A common way to crop pictures

Reproduced in this article to http://www.cocoachina.com/bbs/read.php?tid=177476 this code is the main function of the size or proportion of the image to cut the middle part, or proportionally narrow, there may be insufficient parts, please Daniel:

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+ (UIImage *)handleImage:(UIImage *)originalImage withSize:(CGSize)size{    CGSize originalsize = [originalImage size];    NSLog(@"改变前图片的宽度为%f,图片的高度为%f",originalsize.width,originalsize.height);        //原图长宽均小于标准长宽的，不作处理返回原图    if (originalsize.width<size.width && originalsize.height<size.height)    {        return originalImage;    }        //原图长宽均大于标准长宽的，按比例缩小至最大适应值    else if(originalsize.width>size.width && originalsize.height>size.height)    {        CGFloat rate = 1.0;        CGFloat widthRate = originalsize.width/size.width;        CGFloat heightRate = originalsize.height/size.height;                rate = widthRate>heightRate?heightRate:widthRate;                CGImageRef imageRef = nil;                 if (heightRate>widthRate)        {            imageRef = CGImageCreateWithImageInRect([originalImage CGImage], CGRectMake(0, originalsize.height/2-size.height*rate/2, originalsize.width, size.height*rate));//获取图片整体部分        }        else        {            imageRef = CGImageCreateWithImageInRect([originalImage CGImage], CGRectMake(originalsize.width/2-size.width*rate/2, 0, size.width*rate, originalsize.height));//获取图片整体部分        }        UIGraphicsBeginImageContext(size);//指定要绘画图片的大小        CGContextRef con = UIGraphicsGetCurrentContext();                CGContextTranslateCTM(con, 0.0, size.height);        CGContextScaleCTM(con, 1.0, -1.0);                CGContextDrawImage(con, CGRectMake(0, 0, size.width, size.height), imageRef);                UIImage *standardImage = UIGraphicsGetImageFromCurrentImageContext();        NSLog(@"改变后图片的宽度为%f,图片的高度为%f",[standardImage size].width,[standardImage size].height);                UIGraphicsEndImageContext();        CGImageRelease(imageRef);                return standardImage;    }        //原图长宽有一项大于标准长宽的，对大于标准的那一项进行裁剪，另一项保持不变    else if(originalsize.height>size.height || originalsize.width>size.width)    {        CGImageRef imageRef = nil;                if(originalsize.height>size.height)        {            imageRef = CGImageCreateWithImageInRect([originalImage CGImage], CGRectMake(0, originalsize.height/2-size.height/2, originalsize.width, size.height));//获取图片整体部分        }        else if (originalsize.width>size.width)        {            imageRef = CGImageCreateWithImageInRect([originalImage CGImage], CGRectMake(originalsize.width/2-size.width/2, 0, size.width, originalsize.height));//获取图片整体部分        }                UIGraphicsBeginImageContext(size);//指定要绘画图片的大小        CGContextRef con = UIGraphicsGetCurrentContext();                CGContextTranslateCTM(con, 0.0, size.height);        CGContextScaleCTM(con, 1.0, -1.0);                CGContextDrawImage(con, CGRectMake(0, 0, size.width, size.height), imageRef);                 UIImage *standardImage = UIGraphicsGetImageFromCurrentImageContext();        NSLog(@"改变后图片的宽度为%f,图片的高度为%f",[standardImage size].width,[standardImage size].height);                UIGraphicsEndImageContext();        CGImageRelease(imageRef);                return standardImage;    }        //原图为标准长宽的，不做处理    else    {        return originalImage;    }}

A common way to crop pictures