縮放圖片，並截取中間位置顯示，縮放圖片截取位置

縮放圖片，並截取中間位置顯示，縮放圖片截取位置

代碼：

- (void)viewDidLoad{    [super viewDidLoad];    // Do any additional setup after loading the view.        UIImage *imagePicture=[UIImage imageNamed:@"1.jpg"];    UIImageView *imageView=[[UIImageView alloc]initWithFrame:CGRectMake(50, 100, 200, 200)];    imageView.image=[self scaleImage:imagePicture size:CGSizeMake(300, 200)];    imageView.backgroundColor=[UIColor redColor];    [self.view addSubview:imageView];    }//縮放圖片，並截取中間位置顯示-(UIImage*)scaleImage:(UIImage *)image size:(CGSize )size{    CGSize imgSize = image.size; //原圖大小    CGSize viewSize = size;          //視圖大小    CGFloat imgwidth = 0;            //縮放後的圖片寬度    CGFloat imgheight = 0;          //縮放後的圖片高度        //視圖橫長方形及正方形    if (viewSize.width >= viewSize.height) {        //縮小        if (imgSize.width > viewSize.width && imgSize.height > viewSize.height) {            imgwidth = viewSize.width;            imgheight = imgSize.height/(imgSize.width/imgwidth);        }        //放大        if(imgSize.width < viewSize.width){            imgwidth = viewSize.width;            imgheight = (viewSize.width/imgSize.width)*imgSize.height;        }        //判斷縮放後的高度是否小於視圖高度        imgheight = imgheight < viewSize.height?viewSize.height:imgheight;    }        //視圖豎長方形    if (viewSize.width < viewSize.height) {        //縮小        if (imgSize.width > viewSize.width && imgSize.height > viewSize.height) {            imgheight = viewSize.height;            imgwidth = imgSize.width/(imgSize.height/imgheight);        }                //放大        if(imgSize.height < viewSize.height){            imgheight = viewSize.width;            imgwidth = (viewSize.height/imgSize.height)*imgSize.width;        }        //判斷縮放後的高度是否小於視圖高度        imgwidth = imgwidth < viewSize.width?viewSize.width:imgwidth;    }        //重新繪製圖片大小    UIImage *i;    UIGraphicsBeginImageContext(CGSizeMake(imgwidth, imgheight));    [image drawInRect:CGRectMake(0, 0, imgwidth, imgheight)];    i=UIGraphicsGetImageFromCurrentImageContext();    UIGraphicsEndImageContext();        //截取中間部分圖片顯示    if (imgwidth > 0) {        CGImageRef newImageRef = CGImageCreateWithImageInRect(i.CGImage, CGRectMake((imgwidth-viewSize.width)/2, (imgheight-viewSize.height)/2, viewSize.width, viewSize.height));        return [UIImage imageWithCGImage:newImageRef];    }else{        CGImageRef newImageRef = CGImageCreateWithImageInRect(image.CGImage, CGRectMake((imgwidth-viewSize.width)/2, (imgheight-viewSize.height)/2, viewSize.width, viewSize.height));        return [UIImage imageWithCGImage:newImageRef];    }}