Nonretained Graphic Segments

It is valid segment construction to create a segment bracket while the drawing mode is DM_DRAW. The GPI functions contained within the bracket are drawn immediately rather than being retained for future use. This type of segment is called a nonretained segment.

Because the usual reason for constructing segments is to take advantage of retained graphics, nonretained segments might appear as a contradiction in terms at first. However, there are four particular advantages in their use:

• If ATTR_FASTCHAIN is set to OFF, the GpiOpenSegment implicitly resets all attributes to their defaults.

• The GpiOpenSegment and GpiCloseSegment initialize and reset the viewing transform matrix, just as they do for retained segments.

• Nonretained segments can be recorded in a metafile, just as a retained segment can.

• A graphic in a nonretained segment, with a unique name, can be converted easily to a retained graphic for future use.