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.TH DRAW-RECT 2
.SH NAME
Rect \-
rectangular portion of the plane
.SH SYNOPSIS
.EX
include "draw.m";
draw := load Draw Draw->PATH;
Rect: adt
{
min: Point;
max: Point;
canon: fn(r: self Rect): Rect;
dx: fn(r: self Rect): int;
dy: fn(r: self Rect): int;
eq: fn(r: self Rect, s: Rect): int;
Xrect: fn(r: self Rect, s: Rect): int;
inrect: fn(r: self Rect, s: Rect): int;
clip: fn(r: self Rect, s: Rect): (Rect, int);
combine: fn(r: self Rect, s: Rect): Rect;
contains: fn(r: self Rect, p: Point): int;
addpt: fn(r: self Rect, p: Point): Rect;
subpt: fn(r: self Rect, p: Point): Rect;
inset: fn(r: self Rect; n: int): Rect;
};
.EE
.SH DESCRIPTION
The type
.B Rect
defines a rectangular portion of the integer grid.
.TP 10
.BR min ", " max
These
members define the upper left
.RB ( min )
and lower right
.RB ( max )
points for the rectangle.
The rectangle contains the pixels
.BI "min.x\ \fR\(<=\ " "x\ \fR<\ " max.x
and
.BI "min.y\ \fR\(<=\ " "y\ \fR<\ " max.y\fR.
In general,
.B Rect
coordinates should be in canonical form:
.BR min.x "\ \(<=\ " max.x
and
.BR min.y "\ \(<=\ " max.y .
Some functions give undefined results if the
input rectangles are not canonical.
.TP
.IB r .canon()
Returns a canonical rectangle by sorting the coordinates of
.IR r .
.TP
.IB r .dx()
Returns the horizontal dimension of
.IR r .
.TP
.IB r .dy()
Returns the vertical dimension of
.IR r .
.TP
.IB r .eq( s )
Returns non-zero if the rectangles
.I r
and
.I s
have the same coordinates and zero otherwise.
.TP
.IB r .Xrect( s )
Returns non-zero if the rectangles
.I r
and
.I s
intersect and zero otherwise.
.I Intersection
means the rectangles share at least one pixel; zero-sized rectangles do not intersect.
.TP
.IB r .inrect( s )
Returns non-zero if
.I r
is completely inside
.I s
and zero otherwise.
Rectangles with equal coordinates are considered to be inside each other.
Zero-sized rectangles contain no rectangles.
.TP
.IB r .clip( s )
Computes the intersection between
.I r
and
.IR s .
If the input rectangles intersect,
.B clip
returns the resulting rectangle
and a non-zero integer value.
If the rectangles do not intersect,
.B clip
returns
.I r
and a zero value.
.TP
.IB r .combine( s )
Returns the smallest rectangle sufficient
to cover all the pixels of
.I r
and
.IR s .
.TP
.IB r .contains( p )
Returns non-zero if the rectangle
.I r
contains the pixel with the coordinates of
.I p
and zero otherwise.
Zero-sized rectangles contain no points.
.TP
.IB r .addpt( p )
Returns the rectangle
.BI ( r .min.add( p ),
.IB r .max.add( p ))\fR.
.TP
.IB r .subpt( p )
Returns the rectangle
.BI ( r .min.sub( p ),
.IB r .max.sub( p ))\fR.
.TP
.IB r .inset( n )
Returns the rectangle
.BI ( r .min.add(( n ,
.IB n )),
.IB r .max.sub(( n ,
.IB n ))\fR.
The result will not be in canonical form if the inset amount is
too large for the rectangle.
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