Export PDF to JPG(s) in C#

Question

I need to save a one page pdf document as an image for a thumbnail on a website.

I've been messing around with PDFSharp and have had no luck.

I have tried this: http://www.pdfsharp.net/wiki/ExportImages-sample.ashx?AspxAutoDetectCookieSupport=1 but all it does is extract the embedded images in the PDF file which is not the desired result.

Ideas on how to do this? Anyone know a good library that can handle this?

Edit: Please let me know why this is such a bad question. If anyone has a good solution to this it would be a great resource for many other people. Especially since google searches come up empty.

Answer 1

Take a look at Ghostscript. You can render PDF to images with it.

http://www.mattephraim.com/blog/2009/01/06/a-simple-c-wrapper-for-ghostscript/

Answer 2

Ghostscript is currently the de-facto standard for rendering PDFs. It's a bit tricky to wrap, even using GhostScriptSharp.

Jason Morse wrote a great C# wrapper for rendering PDFs as a plugin to the open-source imageresizing.net library.

If it's an asp.net application, the library allows on-the-fly rendering, so you can just add a querystring to get the jpeg/png version:

/pdfs/letter.pdf?format=jpg&page=2

You can also use the managed API instead (in any application type - not asp.net specific)

ImageBuilder.Current.Build("letter.pdf","dest.jpg",new ResizeSettings("format=jpg;page=2"));

The PdfRenderer plugin is GPL licensed, just like Ghostscript.

Answer 3

ABCpdf exports PDF documents to JPEG with C#. See: http://www.websupergoo.com/helppdfnet/source/4-examples/19-rendering.htm

Answer 4

(disclaimer: I work for Atalasoft and wrote a lot of the PDF technology) If you use the PdfDecoder in Atalasoft dotImage, this is straight forward:

public void PdfToJpegThumb(Stream srcStream, int pageNo, int maxDimension, Stream dstStream)
{
    PdfDecoder decoder = new PdfDecoder();
    decoder.Resolution = 96; // reduce default resolution to speed up rendering
    // render page
    using (AtalaImage pdfimage = decoder.read(srcStream, pageNo, null)) {
        Thumbnail tn = new Thumbnail(maxDimension, maxDimension);
        // make a thumbnail image
        using (AtalaImage tnImage = tn.Create(pdfImage)) {
            // save it
            tnImage.Save(dstStream, new JpegEncoder(), null);
        }
    }
}

Answer 5

I got this from somewhere on the web - can't remember exactly where but it works for me!
I just made it into a nice function.

It uses the GhostScript APIs (GSdll32.dll)

Examples of the imageFormat parameter are "jpeg", "tiff32nc", etc.

    #region GhostScript API functions
    [DllImport("gsdll32.dll", EntryPoint = "gsapi_new_instance")]
    private static extern int CreateAPIInstance(out IntPtr pinstance,
                                            IntPtr caller_handle);

    [DllImport("gsdll32.dll", EntryPoint = "gsapi_init_with_args")]
    private static extern int InitAPI(IntPtr instance, int argc, IntPtr argv);

    [DllImport("gsdll32.dll", EntryPoint = "gsapi_exit")]
    private static extern int ExitAPI(IntPtr instance);

    [DllImport("gsdll32.dll", EntryPoint = "gsapi_delete_instance")]
    private static extern void DeleteAPIInstance(IntPtr instance);
    #endregion

    public bool CreateImage(string inputPath, string outputPath, string imageFormat, int firstPage, int lastPage, int width, int height)
    {
        bool result = false;
        try
        {
            string[] args = GetArgs(inputPath, outputPath, imageFormat, firstPage, lastPage, width, height);
            var argStrHandles = new GCHandle[args.Length];
            var argPtrs = new IntPtr[args.Length];

            // Create a handle for each of the arguments after 
            // they've been converted to an ANSI null terminated
            // string. Then store the pointers for each of the handles
            for (int i = 0; i < args.Length; i++)
            {
                argStrHandles[i] = GCHandle.Alloc(StringToAnsi(args[i]), GCHandleType.Pinned);
                argPtrs[i] = argStrHandles[i].AddrOfPinnedObject();
            }

            // Get a new handle for the array of argument pointers
            var argPtrsHandle = GCHandle.Alloc(argPtrs, GCHandleType.Pinned);

            // Get a pointer to an instance of the GhostScript API 
            // and run the API with the current arguments
            IntPtr gsInstancePtr;
            CreateAPIInstance(out gsInstancePtr, IntPtr.Zero);
            InitAPI(gsInstancePtr, args.Length, argPtrsHandle.AddrOfPinnedObject());

            // Cleanup arguments in memory
            for (int i = 0; i < argStrHandles.Length; i++)
                argStrHandles[i].Free();

            argPtrsHandle.Free();

            // Clear API
            ExitAPI(gsInstancePtr);
            DeleteAPIInstance(gsInstancePtr);

            result = true;
        }
        catch(Exception e)
        {
            throw e;
        }
        return result;
    }