Introduction to wxPython

Introduction

• Python - free, easy to use programming language
  
• wxWidgets - C++ GUI library
  
• wxPython - Python bindings to wxWidgets
  
• wxGlade - GUI builder for wxWidgets/wxPython
  

Getting Started

Install Python and wxPython on:

• Windows
• Mac (already installed with 10.5!)
• Linux

Anatomy of a GUI Application

• Windows
• Dialogs
• Widgets (buttons, etc)
• Event Loop

Minimal Application

import wx
class Minimal(wx.App):
    def OnInit(self):
        main_window = wx.Frame(None, -1, "")
        self.SetTopWindow(main_window)
        main_window.Show()
        return 1
if __name__ == "__main__":
    app = Minimal(0)
    app.MainLoop()

Types of Windows

• wx.Frame
• wx.Panel
• wx.Dialog
• Other windows usually subclass or use one of these

Building up the GUI

• Application creates the top level window
  
• Top level window (wx.Frame) is the parent for:
• menu bar, status bar, panels, dialogs
• Panels and dialogs contain:
• buttons, text boxes, drop downs, etc

Building Menus

• Optionally, create new event IDs
• Create a menu bar
• Create a menu
• Append menu items to the menu
• Append the menu to the menu bar
• Set the frame's menu bar to the one created
• Bind the menu entry ID to an event handling method

Menu Code

class MinimalFrame(wx.Frame):
    def __init__(self, *args, **kwds):
        kwds["style"] = wx.DEFAULT_FRAME_STYLE
        wx.Frame.__init__(self, *args, **kwds)
        self.main_window_menubar = wx.MenuBar()
        self.SetMenuBar(self.main_window_menubar)
        tmp_menu = wx.Menu()
        tmp_menu.Append(wx.ID_EXIT, "Quit", "", wx.ITEM_NORMAL)
        self.main_window_menubar.Append(tmp_menu, "File")
        self.Bind(wx.EVT_MENU, self.OnQuit, id=wx.ID_EXIT)
        
    def OnQuit(self, event): # wxGlade: LadFrame.
        self.Close(True)

Adding a Panel for Widgets

Parent the panel to the creating frame.

self.panel = wx.Panel(self, -1)

Types of Widgets

• Button - wx.Button
  
• Toggle Button - wx.ToggleButton
  
• Text Box - wx.TextCtrl
  
• Static Text - wx.StaticText
  
• Drop Down Menu - wx.Choice, wx.ComboBox
• Selection List - wx.ListBox
• Radio button - wx.RadioButton, wx.RadioBox
• Checkbox - wx.CheckBox
  
• Slider - wx.Slider
  

Adding Widgets

As with the panel, parent widgets to the window containing them. In this case, the new panel.

self.btn = wx.Button(self.panel, -1, "My Button!")
self.btn.Bind(wx.EVT_BUTTON, self.OnQuit)

Documentation

• Python - docs - sidebar
  
• wxWidgets Reference Manual
• wxPython PyDocs

Sizers

Sizers control the placement of widgets, allowing them to grow and shrink depending on font sizes, languages, and window sizes.

• Sizers place widgets, they do not parent them
• Sizers lay items out horizontally, vertically, in grids, etc
  
• Sizers can be added to other sizers
• Sizers are the best and worst feature of wxWidgets/wxPython
• Using wxGlade can make using sizers easy, with preparation
  

wxGlade

• Go through "Building Up the GUI" - frame, panel, etc
• wxGlade adds sizers automatically where appropriate
• Use proportion and flags (wxEXPAND) on added items
• It takes time and experience to get used to effects
  
• Can generate C++, Python, Perl, XRC
• (let's build an app!)

Drawing

• wx.Panel
• wx.ScrolledWindow
• Draw Functions!
• Buffer with wx.BufferedDC or techniques
• LAD!