XUnionRectWithRegion()XUnionRectWithRegion()NameXUnionRectWithRegion – 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.
DescriptionXUnionRectWithRegion() 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 rectan‐
gles. 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 AlsoXClipBox(), XDestroyRegion(), XEmptyRegion(), XEqualRegion(), XInter‐
sectRegion(), XOffsetRegion(), XPointInRegion(), XPolygonRegion(),
XRectInRegion(), XSetRegion(), XShrinkRegion(), XSubtractRegion(),
XUnionRegion(), XXorRegion().
Xlib - Resource Manager XUnionRectWithRegion()