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  • IOS_画图 图片等比压缩 IOS_UIImage

    - (UIImage *)scaleToSize:(UIImage *)img size:(CGSize)size{    
        // 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    
        [img drawInRect:CGRectMake(0,0, size.width, size.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;    
    } 

    压缩成指定大小代码

    等比压缩

    等比例压缩
    -(UIImage *) imageCompressForSize:(UIImage *)sourceImage targetSize:(CGSize)size{
        UIImage *newImage = nil;
        CGSize imageSize = sourceImage.size;
        CGFloat width = imageSize.width;
        CGFloat height = imageSize.height;
        CGFloat targetWidth = size.width;
        CGFloat targetHeight = size.height;
        CGFloat scaleFactor = 0.0;
        CGFloat scaledWidth = targetWidth;
        CGFloat scaledHeight = targetHeight;
        CGPoint thumbnailPoint = CGPointMake(0.0, 0.0);
        if(CGSizeEqualToSize(imageSize, size) == NO){
            CGFloat widthFactor = targetWidth / width;
            CGFloat heightFactor = targetHeight / height;
            if(widthFactor > heightFactor){
                scaleFactor = widthFactor;
            }
            else{
                scaleFactor = heightFactor;
            }
            scaledWidth = width * scaleFactor;
            scaledHeight = height * scaleFactor;
            if(widthFactor > heightFactor){
                thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
            }else if(widthFactor < heightFactor){
                thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
            }
        }
    
        UIGraphicsBeginImageContext(size);
    
        CGRect thumbnailRect = CGRectZero;
        thumbnailRect.origin = thumbnailPoint;
        thumbnailRect.size.width = scaledWidth;
        thumbnailRect.size.height = scaledHeight;
        [sourceImage drawInRect:thumbnailRect];
        newImage = UIGraphicsGetImageFromCurrentImageContext();
        
        if(newImage == nil){
            NSLog(@"scale image fail");
        }
    
        UIGraphicsEndImageContext();
        
        return newImage;
        
    }
    
    -(UIImage *) imageCompressForWidth:(UIImage *)sourceImage targetWidth:(CGFloat)defineWidth{
        UIImage *newImage = nil;
        CGSize imageSize = sourceImage.size;
        CGFloat width = imageSize.width;
        CGFloat height = imageSize.height;
        CGFloat targetWidth = defineWidth;
        CGFloat targetHeight = height / (width / targetWidth);
        CGSize size = CGSizeMake(targetWidth, targetHeight);
        CGFloat scaleFactor = 0.0;
        CGFloat scaledWidth = targetWidth;
        CGFloat scaledHeight = targetHeight;
        CGPoint thumbnailPoint = CGPointMake(0.0, 0.0);
        if(CGSizeEqualToSize(imageSize, size) == NO){
            CGFloat widthFactor = targetWidth / width;
            CGFloat heightFactor = targetHeight / height;
            if(widthFactor > heightFactor){
                scaleFactor = widthFactor;
            }
            else{
                scaleFactor = heightFactor;
            }
            scaledWidth = width * scaleFactor;
            scaledHeight = height * scaleFactor;
            if(widthFactor > heightFactor){
                thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
            }else if(widthFactor < heightFactor){
                thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
            }
        }
        UIGraphicsBeginImageContext(size);
        CGRect thumbnailRect = CGRectZero;
        thumbnailRect.origin = thumbnailPoint;
        thumbnailRect.size.width = scaledWidth;
        thumbnailRect.size.height = scaledHeight;
    
        [sourceImage drawInRect:thumbnailRect];
    
        newImage = UIGraphicsGetImageFromCurrentImageContext();
        if(newImage == nil){
            NSLog(@"scale image fail");
        }
    
        UIGraphicsEndImageContext();
        return newImage;
    }
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  • 原文地址:https://www.cnblogs.com/yswdarren/p/3611934.html
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