoundedCornerBottomRight];
self.imageView.image=round2Image;

}

对于四个角，用下面的角进行逻辑或的方法。

UIImageRoundedCornerTopRight

UIImageRoundedCornerTopLeft

UIImageRoundedCornerBottomRight

UIImageRoundedCornerBottomLeft

项目文件下载

参考URL

http://stackoverflow.com/questions/4847163/round-two-corners-in-uiview

http://stackoverflow.com/questions/4845211/just-two-rounded-corners

http://blog.sallarp.com/iphone-uiimage-round-corners/

本文出自 “人生得意须尽欢” 博客，请务必保留此出处http://no001.blog.51cto.com/1142339/637732