1 files changed, 223 insertions, 0 deletions
diff --git a/Build/source/libs/potrace/potrace-src/src/backend_geojson.c b/Build/source/libs/potrace/potrace-src/src/backend_geojson.c
new file mode 100644
index 00000000000..8ac226b8969
--- /dev/null
+++ b/Build/source/libs/potrace/potrace-src/src/backend_geojson.c
@@ -0,0 +1,223 @@
+/* Copyright (C) 2001-2019 Peter Selinger.
+   This file is part of Potrace. It is free software and it is covered
+   by the GNU General Public License. See the file COPYING for details. */
+
+/* The GeoJSON backend of Potrace. */
+/* Written 2012 by Christoph Hormann <chris_hormann@gmx.de> */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+#include <stdarg.h>
+#include <string.h>
+#include <math.h>
+
+#include "potracelib.h"
+#include "curve.h"
+#include "main.h"
+#include "backend_geojson.h"
+#include "lists.h"
+#include "auxiliary.h"
+
+/* ---------------------------------------------------------------------- */
+/* auxiliary */
+
+/* return a point on a 1-dimensional Bezier segment */
+static inline double bezier(double t, double x0, double x1, double x2, double x3) {
+  double s = 1-t;
+  return s*s*s*x0 + 3*(s*s*t)*x1 + 3*(t*t*s)*x2 + t*t*t*x3;
+}
+
+static const char *format = "%f";
+
+/* Convert a floating-point number to a string, using a pre-determined
+   format. The format must be previously set with set_format().
+   Returns one of a small number of statically allocated strings. */
+static char *round_to_unit(double x) {
+  static int n = 0;
+  static char buf[4][100];
+
+  n++;
+  if (n >= 4) {
+    n = 0;
+  }
+  sprintf(buf[n], format, x);
+  return buf[n];
+}
+
+/* Select a print format for floating point numbers, appropriate for
+   the given scaling and info.unit. Note: the format must be so that
+   the resulting number fits into a buffer of size 100. */
+static void set_format(trans_t tr) {
+  double s;
+  int d;
+  static char buf[10];
+
+  s = min(fabs(tr.scalex), fabs(tr.scaley));
+  if (info.unit != 0.0 && s != 0.0) {
+    d = (int)ceil(log(info.unit/s) / log(10));
+  } else {
+    d = 0;
+  }
+  if (d <= 0) {
+    format = "%.0f";
+  } else if (d <= 20) {
+    sprintf(buf, "%%.%df", d);
+    format = buf;
+  } else {
+    format = "%e";
+  }  
+}
+
+/* ---------------------------------------------------------------------- */
+/* path-drawing auxiliary functions */
+
+static dpoint_t cur;
+
+static void geojson_moveto(FILE *fout, dpoint_t p, trans_t tr) {
+  dpoint_t q;
+
+  q = trans(p, tr);
+
+  fprintf(fout, "[%s, %s]", round_to_unit(q.x), round_to_unit(q.y));
+
+  cur = q;
+}
+
+static void geojson_lineto(FILE *fout, dpoint_t p, trans_t tr) {
+  dpoint_t q;
+
+  q = trans(p, tr);
+
+  fprintf(fout, ", [%s, %s]", round_to_unit(q.x), round_to_unit(q.y));
+
+  cur = q;
+}
+
+static void geojson_curveto(FILE *fout, dpoint_t p1, dpoint_t p2, dpoint_t p3, trans_t tr) {
+  dpoint_t q1;
+  dpoint_t q2;
+  dpoint_t q3;
+  double step, t;
+  int i;
+  double x, y;
+
+  q1 = trans(p1, tr);
+  q2 = trans(p2, tr);
+  q3 = trans(p3, tr);
+
+  step = 1.0 / 8.0;
+
+  for (i=0, t=step; i<8; i++, t+=step) {
+    x = bezier(t, cur.x, q1.x, q2.x, q3.x);
+    y = bezier(t, cur.y, q1.y, q2.y, q3.y);
+
+    fprintf(fout, ", [%s, %s]", round_to_unit(x), round_to_unit(y));
+  }
+
+  cur = q3;
+}
+
+/* ---------------------------------------------------------------------- */
+/* functions for converting a path to an SVG path element */
+
+static int geojson_path(FILE *fout, potrace_curve_t *curve, trans_t tr) {
+  int i;
+  dpoint_t *c;
+  int m = curve->n;
+
+  fprintf(fout, "      [");
+
+  c = curve->c[m-1];
+  geojson_moveto(fout, c[2], tr);
+
+  for (i=0; i<m; i++) {
+    c = curve->c[i];
+    switch (curve->tag[i]) {
+    case POTRACE_CORNER:
+      geojson_lineto(fout, c[1], tr);
+      geojson_lineto(fout, c[2], tr);
+      break;
+    case POTRACE_CURVETO:
+      geojson_curveto(fout, c[0], c[1], c[2], tr);
+      break;
+    }
+  }
+
+  fprintf(fout, " ]");
+
+  return 0;
+}
+
+
+static void write_polygons(FILE *fout, potrace_path_t *tree, trans_t tr, int first) {
+  potrace_path_t *p, *q;
+
+  for (p=tree; p; p=p->sibling) {
+
+    if (!first) fprintf(fout, ",\n");
+
+    fprintf(fout, "{ \"type\": \"Feature\",\n");
+    fprintf(fout, "  \"properties\": { },\n");
+    fprintf(fout, "  \"geometry\": {\n");
+    fprintf(fout, "    \"type\": \"Polygon\",\n");
+    fprintf(fout, "    \"coordinates\": [\n");
+
+    geojson_path(fout, &p->curve, tr);
+
+    for (q=p->childlist; q; q=q->sibling) {
+      fprintf(fout, ",\n");
+      geojson_path(fout, &q->curve, tr);
+    }
+
+    fprintf(fout, "    ]\n");
+    fprintf(fout, "  }\n");
+    fprintf(fout, "}");
+
+    for (q=p->childlist; q; q=q->sibling) {
+      write_polygons(fout, q->childlist, tr, 0);
+    }
+
+    first = 0;
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+/* Backend. */
+
+/* public interface for GeoJSON */
+int page_geojson(FILE *fout, potrace_path_t *plist, imginfo_t *imginfo) {
+
+  trans_t tr;
+
+  /* set up the coordinate transform (rotation) */
+  tr.bb[0] = imginfo->trans.bb[0]+imginfo->lmar+imginfo->rmar;
+  tr.bb[1] = imginfo->trans.bb[1]+imginfo->tmar+imginfo->bmar;
+  tr.orig[0] = imginfo->trans.orig[0]+imginfo->lmar;
+  tr.orig[1] = imginfo->trans.orig[1]+imginfo->bmar;
+  tr.x[0] = imginfo->trans.x[0];
+  tr.x[1] = imginfo->trans.x[1];
+  tr.y[0] = imginfo->trans.y[0];
+  tr.y[1] = imginfo->trans.y[1];
+
+  /* set the print format for floating point numbers */
+  set_format(imginfo->trans);
+
+  /* header */
+  fprintf(fout, "{\n");
+  fprintf(fout, "\"type\": \"FeatureCollection\",\n");
+  fprintf(fout, "\"features\": [\n");
+
+  write_polygons(fout, plist, tr, 1);
+
+  /* write footer */
+  fprintf(fout, "\n]\n");
+  fprintf(fout, "}\n");
+
+  fflush(fout);
+
+  return 0;
+}
+