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Annotation of researchv9/jerq/src/lib/pot/elarc.c, revision 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       <CC/jerq.h>
        !             9: #define HUGE 017777777777
        !            10: #define        sgn(x)  ((x)<0? -1 : (x)==0? 0 : 1)
        !            11: 
        !            12: #ifdef MUX
        !            13: #define        POINT   Ivoid(26)       /* really lpoint, but we're dealing with the cursor */
        !            14: #else
        !            15: extern void point();
        !            16: #define        POINT   point
        !            17: #endif
        !            18: 
        !            19: static struct dist {
        !            20:        Point s;
        !            21:        Point m;
        !            22:        long e;
        !            23: } d1, d2;
        !            24: 
        !            25: static void
        !            26: test(Point x, register struct dist *p)
        !            27: {
        !            28:        register long dx = x.x - p->s.x;
        !            29:        register long dy = x.y - p->s.y;
        !            30:        register long e = dx*dx+dy*dy;
        !            31: 
        !            32:        if(e <= p->e) {
        !            33:                p->m = x;
        !            34:                p->e = e;
        !            35:        }
        !            36: }
        !            37: 
        !            38: static void
        !            39: survey(Bitmap *, Point x, Code)
        !            40: {
        !            41:        test(x, &d1);
        !            42:        test(x, &d2);
        !            43: }
        !            44: 
        !            45: static long emask, enext;
        !            46: 
        !            47: static void
        !            48: paint(Bitmap *bp, Point x, Code f)
        !            49: {
        !            50:        if(enext&emask) POINT(bp, x, f);
        !            51:        enext <<= 1;
        !            52:        if(enext == 0) enext = 1;
        !            53: }
        !            54: 
        !            55: /*
        !            56:  * elarc(bp,p0,a,b,p1,p2,f) draws in bitmap bp an arc of the ellipse
        !            57:  * centered at p0 with half-axes a,b extending counterclockwise
        !            58:  * from a point near p1 to a point near p2
        !            59:  * args reversed because ellip1 draws clockwise 
        !            60:  */
        !            61: extern void
        !            62: elarc(Bitmap *bp, Point p0, int a, int b, Point p1, Point p2, Code f, long mask)
        !            63: {
        !            64:        short inhibited;
        !            65: 
        !            66:        emask = mask;
        !            67:        enext = 1;
        !            68:        inhibited=0;
        !            69:        if(f!=F_XOR){
        !            70:                Jcursinhibit();
        !            71:                inhibited=1;
        !            72:        }
        !            73:        if(a==0)
        !            74:                lsegment(bp, Pt(p0.x, p1.y), Pt(p0.x, p2.y), f);
        !            75:        else if(b==0)
        !            76:                lsegment(bp, Pt(p1.x, p0.y), Pt(p2.x, p0.y), f);
        !            77:        else {
        !            78:                int sx1;
        !            79:                int sy1;
        !            80:                int sx2;
        !            81:                int sy2;
        !            82: 
        !            83:                d1.s = sub(p1, p0);
        !            84:                d2.s = sub(p2, p0);
        !            85:                sx1 = sgn(d1.s.x);
        !            86:                sy1 = sgn(d1.s.y);
        !            87:                sx2 = sgn(d2.s.x);
        !            88:                sy2 = sgn(d2.s.y);
        !            89:                d1.s.x *= sx1;
        !            90:                d1.s.y *= sy1;
        !            91:                d2.s.x *= sx2;
        !            92:                d2.s.y *= sy2;
        !            93:                d1.e = d2.e = HUGE;
        !            94:                survey(bp, Pt(0, b), f);
        !            95:                ellip1(bp, Pt(0, 0), a, b, survey, Pt(0,b), Pt(a, 0), f);
        !            96:                if(d1.m != d2.m)
        !            97:                        paint(bp, d1.m, f);
        !            98:                ellip1(bp, p0, a, b, paint,
        !            99:                        Pt(d1.m.x*sx1, d1.m.y*sy1), Pt(d2.m.x*sx2, d2.m.y*sy2), f);
        !           100:        }
        !           101:        if(inhibited)
        !           102:                Jcursallow();
        !           103: }

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