wxpython：將面板添加到wx.Frame禁用/與wx.Frame的OnPaint衝突？

Question

我剛剛遇到了這種奇怪的情況：我找到一個例子，其中wx.Frame的OnPaint被覆蓋，並繪製了一個圓。有趣的是，只要我在框架中添加一個單獨的面板，該圓就不再被繪製 - 事實上，OnPaint不再被稱爲，所有了！ （順便說一下，我在Ubuntu Lucid上試了一下例子）

任何人都可以解釋我是否這是預期的行爲，以及如果wx.Frame有子面板，如何正確處理wx.Frame的OnPaint？小代碼示例如下..

在此先感謝您的任何答案，
乾杯！

代碼：

#!/usr/bin/env python 

# http://www.linuxquestions.org/questions/programming-9/wxwidgets-wxpython-drawing-problems-with-onpaint-event-703946/ 

import wx 

class MainWindow(wx.Frame): 
    def __init__(self, parent, title, size=wx.DefaultSize): 
     wx.Frame.__init__(self, parent, wx.ID_ANY, title, wx.DefaultPosition, size) 

     self.circles = list() 
     self.displaceX = 30 
     self.displaceY = 30 

     circlePos = (self.displaceX, self.displaceY) 
     self.circles.append(circlePos) 

     ## uncommenting either only first, or both of 
     ## the commands below, causes OnPaint *not* to be called anymore! 
     #~ self.panel = wx.Panel(self, wx.ID_ANY) 
     #~ self.mpanelA = wx.Panel(self.panel, -1, size=(200,50)) 

     self.Bind(wx.EVT_PAINT, self.OnPaint) 

    def OnPaint(self, e): 
     print "OnPaint called" 
     dc = wx.PaintDC(self) 
     dc.SetPen(wx.Pen(wx.BLUE)) 
     dc.SetBrush(wx.Brush(wx.BLUE)) 

     # Go through the list of circles to draw all of them 
     for circle in self.circles: 
      dc.DrawCircle(circle[0], circle[1], 10) 


def main(): 
    app = wx.App() 
    win = MainWindow(None, "Draw delayed circles", size=(620,460)) 
    win.Show() 
    app.MainLoop() 

if __name__ == "__main__": 
    main() 

Answer 1

OK，這是不是真的微不足道，我想......但我發現線程 「wxPython - drawing without paint event - Python answers」，它提到：

一個不錯的從在「wxPython中在行動中」的示例策略是 以下：

• 幀已畫出繪製成BufferedDC，其是方法 鏈接到一個位圖成員，
• paint方法裏，位圖件繪製到屏幕

...但是，那其實是有些誤導 - 如果我們看一下其中的一個例子，如Chapter-06/example1.py，這是顯而易見的，該應用程序產生wx.Frame（如我的例子）;但wx.Frame這裏只是簡單初始化一個wx.Window - 它是這裏這裏所有這些發生的東西DC onPaint。

考慮到這一點，我上面的代碼可以被修改，所以它終於再次工作（即呈現藍色圓圈），如下圖所示：

#!/usr/bin/env python 

# http://www.linuxquestions.org/questions/programming-9/wxwidgets-wxpython-drawing-problems-with-onpaint-event-703946/ 

import wx 

class MainWindowWindow(wx.Window): 
    def __init__(self, parent): 
     wx.Window.__init__(self, parent) 
     self.Bind(wx.EVT_PAINT, self.OnPaint) 
     self.circles = list() 
     self.displaceX = 30 
     self.displaceY = 30 

     circlePos = (self.displaceX, self.displaceY) 
     self.circles.append(circlePos) 

     ## uncommenting either only first, or both of 
     ## the commands below, now calls onPaint 
     ## (without these panels, OnPaint called once - with them, twice) 
     self.panel = wx.Panel(self, wx.ID_ANY) 
     self.mpanelA = wx.Panel(self.panel, -1, size=(200,50)) 

    def OnPaint(self, e): 
     print "OnPaint called" 
     dc = wx.PaintDC(self) 
     dc.SetPen(wx.Pen(wx.BLUE)) 
     dc.SetBrush(wx.Brush(wx.BLUE)) 

     # Go through the list of circles to draw all of them 
     for circle in self.circles: 
      dc.DrawCircle(circle[0], circle[1], 10) 


class MainWindow(wx.Frame): 
    def __init__(self, parent, title, size=wx.DefaultSize): 
     wx.Frame.__init__(self, parent, wx.ID_ANY, title, wx.DefaultPosition, size) 
     MainWindowWindow(self) 


def main(): 
    app = wx.App() 
    win = MainWindow(None, "Draw delayed circles", size=(620,460)) 
    win.Show() 
    app.MainLoop() 

if __name__ == "__main__": 
    main() 

好了，希望這可以幫助別人，
乾杯！