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 "drawer.h"
  29
  30 static char* getToken(const char**p)
  31 {
  32     const char*start;
  33     char*result;
  34     while(**p && strchr(" ,\t\n\r", **p)) {
  35         (*p)++;
  36     }
  37     start = *p;
  38     while(**p && !strchr(" ,\t\n\r", **p)) {
  39         (*p)++;
  40     }
  41     result = malloc((*p)-start+1);
  42     memcpy(result,start,(*p)-start+1);
  43     result[(*p)-start] = 0;
  44     return result;
  45 }
  46
  47 void draw_conicTo(drawer_t*draw, FPOINT*  c, FPOINT*  to)
  48 {
  49     FPOINT* pos = &draw->pos;
  50     FPOINT c1,c2;
  51     c1.x = (pos->x + 2 * c->x) / 3;
  52     c1.y = (pos->y + 2 * c->y) / 3;
  53     c2.x = (2 * c->x + to->x) / 3;
  54     c2.y = (2 * c->y + to->y) / 3;
  55     draw_cubicTo(draw, &c1,&c2,to);
  56
  57     draw->pos = *to;
  58 }
  59
  60 void draw_string(drawer_t*draw, const char*string)
  61 {
  62     const char*p = string;
  63     while(*p) {
  64         char*token = getToken(&p);
  65         if(!token || !*token)
  66             break;
  67         if(!strncmp(token, "moveTo", 6)) {
  68             FPOINT to;
  69             to.x = atoi(getToken(&p));
  70             to.y = atoi(getToken(&p));
  71             draw->moveTo(draw, &to);
  72         }
  73         else if(!strncmp(token, "lineTo", 6)) {
  74             FPOINT to;
  75             to.x = atoi(getToken(&p));
  76             to.y = atoi(getToken(&p));
  77             draw->lineTo(draw, &to);
  78         }
  79         else if(!strncmp(token, "curveTo", 7) || !strncmp(token, "splineTo", 8)) {
  80             FPOINT mid,to;
  81             mid.x = atoi(getToken(&p));
  82             mid.y = atoi(getToken(&p));
  83             to.x = atoi(getToken(&p));
  84             to.y = atoi(getToken(&p));
  85             draw->splineTo(draw, &mid, &to);
  86         }
  87         else if(!strncmp(token, "conicTo", 5)) {
  88             FPOINT mid,to;
  89             mid.x = atoi(getToken(&p));
  90             mid.y = atoi(getToken(&p));
  91             to.x = atoi(getToken(&p));
  92             to.y = atoi(getToken(&p));
  93             draw_conicTo(draw, &mid, &to);
  94         }
  95         else if(!strncmp(token, "cubicTo", 5)) {
  96             FPOINT mid1,mid2,to;
  97             mid1.x = atoi(getToken(&p));
  98             mid1.y = atoi(getToken(&p));
  99             mid2.x = atoi(getToken(&p));
 100             mid2.y = atoi(getToken(&p));
 101             to.x = atoi(getToken(&p));
 102             to.y = atoi(getToken(&p));
 103             draw_cubicTo(draw, &mid1, &mid2, &to);
 104         }
 105         else fprintf(stderr, "drawer: Warning: unknown primitive '%s'\n", token);
 106
 107         free(token);
 108     }
 109 }
 110
 111 struct SPLINEPOINT
 112 {
 113     double x,y;
 114 };
 115
 116 struct qspline
 117 {
 118     struct SPLINEPOINT start;
 119     struct SPLINEPOINT control;
 120     struct SPLINEPOINT end;
 121 };
 122
 123 struct cspline
 124 {
 125     struct SPLINEPOINT start;
 126     struct SPLINEPOINT control1;
 127     struct SPLINEPOINT control2;
 128     struct SPLINEPOINT end;
 129 };
 130
 131 static inline struct SPLINEPOINT cspline_getpoint(const struct cspline*s, double t)
 132 {
 133     struct SPLINEPOINT p;
 134     double tt = t*t;
 135     double ttt = tt*t;
 136     double mt = (1-t);
 137     double mtmt = mt*(1-t);
 138     double mtmtmt = mtmt*(1-t);
 139     p.x= s->end.x*ttt + 3*s->control2.x*tt*mt
 140             + 3*s->control1.x*t*mtmt + s->start.x*mtmtmt;
 141     p.y= s->end.y*ttt + 3*s->control2.y*tt*mt
 142             + 3*s->control1.y*t*mtmt + s->start.y*mtmtmt;
 143     return p;
 144 }
 145 static struct SPLINEPOINT qspline_getpoint(const struct qspline*s, double t)
 146 {
 147     struct SPLINEPOINT p;
 148     p.x= s->end.x*t*t + 2*s->control.x*t*(1-t) + s->start.x*(1-t)*(1-t);
 149     p.y= s->end.y*t*t + 2*s->control.y*t*(1-t) + s->start.y*(1-t)*(1-t);
 150     return p;
 151 }
 152
 153 static int approximate3(const struct cspline*s, struct qspline*q, int size, double quality2)
 154 {
 155     unsigned int gran = 0;
 156     unsigned int istep = 0x80000000;
 157     unsigned int istart = 0;
 158     int num = 0;
 159     int level = 0;
 160
 161     while(istart<0x80000000)
 162     {
 163         unsigned int iend = istart + istep;
 164         double start = istart/(double)0x80000000;
 165         double end = iend/(double)0x80000000;
 166         struct qspline test;
 167         double pos,qpos;
 168         char left = 0,recurse=0;
 169         int t;
 170         int probes = 15;
 171
 172         /* create simple approximation: a qspline which run's through the
 173            qspline point at 0.5 */
 174         test.start = cspline_getpoint(s, start);
 175         test.control = cspline_getpoint(s, (start+end)/2);
 176         test.end = cspline_getpoint(s, end);
 177         /* fix the control point:
 178            move it so that the new spline does runs through it */
 179         test.control.x = -(test.end.x + test.start.x)/2 + 2*(test.control.x);
 180         test.control.y = -(test.end.y + test.start.y)/2 + 2*(test.control.y);
 181
 182         /* depending on where we are in the spline, we either try to match
 183            the left or right tangent */
 184         if(start<0.5)
 185             left=1;
 186         /* get derivative */
 187         pos = left?start:end;
 188         qpos = pos*pos;
 189         test.control.x = s->end.x*(3*qpos) + 3*s->control2.x*(2*pos-3*qpos) +
 190                     3*s->control1.x*(1-4*pos+3*qpos) + s->start.x*(-3+6*pos-3*qpos);
 191         test.control.y = s->end.y*(3*qpos) + 3*s->control2.y*(2*pos-3*qpos) +
 192                     3*s->control1.y*(1-4*pos+3*qpos) + s->start.y*(-3+6*pos-3*qpos);
 193         if(left) {
 194             test.control.x *= (end-start)/2;
 195             test.control.y *= (end-start)/2;
 196             test.control.x += test.start.x;
 197             test.control.y += test.start.y;
 198         } else {
 199             test.control.x *= -(end-start)/2;
 200             test.control.y *= -(end-start)/2;
 201             test.control.x += test.end.x;
 202             test.control.y += test.end.y;
 203         }
 204
 205         /* measure the spline's accurancy, by taking a number of probes */
 206
 207         for(t=0;t<probes;t++) {
 208             struct SPLINEPOINT qr1,qr2,cr1,cr2;
 209             double pos = 0.5/(probes*2)*(t*2+1);
 210             double dx,dy;
 211             double dist1,dist2;
 212             qr1 = qspline_getpoint(&test, pos);
 213             cr1 = cspline_getpoint(s, start+pos*(end-start));
 214
 215             dx = qr1.x - cr1.x;
 216             dy = qr1.y - cr1.y;
 217             dist1 = dx*dx+dy*dy;
 218
 219             if(dist1>quality2) {
 220                 recurse=1;break;
 221             }
 222             qr2 = qspline_getpoint(&test, (1-pos));
 223             cr2 = cspline_getpoint(s, start+(1-pos)*(end-start));
 224
 225             dx = qr2.x - cr2.x;
 226             dy = qr2.y - cr2.y;
 227             dist2 = dx*dx+dy*dy;
 228
 229             if(dist2>quality2) {
 230                 recurse=1;break;
 231             }
 232         }
 233
 234         if(recurse && istep>1 && size-level > num) {
 235             istep >>= 1;
 236             level++;
 237         } else {
 238             *q++ = test;
 239             num++;
 240             istart += istep;
 241             while(!(istart & istep)) {
 242                 level--;
 243                 istep <<= 1;
 244             }
 245         }
 246     }
 247     return num;
 248 }
 249
 250 void draw_cubicTo(drawer_t*draw, FPOINT*  control1, FPOINT* control2, FPOINT*  to)
 251 {
 252     struct qspline q[128];
 253     struct cspline c;
 254     double quality = 80;
 255     double maxerror = (500-(quality*5)>1?500-(quality*5):1)/20.0;
 256     int t,num;
 257
 258     c.start.x = draw->pos.x;
 259     c.start.y = draw->pos.y;
 260     c.control1.x = control1->x;
 261     c.control1.y = control1->y;
 262     c.control2.x = control2->x;
 263     c.control2.y = control2->y;
 264     c.end.x = to->x;
 265     c.end.y = to->y;
 266
 267     num = approximate3(&c, q, 128, maxerror*maxerror);
 268
 269     for(t=0;t<num;t++) {
 270         FPOINT mid;
 271         FPOINT to;
 272         mid.x = q[t].control.x;
 273         mid.y = q[t].control.y;
 274         to.x = q[t].end.x;
 275         to.y = q[t].end.y;
 276         draw->splineTo(draw, &mid, &to);
 277     }
 278 }
 279
 280