l3lib/devel/plugin

How to build a Scripting Plugins in Mozilla. (cross-browser NPAPI extensions )

1. Background.
	A> plugin file type: Mozilla type browsers load plug-in from DLL (IE loads it as an ActiveX control). 
	B> HTML tag: both IE and Firefox(later version) support <object> tag, but IE use 'classid' to find ActiveX
		and Mozilla type browser use MIMETYPE 'type' attribute
		NOTE: you cnanot put a classid attribute there when load plugin in mozilla browser, otherwise plugin
		won't be loaded.
	C> Mozilla requires plugins to be put into sub-folder "plugins" under its program installed folder
	D> Mozilla requires plugins' file has to be format of "NPxxxx.dll"
	E> Mozilla plugin cannot be automatically downloaded by browser like IE when you specified a "codebase" attribute,
		but you can build a xpi package and put it to mozilla web site to ask them to publish your plugin, in this
		case, firefox can download your plugin and install it. but the most better idea is to create your own installation
		program to install your plugin for both IE and firefox. in this case, you put your plugin under firefox
		folder and register it, so that it can loaded by both browsers, otherwise, when installed by IE, it puts plugin
		under its folder,then mozilla cannot loaded it. or installed by mozilla, it will not register plugin, so IE cannot load
		it.
	F> here is how plugin works in mozilla type browser:
		> browser loads plugins info by obtaining plugin's functions throught dll's entry point.
		> mozilla type browser first create a window that will be used to hold plugin
		> browser then calls plugin's function to load plugin
	G> our plugin support both IE and firefox by same code base and same dll by creating same Activex. but for firefix,
		create a Activex is not really neccessary, you can just subclass your control or just work on the HWND mozilla
		create for you. please see source code for more detail.

2. How to build ( following instruction is used to build a MFC activex project that support both IE and mozilla browsers )
***** sample project was built by VC++ 6.0
	A> build a MFC ActiveX project ( or if you already have a activex project )
	B> put all files in 'moz' under our sample projects into new this project folder
	C> There two files need to be modified:
		npp_gete.cpp: put your plugin information in lines that marked as "TODO"
		mplugin.c: modify it so that plugin can load your window. your window will be created here.
	D> add following files into your project:
		mplugin.h, mplugin.cpp,np_entry.cpp, npn_gate.cpp,npp_gate.cpp
	E> add 'XP_WIN' to your project setting / C++ / general / Preprocessor definitions
	F> change dll name to NPxxx.dll ( or you can change it when you copy it to mozilla program folder )
	G> modify project resource file ( .rc file ) by adding a MIME type (following 3 lines ):
            VALUE "MIMEType", "application/x-your-type\0"
            VALUE "FileExtents", "*\0"
            VALUE "FileOpenName", "your-type\0"

	   ********* important ****************************************
	   change block header from "BLOCK "040904b0" to "BLOCK 040904e4"
	   ********* important ***************************************

	H> export mozilla functions in your dll by adding following definitions to xxxx.def file:
		NP_GetEntryPoints   @5
		NP_Initialize       @6
		NP_Shutdown         @7
		
	I> now build your project, you get a dll no matter its extension is .ocx or .dll, change its name
		to NPxxx.dll and copy it to mozilla plugins folder.
		(e.g: c:\program files\mozilla.org\mozilla\plugins\)

	  NOTE: this dll is still an activex component dll, you can register it and load it by IE.

	J> now everything is done, you can run mozilla firefox, in address bar, type "about:plugins",
		your plugin will display there

	K> in sample project folder, their are testforff.html and testforie.html which load this plugin.
	
	L> you can register MIME type for activex so that you can load activex by MIME type from IE.

Tips:
	because container is diffirent between IE and mozilla, so plugin will behave diffirently in 
	diffirent type browsers, like keyboard etc.