UIImage 裁剪图片和等比列缩放图片

转自 http://www.tedz.me/ios/uiimage-crop-resize-image

@ interface UIImage ( UIImageScale )

- ( UIImage* ) getSubImage : ( CGRect ) rect ;

- ( UIImage* ) scaleToSize : ( CGSize ) size ;

@ end

 

@ implementation UIImage ( UIImageScale )

 

//截取部分图像

- ( UIImage* ) getSubImage : ( CGRect ) rect

{

     CGImageRef subImageRef = CGImageCreateWithImageInRect ( self . CGImage , rect ) ;

     CGRect smallBounds = CGRectMake ( 0 , 0 , CGImageGetWidth ( subImageRef ) , CGImageGetHeight ( subImageRef ) ) ;

 

     UIGraphicsBeginImageContext ( smallBounds . size ) ;

     CGContextRef context = UIGraphicsGetCurrentContext ( ) ;

     CGContextDrawImage ( context , smallBounds , subImageRef ) ;

     UIImage* smallImage = [ UIImage imageWithCGImage : subImageRef ] ;

     UIGraphicsEndImageContext ( ) ;

 

     return smallImage ;

}

 

//等比例缩放

- ( UIImage* ) scaleToSize : ( CGSize ) size

{

     CGFloat width = CGImageGetWidth ( self . CGImage ) ;

     CGFloat height = CGImageGetHeight ( self . CGImage ) ;

 

     float verticalRadio = size . height* 1.0 / height ;

     float horizontalRadio = size . width* 1.0 / width ;

 

     float radio = 1 ;

     if ( verticalRadio & gt ; 1 & amp ; & amp ; horizontalRadio & gt ; 1 )

     {

         radio = verticalRadio & gt ; horizontalRadio ? horizontalRadio : verticalRadio ;

     }

     else

     {

         radio = verticalRadio & lt ; horizontalRadio ? verticalRadio : horizontalRadio ;

     }

 

     width = width* radio ;

     height = height* radio ;

 

     int xPos = ( size . width - width ) / 2 ;

     int yPos = ( size . height - height ) / 2 ;

 

     // 创建一个bitmap的context

     // 并把它设置成为当前正在使用的context

     UIGraphicsBeginImageContext ( size ) ;   

 

     // 绘制改变大小的图片

     [ self drawInRect : CGRectMake ( xPos , yPos , width , height ) ] ;   

 

     // 从当前context中创建一个改变大小后的图片

     UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext ( ) ;   

 

     // 使当前的context出堆栈

     UIGraphicsEndImageContext ( ) ;   

 

     // 返回新的改变大小后的图片

     return scaledImage ;

}

@ end

 

然后在下面方法里面调用就可以了！

 

- ( BOOL ) application : ( UIApplication * ) application didFinishLaunchingWithOptions : ( NSDictionary * ) launchOptions

{

     // Override point for customization after application launch.

     UIImage * image = [ [ UIImage alloc ] initWithData : [ NSData dataWithContentsOfURL : [ NSURL URLWithString : @ & quot ; http : //img21.mtime.cn/mg/2011/09/24/112524.53149978.jpg"]] ];

 

     // 裁剪图片

     //image = [image getSubImage:CGRectMake(10, 10, 70, 80)];

 

     //等比列缩放

 

     image = [ image scaleToSize : CGSizeMake ( 200 , 300 ) ] ;

 

     UIImageView * imageView = [ [ UIImageView alloc ] initWithImage : image ] ;

 

     [ self . window addSubview : imageView ] ;

 

     NSLog ( @ & quot ; image . size : % @ & quot ; , NSStringFromCGSize ( CGSizeMake ( imageView . image . size . width , imageView . image . size . height ) ) ) ;    //打印获取的网络图片的宽度和高度

 

     [ self . window makeKeyAndVisible ] ;

     return YES ;

}

 

//--------------截取部分图片到指定位置-------------------------

 

图片 ( UIImage* ) img

要截取的起始坐标 sx : ( int ) sx1 sy : ( int ) sy1

要截取的长度和宽度 sw : ( int ) sw1 sh : ( int ) sh1

最终要显示的坐标 desx : ( int ) desx1 desy : ( int ) desy1

 

- ( UIImage* ) objectiveDrawRegion : ( UIImage* ) img sx : ( int ) sx1 sy : ( int ) sy1 sw : ( int ) sw1 sh : ( int ) sh1 desx : ( int ) desx1 desy : ( int ) desy1 {

[ self saveImage : img name : @ & quot ; objectiveDrawRegion1 . png & quot ; ] ;

 

//创建图片缓冲

void * imageDataRegion = malloc ( screenWidth* screenHeight* 32 ) ;

CGColorSpaceRef iColorSpaceRegion = CGColorSpaceCreateDeviceRGB ( ) ;

     CGContextRefiDeviceRegion = CGBitmapContextCreate ( imageDataRegion , screenWidth , screenHeight , 8 , 4 * screenWidth , iColorSpaceRegion , kCGImageAlphaPremultipliedLast ) ;

 

//剪切区域

     CGRect clipRegion = CGRectMake ( sx1 , sy1 , sw1 , sh1 ) ;

     CGContextClipToRect ( iDeviceRegion , clipRegion ) ;

 

     CGFloat widthf = img . size . width ;

     CGFloat heightf = img . size . height ;

 

CGRect   cg = CGRectMake ( 0.0 , 0.0 , widthf , heightf ) ;

//画底图

     CGContextDrawImage ( iDeviceRegion , cg , img . CGImage ) ;

 

//将缓冲形成图片

     CGImageRef ioffRegion = CGBitmapContextCreateImage ( iDeviceRegion ) ;

 

CGRect   cg1 = CGRectMake ( desx1 , desy1 , sw1 , sh1 ) ;

UIImage * ui = [ UIImage imageWithCGImage : ioffRegion ] ;

 

CGContextDrawImage (当前 context , cg1 , ui . CGImage ) ;

 

//清除缓冲

   CGColorSpaceRelease ( iColorSpaceRegion ) ;

   CGContextRelease ( iDeviceRegion ) ;

   CGImageRelease ( ioffRegion ) ;

   free ( imageDataRegion ) ;

//    iDeviceRegion=NULL;

//    imageDataRegion=0;

 

return ui ;

}