用python写firefox extension

Technorati 标签: firefox,extension,python

直接用javascript写复杂的firefox extension简直是个梦魇，而且performance也会有很多问题，还有一堆限制（同源…），而用C/C++写XPCOM又太大材小用，很不适合于prototype开发。
于是想找找直接用python来写logic的firefox extension，于是就找到了pyxpcomext
其实它也是基于PyXPCOM的，参见说明：
Why do this?

• It gives the power of Python to Mozilla extension developers
• Easy to setup multi-threaded tasks
• Rapidly build cross platform extensions, no compilation issues!
• Great base of core library functionality
• Not limited to JavaScript
• Provides a Python GUI toolkit to build applications (XULRunner)

How does it all work?

• The Python extension is download and installed into a Mozilla application as a regular extension
• Upon starting of the application, the extension is registered, and loads the internal dynamic linked libraries (python, pyxpcom and pydom)
• Additional extension directories are then checked to see if there are any extensions using pyxpcom that need to be registered (and appropriately registers them)
• The internal Python path (sys.path) is updated to reflect any "pylib" directories found in the installed extensions

OK，本着庖丁解牛的精神，这里给出一个step by step的python extension

必备

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首先要做firefox extension，当然得有firefox咯（废话，这里使用ff 3.6），要做xpi当然也得有zip工具了，linux下这不是问题，win上可以去找UnxTools，或者也可以使用ff的Extension Developer。
至于像FireBug，Explore Chrome，Javascript Debugger等等，就看你的心情咯～～～
其次，既然要PyXPCOM，装pyxpcomext先，这个是平台相关的，win/lnx会有不同的xpi：
http://pyxpcomext.mozdev.org/downloads.html
还有，既然俺们好歹也算是个XPCOM，总得搞个XulRunner-SDK/Gecko-SDK玩玩啊，其实主要我们也只是用它帮我们compile一下idl～～～

动工

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如果有firefox extension开发经验，到这一步已经很简单了～～～
首先先做个简单的框架，把下面几个文件按部就班找个sample抄一下：

chrome.manifest

install.rdf

content/

    overlay.xul

    overlay.js

components/

然后定义IDL（components/pyIDemo.idl）

#include "nsISupports.idl"      
#include "nsIVariant.idl"

[scriptable, uuid(2B3D3376-3312-4a2d-8A1E-C93AAFBC8EF7)]      
interface pyIDemo: nsISupports {       
    // attributes, constants, methods, ...       
    nsIVariant doPythonCmd(in wstring code);       
};

写python的实现（components/pyDemo.py）

import os      
import sys       
import time       
import traceback       
from cStringIO import StringIO

from xpcom import components, ServerException, nsError      
from xpcom.server import WrapObject

class pyDemo:      
    _com_interfaces_ = [components.interfaces.pyIDemo]       
    _reg_clsid_ = "{ED590407-D31B-4076-8D3C-3AFA999960A8}"       
    _reg_contractid_ = "@zouf.trendmicro.com.cn/pyDemo;1"       
    _reg_desc_ = "Python Plugin Demo"

    pyshellGlobals = {      
        # Give away some free items...       
        "os": os,       
        "sys": sys,       
        "time": time,       
        # And xpcom accessors.       
        "components": components,       
        "Components": components       
    }

    def __init__(self):      
        pass

    def doPythonCmd(self, code):      
        # Ensure the code ends with an empty newline       
        try:       
            try:       
                result = code + 'Hello'       
                try:       
                    # See if the result can be turned into an xpcom object       
                    return WrapObject(result, components.interfaces.nsIVariant)       
                except ValueError:       
                    # else, we'll just return a string representation       
                    return repr(result)       
            except SyntaxError:       
                return self._exec_code_and_get_output(code)       
        except Exception, e:       
            # Format the exception, removing the exec/eval sections.       
            exc_tb = traceback.format_exception(sys.exc_type, sys.exc_value, sys.exc_traceback)       
            return "".join(exc_tb[:1] + exc_tb[3:])

这个python就太简单不过了，只是在输入的wstring上在加个Hello把它返回～～～
好，实质内容都有了，下一步就是让javascript做个中转器，帮UI来调用python了，这个我们把它放在overlay.js里：

function do_cmd() {      
    _pySvc = Components.classes["@zouf.trendmicro.com.cn/pyDemo;1"].       
                    getService(Components.interfaces.pyIDemo);       
    alert(_pySvc.doPythonCmd('abc'));       
}

OK，基本上到这一步你的coding工作就完成了，当然实际上在这一步你会花费数百倍的精力去写你的python logic～～～
下一步就是收尾，打包，一下的简单批处理可以帮忙（build.cmd）

@echo off

SET XUL_PATH=D:\projects\xulrunner-sdk      
SET PATH=%XUL_PATH%\bin;%PATH%

xpidl -I %XUL_PATH%\idl -I components -o components/pyIDemo -m typelib components/pyIDemo.idl

zip pydemo.xpi install.rdf chrome.manifest pydemo.jar -r components -r content -r locale

它干的活也很干净，只是编译IDL，zip打包，出XPI，大功告成～～～
最后把出来的xpi拖到你的ff里试试吧，看看能不能出结果？
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