为什么 wx.Panel 在这个简单的代码中搞砸了 Sizer？

Question

我是 Python 新手，这周我正在尝试使用 wxPython 模块来创建 GUI。我想我理解了如何使用 sizers，但是这段代码发生的事情让我很感兴趣。有人可以帮我理解为什么吗？

此代码应为工具栏目的创建一个子面板，并在其后创建一些内容：

import wx

class Main_window (wx.Frame):
    def __init__(self):
        super(Main_window, self).__init__(parent = None, title = 'Some App')
        main_panel = wx.Panel(self)
        main_panel_sizer = wx.BoxSizer(wx.VERTICAL)

        # Calling panels
        toolbar = ToolBar(self)
        main_panel_sizer.Add(toolbar, 1, wx.EXPAND)
        button1 = wx.Button(main_panel, label='Button 1')
        main_panel_sizer.Add(button1, 0, wx.ALL|wx.ALIGN_LEFT)
        text = wx.StaticText(main_panel, label = 'Text 1')
        main_panel_sizer.Add(text, wx.ALL|wx.ALIGN_LEFT)

        # Final lines of constructor
        main_panel.SetSizer(main_panel_sizer)
        self.Show()

class ToolBar (wx.Panel):
    def __init__(self, parent):
        super().__init__(parent)
        self.SetBackgroundColour('blue')
        toolbar_sizer = wx.BoxSizer(wx.HORIZONTAL)
        button2 = wx.Button(self, label = 'Button 2')
        toolbar_sizer.Add(button2, 0, wx.ALIGN_LEFT)
        self.SetSizer(toolbar_sizer)

if __name__ == '__main__':
    app = wx.App()
    frame = Main_window()
    app.MainLoop()

但是输出是一团糟。子面板、文本和按钮堆叠在顶部。但如果我评论工具栏调用：

import wx

class Main_window (wx.Frame):
    def __init__(self):
        super(Main_window, self).__init__(parent = None, title = 'Some App')
        main_panel = wx.Panel(self)
        main_panel_sizer = wx.BoxSizer(wx.VERTICAL)

        # Calling panels
        # toolbar = ToolBar(self)
        # main_panel_sizer.Add(toolbar, 1, wx.EXPAND)
        button1 = wx.Button(main_panel, label='Button 1')
        main_panel_sizer.Add(button1, 0, wx.ALL|wx.ALIGN_LEFT)
        text = wx.StaticText(main_panel, label = 'Text 1')
        main_panel_sizer.Add(text, wx.ALL|wx.ALIGN_LEFT)

        # Final lines of constructor
        main_panel.SetSizer(main_panel_sizer)
        self.Show()

class ToolBar (wx.Panel):
    def __init__(self, parent):
        super().__init__(parent)
        self.SetBackgroundColour('blue')
        toolbar_sizer = wx.BoxSizer(wx.HORIZONTAL)
        button2 = wx.Button(self, label = 'Button 2')
        toolbar_sizer.Add(button2, 0, wx.ALIGN_LEFT)
        self.SetSizer(toolbar_sizer)

if __name__ == '__main__':
    app = wx.App()
    frame = Main_window()
    app.MainLoop()

sizer 再次正常工作。有人可以解释一下吗？似乎是巫术。

提前致谢。

Answer 1

粗略地说，您没有将 sizer 应用到 Main_window 并且 ToolBar 是一个独立的面板。
下面我为 self 分配一个 sizer 并将 main_panel 和 toolbar 放入其中，它们都有自己的 sizer。
希望这能说明问题。 （提示：这不是魔法——实际上是魔法，由 Robin Dunn 先生提供）:)

import wx

class Main_window (wx.Frame):
    def __init__(self):
        super(Main_window, self).__init__(parent = None, title = 'Some App')
        main_panel = wx.Panel(self)
        main_panel_sizer = wx.BoxSizer(wx.VERTICAL)
        main_sizer = wx.BoxSizer(wx.VERTICAL)

        # Calling panels
        toolbar = ToolBar(self)

        button1 = wx.Button(main_panel, label='Button 1')
        main_panel_sizer.Add(button1, 0, wx.ALL|wx.ALIGN_LEFT)
        text = wx.StaticText(main_panel, label = 'Text 1')
        main_panel_sizer.Add(text, wx.ALL|wx.ALIGN_LEFT)

        main_panel.SetSizer(main_panel_sizer)
        main_sizer.Add(toolbar, 1, wx.EXPAND)
        main_sizer.Add(main_panel)
        # Final lines of constructor
        self.SetSizer(main_sizer)
        self.Show()

class ToolBar (wx.Panel):
    def __init__(self, parent):
        super().__init__(parent)
        self.SetBackgroundColour('blue')
        toolbar_sizer = wx.BoxSizer(wx.HORIZONTAL)
        button2 = wx.Button(self, label = 'Button 2')
        toolbar_sizer.Add(button2, 0, wx.ALIGN_LEFT)
        self.SetSizer(toolbar_sizer)

if __name__ == '__main__':
    app = wx.App()
    frame = Main_window()
    app.MainLoop()