ggiDrawVLine, ggiPutVLine, ggiGetVLine : Draw, put, and get a vertical line from a visual
#include <ggi/ggi.h> int ggiDrawVLine(ggi_visual_t vis, int x, int y, int h); int ggiPutVLine(ggi_visual_t vis, int x, int y, int h, void *buf); int ggiGetVLine(ggi_visual_t vis, int x, int y, int h, void *buf);
Draw, put, or get a vertical line from (:p:`x`, :p:`y`), extending :p:`h` pixels in the positive y direction (normally down). The width of the line is one pixel.
The :p:`buf` parameter in Get/Put functions points to a buffer from which the pixels will be read, or to which they will be written (it must be correctly allocated), depending on the case. See ggiPackColors and ggiUnmapPixels functions for more on how to deal with pixels.
All three functions return 0 to indicate success.