Initial import of libart 2.3.21

1 files changed, 200 insertions, 0 deletions

diff --git a/art_vpath_dash.c b/art_vpath_dash.c
new file mode 100644
index 0000000..3c98a96
--- /dev/null
+++ b/art_vpath_dash.c
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+/* Libart_LGPL - library of basic graphic primitives
+ * Copyright (C) 1999-2000 Raph Levien
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+/* Apply a dash style to a vector path. */
+
+#include "config.h"
+#include "art_vpath_dash.h"
+
+#include <math.h>
+#include <stdlib.h>
+
+#include "art_misc.h"
+
+#include "art_vpath.h"
+
+
+/* Return the length of the largest subpath within vpath */
+static int
+art_vpath_dash_max_subpath (const ArtVpath *vpath)
+{
+  int max_subpath;
+  int i;
+  int start;
+
+  max_subpath = 0;
+  start = 0;
+  for (i = 0; vpath[i].code != ART_END; i++)
+    {
+      if (vpath[i].code == ART_MOVETO || vpath[i].code == ART_MOVETO_OPEN)
+	{
+	  if (i - start > max_subpath)
+	    max_subpath = i - start;
+	  start = i;
+	}
+    }
+  if (i - start > max_subpath)
+    max_subpath = i - start;
+
+  return max_subpath;
+}
+
+/**
+ * art_vpath_dash: Add dash style to vpath.
+ * @vpath: Original vpath.
+ * @dash: Dash style.
+ *
+ * Creates a new vpath that is the result of applying dash style @dash
+ * to @vpath.
+ *
+ * This implementation has two known flaws:
+ *
+ * First, it adds a spurious break at the beginning of the vpath. The
+ * only way I see to resolve this flaw is to run the state forward one
+ * dash break at the beginning, and fix up by looping back to the
+ * first dash break at the end. This is doable but of course adds some
+ * complexity.
+ *
+ * Second, it does not suppress output points that are within epsilon
+ * of each other.
+ *
+ * Return value: Newly created vpath.
+ **/
+ArtVpath *
+art_vpath_dash (const ArtVpath *vpath, const ArtVpathDash *dash)
+{
+  int max_subpath;
+  double *dists;
+  ArtVpath *result;
+  int n_result, n_result_max;
+  int start, end;
+  int i;
+  double total_dist;
+
+  /* state while traversing dasharray - offset is offset of current dash
+     value, toggle is 0 for "off" and 1 for "on", and phase is the distance
+     in, >= 0, < dash->dash[offset]. */
+  int offset, toggle;
+  double phase;
+
+  /* initial values */
+  int offset_init, toggle_init;
+  double phase_init;
+
+  max_subpath = art_vpath_dash_max_subpath (vpath);
+  dists = art_new (double, max_subpath);
+
+  n_result = 0;
+  n_result_max = 16;
+  result = art_new (ArtVpath, n_result_max);
+
+  /* determine initial values of dash state */
+  toggle_init = 1;
+  offset_init = 0;
+  phase_init = dash->offset;
+  while (phase_init >= dash->dash[offset_init])
+    {
+      toggle_init = !toggle_init;
+      phase_init -= dash->dash[offset_init];
+      offset_init++;
+      if (offset_init == dash->n_dash)
+	offset_init = 0;
+    }
+
+  for (start = 0; vpath[start].code != ART_END; start = end)
+    {
+      for (end = start + 1; vpath[end].code == ART_LINETO; end++);
+      /* subpath is [start..end) */
+      total_dist = 0;
+      for (i = start; i < end - 1; i++)
+	{
+	  double dx, dy;
+
+	  dx = vpath[i + 1].x - vpath[i].x;
+	  dy = vpath[i + 1].y - vpath[i].y;
+	  dists[i - start] = sqrt (dx * dx + dy * dy);
+	  total_dist += dists[i - start];
+	}
+      if (total_dist <= dash->dash[offset_init] - phase_init)
+	{
+	  /* subpath fits entirely within first dash */
+	  if (toggle_init)
+	    {
+	      for (i = start; i < end; i++)
+		art_vpath_add_point (&result, &n_result, &n_result_max,
+				     vpath[i].code, vpath[i].x, vpath[i].y);
+	    }
+	}
+      else
+	{
+	  /* subpath is composed of at least one dash - thus all
+	     generated pieces are open */
+	  double dist;
+
+	  phase = phase_init;
+	  offset = offset_init;
+	  toggle = toggle_init;
+	  dist = 0;
+	  i = start;
+	  if (toggle)
+	    art_vpath_add_point (&result, &n_result, &n_result_max,
+				 ART_MOVETO_OPEN, vpath[i].x, vpath[i].y);
+	  while (i != end - 1)
+	    {
+	      if (dists[i - start] - dist > dash->dash[offset] - phase)
+		{
+		  /* dash boundary is next */
+		  double a;
+		  double x, y;
+
+		  dist += dash->dash[offset] - phase;
+		  a = dist / dists[i - start];
+		  x = vpath[i].x + a * (vpath[i + 1].x - vpath[i].x);
+		  y = vpath[i].y + a * (vpath[i + 1].y - vpath[i].y);
+		  art_vpath_add_point (&result, &n_result, &n_result_max,
+				       toggle ? ART_LINETO : ART_MOVETO_OPEN,
+				       x, y);
+		  /* advance to next dash */
+		  toggle = !toggle;
+		  phase = 0;
+		  offset++;
+		  if (offset == dash->n_dash)
+		    offset = 0;
+		}
+	      else
+		{
+		  /* end of line in vpath is next */
+		  phase += dists[i - start] - dist;
+		  i++;
+		  dist = 0;
+		  if (toggle)
+		    art_vpath_add_point (&result, &n_result, &n_result_max,
+					 ART_LINETO, vpath[i].x, vpath[i].y);
+		}
+	    }
+	}
+    }
+
+  art_vpath_add_point (&result, &n_result, &n_result_max,
+		       ART_END, 0, 0);
+
+  art_free (dists);
+
+  return result;
+}