XSetFillRule()XSetFillRule()NameXSetFillRule – set the fill rule in a graphics context.
Synopsis
XSetFillRule(display, gc, fill_rule)
Display *display;
GC gc;
int fill_rule;
Arguments
display Specifies a connection to an X server; returned from
XOpenDisplay().
gc Specifies the graphics context.
fill_rule Specifies the fill rule you want to set for the specified
graphics context. Possible values are EvenOddRule or Windin‐
gRule.
DescriptionXSetFillRule() sets the fill_rule component of a GC. The fill_rule
member of the GC determines what pixels are drawn in XFillPolygon()
requests. Simply put, WindingRule fills overlapping areas of the poly‐
gon, while EvenOddRule does not fill areas that overlap an odd number
of times. Technically, EvenOddRule means that the point is drawn if an
arbitrary ray drawn from the point would cross the path determined by
the request an odd number of times. WindingRule indicates that a point
is drawn if a point crosses an unequal number of clockwise and counter‐
clockwise path segments, as seen from the point.
A clockwise-directed path segment is one which crosses the ray from
left to right as observed from the point. A counterclockwise segment
is one which crosses the ray from right to left as observed from the
point. The case where a directed line segment is coincident with the
ray is uninteresting because you can simply choose a different ray that
is not coincident with a segment.
All calculations are performed on infinitely small points, so that if
any point within a pixel is considered inside, the entire pixel is
drawn. Pixels with centers exactly on boundaries are considered inside
only if the filled area is to the right, except that on horizontal
boundaries, the pixel is considered inside only if the filled area is
below the pixel.
See Volume One, Chapter 5, The Graphics Context, for more information.
Errors
BadAlloc
BadGC
BadValue
See AlsoXDefaultGC(), XChangeGC(), XCopyGC(), XCreateGC(), XFreeGC(), XGCon‐
textFromGC(), XSetArcMode(), XSetBackground(), XSetClipMask(), XSetCli‐
pOrigin(), XSetClipRectangles(), XSetDashes(), XSetFillStyle(), XSet‐
Foreground(), XSetFunction(), XSetGraphicsExposures(), XSetLineAt‐
tributes(), XSetPlaneMask(), XSetState(), XSetStipple(), XSetSubwindow‐
Mode(), XSetTSOrigin().
Xlib - Graphics Context XSetFillRule()
