ET++: Graphical Contexts (Ports)
ET++ uses the Pen/Paper/Ink pattern to support platform-independent and device-independent
graphics. It defines a class Port which is the ultimate recipient of all drawing commands.
Port implements public drawing primitives,
and all ET++ drawing is done through these Port methods, using that Port's current
pen and Ink attributes.
These public methods call protected
device-dependent drawing primitives (also methods of Port),
which are implemented
differently for each type of drawing "paper" (each subclass of Port;
examples of "paper" include the windows of
various windowing systems, graphics files, and printers).
ET++ also provides, as a convenience feature (it's full of convenience features),
a collection of functions which automatically draws on the current Port,
without requiring the application to determine which port is currently active.
For inheritance information, see a partial inheritance hierarchy for ET++.
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Suggestions to ferrar@uiuc.edu.