6.21 region%
A region% object specifies a portion of a drawing area
(possibly discontinuous). It is normally used for clipping drawing
operations.
Each region% object is associated to a particular
dc<%> object, specified when the region is created. A region
can only be used with its associated dc<%> object. The origin
and scale of a drawing context determine the bounding box and drawing
location of a region at the time that a region is created (or set); a
region is independent of the current scale and origin when the region
is used. For an auto-scrolled canvas, the canvas's current scrolling
applies when the region is used (and it does not affect the region's
bounding box).
See also
set-clipping-region in dc<%> and
get-clipping-region in dc<%>.
Methods
get-bounding-box
get-dc
in-region?
intersect
is-empty?
set-arc
set-ellipse
set-path
set-polygon
set-rectangle
set-rounded-rectangle
subtract
union
xor