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Tk_GetColormap(3)	      Tk Library Procedures	       Tk_GetColormap(3)

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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_Get-
				     Colormap 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 win-
     dow 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 tk-
     win, then Tk_GetColormap returns None and leaves an error	message  in  in-
     terp'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 re-
     leased.

     Tk_FreeColormap should be called when a colormap returned by Tk_GetColormap
     is no longer needed.  Tk maintains a reference count for each colormap  re-
     turned  by  Tk_GetColormap,  so  there  should  eventually  be  one call to
     Tk_FreeColormap for each call to Tk_GetColormap and each  call  to  Tk_Pre-
     serveColormap.  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 cre-
     ated by Tk_GetVisual may later be returned by Tk_GetColormap.   The  refer-
     ence  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 col-
     ormap 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

Tk				       4.0		       Tk_GetColormap(3)

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