NAME

       Tk_GetColormap, Tk_PreserveColormap, Tk_FreeColormap - allocate and free colormaps

SYNOPSIS

       #include <tk.h>

       Colormap
       Tk_GetColormap(interp, tkwin, string)

       Tk_PreserveColormap(display, colormap)

       Tk_FreeColormap(display, colormap)

ARGUMENTS

       Tcl_Interp *interp (in)         Interpreter to use for error reporting.

       Tk_Window tkwin (in)            Token for window in which colormap will be used.

       const char *string (in)         Selects  a  colormap:   either  new or the name of a window with the same
                                       screen and visual as tkwin.

       Display *display (in)           Display for which colormap was allocated.

       Colormap colormap (in)          Colormap to free or preserve;  must have been returned by a previous call
                                       to Tk_GetColormap or Tk_GetVisual.
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DESCRIPTION

       These  procedures  are  used  to manage colormaps.  Tk_GetColormap returns a colormap suitable for use in
       tkwin.  If its string argument is new then a new colormap is created;  otherwise string must be the  name
       of  another  window  with  the  same  screen  and  visual  as tkwin, and the colormap from that window is
       returned.  If string does not make sense, or if it refers to a window on a different screen from tkwin or
       with  a  different  visual  than  tkwin,  then Tk_GetColormap returns None and leaves an error message in
       interp's result.

       Tk_PreserveColormap increases the  internal  reference  count  for  a  colormap  previously  returned  by
       Tk_GetColormap,  which  allows the colormap to be stored in several locations without knowing which order
       they will be released.

       Tk_FreeColormap should be called when a colormap returned by Tk_GetColormap  is  no  longer  needed.   Tk
       maintains  a  reference count for each colormap returned by Tk_GetColormap, so there should eventually be
       one call to Tk_FreeColormap for each call to Tk_GetColormap and each call to Tk_PreserveColormap.  When a
       colormap's reference count becomes zero, Tk releases the X colormap.

       Tk_GetVisual  and  Tk_GetColormap work together, in that a new colormap created by Tk_GetVisual may later
       be returned by Tk_GetColormap.  The reference counting mechanism for colormaps includes both  procedures,
       so  callers of Tk_GetVisual must also call Tk_FreeColormap to release the colormap.  If Tk_GetColormap is
       called with a string value of new then the resulting colormap will never  be  returned  by  Tk_GetVisual;
       however,  it  can  be  used in other windows by calling Tk_GetColormap with the original window's name as
       string.

KEYWORDS

       colormap, visual