## region.api
# Compiled by:
# src/lib/x-kit/draw/xkit-draw.sublib# Api for regions.
### "There is no unhappiness like the
### misery of sighting land (and work)
### again after a cheerful, careless voyage."
###
### -- Mark Twain,
### Letter to Will Bowen
### (prior to sailing on Quaker City)
api Region {
package g: Xgeometry; # Xgeometry is from src/lib/std/2d/xgeometry.api Fill_Rule = EVEN_ODD | WINDING;
Box_Overlap = BOX_OUT | BOX_IN | BOX_PART;
Region;
empty: Region;
# Return list of rectangles composing the region.
# The rectangles are YX banded. Specifically, the rectangles
# are listed in non-decreasing y coordinates. Two rectangles
# with the same y coordinate are listed in increasing x coordinate.
# Additionally, if the y projections of any two rectangles overlap,
# then the projections are equal. (The rectangles lie in non-overlapping
# bands.) Within a band, the rectangles are non-contiguous.
#
boxes_of: Region -> List( g::Box );
box: g::Box -> Region;
#
# Construct a region corresponding to the given rectangle.
polygon: (List( g::Point ), Fill_Rule) -> Region;
#
# Construct a region corresponding to the polygon described by
# the list of points and the fill rule.
offset: (Region, g::Point) -> Region;
#
# Translate a region by the given vector.
shrink: (Region, g::Point) -> Region;
#
# shrink (r, PT { x, y } ) strips a band x pixels horizontally
# and y pixels vertically from the boundary of r. If x or y are
# negative, pixels are added rather than stripped in that dimension.
clip_box: Region -> g::Box;
#
# Return the smallest rectangle containing the region.
# Return the region corresponding to the given set operation
# applied to two argument regions.
#
intersect: (Region, Region) -> Region;
union: (Region, Region) -> Region;
subtract: (Region, Region) -> Region;
xor: (Region, Region) -> Region;
is_empty: Region -> Bool;
#
# TRUE iff the region is empty.
equal: (Region, Region) -> Bool;
#
# TRUE iff the two regions are equal.
overlap: (Region, Region) -> Bool;
#
# TRUE iff the two regions have non-empty intersection.
point_in: (Region, g::Point) -> Bool;
#
# TRUE iff the point lies within the region.
box_in: (Region, g::Box) -> Box_Overlap;
#
# Returns RECTANGLE_IN if the rectangle is entirely contained in the region.
# Returns RECTANGLE_OUT if the rectangle is entirely outside the region.
# Returns RECTANGLE_PART if the rectangle is partly in and partly out of the region.
};
## COPYRIGHT (c) 1994 by AT&T Bell Laboratories
## Subsequent changes by Jeff Prothero Copyright (c) 2010-2013,
## released per terms of SMLNJ-COPYRIGHT.