lib/drawer.c

   1 /*  drawer.c
   2     part of swftools
   3
   4     A generic structure for providing vector drawing.
   5     (Helper routines, spline approximation, simple text drawers)
   6
   7     Copyright (C) 2003 Matthias Kramm <kramm@quiss.org>
   8
   9     This program is free software; you can redistribute it and/or modify
  10     it under the terms of the GNU General Public License as published by
  11     the Free Software Foundation; either version 2 of the License, or
  12     (at your option) any later version.
  13
  14     This program is distributed in the hope that it will be useful,
  15     but WITHOUT ANY WARRANTY; without even the implied warranty of
  16     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17     GNU General Public License for more details.
  18
  19     You should have received a copy of the GNU General Public License
  20     along with this program; if not, write to the Free Software
  21     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
  22
  23 #include <stdlib.h>
  24 #include <stdio.h>
  25 #include <string.h>
  26 #include <memory.h>
  27 #include <math.h>
  28 #include <ctype.h>
  29 #include "drawer.h"
  30
  31 static char* getToken(const char**p)
  32 {
  33     const char*start;
  34     char*result;
  35     while(**p && strchr(" ,()\t\n\r", **p)) {
  36         (*p)++;
  37     }
  38     start = *p;
  39
  40      /*
  41         SVF pathdata can exclude whitespace after L and M commands.
  42         Ref:  http://www.w3.org/TR/SVG11/paths.html#PathDataGeneralInformation
  43         This allows us to use svg files output from gnuplot.
  44         Also checks for relative MoveTo and LineTo (m and l).
  45         051106 Magnus Lundin, lundin@mlu.mine.nu
  46      */
  47     if (strchr("LMlm", **p) && (isdigit(*(*p+1))||strchr("+-", *(*p+1)))) {
  48         (*p)++;
  49     }
  50     else while(**p && !strchr(" ,()\t\n\r", **p)) {
  51         (*p)++;
  52     }
  53     result = (char*)malloc((*p)-start+1);
  54     memcpy(result,start,(*p)-start+1);
  55     result[(*p)-start] = 0;
  56     return result;
  57 }
  58
  59 void draw_conicTo(drawer_t*draw, FPOINT*  c, FPOINT*  to)
  60 {
  61     FPOINT* pos = &draw->pos;
  62     FPOINT c1,c2;
  63     c1.x = (pos->x + 2 * c->x) / 3;
  64     c1.y = (pos->y + 2 * c->y) / 3;
  65     c2.x = (2 * c->x + to->x) / 3;
  66     c2.y = (2 * c->y + to->y) / 3;
  67     draw_cubicTo(draw, &c1,&c2,to);
  68
  69     draw->pos = *to;
  70 }
  71
  72 /* convenience routine */
  73 static void draw_conicTo2(drawer_t*draw, double x1, double y1, double  x2, double y2)
  74 {
  75     FPOINT c1,c2;
  76     c1.x = x1;
  77     c1.y = y1;
  78     c2.x = x2;
  79     c2.y = y2;
  80     draw_conicTo(draw, &c1, &c2);
  81 }
  82 /* convenience routine */
  83 static void draw_moveTo2(drawer_t*draw, double x, double y)
  84 {
  85     FPOINT c;
  86     c.x = x; c.y = y;
  87     draw->moveTo(draw, &c);
  88 }
  89 /* convenience routine */
  90 static void draw_lineTo2(drawer_t*draw, double x, double y)
  91 {
  92     FPOINT c;
  93     c.x = x; c.y = y;
  94     draw->lineTo(draw, &c);
  95 }
  96
  97 static float getFloat(const char** p)
  98 {
  99     char* token = getToken(p);
 100     float result = atof(token);
 101     free(token);
 102     return result;
 103 }
 104
 105 void draw_string(drawer_t*draw, const char*string)
 106 {
 107     const char*p = string;
 108     while(*p) {
 109         char*token = getToken(&p);
 110     if(!token)
 111         break;
 112     if (!*token)
 113     {
 114         free(token);
 115             break;
 116     }
 117         if(!strncmp(token, "moveTo", 6) ||
 118            !strncmp(token, "M", 1) //svg
 119            ) {
 120             FPOINT to;
 121         to.x = getFloat(&p);
 122         to.y = getFloat(&p);
 123             draw->moveTo(draw, &to);
 124         }
 125         else if(!strncmp(token, "lineTo", 6) ||
 126                 !strncmp(token, "L", 1) //svg
 127              ) {
 128             FPOINT to;
 129         to.x = getFloat(&p);
 130         to.y = getFloat(&p);
 131             draw->lineTo(draw, &to);
 132         }
 133         else if(!strncmp(token, "curveTo", 7) || !strncmp(token, "splineTo", 8)) {
 134             FPOINT mid,to;
 135         mid.x = getFloat(&p);
 136         mid.y = getFloat(&p);
 137         to.x = getFloat(&p);
 138         to.y = getFloat(&p);
 139             draw->splineTo(draw, &mid, &to);
 140         }
 141         else if(!strncmp(token, "conicTo", 5)) {
 142             FPOINT mid,to;
 143         mid.x = getFloat(&p);
 144         mid.y = getFloat(&p);
 145         to.x = getFloat(&p);
 146         to.y = getFloat(&p);
 147             draw_conicTo(draw, &mid, &to);
 148         }
 149         else if(!strncmp(token, "circle", 6)) {
 150             int mx,my,r;
 151             double r2;
 152         mx = getFloat(&p);
 153         my = getFloat(&p);
 154         r = getFloat(&p);
 155             r2 = 0.70710678118654757*r;
 156             draw_moveTo2(draw, mx, my-r);
 157             draw_conicTo2(draw, mx+r2, my-r2, mx+r, my);
 158             draw_conicTo2(draw, mx+r2, my+r2, mx, my+r);
 159             draw_conicTo2(draw, mx-r2, my+r2, mx-r, my);
 160             draw_conicTo2(draw, mx-r2, my-r2, mx, my-r);
 161         }
 162         else if(!strncmp(token, "box", 3)) {
 163             int x1,y1,x2,y2;
 164         x1 = getFloat(&p);
 165         y1 = getFloat(&p);
 166         x2 = getFloat(&p);
 167         y2 = getFloat(&p);
 168             draw_moveTo2(draw, x1, y1);
 169             draw_lineTo2(draw, x1, y2);
 170             draw_lineTo2(draw, x2, y2);
 171             draw_lineTo2(draw, x2, y1);
 172             draw_lineTo2(draw, x1, y1);
 173         }
 174         else if(!strncmp(token, "cubicTo", 5) ||
 175                 !strncmp(token, "C", 1) //svg
 176                 ) {
 177             FPOINT mid1,mid2,to;
 178         mid1.x = getFloat(&p);
 179         mid1.y = getFloat(&p);
 180         mid2.x = getFloat(&p);
 181         mid2.y = getFloat(&p);
 182         to.x = getFloat(&p);
 183         to.y = getFloat(&p);
 184             draw_cubicTo(draw, &mid1, &mid2, &to);
 185         }
 186         else if(!strncmp(token, "z", 1) //svg
 187                ) {
 188             // ignore
 189         }
 190         else
 191             fprintf(stderr, "drawer: Warning: unknown primitive '%s'\n", token);
 192
 193         free(token);
 194     }
 195 }
 196
 197 struct SPLINEPOINT
 198 {
 199     double x,y;
 200 };
 201
 202 struct qspline
 203 {
 204     struct SPLINEPOINT start;
 205     struct SPLINEPOINT control;
 206     struct SPLINEPOINT end;
 207 };
 208
 209 struct cspline
 210 {
 211     struct SPLINEPOINT start;
 212     struct SPLINEPOINT control1;
 213     struct SPLINEPOINT control2;
 214     struct SPLINEPOINT end;
 215 };
 216
 217 static inline struct SPLINEPOINT cspline_getpoint(const struct cspline*s, double t)
 218 {
 219     struct SPLINEPOINT p;
 220     double tt = t*t;
 221     double ttt = tt*t;
 222     double mt = (1-t);
 223     double mtmt = mt*(1-t);
 224     double mtmtmt = mtmt*(1-t);
 225     p.x= s->end.x*ttt + 3*s->control2.x*tt*mt
 226             + 3*s->control1.x*t*mtmt + s->start.x*mtmtmt;
 227     p.y= s->end.y*ttt + 3*s->control2.y*tt*mt
 228             + 3*s->control1.y*t*mtmt + s->start.y*mtmtmt;
 229     return p;
 230 }
 231 static struct SPLINEPOINT qspline_getpoint(const struct qspline*s, double t)
 232 {
 233     struct SPLINEPOINT p;
 234     p.x= s->end.x*t*t + 2*s->control.x*t*(1-t) + s->start.x*(1-t)*(1-t);
 235     p.y= s->end.y*t*t + 2*s->control.y*t*(1-t) + s->start.y*(1-t)*(1-t);
 236     return p;
 237 }
 238
 239 static int approximate3(const struct cspline*s, struct qspline*q, int size, double quality2)
 240 {
 241     unsigned int gran = 0;
 242     unsigned int istep = 0x80000000;
 243     unsigned int istart = 0;
 244     int num = 0;
 245     int level = 0;
 246
 247     while(istart<0x80000000)
 248     {
 249         unsigned int iend = istart + istep;
 250         double start = istart/(double)0x80000000;
 251         double end = iend/(double)0x80000000;
 252         struct qspline test;
 253         double pos,qpos;
 254         char left = 0,recurse=0;
 255         int t;
 256         int probes = 15;
 257
 258         /* create simple approximation: a qspline which run's through the
 259            qspline point at 0.5 */
 260         test.start = cspline_getpoint(s, start);
 261         test.control = cspline_getpoint(s, (start+end)/2);
 262         test.end = cspline_getpoint(s, end);
 263         /* fix the control point:
 264            move it so that the new spline does runs through it */
 265         test.control.x = -(test.end.x + test.start.x)/2 + 2*(test.control.x);
 266         test.control.y = -(test.end.y + test.start.y)/2 + 2*(test.control.y);
 267
 268         /* depending on where we are in the spline, we either try to match
 269            the left or right tangent */
 270         if(start<0.5)
 271             left=1;
 272         /* get derivative */
 273         pos = left?start:end;
 274         qpos = pos*pos;
 275         test.control.x = s->end.x*(3*qpos) + 3*s->control2.x*(2*pos-3*qpos) +
 276                     3*s->control1.x*(1-4*pos+3*qpos) + s->start.x*(-3+6*pos-3*qpos);
 277         test.control.y = s->end.y*(3*qpos) + 3*s->control2.y*(2*pos-3*qpos) +
 278                     3*s->control1.y*(1-4*pos+3*qpos) + s->start.y*(-3+6*pos-3*qpos);
 279         if(left) {
 280             test.control.x *= (end-start)/2;
 281             test.control.y *= (end-start)/2;
 282             test.control.x += test.start.x;
 283             test.control.y += test.start.y;
 284         } else {
 285             test.control.x *= -(end-start)/2;
 286             test.control.y *= -(end-start)/2;
 287             test.control.x += test.end.x;
 288             test.control.y += test.end.y;
 289         }
 290
 291 #define PROBES
 292 #ifdef PROBES
 293         /* measure the spline's accurancy, by taking a number of probes */
 294         for(t=0;t<probes;t++) {
 295             struct SPLINEPOINT qr1,qr2,cr1,cr2;
 296             double pos = 0.5/(probes*2)*(t*2+1);
 297             double dx,dy;
 298             double dist1,dist2;
 299             qr1 = qspline_getpoint(&test, pos);
 300             cr1 = cspline_getpoint(s, start+pos*(end-start));
 301
 302             dx = qr1.x - cr1.x;
 303             dy = qr1.y - cr1.y;
 304             dist1 = dx*dx+dy*dy;
 305
 306             if(dist1>quality2) {
 307                 recurse=1;break;
 308             }
 309             qr2 = qspline_getpoint(&test, (1-pos));
 310             cr2 = cspline_getpoint(s, start+(1-pos)*(end-start));
 311
 312             dx = qr2.x - cr2.x;
 313             dy = qr2.y - cr2.y;
 314             dist2 = dx*dx+dy*dy;
 315
 316             if(dist2>quality2) {
 317                 recurse=1;break;
 318             }
 319         }
 320 #else // quadratic error: *much* faster!
 321
 322         /* convert control point representation to
 323            d*x^3 + c*x^2 + b*x + a */
 324         double dx,dy;
 325         dx= s->end.x  - s->control2.x*3 + s->control1.x*3 - s->start.x;
 326         dy= s->end.y  - s->control2.y*3 + s->control1.y*3 - s->start.y;
 327
 328         /* we need to do this for the subspline between [start,end], not [0,1]
 329            as a transformation of t->a*t+b does nothing to highest coefficient
 330            of the spline except multiply it with a^3, we just need to modify
 331            d here. */
 332         {double m = end-start;
 333          dx*=m*m*m;
 334          dy*=m*m*m;
 335         }
 336
 337         /* use the integral over (f(x)-g(x))^2 between 0 and 1
 338            to measure the approximation quality.
 339            (it boils down to const*d^2)
 340          */
 341         recurse = (dx*dx + dy*dy > quality2);
 342 #endif
 343
 344         if(recurse && istep>1 && size-level > num) {
 345             istep >>= 1;
 346             level++;
 347         } else {
 348             *q++ = test;
 349             num++;
 350             istart += istep;
 351             while(!(istart & istep)) {
 352                 level--;
 353                 istep <<= 1;
 354             }
 355         }
 356     }
 357     return num;
 358 }
 359
 360 void draw_cubicTo(drawer_t*draw, FPOINT*  control1, FPOINT* control2, FPOINT*  to)
 361 {
 362     struct qspline q[128];
 363     struct cspline c;
 364     //double quality = 80;
 365     double maxerror = 1;//(500-(quality*5)>1?500-(quality*5):1)/20.0;
 366     int t,num;
 367
 368     c.start.x = draw->pos.x;
 369     c.start.y = draw->pos.y;
 370     c.control1.x = control1->x;
 371     c.control1.y = control1->y;
 372     c.control2.x = control2->x;
 373     c.control2.y = control2->y;
 374     c.end.x = to->x;
 375     c.end.y = to->y;
 376
 377     num = approximate3(&c, q, 128, maxerror*maxerror);
 378
 379     for(t=0;t<num;t++) {
 380         FPOINT mid;
 381         FPOINT to;
 382         mid.x = q[t].control.x;
 383         mid.y = q[t].control.y;
 384         to.x = q[t].end.x;
 385         to.y = q[t].end.y;
 386         draw->splineTo(draw, &mid, &to);
 387     }
 388 }
 389
 390