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.
_________________________________________________________________

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