Regions

Regions are sets of pixels. They are held by the client program and are often used to create masks etc. These are created by

Region XCreateRegion();

which creates an empty region. This can be assigned to using

Region XPolygonRegion(points,n,fill_rule)
XPoint points[];

and destroyed by

XDestroyRegion(r)

To clear a region, destroy and recreate it. To find the smallest enclosing rectangle use

XClipBox(r,rect)
XRectangle rect /*RETURN*/

To use a region as a GC's mask, use

XSetRegion(display,gc,r)

To move a region use

XOffsetRegion(r,dx,dy)

To change the size of a region use

XShrinkRegion(r,dx,dy) /* if dx or dy <0 then the shrink becomes expand*/

Other operations are:-

XIntersectRegion(sra,srb,dr)
Region dr; /*RETURN*/

XUnionRegion(sra,srb,dr)
Region dr; /*RETURN*/

XUnionRectWithRegion(rect, src_region, dest_region)
Rectangle *rect;

XSubtractRegion(sra,srb,dr)
Region dr; /*RETURN (union - intersection)*/

XXorRegion(sra,srb,dr)
Region dr; /*RETURN*/

int XEmptyRegion(r)   /* is the region null ? */

int XEqualRegion(r1,r2)

int XPointInRegion(r,x,y)

int XRectInRegion(r,x,y,width,height)