iphone(objective-c)相当于j2me的drawRegion方法 截取部分图片显示到指定位置

 

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:@"objectiveDrawRegion1.png"];

 

//创建图片缓冲

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

CGColorSpaceRef iColorSpaceRegion=CGColorSpaceCreateDeviceRGB();

    CGContextRef iDeviceRegion=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;

}

 

 

／／这个方法更高效

/*

 实现j2me的drawRegion方法

 sx 图片剪切的x位置

 sy 图片剪切的y位置

 sw 图片剪切的宽度

 sh 图片剪切的高度

 dx 剪切后的x位置

 dy 剪切后的y位置

 device 上下文

 */

-(void) objectiveDrawRegion:(UIImage*) img 

sx:(int) sx1    

sy:(int) sy1 

sw:(int) sw1 

sh:(int) sh1 

dx:(int) dx1

dy:(int) dy1

device:(CGContextRef)idevicecopyOffscr

{

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

CGImageRef imgRef = CGImageCreateWithImageInRect(img.CGImage, rect);

int dy1Trans = screenHeight - dy1 - sh1;

CGContextDrawImage(idevicecopyOffscr

  , CGRectMake(dx1, dy1Trans, sw1, sh1)

  , imgRef);

CGImageRelease(imgRef);

｝