2.4 Graphics Protocols
2.4.2 General Behavior of Drawing Functions
Using draw-line* as an example, calling any of the drawing functions specified previously results in the following series of function calls on a non-output recording sheet:- A program calls draw-line* on arguments sheet, x1, y1, x2, and y2, and perhaps some drawing options.
- draw-line* merges the supplied drawing options into the sheet's medium, and then calls medium-draw-line* on the sheet. (Note that a compiler macro could detect the case where there are no drawing options or constant drawing options, and do this at compile time.)
- medium-draw-line* on the sheet calls the same method--medium-draw-line*--on the medium.
- medium-draw-line* performs the necessary user transformations by applying the medium transformation to x1, y1, x2, and y2, and to the clipping region.
CLIM 2.0 User's Guide - OCT 1998 Generated with Harlequin WebMaker