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IOS_画图 图片等比压缩 IOS_UIImage

内容导读

互联网集市收集整理的这篇技术教程文章主要介绍了IOS_画图 图片等比压缩 IOS_UIImage，小编现在分享给大家，供广大互联网技能从业者学习和参考。文章包含3234字，纯文字阅读大概需要5分钟。

内容图文

- (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;
        }elseif(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;
        }elseif(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;
}

原文：http://www.cnblogs.com/yswdarren/p/3611934.html

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