问题
Looking at other posts for this could not find an adequate solution that for my needs. Trying to just get the first page of a pdf document as a thumbnail. This is to be run as a server application so would not want to write out a pdf document to file to then call a third application that reads the pdf to generate the image on disk.
doc = new PDFdocument("some.pdf");
page = doc.page(1);
Image image = page.image;
Thanks.
回答1:
Matthew Ephraim released an open source wrapper for Ghostscript that sounds like it does what you want and is in C#.
Link to Source Code: https://github.com/mephraim/ghostscriptsharp
Link to Blog Posting: http://www.mattephraim.com/blog/2009/01/06/a-simple-c-wrapper-for-ghostscript/
You can make a simple call to the GeneratePageThumb method to generate a thumbnail (or use GeneratePageThumbs with a start and end page number to generate thumbnails for multiple seperate pages, with each page being a seperate output file), default file format is jpeg but you can change it, and many other options, by using the alternate GenerateOutput method call and specify options such as file format, page size, etc...
回答2:
I think that Windows API Code pack for Microsoft .NET framework might do the trick easiest. What it can is to generate the same thumbnail that Windows Explorer does (and that is first page), and you can chose several sizes, they go up to 1024x1024, so it should be enough. It is quite simple, just create ShellObject.FromParsingName(filepath) and find its Thumbnail subclass.
The problem might be what your server is. This works on Windows 7, Windows Vista and I guess Windows Server 2008. Also, Windows Explorer must be able to show thumbnails on that machine. The easiest way to insure that is to install Adobe Reader. If all of this is not a problem, I think that this is the most elegant way.
UPDATE: Adobe Reader has dropped support for thumbnails in the recent versions so its legacy versions must be used.
UPDATE2: According to comment from Roberto, you can still use latest version of Adobe Reader if you turn on thumbnails option in Edit - Preferences - General.
回答3:
Download PDFLibNet and use the following code
public void ConvertPDFtoJPG(string filename, String dirOut)
{
PDFLibNet.PDFWrapper _pdfDoc = new PDFLibNet.PDFWrapper();
_pdfDoc.LoadPDF(filename);
for (int i = 0; i < _pdfDoc.PageCount; i++)
{
Image img = RenderPage(_pdfDoc, i);
img.Save(Path.Combine(dirOut, string.Format("{0}{1}.jpg", i,DateTime.Now.ToString("mmss"))));
}
_pdfDoc.Dispose();
return;
}
public Image RenderPage(PDFLibNet.PDFWrapper doc, int page)
{
doc.CurrentPage = page + 1;
doc.CurrentX = 0;
doc.CurrentY = 0;
doc.RenderPage(IntPtr.Zero);
// create an image to draw the page into
var buffer = new Bitmap(doc.PageWidth, doc.PageHeight);
doc.ClientBounds = new Rectangle(0, 0, doc.PageWidth, doc.PageHeight);
using (var g = Graphics.FromImage(buffer))
{
var hdc = g.GetHdc();
try
{
doc.DrawPageHDC(hdc);
}
finally
{
g.ReleaseHdc();
}
}
return buffer;
}
回答4:
I used to do this kind of stuff with imagemagick (Convert) long ago. There is a .Net Wrapper for that, maybe it's worth checking out : http://imagemagick.codeplex.com/releases/view/30302
回答5:
http://www.codeproject.com/KB/cs/GhostScriptUseWithCSharp.aspx
This works very well. The only dependencies are GhostScript's gsdll32.dll (you need to download GhostScript separately to get this, but there is no need to have GhostScript installed in your production environment), and PDFSharp.dll which is included in the project.
来源：https://stackoverflow.com/questions/1592112/generate-a-pdf-thumbnail-open-source-free