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Tk_GetColormap(3) Tk Library Procedures Tk_GetColormap(3)
Tk_GetColormap, Tk_PreserveColormap, Tk_FreeColormap - allocate and
Tk_GetColormap(interp, tkwin, string)
Tcl_Interp *interp (in) Interpreter to use for error reporting.
Tk_Window tkwin (in) Token for window in which colormap will
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
Colormap colormap (in) Colormap to free or preserve; must
have been returned by a previous call
to Tk_GetColormap or Tk_GetVisual.
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.
Tk 4.0 Tk_GetColormap(3)