Treemap Overview
Sample Application: Usenet Views
How to Add a Treemap to Your Application
A treemap is a rendering of hierarchical data as a set of nested boxes, where each box corresponds to one data element. The nesting indicates the hierarchy, the box sizes are proportional to some attribute on each element, and the box colors are based on another attribute. Here is a sample treemap:
For a history of treemaps, see Treemaps for Space-Constrained Visualization of Hierarchies, by Ben Shneiderman at the University of Maryland. Dr. Shneiderman invented treemaps.
The Microsoft Research Community Technologies team has developed two .NET components that render treemaps. The TreemapGenerator is a drawing engine without its own user interface. It takes a set of hierarchical data, generates a treemap from the data, and draws it onto a bitmap or Graphics object provided by the caller. It can be used in a variety of environments, including Web applications that generate images on the server for downloading to client browsers.
The TreemapControl wraps the TreemapGenerator into a Windows Forms control. It can be added to the Visual Studio toolbox and dropped into any Windows Forms application.
Sample Application: Usenet Views
Usenet Views is a .NET Windows Forms application that displays Usenet statistics in a variety of graphical formats. Several of the application's views use the TreemapControl. Here, for example, is the microsoft.public newsgroup hierarchy displayed as a treemap:
In this example, the size of each newsgroup's box is proportional to the number of posts that were made to that newsgroup in September 2002. The color indicates the change from the previous month: green is more, red is fewer. The application lets you zoom into the hierarchy by double-clicking on the boxes. You can select which Usenet metrics to display, change the colors, alter the border widths and padding between boxes, save the treemap as an image or as XML, and so on.
Usenet Views is currently not available outside of Microsoft, but see the Netscan Web site for a related application.
How to Add a Treemap to Your Application
TreemapGenerator and TreemapControl are just two of the data visualization components that have been developed by the Microsoft Research Community Technologies team. See the Visualization Components overview for further information.
Questions and comments can be posted to the microsoft.public.research.netscan.discussion newsgroup.