简单的 wxPython 进程事件发布

Question

我正在尝试创建一个窗口，用来接收来自一个进程的简单事件通知。以下是我目前写的代码：

import wx, wx.lib.newevent, time, sys
from multiprocessing import Process

size_width = 320
size_height = 240
background_color = (226,223,206)

SomeNewEvent, EVT_SOME_NEW_EVENT = wx.lib.newevent.NewEvent()


class StatusWindow(wx.Frame):
    def __init__(self, parent):
        super(StatusWindow, self).__init__(parent, title='Monitor', size=(size_width, size_height))

        self.Bind(EVT_SOME_NEW_EVENT, self.updateStatus)

        staticBox = wx.StaticBox(self, label='Monitor Status:', pos=(5, 105), size=(size_width - 28, size_height/3))
        self.statusLabel = wx.StaticText(staticBox, label='None', pos=(10, 35), size=(size_width, 20), style=wx.ALIGN_LEFT)
        self.count = 0
        self.InitUI()

        self.monitor = cMonitor()
        self.monitor.start()

    def InitUI(self):
        panel = wx.Panel(self)    
        self.SetBackgroundColour(background_color)
        self.Centre()
        self.Show()

    def updateStatus(self, evt):
        self.statusLabel.SetLabel(evt.attr1)

class cMonitor(Process):
    def __init__(self):
        super(cMonitor, self).__init__()

    def run(self):
        time.sleep(2)
        print 'This is an update'
        #create the event
        evt = SomeNewEvent(attr1="Some event has just occured")
        #post the event
        wx.PostEvent(EVT_SOME_NEW_EVENT, evt)

if __name__ == '__main__':
    app = wx.App()
    window = StatusWindow(None)
    app.MainLoop()

窗口是创建成功了，但这个进程似乎没有在运行，也没有正确发送事件通知。我还注意到，运行方法里的打印语句也没有显示出来。是什么原因导致这个图形界面没有更新呢？这是我参考的资料：

http://wiki.wxpython.org/CustomEventClasses

Answer 1

首先，你的代码出现了错误：

Traceback (most recent call last):
  File "C:\Python27\lib\multiprocessing\process.py", line 232, in _bootstrap
    self.run()
  File "C:\PyProgs\stackoverflow_answers\wx_answers\wx_events1.py", line 44, in run
    wx.PostEvent(EVT_SOME_NEW_EVENT, evt)
  File "C:\Python27\lib\site-packages\wx-3.0-msw\wx\_core.py", line 8410, in PostEvent
    return _core_.PostEvent(*args, **kwargs)
TypeError: in method 'PostEvent', expected argument 1 of type 'wxEvtHandler *'

根据文档，PostEvent(dest, event) 是用来发送一个事件到窗口或其他的 wx.EvtHandler，让它稍后处理。但是在你的代码中，第一个参数的类型是 PyEventBinder。你的代码应该像这样：

wx.PostEvent(self.wxWindow, evt)

这里的 self.wxWindow 是 StatusWindow 类的一个对象。不过还有另一个问题：你不能把 wxPython 对象作为多进程的参数使用（链接）。

想要实现你想要的功能，可以使用线程模块，而不是多进程：

import wx, wx.lib.newevent, time, sys
from threading import *
size_width = 320
size_height = 240
background_color = (226,223,206)

SomeNewEvent, EVT_SOME_NEW_EVENT = wx.lib.newevent.NewEvent()


class StatusWindow(wx.Frame):
    def __init__(self, parent):
        super(StatusWindow, self).__init__(parent, title='Monitor', size=(size_width, size_height))

        self.Bind(EVT_SOME_NEW_EVENT, self.updateStatus)

        staticBox = wx.StaticBox(self, label='Monitor Status:', pos=(5, 105), size=(size_width - 28, size_height/3))
        self.statusLabel = wx.StaticText(staticBox, label='None', pos=(10, 35), size=(size_width, 20), style=wx.ALIGN_LEFT)
        self.count = 0
        self.InitUI()

        # Set up event handler for any worker thread results
        self.monitor = cMonitor(self)
        self.monitor.start()

    def InitUI(self):
        panel = wx.Panel(self)    
        self.SetBackgroundColour(background_color)
        self.Centre()
        self.Show()

    def updateStatus(self, evt):
        self.statusLabel.SetLabel(evt.attr1)



class cMonitor(Thread):
    def __init__(self, wxWindow):
        super(cMonitor, self).__init__()
        self.wxWindow = wxWindow


    def run(self):
        time.sleep(2)
        print 'This is an update'
        #create the event
        evt = SomeNewEvent(attr1="Some event has just occured")
        #post the event
        wx.PostEvent(self.wxWindow, evt)

if __name__ == '__main__':

    app = wx.App()
    window = StatusWindow(None)
    app.MainLoop()