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

enum
{
        Arrow1 = 8,
        Arrow2 = 10,
        Arrow3 = 3,
};

static
int
lmin(int a, int b)
{
        if(a < b)
                return a;
        return b;
}

static
int
lmax(int a, int b)
{
        if(a > b)
                return a;
        return b;
}

#ifdef NOTUSED
/*
 * Rather than line clip, we run the Bresenham loop over the full line,
 * and clip on each pixel.  This is more expensive but means that
 * lines look the same regardless of how the windowing has tiled them.
 * For speed, we check for clipping outside the loop and make the
 * test easy when possible.
 */

static
void
horline1(Memimage *dst, Point p0, Point p1, int srcval, Rectangle clipr)
{
        int x, y, dy, deltay, deltax, maxx;
        int dd, easy, e, bpp, m, m0;
        uchar *d;

        deltax = p1.x - p0.x;
        deltay = p1.y - p0.y;
        dd = dst->width*sizeof(ulong);
        dy = 1;
        if(deltay < 0){
                dd = -dd;
                deltay = -deltay;
                dy = -1;
        }
        maxx = lmin(p1.x, clipr.max.x-1);
        bpp = dst->depth;
        m0 = 0xFF^(0xFF>>bpp);
        m = m0 >> (p0.x&(7/dst->depth))*bpp;
        easy = ptinrect(p0, clipr) && ptinrect(p1, clipr);
        e = 2*deltay - deltax;
        y = p0.y;
        d = byteaddr(dst, p0);
        deltay *= 2;
        deltax = deltay - 2*deltax;
        for(x=p0.x; x<=maxx; x++){
                if(easy || (clipr.min.x<=x && clipr.min.y<=y && y<clipr.max.y))
                        *d ^= (*d^srcval) & m;
                if(e > 0){
                        y += dy;
                        d += dd;
                        e += deltax;
                }else
                        e += deltay;
                d++;
                m >>= bpp;
                if(m == 0)
                        m = m0;
        }
}

static
void
verline1(Memimage *dst, Point p0, Point p1, int srcval, Rectangle clipr)
{
        int x, y, deltay, deltax, maxy;
        int easy, e, bpp, m, m0, dd;
        uchar *d;

        deltax = p1.x - p0.x;
        deltay = p1.y - p0.y;
        dd = 1;
        if(deltax < 0){
                dd = -1;
                deltax = -deltax;
        }
        maxy = lmin(p1.y, clipr.max.y-1);
        bpp = dst->depth;
        m0 = 0xFF^(0xFF>>bpp);
        m = m0 >> (p0.x&(7/dst->depth))*bpp;
        easy = ptinrect(p0, clipr) && ptinrect(p1, clipr);
        e = 2*deltax - deltay;
        x = p0.x;
        d = byteaddr(dst, p0);
        deltax *= 2;
        deltay = deltax - 2*deltay;
        for(y=p0.y; y<=maxy; y++){
                if(easy || (clipr.min.y<=y && clipr.min.x<=x && x<clipr.max.x))
                        *d ^= (*d^srcval) & m;
                if(e > 0){
                        x += dd;
                        d += dd;
                        e += deltay;
                }else
                        e += deltax;
                d += dst->width*sizeof(ulong);
                m >>= bpp;
                if(m == 0)
                        m = m0;
        }
}

static
void
horliner(Memimage *dst, Point p0, Point p1, Memimage *src, Point dsrc, Rectangle clipr)
{
        int x, y, sx, sy, deltay, deltax, minx, maxx;
        int bpp, m, m0;
        uchar *d, *s;

        deltax = p1.x - p0.x;
        deltay = p1.y - p0.y;
        sx = drawreplxy(src->r.min.x, src->r.max.x, p0.x+dsrc.x);
        minx = lmax(p0.x, clipr.min.x);
        maxx = lmin(p1.x, clipr.max.x-1);
        bpp = dst->depth;
        m0 = 0xFF^(0xFF>>bpp);
        m = m0 >> (minx&(7/dst->depth))*bpp;
        for(x=minx; x<=maxx; x++){
                y = p0.y + (deltay*(x-p0.x)+deltax/2)/deltax;
                if(clipr.min.y<=y && y<clipr.max.y){
                        d = byteaddr(dst, Pt(x, y));
                        sy = drawreplxy(src->r.min.y, src->r.max.y, y+dsrc.y);
                        s = byteaddr(src, Pt(sx, sy));
                        *d ^= (*d^*s) & m;
                }
                if(++sx >= src->r.max.x)
                        sx = src->r.min.x;
                m >>= bpp;
                if(m == 0)
                        m = m0;
        }
}

static
void
verliner(Memimage *dst, Point p0, Point p1, Memimage *src, Point dsrc, Rectangle clipr)
{
        int x, y, sx, sy, deltay, deltax, miny, maxy;
        int bpp, m, m0;
        uchar *d, *s;

        deltax = p1.x - p0.x;
        deltay = p1.y - p0.y;
        sy = drawreplxy(src->r.min.y, src->r.max.y, p0.y+dsrc.y);
        miny = lmax(p0.y, clipr.min.y);
        maxy = lmin(p1.y, clipr.max.y-1);
        bpp = dst->depth;
        m0 = 0xFF^(0xFF>>bpp);
        for(y=miny; y<=maxy; y++){
                if(deltay == 0) /* degenerate line */
                        x = p0.x;
                else
                        x = p0.x + (deltax*(y-p0.y)+deltay/2)/deltay;
                if(clipr.min.x<=x && x<clipr.max.x){
                        m = m0 >> (x&(7/dst->depth))*bpp;
                        d = byteaddr(dst, Pt(x, y));
                        sx = drawreplxy(src->r.min.x, src->r.max.x, x+dsrc.x);
                        s = byteaddr(src, Pt(sx, sy));
                        *d ^= (*d^*s) & m;
                }
                if(++sy >= src->r.max.y)
                        sy = src->r.min.y;
        }
}

static
void
horline(Memimage *dst, Point p0, Point p1, Memimage *src, Point dsrc, Rectangle clipr)
{
        int x, y, deltay, deltax, minx, maxx;
        int bpp, m, m0;
        uchar *d, *s;

        deltax = p1.x - p0.x;
        deltay = p1.y - p0.y;
        minx = lmax(p0.x, clipr.min.x);
        maxx = lmin(p1.x, clipr.max.x-1);
        bpp = dst->depth;
        m0 = 0xFF^(0xFF>>bpp);
        m = m0 >> (minx&(7/dst->depth))*bpp;
        for(x=minx; x<=maxx; x++){
                y = p0.y + (deltay*(x-p0.x)+deltay/2)/deltax;
                if(clipr.min.y<=y && y<clipr.max.y){
                        d = byteaddr(dst, Pt(x, y));
                        s = byteaddr(src, addpt(dsrc, Pt(x, y)));
                        *d ^= (*d^*s) & m;
                }
                m >>= bpp;
                if(m == 0)
                        m = m0;
        }
}

static
void
verline(Memimage *dst, Point p0, Point p1, Memimage *src, Point dsrc, Rectangle clipr)
{
        int x, y, deltay, deltax, miny, maxy;
        int bpp, m, m0;
        uchar *d, *s;

        deltax = p1.x - p0.x;
        deltay = p1.y - p0.y;
        miny = lmax(p0.y, clipr.min.y);
        maxy = lmin(p1.y, clipr.max.y-1);
        bpp = dst->depth;
        m0 = 0xFF^(0xFF>>bpp);
        for(y=miny; y<=maxy; y++){
                if(deltay == 0) /* degenerate line */
                        x = p0.x;
                else
                        x = p0.x + deltax*(y-p0.y)/deltay;
                if(clipr.min.x<=x && x<clipr.max.x){
                        m = m0 >> (x&(7/dst->depth))*bpp;
                        d = byteaddr(dst, Pt(x, y));
                        s = byteaddr(src, addpt(dsrc, Pt(x, y)));
                        *d ^= (*d^*s) & m;
                }
        }
}
#endif /* NOTUSED */

static Memimage*
membrush(int radius)
{
        static Memimage *brush;
        static int brushradius;

        if(brush==nil || brushradius!=radius){
                freememimage(brush);
                brush = allocmemimage(Rect(0, 0, 2*radius+1, 2*radius+1), memopaque->chan);
                if(brush != nil){
                        memfillcolor(brush, DTransparent);      /* zeros */
                        memellipse(brush, Pt(radius, radius), radius, radius, -1, memopaque, Pt(radius, radius), S);
                }
                brushradius = radius;
        }
        return brush;
}

static
void
discend(Point p, int radius, Memimage *dst, Memimage *src, Point dsrc, int op)
{
        Memimage *disc;
        Rectangle r;

        disc = membrush(radius);
        if(disc != nil){
                r.min.x = p.x - radius;
                r.min.y = p.y - radius;
                r.max.x = p.x + radius+1;
                r.max.y = p.y + radius+1;
                memdraw(dst, r, src, addpt(r.min, dsrc), disc, Pt(0,0), op);
        }
}

static
void
arrowend(Point tip, Point *pp, int end, int sin, int cos, int radius)
{
        int x1, x2, x3;

        /* before rotation */
        if(end == Endarrow){
                x1 = Arrow1;
                x2 = Arrow2;
                x3 = Arrow3;
        }else{
                x1 = (end>>5) & 0x1FF;  /* distance along line from end of line to tip */
                x2 = (end>>14) & 0x1FF; /* distance along line from barb to tip */
                x3 = (end>>23) & 0x1FF; /* distance perpendicular from edge of line to barb */
        }

        /* comments follow track of right-facing arrowhead */
        pp->x = tip.x+((2*radius+1)*sin/2-x1*cos);              /* upper side of shaft */
        pp->y = tip.y-((2*radius+1)*cos/2+x1*sin);
        pp++;
        pp->x = tip.x+((2*radius+2*x3+1)*sin/2-x2*cos);         /* upper barb */
        pp->y = tip.y-((2*radius+2*x3+1)*cos/2+x2*sin);
        pp++;
        pp->x = tip.x;
        pp->y = tip.y;
        pp++;
        pp->x = tip.x+(-(2*radius+2*x3+1)*sin/2-x2*cos);        /* lower barb */
        pp->y = tip.y-(-(2*radius+2*x3+1)*cos/2+x2*sin);
        pp++;
        pp->x = tip.x+(-(2*radius+1)*sin/2-x1*cos);             /* lower side of shaft */
        pp->y = tip.y+((2*radius+1)*cos/2-x1*sin);
}

void
_memimageline(Memimage *dst, Point p0, Point p1, int end0, int end1, int radius, Memimage *src, Point sp, Rectangle clipr, int op)
{
        /*
         * BUG: We should really really pick off purely horizontal and purely
         * vertical lines and handle them separately with calls to memimagedraw
         * on rectangles.
         */

        int hor;
        int sin, cos, dx, dy, t;
        Rectangle oclipr, r;
        Point q, pts[10], *pp, d;

        if(radius < 0)
                return;
        if(rectclip(&clipr, dst->r) == 0)
                return;
        if(rectclip(&clipr, dst->clipr) == 0)
                return;
        d = subpt(sp, p0);
        if(rectclip(&clipr, rectsubpt(src->clipr, d)) == 0)
                return;
        if((src->flags&Frepl)==0 && rectclip(&clipr, rectsubpt(src->r, d))==0)
                return;
        /* this means that only verline() handles degenerate lines (p0==p1) */
        hor = (abs(p1.x-p0.x) > abs(p1.y-p0.y));
        /*
         * Clipping is a little peculiar.  We can't use Sutherland-Cohen
         * clipping because lines are wide.  But this is probably just fine:
         * we do all math with the original p0 and p1, but clip when deciding
         * what pixels to draw.  This means the layer code can call this routine,
         * using clipr to define the region being written, and get the same set
         * of pixels regardless of the dicing.
         */
        if((hor && p0.x>p1.x) || (!hor && p0.y>p1.y)){
                q = p0;
                p0 = p1;
                p1 = q;
                t = end0;
                end0 = end1;
                end1 = t;
        }

        if((p0.x == p1.x || p0.y == p1.y) && (end0&0x1F) == Endsquare && (end1&0x1F) == Endsquare){
                r.min = p0;
                r.max = p1;
                if(p0.x == p1.x){
                        r.min.x -= radius;
                        r.max.x += radius+1;
                }
                else{
                        r.min.y -= radius;
                        r.max.y += radius+1;
                }
                oclipr = dst->clipr;
                sp = addpt(r.min, d);
                dst->clipr = clipr;
                memimagedraw(dst, r, src, sp, memopaque, sp, op);
                dst->clipr = oclipr;
                return;
        }

/*    Hard: */
        /* draw thick line using polygon fill */
        icossin2(p1.x-p0.x, p1.y-p0.y, &cos, &sin);
        dx = (sin*(2*radius+1))/2;
        dy = (cos*(2*radius+1))/2;
        pp = pts;
        oclipr = dst->clipr;
        dst->clipr = clipr;
        q.x = ICOSSCALE*p0.x+ICOSSCALE/2-cos/2;
        q.y = ICOSSCALE*p0.y+ICOSSCALE/2-sin/2;
        switch(end0 & 0x1F){
        case Enddisc:
                discend(p0, radius, dst, src, d, op);
                /* fall through */
        case Endsquare:
        default:
                pp->x = q.x-dx;
                pp->y = q.y+dy;
                pp++;
                pp->x = q.x+dx;
                pp->y = q.y-dy;
                pp++;
                break;
        case Endarrow:
                arrowend(q, pp, end0, -sin, -cos, radius);
                _memfillpolysc(dst, pts, 5, ~0, src, addpt(pts[0], mulpt(d, ICOSSCALE)), 1, 10, 1, op);
                pp[1] = pp[4];
                pp += 2;
        }
        q.x = ICOSSCALE*p1.x+ICOSSCALE/2+cos/2;
        q.y = ICOSSCALE*p1.y+ICOSSCALE/2+sin/2;
        switch(end1 & 0x1F){
        case Enddisc:
                discend(p1, radius, dst, src, d, op);
                /* fall through */
        case Endsquare:
        default:
                pp->x = q.x+dx;
                pp->y = q.y-dy;
                pp++;
                pp->x = q.x-dx;
                pp->y = q.y+dy;
                pp++;
                break;
        case Endarrow:
                arrowend(q, pp, end1, sin, cos, radius);
                _memfillpolysc(dst, pp, 5, ~0, src, addpt(pp[0], mulpt(d, ICOSSCALE)), 1, 10, 1, op);
                pp[1] = pp[4];
                pp += 2;
        }
        _memfillpolysc(dst, pts, pp-pts, ~0, src, addpt(pts[0], mulpt(d, ICOSSCALE)), 0, 10, 1, op);
        dst->clipr = oclipr;
        return;
}

void
memimageline(Memimage *dst, Point p0, Point p1, int end0, int end1, int radius, Memimage *src, Point sp, int op)
{
        _memimageline(dst, p0, p1, end0, end1, radius, src, sp, dst->clipr, op);
}

/*
 * Simple-minded conservative code to compute bounding box of line.
 * Result is probably a little larger than it needs to be.
 */
static
void
addbbox(Rectangle *r, Point p)
{
        if(r->min.x > p.x)
                r->min.x = p.x;
        if(r->min.y > p.y)
                r->min.y = p.y;
        if(r->max.x < p.x+1)
                r->max.x = p.x+1;
        if(r->max.y < p.y+1)
                r->max.y = p.y+1;
}

int
memlineendsize(int end)
{
        int x3;

        if((end&0x3F) != Endarrow)
                return 0;
        if(end == Endarrow)
                x3 = Arrow3;
        else
                x3 = (end>>23) & 0x1FF;
        return x3;
}

Rectangle
memlinebbox(Point p0, Point p1, int end0, int end1, int radius)
{
        Rectangle r, r1;
        int extra;

        r.min.x = 10000000;
        r.min.y = 10000000;
        r.max.x = -10000000;
        r.max.y = -10000000;
        extra = lmax(memlineendsize(end0), memlineendsize(end1));
        r1 = insetrect(canonrect(Rpt(p0, p1)), -(radius+extra));
        addbbox(&r, r1.min);
        addbbox(&r, r1.max);
        return r;
}