V8/usr/man/man9/add.9

.TH ADD 9.3
.SH NAME
add, sub, mul, div, eqpt, eqrect, inset, muldiv, ptinrect, raddp, rsubp, rectXrect, rectclip \- arithmetic on points and rectangles
.SH SYNOPSIS
.B #include <jerq.h>
.PP
.B Point add(p, q)
.B Point p, q;
.PP
.B Point sub(p, q)
.B  Point p, q;
.PP
.B Point mul(p, a)
.B  Point p; int a;
.PP
.B Point div(p, a)
.B  Point p; int a;
.PP
.B int eqpt(p, q)
.B  Point p, q;
.PP
.B int eqrect(r, s)
.B  Rectangle r, s;
.PP
.B Rectangle inset(r, n)
.B  Rectangle r; int n;
.PP
.B int muldiv(a, b, c)
.B  int a, b, c;
.PP
.B int ptinrect(p, r)
.B  Point p; Rectangle r;
.PP
.B Rectangle raddp(r, p)
.B  Rectangle r; Point p;
.PP
.B Rectangle rsubp(r, p)
.B  Rectangle r; Point p;
.PP
.B int rectXrect(r, s)
.B  Rectangle r, s;
.PP
.B int rectclip(rp, s)
.B Rectangle *rp, s;
.SH DESCRIPTION
.I Add
returns the Point sum of its arguments:
.RI ( p.x + q.x ,
.IR p.y + q.y ).
.I Sub
returns the Point difference of its arguments:
.RI ( p.x \- q.x ,
.IR p.y \- q.y ).
.I Mul
returns the Point
.RI ( p.x * a ,
.IR p.y * a ).
.I Div
returns the Point
.RI ( p.x / a ,
.IR p.y / a ).
.PP
.I Eqpt
and
.I eqrect
return the equality of their arguments:
0
if unequal,
1
if equal.
Two
Points
or
Rectangles
are equal if their corresponding coordinates are equal.
.PP
.I Inset
returns the Rectangle
.RI ( r.origin.x+n ,
.IR r.origin.y+n ,
.IR r.corner.x\-n ,
.IR r.corner.y\-n ).
The following code creates a clear rectangle
.I r
with a 2-dot wide border
.ul
inside
.IR r :
.nf
.IP
rectf(&display, r, F_OR);
rectf(&display, inset(r, 2), F_CLR);
.fi
.PP
.I Muldiv
is a macro that returns the 16-bit result
.RI ( a*b ) / c ,
with
.RI ( a*b )
calculated to 32 bits, so
no precision is lost.
.I Muldiv
is convenient for calculating transformations.
.PP
.I Ptinrect
returns 1 if
.I p
is a point within
.IR r ,
and 0 otherwise.
.PP
.I Raddp
returns the Rectangle
.RI ( add ( r.origin ,
.IR p ),
.IR add ( r.corner ,
.IR p ));
.I rsubp
returns the Rectangle
.RI ( sub ( r.origin ,
.IR p ),
.IR sub ( r.corner ,
.IR p )).
.PP
.I RectXrect
returns 1 if
.I r
and
.I s
share any point; 0 otherwise.
.PP
.I Rectclip
clips in place
the Rectangle pointed to by
.I rp
so that it is completely contained within
.IR s .
The return value is 1 if any part of
.RI * rp
is within
.IR s .
Otherwise, the return value is 0 and
.RI * rp
is unchanged.
.SH SEE ALSO
types(9.5)