wxpython：将面板添加到 wx.Frame 会禁用/与 wx.Frame 的 OnPaint 发生冲突？

Question

刚刚遇到这个奇怪的情况：找了个例子，wx.Frame的OnPaint被覆盖，画了一个圆。有趣的是，只要我在框架中添加了一个面板，就不再绘制圆圈了 - 事实上，OnPaint 根本不再被称为 ！ （顺便说一句，我在 Ubuntu Lucid 上试过这个例子）

如果这是预期的行为，谁能解释我，如果 wx.Frame 有子面板，如何正确处理 wx.Frame 的OnPaint？小代码示例如下..

提前感谢您的任何回答，
干杯!

代码：

#!/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

好的，我想这不是微不足道的......但我找到了线程“wxPython - drawing without paint event - Python answers”，其中提到了它：

“wxPython in Action”中一个很好的策略是 以下：

• 框架具有可绘制到 BufferedDC 中的 Draw 方法，该 BufferedDC 是 链接到位图成员，
• 在paint方法中，位图成员被绘制到屏幕上

...然而，这实际上有点误导 - 如果我们查看其中一个示例，例如 Chapter-06/example1.py，很明显该应用程序产生了一个 wx.Frame（如我的示例）；但是这里的wx.Frame 只是通过实例化wx.Window 来简单地初始化 - 它是 here 所有这些 DC onPaint 发生的地方。

考虑到这一点，我上面的代码可以修改，所以它终于可以再次工作（即呈现蓝色圆圈），如下所示：

#!/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()

嗯，希望这对某人有所帮助，
干杯！