Book Image

Tkinter GUI Application Development Blueprints

By : Bhaskar Chaudhary
Book Image

Tkinter GUI Application Development Blueprints

By: Bhaskar Chaudhary

Overview of this book

Tkinter is the built-in GUI package that comes with standard Python distributions. It is a cross-platform package, which means you build once and deploy everywhere. It is simple to use and intuitive in nature, making it suitable for programmers and non-programmers alike. This book will help you master the art of GUI programming. It delivers the bigger picture of GUI programming by building real-world, productive, and fun applications such as a text editor, drum machine, game of chess, media player, drawing application, chat application, screen saver, port scanner, and many more. In every project, you will build on the skills acquired in the previous project and gain more expertise. You will learn to write multithreaded programs, network programs, database driven programs and more. You will also get to know the modern best practices involved in writing GUI apps. With its rich source of sample code, you can build upon the knowledge gained with this book and use it in your own projects in the discipline of your choice.
Table of Contents (15 chapters)
Tkinter GUI Application Development Blueprints
About the Author
About the Reviewers

Tracing Tkinter variables

When you specify a Tkinter variable as textvariable for a widget (textvariable = myvar), the widget automatically gets updated whenever the value of the variable changes. However, there might be times when, in addition to updating the widget, you need to do some extra processing at the time of reading or writing (or modifying) the variable.

Tkinter provides a method to attach a callback method that will be triggered every time the value of a variable is accessed. Thus, the callback acts as a variable observer. The callback method is named trace_variable(self, mode, callback), or simply trace(self, mode, callback).

The mode argument can take a value of r, w, or u, which stand for read, write, or undefined. Depending upon the mode specifications, the callback method is triggered when the variable is read or written.

By default, the callback method gets three arguments. The arguments, in order of their position, are as follows:

  • Name of the Tkinter variable

  • The index of...