Create professional-looking charts for data visualization using Perl and GD. Move beyond standard pie charts to incorporate annotations, indicators, and layering for enhanced informational delivery.
More than just another "pie-graphs-with-GD" tutorial, this article describes techniques you can use to create new levels of usefulness in your dynamically generated charts. Cook up some automatically generated graphs for your organizational meetings or live enterprise directory data. Annotate the charts with readable text that delivers more information than the standard pie chart.
Perl and the GD modules have been used together for many years to create useful dynamic charts and graphics for Web sites and presentations. This article shows how to use these tools to create professional-looking, focused, and highly informative charts in near real time for your organizational needs.
Using a modified version of the GD::Pie.pm module, we will build custom charts, then use the acquired data points to create indicators and text annotations. Additionally, we show a method of layering geometric primitives and using transparent pass-throughs to create separate channels of information inside the charts.
The techniques described allow you to create complex charts and use the GD tools as starting points for creating your own programs.
Any PC manufactured after 2000 should provide enough horsepower for compiling and running the code. The layering and annotation processes are CPU-intensive, so if you plan to create many of these charts on the fly on a Web server, faster and multiple processors offer better user experiences.
Assuming your operating environment of choice contains a recent version of Perl, you'll need to download and install the GD Perl module. You might also consider using a fast and simple image viewer application like feh.