wxpython。需要帮助解决令人困惑的错误

Question

此代码适用于另一台计算机上的其他人，但它似乎不适用于我。我正在使用 python 2.7.7。它对另外两个人效果很好，但它似乎不喜欢我或我的电脑，因为每当我运行它时，它都会给我一条错误消息。大家觉得呢？

Traceback (most recent call last):
  File "C:\Python27\python projects\client with gui.py", line 43, in <module>
    frame = WindowFrame(None, 'ChatClient')
  File "C:\Python27\python projects\client with gui.py", line 10, in __init__
    self.dc = wx.PaintDC(self.panel)  # <<< This was changed
  File "C:\Python27\python projects\lib\site-packages\wx-3.0-msw\wx\_gdi.py", line 5215, in __init__
    _gdi_.PaintDC_swiginit(self,_gdi_.new_PaintDC(*args, **kwargs))
PyAssertionError: C++ assertion "Assert failure" failed at ..\..\src\msw\dcclient.cpp(277) in wxPaintDCImpl::wxPaintDCImpl(): wxPaintDCImpl may be created only in EVT_PAINT handler!





import socket
import wx

class WindowFrame(wx.Frame):
    def __init__(self, parent, title):
        wx.Frame.__init__(self, parent, title = title, size=(500, 400))
        self.panel=wx.Panel(self)
        self.panel.SetBackgroundColour("#0B3861")
        self.control = wx.TextCtrl(self.panel, style = wx.TE_MULTILINE, size =(410, 28), pos=(0,329))
        self.dc = wx.PaintDC(self.panel)  # <<< This was changed
        # Sets up the socket connection
        self.s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        host = "127.0.0.1"
        port = 6667
        self.s.connect((host,port))

        # creates send button and binds to event
        sendbutton=wx.Button(self.panel, label ="Send", pos =(414,325), size=(65,35))
        self.panel.Bind(wx.EVT_PAINT, self.OnPaint)
        self.Bind(wx.EVT_BUTTON, self.SendPress, sendbutton )

        self.Centre()
        self.Show()

        #Draws white rectangle
    def OnPaint(self, event):
        self.dc.SetPen(wx.Pen('black'))
        self.dc.SetBrush(wx.Brush('white'))
        self.shapeRectangle=self.dc.DrawRectangle(20, 20, 444, 280)
        self.Show(True)


        # Sets the function of the send button
    def SendPress(self, event):
        self.sent = self.control.GetValue()
        self.s.send(self.sent)
        self.control.Clear()
        self.dc.DrawText(self.sent, 0, 300 )
        self.s.close()

if __name__=="__main__":
    app = wx.App(False)
    frame = WindowFrame(None, 'ChatClient')
    app.MainLoop()

Answer 1

运行此代码时，我遇到了与您相同的错误。查看下面链接的文档“如果应用程序希望在 EVT_PAINT 事件处理程序中在窗口的客户区域上绘画，则必须构造 wx.PaintDC。”

http://www.wxpython.org/docs/api/wx.PaintDC-class.html

您是否考虑将其更改为客户端 DC？ "如果应用程序希望从 EVT_PAINT 事件之外在窗口的客户区域上绘画，则必须构造 wx.ClientDC"

http://www.wxpython.org/docs/api/wx.ClientDC-class.html

通常我认为您会在绑定到 EVT_PAINT 事件的方法中创建 PaintDC，我检查了一些代码示例，当我希望从外部查找属性或影响画布时，我通常似乎使用 ClientDC画法。

为此，我会改变：

self.dc = wx.PaintDC(self.panel)

到：

self.dc = wx.ClientDC(self.panel)

这是您的代码的完整修改版本，使用原始 PaintDC 执行我认为您正在尝试执行的操作。

import socket
import wx

class WindowFrame(wx.Frame):
    def __init__(self, parent, title):
        wx.Frame.__init__(self, parent, title = title, size=(500, 400))
        self.panel=wx.Panel(self)
        self.panel.SetBackgroundColour("#0B3861")
        self.control = wx.TextCtrl(self.panel, style = wx.TE_MULTILINE, size =(410, 28), pos=(0,329))
        self.textLog = []
        # Sets up the socket connection
        self.s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        host = "127.0.0.1"
        port = 6667
        self.s.connect((host,port))

        # creates send button and binds to event
        sendbutton=wx.Button(self.panel, label ="Send", pos =(414,325), size=(65,35))
        self.panel.Bind(wx.EVT_PAINT, self.OnPaint)
        self.Bind(wx.EVT_BUTTON, self.SendPress, sendbutton )

        self.Centre()
        self.Show()

        #Draws white rectangle
    def OnPaint(self, event):
        dc = wx.PaintDC(self.panel) 
        dc.SetPen(wx.Pen('black'))
        dc.SetBrush(wx.Brush('white'))
        dc.Clear()
        x, y = 20,20
        self.shapeRectangle=dc.DrawRectangle(x, y, 444, 280)
        fnt = dc.GetFont()        
        for i,line in enumerate(self.textLog):
            if i%2:
                dc.SetTextForeground(wx.RED)
            else:
                dc.SetTextForeground(wx.BLUE)
        dc.SetFont(fnt)
            dc.DrawText(line, x, y)
            y += dc.GetCharHeight()

        # Sets the function of the send button
    def SendPress(self, event):
        self.sent = self.control.GetValue()
        self.s.send(self.sent)
        self.control.Clear()
        self.textLog.append(self.sent)
        self.panel.Refresh()
        self.s.close()

if __name__=="__main__":
    app = wx.App(False)
    frame = WindowFrame(None, 'ChatClient')
    app.MainLoop()

Answer 2

这个例子有不少问题：

• 绝对定位而不是 sizers
• 绘图时不自动换行（通常自己渲染文本是个坏主意）
• 区分发送/接收的奇怪方法 (i%2 ???)

在这种情况下，使用适当的控件来显示彩色文本会更合适。插入您认为合适的发送/接收机制

import wx
from wx.stc import StyledTextCtrl

class WindowFrame(wx.Frame):
    def __init__(self, parent, title):
        wx.Frame.__init__(self, parent, title = title, size=(500, 400))

        self.panel = wx.Panel(self)
        self.panel.SetBackgroundColour("#0B3861")
        self.stc = StyledTextCtrl(self.panel, -1)
        self.control = wx.TextCtrl(self.panel, style = wx.TE_MULTILINE)
        sendbutton=wx.Button(self.panel, label ="Send")
        recvbutton=wx.Button(self.panel, label ="Receive")

        sendbutton.Bind(wx.EVT_BUTTON, self.SendPress)
        recvbutton.Bind(wx.EVT_BUTTON, self.RecvPress)

        szmain = wx.BoxSizer(wx.VERTICAL)
        szmain.Add(self.stc, 1, wx.EXPAND|wx.ALL, 4)
        szsub = wx.BoxSizer(wx.HORIZONTAL)
        szsub.Add(self.control, 1, wx.EXPAND|wx.ALL, 4)
        szsub.Add(sendbutton, 0, wx.EXPAND|wx.ALL, 4)
        szsub.Add(recvbutton, 0, wx.EXPAND|wx.ALL, 4)
        szmain.Add(szsub, 0, wx.EXPAND|wx.ALL, 0)

        self.panel.SetSizer(szmain)
        self.Centre()
        self.Show()

        # define styles for stc, 0 red fore color, 1 blue fore color
        self.stc.StyleSetSpec(0, "fore:#FF0000")
        self.stc.StyleSetSpec(1, "fore:#0000FF")
        self.stc.SetWrapMode(True) #autowrap

    def add_text(self, text, style):
        curpos = self.stc.GetCurrentPos()
        self.stc.AddText(text)
        self.stc.AddText('\r\n')
        newpos = self.stc.GetCurrentPos()
        delta = newpos-curpos

        # consult the Scintilla doc (stc is based on it) to understand how styling works
        # http://www.scintilla.org/ScintillaDoc.html#Styling
        self.stc.StartStyling(curpos, 31) # mask 31 allows setting of styles
        self.stc.SetStyling(delta, style)
        self.stc.ScrollToEnd() # keep last line visible

        # Sets the function of the send button
    def SendPress(self, event):
        self.add_text(self._get_text(), 0)

        # Sets the function of the recv button
    def RecvPress(self, event):
        self.add_text(self._get_text(), 1)

    def _get_text(self):
        text = self.control.GetValue()
        self.control.Clear()
        return text


if __name__=="__main__":
    app = wx.App(False)
    frame = WindowFrame(None, 'ChatClient')
    app.MainLoop()

查看 wxPython 演示如何使用StyledTextControl（基于 Scintilla）。最后但并非最不重要的一点是它让我学习了STC。