Ellipse shape. It is possible to define a graphical->texture
for the line and a
ellipse->fill
for the interior. See also class circle.
For consistency with boxes, etc., the graphical->position
of an ellipse is the top-left corner. Use graphical->center
to define the center.
|{foreground,background}*Defaults: @nil
<-device
coordinate system — lies inside the ellipse inscribed in the bounding
box
graphical<-area.
Uses the standard ellipse equation
((X - cx) / rx)² + ((Y - cy) / ry)² ≤ 1
where (cx, cy) is the centre and (rx, ry) the semi-axes. Bbox corners just miss the shape.
This is the same test used by graphical->in_event_area
to accept a click: that method additionally inflates the ellipse by
event_tolerance pixels on each side so hits within
tolerance of the outline still count.