Graphics Ports allow users to write source-compatible applications for different host window systems. Graphics Ports are the destinations for drawing primitives. They are implemented with a generic host-independent part and a small host-specific part.
Graphics Ports implement a set of drawing functions and a mechanism for specifying the graphics state to be used in each drawing function call. There are four categories of graphics ports: on-screen, pixmap, printer, and metafile.
On-screen ports correspond to visible windows. Pixmap ports can be used for double-buffering graphics whereby you draw to the off-screen pixmap port and then copy the contents to the screen with
. Printer ports are used for drawing to a printer. Metafile ports are used for recording drawing operations so that they can be realized later.
The off-screen ports (pixmap, printer and metafile) are usually created transiently by a modification of an on-screen port using
respectively. The on-screen port is modified so that drawing is redirected as appropriate.
See the LispWorks CAPI Reference Manual for full reference entries on all the Graphics Ports functions, macros, classes and types.