iOS 图片压缩 和等比压缩 指定缩放比例压缩

- (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;    
}

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;
}

 //指定缩放比例压缩
  NSData *thumbImageData = UIImageJPEGRepresentation([UIImage imageWithData:logoData], 0.5);

标签：

版权申明：本站文章部分自网络，如有侵权，请联系：west999com@outlook.com
特别注意：本站所有转载文章言论不代表本站观点！
本站所提供的图片等素材，版权归原作者所有，如需使用，请与原作者联系。