.TH ADDPT 2
.SH NAME
addpt, subpt, mulpt, divpt, rectaddpt, rectsubpt, insetrect, canonrect, eqpt, eqrect, ptinrect, rectinrect, rectXrect, rectclip, combinerect, Dx, Dy, Pt, Rect, Rpt \- arithmetic on points and rectangles
.SH SYNOPSIS
.B #include <u.h>
.br
.B #include <libc.h>
.br
.B #include <draw.h>
.PP
.B
Point	addpt(Point p, Point q)
.PP
.B
Point	subpt(Point p, Point q)
.PP
.B
Point	mulpt(Point p, int a)
.PP
.B
Point	divpt(Point p, int a)
.PP
.B
Rectangle	rectaddpt(Rectangle r, Point p)
.PP
.B
Rectangle	rectsubpt(Rectangle r, Point p)
.PP
.B
Rectangle	insetrect(Rectangle r, int n)
.PP
.B
Rectangle	canonrect(Rectangle r)
.PP
.B
int		eqpt(Point p, Point q)
.PP
.B
int		eqrect(Rectangle r, Rectangle s)
.PP
.B
int		ptinrect(Point p, Rectangle r)
.PP
.B
int		rectinrect(Rectangle r, Rectangle s)
.PP
.B
int		rectXrect(Rectangle r, Rectangle s)
.PP
.B
int		rectclip(Rectangle *rp, Rectangle b)
.PP
.B
void		combinerect(Rectangle *rp, Rectangle b)
.PP
.B
int		Dx(Rectangle r)
.PP
.B
int		Dy(Rectangle r)
.PP
.B
Point	Pt(int x, int y)
.PP
.B
Rectangle	Rect(int x0, int y0, int x1, int y1)
.PP
.B
Rectangle	Rpt(Point p, Point q)
.SH DESCRIPTION
The functions
.IR Pt ,
.I Rect
and
.I Rpt
construct geometrical data types from their components.
.PP
.I Addpt
returns the Point
sum of its arguments:
.BI Pt( p .x+ q .x,
.IB p .y+ q .y) \f1.
.I Subpt
returns the Point
difference of its arguments:
.BI Pt( p .x- q .x,
.IB p .y- q .y) \f1.
.I Mulpt
returns the Point
.BI Pt( p .x* a ,
.IB p .y* a ) \f1.
.I Divpt
returns the Point
.BI Pt( p .x/ a ,
.IB p .y/ a ) \f1.
.PP
.I Rectaddpt
returns the Rectangle
.BI Rect(add( r .min,
.IB p ) \f1,
.BI add( r .max,
.IB p )) \f1;
.I rectsubpt
returns the Rectangle
.BI Rpt(sub( r .min,
.IB p ),
.BI sub( r .max,
.IB p ))\fR.
.PP
.I Insetrect
returns the Rectangle
.BI Rect( r .min.x+ n \f1,
.IB r .min.y+ n \f1,
.IB r .max.x- n \f1,
.IB r .max.y- n ) \f1.
.PP
.I Canonrect
returns a rectangle with the same extent as
.IR r ,
canonicalized so that
.B min.x
≤
.BR max.x ,
and
.B min.y
≤
.BR max.y .
.PP
.I Eqpt
compares its argument Points and returns
0 if unequal,
1 if equal.
.I Eqrect
does the same for its argument Rectangles.
.PP
.I Ptinrect
returns 1 if
.I p
is a point within
.IR r ,
and 0 otherwise.
.PP
.I Rectinrect
returns 1 if all the pixels in
.I r
are also in
.IR s ,
and 0 otherwise.
.PP
.I RectXrect
returns 1 if
.I r
and
.I s
share any point, and 0 otherwise.
.PP
.I Rectclip
clips in place
the Rectangle pointed to by
.I rp
so that it is completely contained within
.IR b .
The return value is 1 if any part of
.RI * rp
is within
.IR b .
Otherwise, the return value is 0 and
.RI * rp
is unchanged.
.PP
.I Combinerect
overwrites
.B *rp
with the smallest rectangle sufficient to cover all the pixels of
.B *rp
and
.BR b .
.PP
The functions
.I Dx
and
.I Dy
give the width (Δx) and height (Δy) of a Rectangle.
They are implemented as macros.
.SH SOURCE
.B /sys/src/libdraw
.SH SEE ALSO
.IR graphics (2)