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Annotation of researchv9/jerq/src/lib/mj/elarc.c, revision 1.1.1.1

1.1       root        1: #ifndef        MUX
                      2: #define        Jcursinhibit()  cursinhibit()
                      3: #define        Jcursallow()    cursallow()
                      4: #define        lrectf(l, r, f) rectf(l, r, f)
                      5: #define        lsegment(l, p, q, f)    segment(l, p, q, f)
                      6: #endif
                      7: 
                      8: #include       <jerq.h>
                      9: #define        DB              ((Word *)0x700000)
                     10: #define        ONSCREEN(b)     (b->base>=DB && b->base<DB+XMAX/WORDSIZE*YMAX)
                     11: #define HUGE 017777777777
                     12: #define        sgn(x)  ((x)<0? -1 : (x)==0? 0 : 1)
                     13: 
                     14: #ifdef MUX
                     15: #define        POINT   Tvoid(26)       /* really lpoint, but we're dealing with the cursor */
                     16: #else
                     17: extern void point();
                     18: #define        POINT   point
                     19: #endif
                     20: 
                     21: static struct dist {
                     22:        Point s;
                     23:        Point m;
                     24:        long e;
                     25: } d1, d2;
                     26: 
                     27: static void
                     28: test(x, p)
                     29:        Point x;
                     30:        register struct dist *p;
                     31: {
                     32:        register long dx = x.x - p->s.x;
                     33:        register long dy = x.y - p->s.y;
                     34:        register long e = dx*dx+dy*dy;
                     35: 
                     36:        if(e <= p->e) {
                     37:                p->m = x;
                     38:                p->e = e;
                     39:        }
                     40: }
                     41: 
                     42: static void
                     43: survey(bp, x, f)
                     44:        Bitmap *bp;
                     45:        Point x;
                     46:        Code f;
                     47: {
                     48:        test(x, &d1);
                     49:        test(x, &d2);
                     50: }
                     51: /*
                     52:  * elarc(bp,p0,a,b,p1,p2,f) draws in bitmap bp an arc of the ellipse
                     53:  * centered at p0 with half-axes a,b extending counterclockwise
                     54:  * from a point near p1 to a point near p2
                     55:  * args reversed because ellip1 draws clockwise 
                     56:  */
                     57: elarc(bp,p0,a,b,p1,p2,f)
                     58:        Bitmap *bp;
                     59:        Point p0, p1, p2;
                     60:        Code f;
                     61: {
                     62:        short inhibited;
                     63:        inhibited=0;
                     64:        if(f!=F_XOR && ONSCREEN(bp)){
                     65:                Jcursinhibit();
                     66:                inhibited=1;
                     67:        }
                     68:        if(a==0)
                     69:                lsegment(bp, Pt(p0.x, p1.y), Pt(p0.x, p2.y), f);
                     70:        else if(b==0)
                     71:                lsegment(bp, Pt(p1.x, p0.y), Pt(p2.x, p0.y), f);
                     72:        else {
                     73:                int sx1;
                     74:                int sy1;
                     75:                int sx2;
                     76:                int sy2;
                     77: 
                     78:                d1.s = sub(p1, p0);
                     79:                d2.s = sub(p2, p0);
                     80:                sx1 = sgn(d1.s.x);
                     81:                sy1 = sgn(d1.s.y);
                     82:                sx2 = sgn(d2.s.x);
                     83:                sy2 = sgn(d2.s.y);
                     84:                d1.s.x *= sx1;
                     85:                d1.s.y *= sy1;
                     86:                d2.s.x *= sx2;
                     87:                d2.s.y *= sy2;
                     88:                d1.e = d2.e = HUGE;
                     89:                survey(bp, Pt(0, b), f);
                     90:                ellip1(bp, Pt(0, 0), a, b, survey, Pt(0,b), Pt(a, 0), f);
                     91:                if(!eqpt(d1.m, d2.m))
                     92:                        POINT(bp, d1.m, f);
                     93:                ellip1(bp, p0, a, b, POINT,
                     94:                        Pt(d1.m.x*sx1, d1.m.y*sy1), Pt(d2.m.x*sx2, d2.m.y*sy2), f);
                     95:        }
                     96:        if(inhibited)
                     97:                Jcursallow();
                     98: }

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