# man(1) Manual page archive

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NAME
rcanon, eqpt, eqrect, ptinrect, rectinrect, rectXrect,
rectclip, Dx, Dy, Pt, Rect, Rpt - arithmetic on points and
rectangles

SYNOPSIS
#include <u.h>
#include <libc.h>
#include <libg.h>

Point       sub(Point p, Point q)

Point       mul(Point p, int a)

Point       div(Point p, int a)

Rectangle   rsubp(Rectangle r, Point p)

Rectangle   rmul(Rectangle r, int a)

Rectangle   rdiv(Rectangle r, int a)

Rectangle   rshift(Rectangle r, int a)

Rectangle   inset(Rectangle r, int n)

Rectangle   rcanon(Rectangle r)

int         eqpt(Point p, Point q)

int         eqrect(Rectangle r, Rectangle s)

int         ptinrect(Point p, Rectangle r)

int         rectinrect(Rectangle r, Rectangle s)

int         rectXrect(Rectangle r, Rectangle s)

int         rectclip(Rectangle *rp, Rectangle b)

int         Dx(Rectangle r)

int         Dy(Rectangle r)

Point       Pt(int x, int y)

Rectangle   Rect(int x0, int y0, int x1, int y1)

Rectangle   Rpt(Point p, Point q)

DESCRIPTION
The functions Pt, Rect and Rpt construct geometrical data
types from their components.  These are implemented as mac-
ros.

Add returns the Point sum of its arguments: Pt(p.x+q.x,
p.y+q.y).  Sub returns the Point difference of its argu-
ments: Pt(p.x-q.x, p.y-q.y).  Mul returns the Point
Pt(p.x*a, p.y*a).  Div returns the Point Pt(p.x/a, p.y/a).

p)); rsubp returns the Rectangle Rpt(sub(r.min, p),
sub(r.max, p)).  Rmul returns the Rectangle
Rpt(mul(r.min,a), mul(r.max,a)); Rdiv returns the Rectangle
Rpt(div(r.min,a), div(r.max,a)).

Rshift returns the rectangle r with all coordinates either
left-shifted or right-shifted by a, depending on whether a
is positive or negative, respectively.

Inset returns the Rectangle Rect(r.min.x+n, r.min.y+n,
r.max.x-n, r.max.y-n).

Rcanon returns a rectangle with the same extent as r, canon-
icalized so that min.x <= max.x, and min.y <= max.y.

Eqpt compares its argument Points and returns 0 if unequal,
1 if equal.  Eqrect does the same for its argument Rectan-
gles.

Ptinrect returns 1 if p is a point within r, and 0 other-
wise.

Rectinrect returns 1 if all the pixels in r are also in s,
and 0 otherwise.

RectXrect returns 1 if r and s share any point, and 0 other-
wise.

Rectclip clips in place the Rectangle pointed to by rp so
that it is completely contained within b. The return value
is 1 if any part of *rp is within b. Otherwise, the return
value is 0 and *rp is unchanged.

The functions Dx and Dy give the width (Δx) and height (Δy)
of a Rectangle.  They are implemented as macros.