--- /dev/null
+/* 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;
+}
git.asbjorn.biz / swftools.git / blobdiff