Compiling The npruntime Sample Plugin in Visual Studio

General decisions

  • filename of DLL
    must start with "np" (not "ns") and ends with ".dll" (I wasted hours on this - repeatedly)
  • mimetype
    reflects the data type handled by the plugin. this is how webpages invoke your plugin. should either be like "application/x-vnd-yourorganization-yourfiletype" or be officially registered with IANA (unlikely) or be a standard type (e.g. if you want to play MPEG files).
  • file extension
    reflects the data type handled by the plugin, esp. when loaded from local disk on Windows.


  1. Create a new project in Visual Studio for a Win32 GUI library (DLL) (in .NET 2003: Win32 template, then switch to DLL in Application Settings in the following dialog, export symbols too?)(in Visual Studio 2008, it is Visualc++|Win32|Win32 Project, then check DLL in the wizard).
  2. If a wizard gives you a checkbox to create an empty project, then check it. Otherwise you'll delete files later.
  3. Again note that the resulting DLL filename must start with "np", so either call your project like this or rename the file later
  4. Delete the .cpp and .h and ReadMe files from the project and disk (if you did not create an empty project)
  5. Copy the npruntime sample plugin source code into the dir of the new VS project and add the files to the project using the VS GUI (.cpp files to "Source Files", .h files to "Header Files", .rc file to "Resource Files"). Samples can be obtained from:
  6. Get the NPAPI SDK.
  7. Add the NPAPI SDK include path (example : C:\npapi-sdk\headers) to Project Properties|(all configurations)|C++|General|Additional Include Directories. Note: If your project is still empty, the C++ tree might not be visible. So, add some files first.
  8. Add the following preprocessor definitions to Project Properties|(all configurations)|C++|Preprocessor|Preprocessor Definitions: WIN32;_WINDOWS;XP_WIN32;XP_WIN;_X86_;NPSIMPLE_EXPORTS
  9. Disable precompiled headers using Project Properties|(all configurations)|C++|Precompiled headers|Create/Use precompiled header. They may be already disabled.
  10. Define the function exports by adding the .def filename (e.g. nprt.def) to Project Properties|(all configurations)|Linker|Input|Module Definition File. It could be either the full path or the path relative to the project directory.
  11. Optional: Open the above .def file and change "NPRT" to the filename of your dll as VS sees it (without "np", if you decided to rename later)
  12. Optional: Edit the .rc file and and the top of npp_gate.cpp for the description, mimetype, file extension etc. to reflect your plugin
  13. Remove the function NPP_GetJavaClass from npp_gate.cpp
  14. Build
  15. Rename the resulting DLL so that the filename starts with "np" and ends with ".dll" (or "32.dll"? 8.3?) and copy it in Mozilla's "plugins" folder
  16. Start Mozilla and open about:plugins to verify the plugin is detected
  17. Open the file "test.html" and begin testing. Make sure the mimetypes of your html embed tags match the mimetype specified in your nprt.rc file and the top of your npp_gate.cpp file

Version Issues

  1. If VC++ compiler throws you error C2664 on 'DrawText' function call, you may replace it by 'DrawTextA'. In fact, all win32 API functions dealing with character strings can be added an 'A' to the end to avoid unicode cast errors.
  2. Visual C++ 2008 Express don't support C99 standard about int32_t, uint32_t. You have to add #include "nptypes.h" in top of plugin.h file.
  3. Feel free to append here your issues fixes if the above guide helped you.