View PDF files in C# using the Xpdf and muPDF library, Print PostScript.
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Wrapper C# class written in C++\CLI and a sample implementation in C# to render PDF files.
Introduction
Xpdf is an Open Source library released under GPL license; they have an ActiveX with commercial license, but some time ago, before I knew about this commercial control, I wrote this wrapper library to render PDF files in C#.
Background
The basic idea is create a preview of PDF files in C#. After looking at many places in the internet, I found this wonderful library; the only problem is that the library uses XLib, and there is no XLib available for Windows. Fortunately, Xpdf can render the generated PDF into a Win32 DC.
Writting the wrapper
C++\CLI can mix managed and unmanaged code thanks to the IJW technology, so I was thinking that maybe I could to link the xpdf lib to the wrapper. The problem is that xpdf has some classes that are also declared in .Net, the solution was compile a C++ project with a class that includes only the necessary files to do the interop.This library (AFPDFLib) contains a simple class that works like a proxy between C++ and C++\CLI, keeping the xpdf objects into the unmanaged Heap.
The C# wrapper is linked to AFPDFLib statically, and this only includes:
AFPDFDocInterop.h
OutlineItemInterop.h
SearchResultInterop.h
The classes:
AFPDFDoc -> Implement the methods that needs xpdf.
AFPDFDocInterop -> Write the methods to wrap into C#
PDFWrapper -> Wrapped methods
Marshal Strings:
IntPtr ptr = Marshal::StringToCoTaskMemAnsi(fileName);
char *singleByte= (char*)ptr.ToPointer();
try{
}finally{
Marshal::FreeCoTaskMem(ptr);
} For releasing resources is necessary implement IDisposable:
!PDFWrapper()
{
_pdfDoc->Dispose();
}
Using the code
The file xpdfWin-Interop.sln includes all the necessary files, you can also download the last version from http://www.foolabs.com/xpdf/ and recompile without the files that requires XLib.
The Build Project Order is as follows: freetype,xpdf,AFPDFLib, PDFLibNet. Once compiled PDFLibNet, it can be used in C# code:
OpenFileDialog dlg = new OpenFileDialog();
dlg.Filter = "Portable Document Format (*.pdf)|*.pdf";
if (dlg.ShowDialog() == DialogResult.OK)
{
_pdfDoc = new PDFLibNet.PDFWrapper();
_pdfDoc.LoadPDF(dlg.FileName);
_pdfDoc.CurrentPage = 1;
PictureBox pic =new PictureBox();
pic.Width=800;
pic.Height=1024;
_pdfDoc.FitToWidth(pic.Handle);
pic.Height = _pdfDoc.PageHeight;
_pdfDoc.RenderPage(pic.Handle);
Bitmap _backbuffer = new Bitmap(_pdfDoc.PageWidth, _pdfDoc.PageHeight);
using (Graphics g = Graphics.FromImage(_backbuffer))
{
_pdfDoc.RenderHDC(g.GetHdc);
g.ReleaseHdc();
}
pic.Image = _backbuffer;
}
It is necessary create a PictureBox because the class implements only a method that accepts an HWND, because in the first instance,
I was trying to implement the scroll into the same control that the PDF is rendered. In the included sample, the scroll is controlled by a Panel container.
Xpdf can export the PDF to a PostScript file. For printing this is the best option if you have a PostScript Printer:
PSOutputDev *psOut =new PSOutputDev((char *)fileName,m_PDFDoc->getXRef(),m_PDFDoc->getCatalog(),fromPage,toPage,psModePS);
if(psOut->isOk()){
m_PDFDoc->displayPages(psOut,fromPage,toPage,PRINT_DPI,PRINT_DPI,0,gTrue,globalParams->getPSCrop(),gTrue);
}
delete psOut; The file must be sended in RAW format (http://support.microsoft.com/kb/322091)
JPG Export
For async export:
_doc.ExportJpg(filename,
1, //From page
1, //To page
150, //Resolution in DPI
90, //Jpg quality
if you need a sync operation its posible especify a wait time:
_doc.ExportJpg(filename,
1, //From page
1, //To page
150, //Resolution in DPI
90, //Jpg quality
-1); //Time to wait, -1 to infinite.
If the file name does not contains a %d token (for the page number), then the procedure replaces .jpg with -page%d.jpg.
PDFWrapper exposes two events ExportJpgProgress and ExportJpgFinished. Both events are called from the exporting Thread, so it is necesary to make a security call using Invoke, check frmExportJpg for a sample.
History:
06\July\2009:- Full deployed solution.
- Updated to xpdf 3.0.2 version.
- FreeType updated to 2.3.1
- When click in a bookmark and search, the page scroll to the correct position.
- PostScript implemented.
- Now gets the Title, Author.
- Some memory leaks corrected
- Prerender next page in new thread
- Cache of pages
- Mouse Scrolling
- Mouse Navigation
- Load links from page (LinkURI, LinkGoTo)
- Using DIB Sections, fixes the problem with the zoom.
- Added control PageViewer, now render only the viewable area
- Open password protected files.
- Export to txt
- Export to jpg
- Added support for Unicode in Bookmarks, title, subject, keywords...
- Added support for named destinations
- Fixed some bugs.
- Added support for unicode search
- Multithread jpg export
- Fixed others bugs
- Added MuPDF as second renderer.
- Added support for swf convert using swftools (http://www.swftools.org/)
- Added support for html convert using html2text (http://pdftohtml.sourceforge.net/), I modified the HtmlOuputDev because originally it uses ghoscript to render the background. Now it uses SplashOutputDev.