XcupStoreColors man page
XcupStoreColors — initialize shareable colormap entries at specific locations
cc [ flag ... ] file ... -lXext [ library ... ] #include <X11/extensions/Xcup.h> Status XcupStoreColors(Display *display, Colormap colormap, XColor *colors_in_out, int ncolors);
Specifies the connection to the X server
Specifies the colormap
Specifies and returns the values actually used in the colormap
Specifies the number of items in colors_in_out
The XcupStoreColors function changes the colormap entries of the pixel values in the pixel members of the XColor structures. The colormap entries are allocated as if an AllocColor has been used instead, i.e. the colors are read-only (shareable). XcupStoreColors returns the number of colors that were successfully allocated in the colormap.
A Value error is generated if a pixel is not a valid index into the colormap. A BadMatch error is generated if the colormap does not belong to a GrayScale, PseudoColor, or DirectColor visual.
Applications which allocate many colors in a screen's default colormap, e.g. a color-cube or a gray-ramp, should allocate them with XCupStoreColors. By using XCupStoreColors the colors will be allocated sharable (read-only) and any other application which allocates the same color will share that color cell.
Colormap Utilization Policy and Extension