harvey/sys/src/libdraw/arith.c

#include <u.h>
#include <libc.h>
#include <draw.h>

Point
Pt(int x, int y)
{
	Point p;

	p.x = x;
	p.y = y;
	return p;
}

Rectangle
Rect(int x, int y, int bx, int by)
{
	Rectangle r;

	r.min.x = x;
	r.min.y = y;
	r.max.x = bx;
	r.max.y = by;
	return r;
}

Rectangle
Rpt(Point min, Point max)
{
	Rectangle r;

	r.min = min;
	r.max = max;
	return r;
}

Point
addpt(Point a, Point b)
{
	a.x += b.x;
	a.y += b.y;
	return a;
}

Point
subpt(Point a, Point b)
{
	a.x -= b.x;
	a.y -= b.y;
	return a;
}

Rectangle
insetrect(Rectangle r, int n)
{
	r.min.x += n;
	r.min.y += n;
	r.max.x -= n;
	r.max.y -= n;
	return r;
}

Point
divpt(Point a, int b)
{
	a.x /= b;
	a.y /= b;
	return a;
}

Point
mulpt(Point a, int b)
{
	a.x *= b;
	a.y *= b;
	return a;
}

Rectangle
rectsubpt(Rectangle r, Point p)
{
	r.min.x -= p.x;
	r.min.y -= p.y;
	r.max.x -= p.x;
	r.max.y -= p.y;
	return r;
}

Rectangle
rectaddpt(Rectangle r, Point p)
{
	r.min.x += p.x;
	r.min.y += p.y;
	r.max.x += p.x;
	r.max.y += p.y;
	return r;
}

int
eqpt(Point p, Point q)
{
	return p.x==q.x && p.y==q.y;
}

int
eqrect(Rectangle r, Rectangle s)
{
	return r.min.x==s.min.x && r.max.x==s.max.x &&
	       r.min.y==s.min.y && r.max.y==s.max.y;
}

int
rectXrect(Rectangle r, Rectangle s)
{
	return r.min.x<s.max.x && s.min.x<r.max.x &&
	       r.min.y<s.max.y && s.min.y<r.max.y;
}

int
rectinrect(Rectangle r, Rectangle s)
{
	return s.min.x<=r.min.x && r.max.x<=s.max.x && s.min.y<=r.min.y && r.max.y<=s.max.y;
}

int
ptinrect(Point p, Rectangle r)
{
	return p.x>=r.min.x && p.x<r.max.x &&
	       p.y>=r.min.y && p.y<r.max.y;
}

Rectangle
canonrect(Rectangle r)
{
	int t;
	if (r.max.x < r.min.x) {
		t = r.min.x;
		r.min.x = r.max.x;
		r.max.x = t;
	}
	if (r.max.y < r.min.y) {
		t = r.min.y;
		r.min.y = r.max.y;
		r.max.y = t;
	}
	return r;
}

void
combinerect(Rectangle *r1, Rectangle r2)
{
	if(r1->min.x > r2.min.x)
		r1->min.x = r2.min.x;
	if(r1->min.y > r2.min.y)
		r1->min.y = r2.min.y;
	if(r1->max.x < r2.max.x)
		r1->max.x = r2.max.x;
	if(r1->max.y < r2.max.y)
		r1->max.y = r2.max.y;
}

extern ulong
drawld2chan[] = {
	GREY1,
	GREY2,
	GREY4,
	CMAP8,
};

int log2[] = { -1, 0, 1, -1, 2, -1, -1, -1, 3, -1, -1, -1, -1, -1, -1, -1, 4, -1, -1, -1, -1, -1, -1, -1, 4 /* BUG */, -1, -1, -1, -1, -1, -1, -1, 5 };

ulong
setalpha(ulong color, uchar alpha)
{
	int red, green, blue;

	red = (color >> 3*8) & 0xFF;
	green = (color >> 2*8) & 0xFF;
	blue = (color >> 1*8) & 0xFF;
	/* ignore incoming alpha */
	red = (red * alpha)/255;
	green = (green * alpha)/255;
	blue = (blue * alpha)/255;
	return (red<<3*8) | (green<<2*8) | (blue<<1*8) | (alpha<<0*8);
}

Point	ZP;
Rectangle ZR;