1 files changed, 233 insertions, 0 deletions
diff --git a/plug-ins/selection-to-path/spline.c b/plug-ins/selection-to-path/spline.c
new file mode 100644
index 0000000..1e8c2e7
--- /dev/null
+++ b/plug-ins/selection-to-path/spline.c
@@ -0,0 +1,233 @@
+/* spline.c: spline and spline list (represented as arrays) manipulation.
+ *
+ * Copyright (C) 1992 Free Software Foundation, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3, or (at your option)
+ * any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <assert.h>
+
+#include <glib.h>
+
+#include "global.h"
+#include "bounding-box.h"
+#include "spline.h"
+#include "vector.h"
+
+/* Return a new spline structure, initialized with (recognizable)
+   garbage.  */
+
+spline_type
+new_spline (void)
+{
+  real_coordinate_type coord = { -100.0, -100.0 };
+  spline_type spline;
+
+  START_POINT (spline)
+    = CONTROL1 (spline)
+    = CONTROL2 (spline)
+    = END_POINT (spline)
+    = coord;
+  SPLINE_DEGREE (spline) = -1;
+  SPLINE_LINEARITY (spline) = 0;
+
+  return spline;
+}
+
+
+/* Print a spline in human-readable form.  */
+
+void
+print_spline (FILE *f, spline_type s)
+{
+  if (SPLINE_DEGREE (s) == LINEAR)
+    fprintf (f, "(%.3f,%.3f)--(%.3f,%.3f).\n",
+                START_POINT (s).x, START_POINT (s).y,
+                END_POINT (s).x, END_POINT (s).y);
+
+  else if (SPLINE_DEGREE (s) == CUBIC)
+    fprintf (f, "(%.3f,%.3f)..ctrls(%.3f,%.3f)&(%.3f,%.3f)..(%.3f,%.3f).\n",
+                START_POINT (s).x, START_POINT (s).y,
+                CONTROL1 (s).x, CONTROL1 (s).y,
+                CONTROL2 (s).x, CONTROL2 (s).y,
+                END_POINT (s).x, END_POINT (s).y);
+
+  else
+    {
+/*       FATAL1 ("print_spline: strange degree (%d)", SPLINE_DEGREE (s)); */
+    }
+}
+
+/* Evaluate the spline S at a given T value.  This is an implementation
+   of de Casteljau's algorithm.  See Schneider's thesis (reference in
+   ../limn/README), p.37.  The variable names are taken from there.  */
+
+real_coordinate_type
+evaluate_spline (spline_type s, real t)
+{
+  spline_type V[4];    /* We need degree+1 splines, but assert degree <= 3.  */
+  unsigned i, j;
+  real one_minus_t = 1.0 - t;
+  polynomial_degree degree = SPLINE_DEGREE (s);
+
+  for (i = 0; i <= degree; i++)
+    V[0].v[i] = s.v[i];
+
+  for (j = 1; j <= degree; j++)
+    for (i = 0; i <= degree - j; i++)
+      {
+#if defined (__GNUC__)
+        real_coordinate_type t1 = Pmult_scalar (V[j - 1].v[i], one_minus_t);
+        real_coordinate_type t2 = Pmult_scalar (V[j - 1].v[i + 1], t);
+        V[j].v[i] = Padd (t1, t2);
+#else
+	/* HB: the above is really nice, but is there any other compiler
+	 * supporting this ??
+	 */
+        real_coordinate_type t1;
+        real_coordinate_type t2;
+        t1.x = V[j - 1].v[i].x * one_minus_t;
+        t1.y = V[j - 1].v[i].y * one_minus_t;
+        t2.x = V[j - 1].v[i + 1].x * t;
+        t2.y = V[j - 1].v[i + 1].y * t;
+        V[j].v[i].x = t1.x + t2.x;
+        V[j].v[i].y = t1.y + t2.y;
+#endif
+      }
+
+  return V[degree].v[0];
+}
+
+
+
+/* Return a new, empty, spline list.  */
+
+spline_list_type *
+new_spline_list (void)
+{
+  spline_list_type *answer = g_new (spline_list_type, 1);
+
+  SPLINE_LIST_DATA (*answer) = NULL;
+  SPLINE_LIST_LENGTH (*answer) = 0;
+
+  return answer;
+}
+
+
+/* Return a new spline list with SPLINE as the first element.  */
+
+spline_list_type *
+init_spline_list (spline_type spline)
+{
+  spline_list_type *answer = g_new (spline_list_type, 1);
+
+  SPLINE_LIST_DATA (*answer) = g_new (spline_type, 1);
+  SPLINE_LIST_ELT (*answer, 0) = spline;
+  SPLINE_LIST_LENGTH (*answer) = 1;
+
+  return answer;
+}
+
+
+/* Free the storage in a spline list.  We don't have to free the
+   elements, since they are arrays in automatic storage.  And we don't
+   want to free the list if it was empty.  */
+
+void
+free_spline_list (spline_list_type *spline_list)
+{
+  if (SPLINE_LIST_DATA (*spline_list) != NULL)
+    safe_free ((address *) &(SPLINE_LIST_DATA (*spline_list)));
+}
+
+
+/* Append the spline S to the list SPLINE_LIST.  */
+
+void
+append_spline (spline_list_type *l, spline_type s)
+{
+  assert (l != NULL);
+
+  SPLINE_LIST_LENGTH (*l)++;
+  SPLINE_LIST_DATA (*l) = g_realloc (SPLINE_LIST_DATA (*l),
+                               SPLINE_LIST_LENGTH (*l) * sizeof (spline_type));
+  LAST_SPLINE_LIST_ELT (*l) = s;
+}
+
+
+/* Tack the elements in the list S2 onto the end of S1.
+   S2 is not changed.  */
+
+void
+concat_spline_lists (spline_list_type *s1, spline_list_type s2)
+{
+  unsigned this_spline;
+  unsigned new_length;
+
+  assert (s1 != NULL);
+
+  new_length = SPLINE_LIST_LENGTH (*s1) + SPLINE_LIST_LENGTH (s2);
+
+  SPLINE_LIST_DATA (*s1) = g_realloc(SPLINE_LIST_DATA (*s1),new_length * sizeof(spline_type));
+
+  for (this_spline = 0; this_spline < SPLINE_LIST_LENGTH (s2); this_spline++)
+    SPLINE_LIST_ELT (*s1, SPLINE_LIST_LENGTH (*s1)++)
+      = SPLINE_LIST_ELT (s2, this_spline);
+}
+
+
+/* Return a new, empty, spline list array.  */
+
+spline_list_array_type
+new_spline_list_array (void)
+{
+  spline_list_array_type answer;
+
+  SPLINE_LIST_ARRAY_DATA (answer) = NULL;
+  SPLINE_LIST_ARRAY_LENGTH (answer) = 0;
+
+  return answer;
+}
+
+
+/* Free the storage in a spline list array.  We don't
+   want to free the list if it is empty.  */
+
+void
+free_spline_list_array (spline_list_array_type *spline_list_array)
+{
+  unsigned this_list;
+
+  for (this_list = 0;
+       this_list < SPLINE_LIST_ARRAY_LENGTH (*spline_list_array);
+       this_list++)
+    free_spline_list (&SPLINE_LIST_ARRAY_ELT (*spline_list_array, this_list));
+
+  if (SPLINE_LIST_ARRAY_DATA (*spline_list_array) != NULL)
+    safe_free ((address *) &(SPLINE_LIST_ARRAY_DATA (*spline_list_array)));
+}
+
+
+/* Append the spline S to the list SPLINE_LIST_ARRAY.  */
+
+void
+append_spline_list (spline_list_array_type *l, spline_list_type s)
+{
+  SPLINE_LIST_ARRAY_LENGTH (*l)++;
+
+  SPLINE_LIST_ARRAY_DATA (*l) = g_realloc(SPLINE_LIST_ARRAY_DATA (*l),(SPLINE_LIST_ARRAY_LENGTH (*l))*sizeof(spline_list_type));
+  LAST_SPLINE_LIST_ARRAY_ELT (*l) = s;
+}