问Windows服务器上PDF文件的自动压缩

EN

public static void compressPdf(string path, string outputPath)
{
    using (PdfDocument doc = new PdfDocument(path))
    {
        foreach (PdfImage image in doc.Images)
        {
            // image that is used as mask or image with attached mask are
            // not good candidates for recompression
            // 
            // also, small images might be used as mask even though image.IsMask for them is false
            //
            if (!image.IsMask && image.Mask == null && image.Width >= 8 && image.Height >= 8)
            {
                if (image.ComponentCount == 1)
                {
                    // for black-and-white images fax compression gives better results
                    image.RecompressWithGroup4Fax();
                }
                else
                {
                    // scale image and recompress it with JPEG compression
                    // this will cause image to be smaller in terms of bytes
                    // please note that some of the image quality will be lost
                    image.Scale(0.5, PdfImageCompression.Jpeg, 65);
                    
                    // or you can just recompress the image without scaling
                    //image.RecompressWithJpeg(65);
                    
                    // or you can resize the image to specific size
                    //image.ResizeTo(640, 480, PdfImageCompression.Jpeg, 65);
                }
            }
        }
            
        var saveOptions = new PdfSaveOptions
        {
            RemoveUnusedObjects = true,

            // this option causes smaller files but 
            // such files can only be opened with Acrobat 6 (released in 2003) or newer
            UseObjectStreams = true,

            // this option will cause output file to be optimized for Fast Web View
            Linearize = true
        };
        doc.Save(outputPath, saveOptions);
    }
}