Drawing a clock with Python and the Cairo graphics library
Around the Clock
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Build graphic elements into your Python programs with the Cairo graphics library. We'll show you how to draw an analog clock face that displays the current time.
Tutorials and guides for programming and using command-line tools abound for Linux. Graphics programming, however, is rarely even touched upon. Although drawing graphics is indeed more tedious than printing text on a terminal, and some knowledge of mathematics is usually required, graphics programming is not terribly difficult. In this article, I will demonstrate how to write a functional, usable program to draw an analog clock face to an image file. By the end of this article, you will have a Python program that generates a stylish analog clock depicting the current time (Figure 1).
For this article, I will use the Cairo [1] graphics library to draw the images. Cairo might not be the most intuitive graphics library at first, but it is ubiquitous: Once you know how to use it, you can quickly adapt to drawing with other libraries, such as the GTK [2] graphical user interface toolkit, which also uses Cairo.
Python is not the only programming language you can use with Cairo: Cairo was originally written for the C language, and so-called "language bindings" are available for most popular languages. For more on coding with Cairo, see the official Cairo documentation [3], as well as the exhaustive programmer's reference [4].
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