How to reference Ghostscript DLL in C#

Question

I'm using a C# wrapper to convert PDFs to images using Ghostscript, however i cant seem to reference the dll correctly. I have the DLL stored in the bin folder (also don't know if that's the best place to keep it there or not) Here's my code:

 byte[] fileData = null;
            using (var binaryReader = new BinaryReader(Request.Files[0].InputStream))
            {
                fileData = binaryReader.ReadBytes(Request.Files[0].ContentLength);
            }

    string path = Path.GetDirectoryName(Assembly.GetExecutingAssembly().CodeBase);

    Ghostscript.NET.Rasterizer.GhostscriptRasterizer rasterizer = null;
    Ghostscript.NET.GhostscriptVersionInfo vesion = new Ghostscript.NET.GhostscriptVersionInfo(new Version(0, 0, 0), path + @"\gsdll64.dll", string.Empty, Ghostscript.NET.GhostscriptLicense.GPL);
    Stream inStream = new MemoryStream(fileData);
    MemoryStream outStream = new MemoryStream();
    List<Image> imageList = new List<Image>();
    using (rasterizer = new Ghostscript.NET.Rasterizer.GhostscriptRasterizer())
    {
        rasterizer.Open(inStream, vesion, false);
         for (int i = 1; i <= rasterizer.PageCount; i++)
        {
            //string pageFilePath = Path.Combine(outputPath, Path.GetFileNameWithoutExtension(file) + "-p" + i.ToString() + ".jpg");
            int dpi = 200;
            Image img = rasterizer.GetPage(dpi, dpi, i);
            img.Save(outStream, ImageFormat.Jpeg);
            Image img = new Image
            {
                imgByteArray = outStream.ToArray()
            };
            imageList.Add(image);
        }
         rasterizer.Close();
    }

I'm getting the Ghostscript native library could not be found error. Here's the path I get

I think it has to do with the double / and 'file://' in the DLLPath string. And should I also specify the LipPath as well? Any help??

Answer 1

In your case you should make ghostscript dll path this way:

string binPath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
string gsDllPath = Path.Combine(binPath, Environment.Is64BitProcess ? "gsdll64.dll" : "gsdll32.dll");

Answer 2

Even though this does not answer the question directly, I think it's worth mentioning, because I've ran into a problem using the OP's code with Ghostscript.NET version 1.2.1 published in 2016. Here's the fix I found:

In the source code, Ghostscript.NET\Helpers\StreamHelper.cs:171

n = output.Read(buffer, 0, buffer.Length);

really should've been

n = input.Read(buffer, 0, buffer.Length);

If you're opening a stream instead of a path, without modifying the above mentioned code, you'll get empty result because the input stream did not get copied.

Reading into the code in more depth finds that the input stream is written into a temp file then read again into memory. You'll be better off just using rasterizer.Open by the path instead of stream, if it were a PDF file on disk to begin with.