HOWTO: Your first wxPython application

Hello World

Every programming language and UI toolkit needs to have a Hello World example. I think it’s the law in most jurisdictions. :thinking: Their intent is obviously to tell you everything you need to know in order to select the language or toolkit for your own use.

So, here is wxPython’s Hello World:

# First things, first. Import the wxPython package.
import wx

# Next, create an application object.
app = wx.App()

# Then a frame.
frm = wx.Frame(None, title="Hello World")

# Show it.

# Start the event loop.

Just five lines of code to create and show a window, and run an event handler. That’s really all it takes.

What, you think 5 lines is too many? Okay, fine. Here it is in one line :stuck_out_tongue_winking_eye: :

import wx; a=wx.App(); wx.Frame(None, title="Hello World").Show(); a.MainLoop()

Hello World, Part 2

Okay, now let’s put a little more flesh on the bones of that Hello World sample to give a little better idea of what creating a wxPython application is all about. The finished application looks like these screenshots when run:



And here is the source code. The docstrings and the comments in the code will help you understand what it is doing.

Hello World, but with more meat.

import wx

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

    def __init__(self, *args, **kw):
        # ensure the parent class'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="Hello World!")
        font = st.GetFont()
        font.PointSize += 10
        font = font.Bold()

        # 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))

        # create a menu bar

        # and a status bar
        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")
        # 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 the 
        # menu item can be triggered from the keyboard.
        menuBar = wx.MenuBar()
        menuBar.Append(fileMenu, "&File")
        menuBar.Append(helpMenu, "&Help")

        # Give the menu bar to the frame

        # 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."""

    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",

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')
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