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_GetColormap or Tk_GetVi-
sual.
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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 col-
ormap 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
Tk 4.0 Tk_GetColormap(3)
