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裁剪图片的通用方法

裁剪图片的通用方法

作者: 番茄炒西红柿啊 | 来源:发表于2017-02-16 17:51 被阅读12次
    + (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;
        }
    }
    

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