svgpic: new program to convert pic to svg
This is an experiment. Like tpic it's a copy-and-paste fork of pic. Change-Id: Ia22772bd5881c7904a6d8f8e0b46fde8cea89cbd Reviewed-on: https://plan9port-review.googlesource.com/2920 Reviewed-by: Russ Cox <rsc@swtch.com>
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Russ Cox
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src/cmd/svgpic/arcgen.c
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224
src/cmd/svgpic/arcgen.c
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#include <stdio.h>
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#include <math.h>
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#include "pic.h"
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#include "y.tab.h"
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void arc_extreme(double, double, double, double, double, double);
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int quadrant(double x, double y);
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obj *arcgen(int type) /* handles circular and (eventually) elliptical arcs */
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{
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static double prevw = HT10;
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static double prevh = HT5;
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static double prevrad = HT2;
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static int dtox[2][4] ={ { 1, -1, -1, 1}, {1, 1, -1, -1} };
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static int dtoy[2][4] ={ {1, 1, -1, -1}, {-1, 1, 1, -1} };
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static int dctrx[2][4] ={ {0, -1, 0, 1}, {0, 1, 0, -1} };
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static int dctry[2][4] ={ {1, 0, -1, 0}, {-1, 0, 1, 0} };
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static int nexthv[2][4] ={ {U_DIR, L_DIR, D_DIR, R_DIR}, {D_DIR, R_DIR, U_DIR, L_DIR} };
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double dx2, dy2, ht, phi, r, d;
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int i, head, to, at, cw, invis, ddtype, battr;
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obj *p, *ppos;
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double fromx, fromy, tox, toy, fillval = 0;
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Attr *ap;
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tox=toy=0.0; /* Botch? (gcc) */
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prevrad = getfval("arcrad");
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prevh = getfval("arrowht");
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prevw = getfval("arrowwid");
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fromx = curx;
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fromy = cury;
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head = to = at = cw = invis = ddtype = battr = 0;
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for (i = 0; i < nattr; i++) {
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ap = &attr[i];
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switch (ap->a_type) {
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case TEXTATTR:
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savetext(ap->a_sub, ap->a_val.p);
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break;
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case HEAD:
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head += ap->a_val.i;
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break;
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case INVIS:
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invis = INVIS;
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break;
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case HEIGHT: /* length of arrowhead */
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prevh = ap->a_val.f;
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break;
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case WIDTH: /* width of arrowhead */
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prevw = ap->a_val.f;
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break;
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case RADIUS:
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prevrad = ap->a_val.f;
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break;
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case DIAMETER:
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prevrad = ap->a_val.f / 2;
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break;
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case CW:
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cw = 1;
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break;
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case FROM: /* start point of arc */
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ppos = ap->a_val.o;
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fromx = ppos->o_x;
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fromy = ppos->o_y;
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break;
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case TO: /* end point of arc */
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ppos = ap->a_val.o;
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tox = ppos->o_x;
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toy = ppos->o_y;
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to++;
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break;
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case AT: /* center of arc */
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ppos = ap->a_val.o;
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curx = ppos->o_x;
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cury = ppos->o_y;
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at = 1;
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break;
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case UP:
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hvmode = U_DIR;
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break;
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case DOWN:
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hvmode = D_DIR;
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break;
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case RIGHT:
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hvmode = R_DIR;
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break;
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case LEFT:
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hvmode = L_DIR;
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break;
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case FILL:
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battr |= FILLBIT;
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if (ap->a_sub == DEFAULT)
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fillval = getfval("fillval");
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else
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fillval = ap->a_val.f;
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break;
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}
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}
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if (!at && !to) { /* the defaults are mostly OK */
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curx = fromx + prevrad * dctrx[cw][hvmode];
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cury = fromy + prevrad * dctry[cw][hvmode];
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tox = fromx + prevrad * dtox[cw][hvmode];
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toy = fromy + prevrad * dtoy[cw][hvmode];
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hvmode = nexthv[cw][hvmode];
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}
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else if (!at) {
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dx2 = (tox - fromx) / 2;
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dy2 = (toy - fromy) / 2;
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phi = atan2(dy2, dx2) + (cw ? -PI/2 : PI/2);
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if (prevrad <= 0.0)
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prevrad = dx2*dx2+dy2*dy2;
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for (r=prevrad; (d = r*r - (dx2*dx2+dy2*dy2)) <= 0.0; r *= 2)
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; /* this kludge gets around too-small radii */
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prevrad = r;
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ht = sqrt(d);
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curx = fromx + dx2 + ht * cos(phi);
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cury = fromy + dy2 + ht * sin(phi);
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dprintf("dx2,dy2=%g,%g, phi=%g, r,ht=%g,%g\n",
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dx2, dy2, phi, r, ht);
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}
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else if (at && !to) { /* do we have all the cases??? */
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tox = fromx + prevrad * dtox[cw][hvmode];
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toy = fromy + prevrad * dtoy[cw][hvmode];
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hvmode = nexthv[cw][hvmode];
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}
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if (cw) { /* interchange roles of from-to and heads */
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double temp;
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temp = fromx; fromx = tox; tox = temp;
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temp = fromy; fromy = toy; toy = temp;
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if (head == HEAD1)
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head = HEAD2;
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else if (head == HEAD2)
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head = HEAD1;
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}
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p = makenode(type, 7);
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arc_extreme(fromx, fromy, tox, toy, curx, cury);
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p->o_val[0] = fromx;
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p->o_val[1] = fromy;
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p->o_val[2] = tox;
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p->o_val[3] = toy;
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if (cw) {
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curx = fromx;
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cury = fromy;
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} else {
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curx = tox;
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cury = toy;
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}
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p->o_val[4] = prevw;
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p->o_val[5] = prevh;
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p->o_val[6] = prevrad;
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p->o_attr = head | (cw ? CW_ARC : 0) | invis | ddtype | battr;
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p->o_fillval = fillval;
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if (head)
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p->o_nhead = getfval("arrowhead");
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dprintf("arc rad %g at %g %g from %g %g to %g %g head %g %g\n",
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prevrad, p->o_x, p->o_y,
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p->o_val[0], p->o_val[1], p->o_val[2], p->o_val[3], p->o_val[4], p->o_val[5]);
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return(p);
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}
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/***************************************************************************
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bounding box of a circular arc Eric Grosse 24 May 84
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Conceptually, this routine generates a list consisting of the start,
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end, and whichever north, east, south, and west points lie on the arc.
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The bounding box is then the range of this list.
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list = {start,end}
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j = quadrant(start)
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k = quadrant(end)
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if( j==k && long way 'round ) append north,west,south,east
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else
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while( j != k )
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append center+radius*[j-th of north,west,south,east unit vectors]
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j += 1 (mod 4)
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return( bounding box of list )
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The following code implements this, with simple optimizations.
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***********************************************************************/
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void arc_extreme(double x0, double y0, double x1, double y1, double xc, double yc)
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/* start, end, center */
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{
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/* assumes center isn't too far out */
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double r, xmin, ymin, xmax, ymax;
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int j, k;
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x0 -= xc; y0 -= yc; /* move to center */
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x1 -= xc; y1 -= yc;
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xmin = (x0<x1)?x0:x1; ymin = (y0<y1)?y0:y1;
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xmax = (x0>x1)?x0:x1; ymax = (y0>y1)?y0:y1;
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r = sqrt(x0*x0 + y0*y0);
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if (r > 0.0) {
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j = quadrant(x0,y0);
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k = quadrant(x1,y1);
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if (j == k && y1*x0 < x1*y0) {
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/* viewed as complex numbers, if Im(z1/z0)<0, arc is big */
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if( xmin > -r) xmin = -r; if( ymin > -r) ymin = -r;
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if( xmax < r) xmax = r; if( ymax < r) ymax = r;
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} else {
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while (j != k) {
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switch (j) {
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case 1: if( ymax < r) ymax = r; break; /* north */
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case 2: if( xmin > -r) xmin = -r; break; /* west */
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case 3: if( ymin > -r) ymin = -r; break; /* south */
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case 4: if( xmax < r) xmax = r; break; /* east */
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}
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j = j%4 + 1;
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}
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}
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}
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xmin += xc; ymin += yc;
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xmax += xc; ymax += yc;
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extreme(xmin, ymin);
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extreme(xmax, ymax);
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}
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int
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quadrant(double x, double y)
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{
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if ( x>=0.0 && y> 0.0) return(1);
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else if( x< 0.0 && y>=0.0) return(2);
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else if( x<=0.0 && y< 0.0) return(3);
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else if( x> 0.0 && y<=0.0) return(4);
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else return 0; /* shut up lint */
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}
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