xtaddexposuretoregion(3xt) [redhat man page]

XtAddExposureToRegion(3Xt)					   XT FUNCTIONS 					XtAddExposureToRegion(3Xt)

NAME

       XtAddExposureToRegion - merge exposure events into a region

SYNTAX

       void XtAddExposureToRegion(event, region)
	    XEvent *event;
	    Region region;

ARGUMENTS

       event	 Specifies a pointer to the Expose or GraphicsExpose event.

       region	 Specifies the region object (as defined in <X11/Xutil.h>).

DESCRIPTION

       The XtAddExposureToRegion function computes the union of the rectangle defined by the exposure event and the specified region.  Then, it
       stores the results back in region.  If the event argument is not an Expose or GraphicsExpose event, XtAddExposureToRegion returns without
       an error and without modifying region.

       This function is used by the exposure compression mechanism (see Section 7.9.3).

SEE ALSO

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

X Version 11							    Release 6.6 					XtAddExposureToRegion(3Xt)

XUnionRectWithRegion()													    XUnionRectWithRegion()

Name
  XUnionRectWithRegion - add a rectangle to a region.

Synopsis
  XUnionRectWithRegion(rectangle, src_region, dest_region_return)
	  XRectangle *rectangle;
	  Region src_region;
	  Region dest_region_return;

Arguments
  rectangle Specifies the rectangle to add to the region.

  src_region
	    Specifies the source region to be used.

  dest_region_return
	    Specifies the resulting region.  May be the same as src_region.

Description
  XUnionRectWithRegion() computes the destination region from a union of the specified rectangle and the specified source region.  The source
  and destination regions may be the same.

  One common application of this function is to simplify the combining of the  rectangles  specified  in  contiguous  Expose  events  into  a
  clip_mask  in the GC, thus restricting the redrawn areas to the exposed rectangles.  Use XUnionRectWithRegion() to combine the rectangle in
  each Expose event into a region, then call XSetRegion().  XSetRegion() sets the clip_mask in a GC to the region.  In this case,  src_region
  and dest_region_return would be the same region.

  If  src_region  and dest_region_return are not the same region, src_region is copied to dest_region_return before the rectangle is added to
  dest_region_return.

  For more information on regions, see Volume One, Chapter 6, Drawing Graphics and Text.

Structures
     typedef struct {
	 short x, y;
	 unsigned short width, height;
     } XRectangle;

  Region is a pointer to an opaque data type.

See Also
  XClipBox(), XDestroyRegion(), XEmptyRegion(),  XEqualRegion(),  XIntersectRegion(),  XOffsetRegion(),  XPointInRegion(),  XPolygonRegion(),
  XRectInRegion(), XSetRegion(), XShrinkRegion(), XSubtractRegion(), XUnionRegion(), XXorRegion().

Xlib - Resource Manager 												    XUnionRectWithRegion()