geekdoc-python-zh/docs/pythonlibrary/getting-the-correct-notebook-tab-across-platforms-in-wxpython.md

在 wxPython 中跨平台获取正确的笔记本选项卡

原文：https://www.blog.pythonlibrary.org/2019/06/05/getting-the-correct-notebook-tab-across-platforms-in-wxpython/

我最近在开发一个 GUI 应用程序，它有一个wx.Notebook in it. When the user changed tabs in the notebook, I wanted the application to do an update based on the newly shown (i.e. selected) tab. I quickly discovered that while it is easy to catch the tab change event, getting the right tab is not as obvious.

这篇文章将带你了解我的错误，并向你展示两个解决问题的方法。

下面是我最初做的一个例子:

# simple_note.py

import random
import wx

class TabPanel(wx.Panel):

    def __init__(self, parent, name):
        """"""
        super().__init__(parent=parent)
        self.name = name

        colors = ["red", "blue", "gray", "yellow", "green"]
        self.SetBackgroundColour(random.choice(colors))

        btn = wx.Button(self, label="Press Me")
        sizer = wx.BoxSizer(wx.VERTICAL)
        sizer.Add(btn, 0, wx.ALL, 10)
        self.SetSizer(sizer)

class DemoFrame(wx.Frame):
    """
    Frame that holds all other widgets
    """

    def __init__(self):
        """Constructor"""
        super().__init__(None, wx.ID_ANY,
                         "Notebook Tutorial",
                         size=(600,400)
                         )
        panel = wx.Panel(self)

        self.notebook = wx.Notebook(panel)
        self.notebook.Bind(wx.EVT_NOTEBOOK_PAGE_CHANGED, self.on_tab_change)
        tabOne = TabPanel(self.notebook, name='Tab 1')
        self.notebook.AddPage(tabOne, "Tab 1")

        tabTwo = TabPanel(self.notebook, name='Tab 2')
        self.notebook.AddPage(tabTwo, "Tab 2")

        sizer = wx.BoxSizer(wx.VERTICAL)
        sizer.Add(self.notebook, 1, wx.ALL|wx.EXPAND, 5)
        panel.SetSizer(sizer)
        self.Layout()

        self.Show()

    def on_tab_change(self, event):
        # Works on Windows and Linux, but not Mac
        current_page = self.notebook.GetCurrentPage()
        print(current_page.name)
        event.Skip()

if __name__ == "__main__":
    app = wx.App(False)
    frame = DemoFrame()
    app.MainLoop()

这段代码可以在 Linux 和 Windows 上正常运行。然而，当你在 Mac OSX 上运行它时，报告的当前页面总是你在选择当前页面之前所在的标签。这有点像一个错误，但是是在 GUI 中。

在尝试了我自己的一些想法后，我决定向 wxPython Google group 寻求帮助。

他们有两种解决方法:

• 使用GetSelection() along with the notebook's GetPage() method``
• 使用平板笔记本小部件

---

使用 GetSelection()

使用事件对象的GetSelection() method will return the index of the currently selected tab. Then you can use the notebook's GetPage() method to get the actual page. This was the suggestion that Robin Dunn, the maintainer of wxPython, gave to me.``

下面是更新后使用该修复程序的代码:

# simple_note2.py

import random
import wx

class TabPanel(wx.Panel):

    def __init__(self, parent, name):
        """"""
        super().__init__(parent=parent)
        self.name = name

        colors = ["red", "blue", "gray", "yellow", "green"]
        self.SetBackgroundColour(random.choice(colors))

        btn = wx.Button(self, label="Press Me")
        sizer = wx.BoxSizer(wx.VERTICAL)
        sizer.Add(btn, 0, wx.ALL, 10)
        self.SetSizer(sizer)

class DemoFrame(wx.Frame):
    """
    Frame that holds all other widgets
    """

    def __init__(self):
        """Constructor"""
        super().__init__(None, wx.ID_ANY,
                         "Notebook Tutorial",
                         size=(600,400)
                         )
        panel = wx.Panel(self)

        self.notebook = wx.Notebook(panel)
        self.notebook.Bind(wx.EVT_NOTEBOOK_PAGE_CHANGED, self.on_tab_change)
        tabOne = TabPanel(self.notebook, name='Tab 1')
        self.notebook.AddPage(tabOne, "Tab 1")

        tabTwo = TabPanel(self.notebook, name='Tab 2')
        self.notebook.AddPage(tabTwo, "Tab 2")

        sizer = wx.BoxSizer(wx.VERTICAL)
        sizer.Add(self.notebook, 1, wx.ALL|wx.EXPAND, 5)
        panel.SetSizer(sizer)
        self.Layout()

        self.Show()

    def on_tab_change(self, event):
        # Works on Windows, Linux and Mac
        current_page = self.notebook.GetPage(event.GetSelection())
        print(current_page.name)
        event.Skip()

if __name__ == "__main__":
    app = wx.App(False)
    frame = DemoFrame()
    app.MainLoop()

这是一个相当简单的修复，但有点烦人，因为不清楚为什么需要这么做。

---

使用平板笔记本

另一个选择是换掉wx.Notebook for the FlatNotebook. Let's see how that looks:

# simple_note.py

import random
import wx
import wx.lib.agw.flatnotebook as fnb

class TabPanel(wx.Panel):

    def __init__(self, parent, name):
        """"""
        super().__init__(parent=parent)
        self.name = name

        colors = ["red", "blue", "gray", "yellow", "green"]
        self.SetBackgroundColour(random.choice(colors))

        btn = wx.Button(self, label="Press Me")
        sizer = wx.BoxSizer(wx.VERTICAL)
        sizer.Add(btn, 0, wx.ALL, 10)
        self.SetSizer(sizer)

class DemoFrame(wx.Frame):
    """
    Frame that holds all other widgets
    """

    def __init__(self):
        """Constructor"""
        super().__init__(None, wx.ID_ANY,
                         "Notebook Tutorial",
                         size=(600,400)
                         )
        panel = wx.Panel(self)

        self.notebook = fnb.FlatNotebook(panel)
        self.notebook.Bind(wx.EVT_NOTEBOOK_PAGE_CHANGED, self.on_tab_change)
        tabOne = TabPanel(self.notebook, name='Tab 1')
        self.notebook.AddPage(tabOne, "Tab 1")

        tabTwo = TabPanel(self.notebook, name='Tab 2')
        self.notebook.AddPage(tabTwo, "Tab 2")

        sizer = wx.BoxSizer(wx.VERTICAL)
        sizer.Add(self.notebook, 1, wx.ALL|wx.EXPAND, 5)
        panel.SetSizer(sizer)
        self.Layout()

        self.Show()

    def on_tab_change(self, event):
        # Works on Windows, Linux and Mac
        current_page = self.notebook.GetCurrentPage()
        print(current_page.name)
        event.Skip()

if __name__ == "__main__":
    app = wx.App(False)
    frame = DemoFrame()
    app.MainLoop()

现在你可以回到使用笔记本的GetCurrentPage() method. You can also use self.notebook.GetPage(event.GetSelection()) like you do in the other workaround, but I feel like `GetCurrentPage() is just more obvious what it is that you are doing.

---

包扎

这是我在 wxPython 中被一个奇怪的陷阱抓住的少数几次之一。当您编写旨在跨多个平台运行的代码时，您会不时地遇到这类事情。检查文档以确保您没有使用并非所有平台都支持的方法总是值得的。然后你会想自己做一些研究和测试。但是一旦你做了你的尽职调查，不要害怕寻求帮助。我会一直寻求帮助，避免浪费我自己的时间，尤其是当我的解决方案在三分之二的情况下都有效的时候。