Tk_GetGC - only graphics contexts
#include <tk.h> GC Tk_GetGC(tkwin, valueMask, valuePtr) Tk_FreeGC(display, gc)
Tk_GetGC(3tk) Tk Library Procedures Tk_GetGC(3tk)
______________________________________________________________________________
NAME
Tk_GetGC, Tk_FreeGC - maintain database of read-only graphics contexts
SYNOPSIS
#include <tk.h>
GC
Tk_GetGC(tkwin, valueMask, valuePtr)
Tk_FreeGC(display, gc)
ARGUMENTS
Tk_Window tkwin (in) Token for window in which the
graphics context will be used.
unsigned long valueMask (in) Mask of bits (such as GCFore-
ground or GCStipple) indicating
which fields of *valuePtr are
valid.
XGCValues *valuePtr (in) Pointer to structure describing
the desired values for the graph-
ics context.
Display *display (in) Display for which gc was allo-
cated.
GC gc (in) X identifier for graphics context
that is no longer needed. Must
have been allocated by Tk_GetGC.
______________________________________________________________________________
DESCRIPTION
Tk_GetGC and Tk_FreeGC manage a collection of graphics contexts being
used by an application. The procedures allow graphics contexts to be
shared, thereby avoiding the server overhead that would be incurred if
a separate GC were created for each use. Tk_GetGC takes arguments
describing the desired graphics context and returns an X identifier for
a GC that fits the description. The graphics context that is returned
will have default values in all of the fields not specified explicitly
by valueMask and valuePtr.
Tk_GetGC maintains a database of all the graphics contexts it has cre-
ated. Whenever possible, a call to Tk_GetGC will return an existing
graphics context rather than creating a new one. This approach can
substantially reduce server overhead, so Tk_GetGC should generally be
used in preference to the Xlib procedure XCreateGC, which creates a new
graphics context on each call.
Since the return values of Tk_GetGC are shared, callers should never
modify the graphics contexts returned by Tk_GetGC. If a graphics con-
text must be modified dynamically, then it should be created by calling
XCreateGC instead of Tk_GetGC.
When a graphics context is no longer needed, Tk_FreeGC should be called
to release it. There should be exactly one call to Tk_FreeGC for each
call to Tk_GetGC. When a graphics context is no longer in use anywhere
(i.e. it has been freed as many times as it has been gotten) Tk_FreeGC
will release it to the X server and delete it from the database.
KEYWORDS
graphics context
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
+---------------+------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+------------------+
|Availability | runtime/tk-8 |
+---------------+------------------+
|Stability | Uncommitted |
+---------------+------------------+
NOTES
Source code for open source software components in Oracle Solaris can
be found at https://www.oracle.com/downloads/opensource/solaris-source-
code-downloads.html.
This software was built from source available at
https://github.com/oracle/solaris-userland. The original community
source was downloaded from https://source-
forge.net/projects/tcl/files/Tcl/8.6.7/tk8.6.7-src.tar.gz/download.
Further information about this software can be found on the open source
community website at https://www.tcl.tk/.
Tk Tk_GetGC(3tk)