Manipulating graphics segments

GDDM V3R2 Base Application Programming Guide

Manipulating graphics segments

GDDM V3R2 Base Application Programming Guide
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A segment is a group of graphics primitives and attributes that can be handled as an entity, separate from other segments and primitives. This topic describes the calls that create, delete, and copy segments, and those that change a segment's appearance by moving, rotating, rescaling, or shearing it. "Storing and retrieving graphics pictures" in topic 10.0 explains how to store segments on external storage.

Segments can also call other segments. This means that you can organize your graphics segments into a structure or hierarchy. Just like well-structured programs, well-structured data has the advantages of increased clarity and ease of maintenance. You do not have to divide a picture into segments. The complete picture can be a single segment, or primitives can be drawn outside segments altogether. A segmentation scheme should be the most convenient and efficient implementation of the functions that the end user requires.

Segments have major uses in interactive graphics applications. Such applications generally enable the end user to manipulate parts of pictures. For instance, a program for designing the external appearance of a house might have the house outline, the doors, and the windows as separate segments. It would then be relatively simple to enable the end user to position, rescale, and manipulate each of these items independently.

"Writing interactive graphics applications" in topic 11.0 describes calls and techniques for making a graphics application interactive.

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