last modified January 10, 2023
This chapter is an introduction to the wxPython toolkit.
wxPython is a cross platform toolkit for creating desktop GUI applications. The principal author of wxPython is Robin Dunn. With wxPython developers can create applications on Windows, Mac and on various Unix systems. wxPython is a wrapper around wxWidgets, which is a mature cross platform C++ library.
PythonPython is a successful scripting language. It was initially developed by Guido van Rossum. It was first released in 1991. Python was inspired by ABC and Haskell programming languages. Python is a high level, general purpose, multiplatform, interpreted language. Some prefer to call it a dynamic language. It is easy to learn. Python is a minimalistic language. One of its most visible features is that it does not use semicolons nor brackets. Python uses indentation instead. Today Python is maintained by a large group of volunteers worldwide.
For creating graphical user interfaces, Python programmers can choose among three decent options: PyGTK, wxPython, and PyQt.
wxPython moduleswxPython is a cross platform toolkit for creating desktop GUI applications. The principal author of wxPython is Robin Dunn. With wxPython developers can create applications on Windows, Mac and on various Unix systems. wxPython is a wrapper around wxWidgets, which is a mature cross platform C++ library. wxPython consists of the five basic modules.
Figure: wxPython modulesControls module provides the common widgets found in graphical applications. For example a Button, a Toolbar, or a Notebook. Widgets are called controls under Windows OS. The Core module consists of elementary classes that are used in development. These classes include the Object class, which is the mother of all classes, Sizers, which are used for widget layout, Events, basic geometry classes like Point and Rectangle. The Graphics Device Interface (GDI) is a set of classes used for drawing onto the widgets. This module contains classes for manipulation of Fonts, Colours, Brushes, Pens or Images. The Misc module contains of various other classes and module functions. These classes are used for logging, application configuration, system settings, working with display or joystick. The Windows module consists of various windows that form an application, for instance a Panel, a Dialog, a Frame, or a Scrolled Window.
wxPython APIwxPython API is a set of methods and objects. Widgets are essential building blocks of a GUI application. Under Windows widgets are calles controls. We can roughly divide programmers into two groups: they code either applications or libraries. In our case, wxPython is a library that is used by application programmers to code applications. Technically, wxPython is a wrapper over a C++ GUI API called wxWidgets. So it is not a native API; i.e. it is not written directly in Python.
In wxPython we have lots of widgets. These can be divided into some logical groups.
Base WidgetsThese widgets provide basic functionality for derived widgets. They are called ancestors. They are usually not used directly.
Figure: Base widgets Top level WidgetsThese widgets exist independently of each other.
Figure: Top-level widgets ContainersContainers contain other widgets.
Figure: Containers Dynamic WidgetsThese widgets can be edited by users.
Figure: Dynamic widgets Static WidgetsThese widgets display information. They cannot be edited by user.
Figure: Static widgets Other WidgetsThese widgets implement statusbar, toolbar and menubar in an application.
Figure: Other widgets InheritanceThere is a specific relation among widgets in wxPython. This relation is developed by inheritance. The inheritance is a crucial part of the object oriented programming. Widgets form a hierarchy. Widgets can inherit functionality from other widgets. Existing classes are called base classes, parents, or ancestors. The widgets that inherit we call derived widgets, child widgets or descendants.
Figure: Inheritance diagramSay we use a button widget in our application. The button widget inherits from four different base classes. The closest class is the wx.Control
class. A button widget is a kind of a small window. All widgets that appear on the screen are windows. Therefore they inherit from wx.Window
class. There are objects that are invisible. Examples are sizers, device context or locale object. There are also classes that are visible but they are not windows. For example a colour object, caret object or a cursor object. Not all widgets are controls. For example wx.Dialog
is not a kind of control. The controls are widgets that are placed on other widgets called containers. That's why we have a separate wx.Control
base class.
Every window can react to events. So does the button widget. By clicking on the button, we launch the wx.EVT_COMMAND_BUTTON_CLICKED
event. The button widget inherits the wx.EvtHandler
via the wx.Window
class. Each widget that reacts to events must inherit from wx.EvtHandler
class. Finally all objects inherit from wx.Object
class.
This was an introduction to wxPython.
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