NAME

XPolygonRegion — generate a region from points in a polygon. 

SYNOPSIS

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

ARGUMENTS

pointsSpecifies a pointer to an array of points. 

nSpecifies the number of points in the polygon. 

fill_ruleSpecifies whether areas overlapping an odd number of times should be part of the region (WindingRule) or not part of the region (EvenOddRule).  See Volume One, Chapter 5, The Graphics Context, for a description of the fill rule. 

RETURNS

The created region. 

DESCRIPTION

XPolygonRegion() creates a region defined by connecting the specified points, and returns a pointer to be used to refer to the region. 

Regions are located relative to a point (the region origin) which is common to all regions.  In XPolygonRegion(), the coordinates specified in points are relative to the region origin.  By specifying all points relative to the drawable in which they will be used, the region origin can be coincident with the drawable origin.  It is up to the application whether to interpret the location of the region relative to a drawable or not. 

If the region is to be used as a clip_mask by calling XSetRegion(), the upper-left corner of the region relative to the drawable used in the graphics request will be at (xoffset + clip_x_origin, yoffset + clip_y_origin), where xoffset and yoffset are the offset of the region (if any) and clip_x_origin and clip_y_origin are elements of the GC used in the graphics request.  The fill_rule can be either of these values:

•   EvenOddRuleAreas overlapping an odd number of times are not part of the region. 

•   WindingRuleOverlapping areas are always filled. 

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

STRUCTURES

Region is a pointer to an opaque structure type. 

SEE ALSO

XClipBox(), XCreateRegion(), XDestroyRegion(), XEmptyRegion(), XEqualRegion(), XIntersectRegion(), XOffsetRegion(), XPointInRegion(), XRectInRegion(), XSetRegion(), XShrinkRegion(), XSubtractRegion(), XUnionRectWithRegion(), XUnionRegion(), XXorRegion(). 

Xlib Reference Manual