xtreleasegc(3) [debian man page]

XtGetGC(3)							   XT FUNCTIONS 							XtGetGC(3)

NAME

       XtGetGC, XtReleaseGC - obtain and destroy a sharable GC

SYNTAX

       GC XtGetGC(Widget w, XtGCMask value_mask, XGCValues *values);

       void XtReleaseGC(Widget w, GC gc);

ARGUMENTS

       gc	 Specifies the GC to be deallocated.

       values	 Specifies the actual values for this GC.

       value_mask
		 Specifies which fields of the values are specified.

       w	 Specifies the widget.

DESCRIPTION

       The XtGetGC function returns a sharable, read-only GC.  The parameters to this function are the same as those for XCreateGC except that a
       widget is passed instead of a display.  XtGetGC shares only GCs in which all values in the GC returned by XCreateGC are the same.  In par-
       ticular, it does not use the value_mask provided to determine which fields of the GC a widget considers relevant.  The value_mask is used
       only to tell the server which fields should be filled in with widget data and which it should fill in with default values.  For further
       information about value_mask and values, see XCreateGC in the Xlib - C Language X Interface.

       The XtReleaseGC function deallocate the specified shared GC.

SEE ALSO

       X Toolkit Intrinsics - C Language Interface
       Xlib - C Language X Interface

X Version 11							    libXt 1.1.3 							XtGetGC(3)

XtGetGC()																 XtGetGC()

Name
  XtGetGC - obtain a read-only, sharable GC.

Synopsis
  GC XtGetGC(object, value_mask, values)
	 Widget object;
	 XtGCMask value_mask;
	 XGCValues *values;

Inputs
  object    Specifies the object with which the GC is to be associated; may be of class Object or any subclass thereof.

  value_mask
	    Specifies which fields of the GC are to be filled in with widget data.

  values    Specifies the actual values for this GC.

Returns
  A read-only GC with fields as specified in value_mask and values.

Description
  XtGetGC()  returns  a  sharable,  read-only  GC with values as specified in values for each bit set in value_mask.  The GC is valid for the
  screen and depth of object, or the nearest widget ancestor if object is not a subclass of Core.

  XtGetGC() shares only GCs in which all values in the GC are the same.  In particular, it does not use the value_mask provided to  determine
  which  fields of the GC a widget considers relevant.	value_mask is used only to tell the server which fields should be filled in with wid-
  get data and which it should fill in with default values.

Usage
  The Intrinsics provide a mechanism whereby widgets can share a graphics context (GC), reducing  the  number  of  GCs	created  and  thereby
  improving server performance.  The mechanism is a simple caching scheme, and all GCs obtained by means of this mechanism must be treated as
  read-only.

  If a GC with modifiable fields is needed, in Release 4 or previous releases the Xlib XCreateGC() function must  be  used.   In  Release  5,
  XtAllocateGC() allows a widget to allocate a shared GC with modifiable fields.

  Generally  only  widgets  will  need to allocate GCs, though some applications may also want to do so.  When done with a shared GC, free it
  with XtReleaseGC().

Structures
  The XtGCMask type is defined as follows:

     typedef unsigned long  XtGCMask; /* Mask of values that are used by widget*/

  Each of the symbols in the table below sets a single bit in an XtGCMask.  The value_mask, argument is formed	by  combining  these  symbols
  with the bitwise OR operator ( ):

GCArcMode	GCFillRule	      GCLineWidth
GCBackground	GCFillStyle	      GCPlaneMask
GCCapStyle	GCFont		      GCStipple
GCClipMask	GCForeground	      GCSubwindowMode
GCClipXOrigin	GCFunction	      GCTile
GCClipYOrigin	GCGraphicsExposures   GCTileStipXOrigin
GCDashList	GCJoinStyle	      GCTileStipYOrigin
GCDashOffset	GCLineStyle

The XGCValues structure contains the GC fields:

typedef struct {
  int function;       /* logical operation */
  unsigned long plane_mask;/* plane mask */
  unsigned long foreground;/* foreground pixel */
  unsigned long background;/* background pixel */
  int line_width;     /* line width */
  int line_style;     /* LineSolid, LineOnOffDash,
			 LineDoubleDash */
  int cap_style;      /* CapNotLast, CapButt,
			 CapRound, CapProjecting */
  int join_style;     /* JoinMiter, JoinRound, JoinBevel */
  int fill_style;     /* FillSolid, FillTiled,
			 FillStippled, FillOpaqueStippled */
  int fill_rule;      /* EvenOddRule, WindingRule */
  int arc_mode;       /* ArcChord, ArcPieSlice */
  Pixmap tile;	      /* tile pixmap for tiling operations */
  Pixmap stipple;     /* stipple 1 plane pixmap for stippling */
  int ts_x_origin;    /* offset for tile or
  int ts_y_origin;     * stipple operations */
  Font font;	      /* default text font for text operations */
  int subwindow_mode; /* ClipByChildren, IncludeInferiors */
  Bool graphics_exposures;/* should exposures be generated? */
  int clip_x_origin;  /* origin for clipping */
  int clip_y_origin;
  Pixmap clip_mask;   /* bitmap clipping; other calls for rects */
  int dash_offset;    /* patterned/dashed line information */
  char dashes;
} XGCValues;

See Also
  XtAllocateGC(1), XtReleaseGC(1).

Xt - Graphics Context															 XtGetGC()