树莓派4

新推出的树莓派4性能卓越。运行桌面应用，比如浏览网页，看视频非常流畅。这一节我们在树莓派4上安装wxPython库，并编写一个桌面应用的例子。

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树莓派的桌面例子

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树莓派系统没有预装wxPython的库，导入wxPython的库会报错

import wx

第一步，安装GTK3.0的库

sudo apt-get install libgtk-3-dev

第二步，安装wxPython库

刚开始使用下面的命令安装

sudo apt-get install python-wxgtk3.0

安装完成后，python2.7版本可以运行最简单的窗口应用。但Python3不行
最后使用下面的命令安装

sudo python3 -m pip install wxPython -i https://mirrors.aliyun.com/pypi/simple

安装成功。
但编译的过程花了很长时间（n小时以上。。。)

直接安装whl文件

将编译好的whl文件上传了。有需要的可以下载试试。

下载地址：
百度云盘链接 提取码: kfjn

运行以下命令，很快就可以安装好

sudo python3 -m pip install wxPython-4.0.7.post2-cp37-cp37m-linux_armv7l.whl

附测试的例子。
这个例子是在wxPython官网的例子基础上加了一个按钮和输入框

# coding: utf-8
import wx
# First things, first. Import the wxPython package.


class HelloFrame(wx.Frame):
    """
    A Frame that says Hello World
    """

    def __init__(self, *args, **kw):
        # ensure the parent's __init__ is called
        super(HelloFrame, self).__init__(*args, **kw)

        # create a panel in the frame
        pnl = wx.Panel(self)

        # put some text with a larger bold font on it
        st = wx.StaticText(pnl, label="Python示例")
        font = st.GetFont()
        font.PointSize += 10
        font = font.Bold()
        st.SetFont(font)

        # and create a sizer to manage the layout of child widgets
        sizer = wx.BoxSizer(wx.VERTICAL)
        sizer.Add(st, wx.SizerFlags().Border(wx.TOP|wx.LEFT, 25))
        pnl.SetSizer(sizer)


        self.inputText = wx.TextCtrl(pnl,-1,"",pos=(80,100),size=(150,-1))
        self.inputText.SetInsertionPoint(0) #设置焦点位置

        openButton = wx.Button(pnl,label="Open",pos=(255,100),size=(80,25))
        openButton.Bind(wx.EVT_BUTTON,self.openButtonClicked)

        # create a menu bar
        self.makeMenuBar()

        # and a status bar
        self.CreateStatusBar()
        self.SetStatusText("Welcome to wxPython!")


    def makeMenuBar(self):
        """
        A menu bar is composed of menus, which are composed of menu items.
        This method builds a set of menus and binds handlers to be called
        when the menu item is selected.
        """

        # Make a file menu with Hello and Exit items
        fileMenu = wx.Menu()
        # The "\t..." syntax defines an accelerator key that also triggers
        # the same event
        helloItem = fileMenu.Append(-1, "&Hello...\tCtrl-H",
                "Help string shown in status bar for this menu item")
        fileMenu.AppendSeparator()
        # When using a stock ID we don't need to specify the menu item's
        # label
        exitItem = fileMenu.Append(wx.ID_EXIT)

        # Now a help menu for the about item
        helpMenu = wx.Menu()
        aboutItem = helpMenu.Append(wx.ID_ABOUT)

        # Make the menu bar and add the two menus to it. The '&' defines
        # that the next letter is the "mnemonic" for the menu item. On the
        # platforms that support it those letters are underlined and can be
        # triggered from the keyboard.
        menuBar = wx.MenuBar()
        menuBar.Append(fileMenu, "&File")
        menuBar.Append(helpMenu, "&Help")

        # Give the menu bar to the frame
        self.SetMenuBar(menuBar)

        # Finally, associate a handler function with the EVT_MENU event for
        # each of the menu items. That means that when that menu item is
        # activated then the associated handler function will be called.
        self.Bind(wx.EVT_MENU, self.OnHello, helloItem)
        self.Bind(wx.EVT_MENU, self.OnExit,  exitItem)
        self.Bind(wx.EVT_MENU, self.OnAbout, aboutItem)


    def OnExit(self, event):
        """Close the frame, terminating the application."""
        self.Close(True)


    def OnHello(self, event):
        """Say hello to the user."""
        wx.MessageBox("Hello again from wxPython")


    def OnAbout(self, event):
        """Display an About Dialog"""
        wx.MessageBox("This is a wxPython Hello World sample",
                      "About Hello World 2",
                      wx.OK|wx.ICON_INFORMATION)

    def openButtonClicked(self, event):
        #"""Say hello to the user."""
        wx.MessageBox("你输入了："+self.inputText.GetValue())
        

        #res = dialog.ShowModal()
        print(self.inputText.GetValue())

if __name__ == '__main__':
    # When this module is run (not imported) then create the app, the
    # frame, show it, and start the event loop.
    app = wx.App()
    frm = HelloFrame(None, title='Hello World 2')
    frm.Show()
    app.MainLoop()