GetClrmap.3

'\"
'\" Copyright (c) 1994 The Regents of the University of California.
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
'\"
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'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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.TH Tk_GetColormap 3 4.0 Tk "Tk Library Procedures"
.so man.macros
.BS
.SH NAME
Tk_GetColormap, Tk_PreserveColormap, Tk_FreeColormap \- allocate and free colormaps
.SH SYNOPSIS
.nf
\fB#include <tk.h>\fR
.sp
Colormap
\fBTk_GetColormap(\fIinterp, tkwin, string\fB)\fR
.sp
\fBTk_PreserveColormap(\fIdisplay, colormap\fB)\fR
.sp
\fBTk_FreeColormap(\fIdisplay, colormap\fB)\fR
.SH ARGUMENTS
.AS "Colormap" colormap
.AP Tcl_Interp *interp in
Interpreter to use for error reporting.
.AP Tk_Window tkwin in
Token for window in which colormap will be used.
.AP "const char" *string in
Selects a colormap:  either \fBnew\fR or the name of a window
with the same screen and visual as \fItkwin\fR.
.AP Display *display in
Display for which \fIcolormap\fR was allocated.
.AP Colormap colormap in
Colormap to free or preserve;  must have been returned by a previous
call to \fBTk_GetColormap\fR or \fBTk_GetVisual\fR.
.BE
.SH DESCRIPTION
.PP
These procedures are used to manage colormaps.
\fBTk_GetColormap\fR returns a colormap suitable for use in \fItkwin\fR.
If its \fIstring\fR argument is \fBnew\fR then a new colormap is
created;  otherwise \fIstring\fR must be the name of another window
with the same screen and visual as \fItkwin\fR, and the colormap from that
window is returned.
If \fIstring\fR does not make sense, or if it refers to a window on
a different screen from \fItkwin\fR or with
a different visual than \fItkwin\fR, then \fBTk_GetColormap\fR returns
\fBNone\fR and leaves an error message in \fIinterp\fR's result.
.PP
\fBTk_PreserveColormap\fR increases the internal reference count for a
colormap previously returned by \fBTk_GetColormap\fR, which allows the
colormap to be stored in several locations without knowing which order
they will be released.
.PP
\fBTk_FreeColormap\fR should be called when a colormap returned by
\fBTk_GetColormap\fR is no longer needed.
Tk maintains a reference count for each colormap returned by
\fBTk_GetColormap\fR, so there should eventually be one call to
\fBTk_FreeColormap\fR for each call to \fBTk_GetColormap\fR and each
call to \fBTk_PreserveColormap\fR.
When a colormap's reference count becomes zero, Tk releases the
X colormap.
.PP
\fBTk_GetVisual\fR and \fBTk_GetColormap\fR work together, in that
a new colormap created by \fBTk_GetVisual\fR may later be returned
by \fBTk_GetColormap\fR.
The reference counting mechanism for colormaps includes both procedures,
so callers of \fBTk_GetVisual\fR must also call \fBTk_FreeColormap\fR
to release the colormap.
If \fBTk_GetColormap\fR is called with a \fIstring\fR value of
\fBnew\fR then the resulting colormap will never
be returned by \fBTk_GetVisual\fR;  however, it can be used in other
windows by calling \fBTk_GetColormap\fR with the original window's
name as \fIstring\fR.
.SH KEYWORDS
colormap, visual