Adding upstream version 2.10.34.upstream/2.10.34upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1431 insertions, 0 deletions

diff --git a/app/vectors/gimpstroke.c b/app/vectors/gimpstroke.c
new file mode 100644
index 0000000..3a3ab90
--- /dev/null
+++ b/app/vectors/gimpstroke.c
@@ -0,0 +1,1431 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpstroke.c
+ * Copyright (C) 2002 Simon Budig  <simon@gimp.org>
+ *
+ * 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 of the License, 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 <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "vectors-types.h"
+
+#include "core/gimp-memsize.h"
+#include "core/gimpcoords.h"
+#include "core/gimpparamspecs.h"
+#include "core/gimp-transform-utils.h"
+
+#include "gimpanchor.h"
+#include "gimpstroke.h"
+
+enum
+{
+  PROP_0,
+  PROP_CONTROL_POINTS,
+  PROP_CLOSED
+};
+
+/* Prototypes */
+
+static void    gimp_stroke_set_property              (GObject      *object,
+                                                      guint         property_id,
+                                                      const GValue *value,
+                                                      GParamSpec   *pspec);
+static void    gimp_stroke_get_property              (GObject      *object,
+                                                      guint         property_id,
+                                                      GValue       *value,
+                                                      GParamSpec   *pspec);
+static void    gimp_stroke_finalize                  (GObject      *object);
+
+static gint64  gimp_stroke_get_memsize               (GimpObject   *object,
+                                                      gint64       *gui_size);
+
+static GimpAnchor * gimp_stroke_real_anchor_get      (GimpStroke       *stroke,
+                                                      const GimpCoords *coord);
+static GimpAnchor * gimp_stroke_real_anchor_get_next (GimpStroke       *stroke,
+                                                      const GimpAnchor *prev);
+static void         gimp_stroke_real_anchor_select   (GimpStroke       *stroke,
+                                                      GimpAnchor       *anchor,
+                                                      gboolean          selected,
+                                                      gboolean          exclusive);
+static void    gimp_stroke_real_anchor_move_relative (GimpStroke       *stroke,
+                                                      GimpAnchor       *anchor,
+                                                      const GimpCoords *delta,
+                                                      GimpAnchorFeatureType feature);
+static void    gimp_stroke_real_anchor_move_absolute (GimpStroke       *stroke,
+                                                      GimpAnchor       *anchor,
+                                                      const GimpCoords *delta,
+                                                      GimpAnchorFeatureType feature);
+static void         gimp_stroke_real_anchor_convert  (GimpStroke       *stroke,
+                                                      GimpAnchor       *anchor,
+                                                      GimpAnchorFeatureType  feature);
+static void         gimp_stroke_real_anchor_delete   (GimpStroke       *stroke,
+                                                      GimpAnchor       *anchor);
+static gboolean     gimp_stroke_real_point_is_movable
+                                              (GimpStroke            *stroke,
+                                               GimpAnchor            *predec,
+                                               gdouble                position);
+static void         gimp_stroke_real_point_move_relative
+                                              (GimpStroke            *stroke,
+                                               GimpAnchor            *predec,
+                                               gdouble                position,
+                                               const GimpCoords      *deltacoord,
+                                               GimpAnchorFeatureType  feature);
+static void         gimp_stroke_real_point_move_absolute
+                                              (GimpStroke            *stroke,
+                                               GimpAnchor            *predec,
+                                               gdouble                position,
+                                               const GimpCoords      *coord,
+                                               GimpAnchorFeatureType  feature);
+
+static void         gimp_stroke_real_close           (GimpStroke       *stroke);
+static GimpStroke * gimp_stroke_real_open            (GimpStroke       *stroke,
+                                                      GimpAnchor       *end_anchor);
+static gboolean     gimp_stroke_real_anchor_is_insertable
+                                                     (GimpStroke       *stroke,
+                                                      GimpAnchor       *predec,
+                                                      gdouble           position);
+static GimpAnchor * gimp_stroke_real_anchor_insert   (GimpStroke       *stroke,
+                                                      GimpAnchor       *predec,
+                                                      gdouble           position);
+
+static gboolean     gimp_stroke_real_is_extendable   (GimpStroke       *stroke,
+                                                      GimpAnchor       *neighbor);
+
+static GimpAnchor * gimp_stroke_real_extend (GimpStroke           *stroke,
+                                             const GimpCoords     *coords,
+                                             GimpAnchor           *neighbor,
+                                             GimpVectorExtendMode  extend_mode);
+
+gboolean     gimp_stroke_real_connect_stroke (GimpStroke          *stroke,
+                                              GimpAnchor          *anchor,
+                                              GimpStroke          *extension,
+                                              GimpAnchor          *neighbor);
+
+
+static gboolean     gimp_stroke_real_is_empty        (GimpStroke       *stroke);
+
+static gdouble      gimp_stroke_real_get_length      (GimpStroke       *stroke,
+                                                      gdouble           precision);
+static gdouble      gimp_stroke_real_get_distance    (GimpStroke       *stroke,
+                                                      const GimpCoords *coord);
+static GArray *     gimp_stroke_real_interpolate     (GimpStroke       *stroke,
+                                                      gdouble           precision,
+                                                      gboolean         *closed);
+static GimpStroke * gimp_stroke_real_duplicate       (GimpStroke       *stroke);
+static GimpBezierDesc * gimp_stroke_real_make_bezier (GimpStroke       *stroke);
+
+static void         gimp_stroke_real_translate       (GimpStroke       *stroke,
+                                                      gdouble           offset_x,
+                                                      gdouble           offset_y);
+static void         gimp_stroke_real_scale           (GimpStroke       *stroke,
+                                                      gdouble           scale_x,
+                                                      gdouble           scale_y);
+static void         gimp_stroke_real_rotate          (GimpStroke       *stroke,
+                                                      gdouble           center_x,
+                                                      gdouble           center_y,
+                                                      gdouble           angle);
+static void         gimp_stroke_real_flip            (GimpStroke       *stroke,
+                                                      GimpOrientationType flip_type,
+                                                      gdouble           axis);
+static void         gimp_stroke_real_flip_free       (GimpStroke       *stroke,
+                                                      gdouble           x1,
+                                                      gdouble           y1,
+                                                      gdouble           x2,
+                                                      gdouble           y2);
+static void         gimp_stroke_real_transform       (GimpStroke        *stroke,
+                                                      const GimpMatrix3 *matrix,
+                                                      GQueue            *ret_strokes);
+
+static GList    * gimp_stroke_real_get_draw_anchors  (GimpStroke       *stroke);
+static GList    * gimp_stroke_real_get_draw_controls (GimpStroke       *stroke);
+static GArray   * gimp_stroke_real_get_draw_lines    (GimpStroke       *stroke);
+static GArray *  gimp_stroke_real_control_points_get (GimpStroke       *stroke,
+                                                      gboolean         *ret_closed);
+static gboolean   gimp_stroke_real_get_point_at_dist (GimpStroke       *stroke,
+                                                      gdouble           dist,
+                                                      gdouble           precision,
+                                                      GimpCoords       *position,
+                                                      gdouble          *slope);
+
+
+G_DEFINE_TYPE (GimpStroke, gimp_stroke, GIMP_TYPE_OBJECT)
+
+#define parent_class gimp_stroke_parent_class
+
+
+static void
+gimp_stroke_class_init (GimpStrokeClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GParamSpec      *param_spec;
+
+  object_class->finalize          = gimp_stroke_finalize;
+  object_class->get_property      = gimp_stroke_get_property;
+  object_class->set_property      = gimp_stroke_set_property;
+
+  gimp_object_class->get_memsize  = gimp_stroke_get_memsize;
+
+  klass->changed                  = NULL;
+  klass->removed                  = NULL;
+
+  klass->anchor_get               = gimp_stroke_real_anchor_get;
+  klass->anchor_get_next          = gimp_stroke_real_anchor_get_next;
+  klass->anchor_select            = gimp_stroke_real_anchor_select;
+  klass->anchor_move_relative     = gimp_stroke_real_anchor_move_relative;
+  klass->anchor_move_absolute     = gimp_stroke_real_anchor_move_absolute;
+  klass->anchor_convert           = gimp_stroke_real_anchor_convert;
+  klass->anchor_delete            = gimp_stroke_real_anchor_delete;
+
+  klass->point_is_movable         = gimp_stroke_real_point_is_movable;
+  klass->point_move_relative      = gimp_stroke_real_point_move_relative;
+  klass->point_move_absolute      = gimp_stroke_real_point_move_absolute;
+
+  klass->nearest_point_get        = NULL;
+  klass->nearest_tangent_get      = NULL;
+  klass->nearest_intersection_get = NULL;
+  klass->close                    = gimp_stroke_real_close;
+  klass->open                     = gimp_stroke_real_open;
+  klass->anchor_is_insertable     = gimp_stroke_real_anchor_is_insertable;
+  klass->anchor_insert            = gimp_stroke_real_anchor_insert;
+  klass->is_extendable            = gimp_stroke_real_is_extendable;
+  klass->extend                   = gimp_stroke_real_extend;
+  klass->connect_stroke           = gimp_stroke_real_connect_stroke;
+
+  klass->is_empty                 = gimp_stroke_real_is_empty;
+  klass->get_length               = gimp_stroke_real_get_length;
+  klass->get_distance             = gimp_stroke_real_get_distance;
+  klass->get_point_at_dist        = gimp_stroke_real_get_point_at_dist;
+  klass->interpolate              = gimp_stroke_real_interpolate;
+
+  klass->duplicate                = gimp_stroke_real_duplicate;
+  klass->make_bezier              = gimp_stroke_real_make_bezier;
+
+  klass->translate                = gimp_stroke_real_translate;
+  klass->scale                    = gimp_stroke_real_scale;
+  klass->rotate                   = gimp_stroke_real_rotate;
+  klass->flip                     = gimp_stroke_real_flip;
+  klass->flip_free                = gimp_stroke_real_flip_free;
+  klass->transform                = gimp_stroke_real_transform;
+
+
+  klass->get_draw_anchors         = gimp_stroke_real_get_draw_anchors;
+  klass->get_draw_controls        = gimp_stroke_real_get_draw_controls;
+  klass->get_draw_lines           = gimp_stroke_real_get_draw_lines;
+  klass->control_points_get       = gimp_stroke_real_control_points_get;
+
+  param_spec = g_param_spec_boxed ("gimp-anchor",
+                                   "Gimp Anchor",
+                                   "The control points of a Stroke",
+                                   GIMP_TYPE_ANCHOR,
+                                   GIMP_PARAM_WRITABLE |
+                                   G_PARAM_CONSTRUCT_ONLY);
+  g_object_class_install_property (object_class, PROP_CONTROL_POINTS,
+                                   gimp_param_spec_value_array ("control-points",
+                                                                "Control Points",
+                                                                "This is an ValueArray "
+                                                                "with the initial "
+                                                                "control points of "
+                                                                "the new Stroke",
+                                                                param_spec,
+                                                                GIMP_PARAM_WRITABLE |
+                                                                G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_CLOSED,
+                                   g_param_spec_boolean ("closed",
+                                                         "Close Flag",
+                                                         "this flag indicates "
+                                                         "whether the stroke "
+                                                         "is closed or not",
+                                                         FALSE,
+                                                         GIMP_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_stroke_init (GimpStroke *stroke)
+{
+  stroke->anchors = g_queue_new ();
+}
+
+static void
+gimp_stroke_set_property (GObject      *object,
+                          guint         property_id,
+                          const GValue *value,
+                          GParamSpec   *pspec)
+{
+  GimpStroke     *stroke = GIMP_STROKE (object);
+  GimpValueArray *val_array;
+  gint            length;
+  gint            i;
+
+  switch (property_id)
+    {
+    case PROP_CLOSED:
+      stroke->closed = g_value_get_boolean (value);
+      break;
+
+    case PROP_CONTROL_POINTS:
+      g_return_if_fail (g_queue_is_empty (stroke->anchors));
+      g_return_if_fail (value != NULL);
+
+      val_array = g_value_get_boxed (value);
+
+      if (val_array == NULL)
+        return;
+
+      length = gimp_value_array_length (val_array);
+
+      for (i = 0; i < length; i++)
+        {
+          GValue *item = gimp_value_array_index (val_array, i);
+
+          g_return_if_fail (G_VALUE_HOLDS (item, GIMP_TYPE_ANCHOR));
+          g_queue_push_tail (stroke->anchors, g_value_dup_boxed (item));
+        }
+
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_stroke_get_property (GObject    *object,
+                          guint       property_id,
+                          GValue     *value,
+                          GParamSpec *pspec)
+{
+  GimpStroke *stroke = GIMP_STROKE (object);
+
+  switch (property_id)
+    {
+    case PROP_CLOSED:
+      g_value_set_boolean (value, stroke->closed);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_stroke_finalize (GObject *object)
+{
+  GimpStroke *stroke = GIMP_STROKE (object);
+
+  g_queue_free_full (stroke->anchors, (GDestroyNotify) gimp_anchor_free);
+  stroke->anchors = NULL;
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gint64
+gimp_stroke_get_memsize (GimpObject *object,
+                         gint64     *gui_size)
+{
+  GimpStroke *stroke  = GIMP_STROKE (object);
+  gint64      memsize = 0;
+
+  memsize += gimp_g_queue_get_memsize (stroke->anchors, sizeof (GimpAnchor));
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+void
+gimp_stroke_set_ID (GimpStroke *stroke,
+                    gint        id)
+{
+  g_return_if_fail (GIMP_IS_STROKE (stroke));
+  g_return_if_fail (stroke->ID == 0 /* we don't want changing IDs... */);
+
+  stroke->ID = id;
+}
+
+gint
+gimp_stroke_get_ID (GimpStroke *stroke)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), -1);
+
+  return stroke->ID;
+}
+
+
+GimpAnchor *
+gimp_stroke_anchor_get (GimpStroke       *stroke,
+                        const GimpCoords *coord)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), NULL);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->anchor_get (stroke, coord);
+}
+
+
+gdouble
+gimp_stroke_nearest_point_get (GimpStroke       *stroke,
+                               const GimpCoords *coord,
+                               const gdouble     precision,
+                               GimpCoords       *ret_point,
+                               GimpAnchor      **ret_segment_start,
+                               GimpAnchor      **ret_segment_end,
+                               gdouble          *ret_pos)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), FALSE);
+  g_return_val_if_fail (coord != NULL, FALSE);
+
+  if (GIMP_STROKE_GET_CLASS (stroke)->nearest_point_get)
+    return GIMP_STROKE_GET_CLASS (stroke)->nearest_point_get (stroke,
+                                                              coord,
+                                                              precision,
+                                                              ret_point,
+                                                              ret_segment_start,
+                                                              ret_segment_end,
+                                                              ret_pos);
+  return -1;
+}
+
+gdouble
+gimp_stroke_nearest_tangent_get (GimpStroke            *stroke,
+                                 const GimpCoords      *coords1,
+                                 const GimpCoords      *coords2,
+                                 gdouble                precision,
+                                 GimpCoords            *nearest,
+                                 GimpAnchor           **ret_segment_start,
+                                 GimpAnchor           **ret_segment_end,
+                                 gdouble               *ret_pos)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), FALSE);
+  g_return_val_if_fail (coords1 != NULL, FALSE);
+  g_return_val_if_fail (coords2 != NULL, FALSE);
+
+  if (GIMP_STROKE_GET_CLASS (stroke)->nearest_tangent_get)
+    return GIMP_STROKE_GET_CLASS (stroke)->nearest_tangent_get (stroke,
+                                                                coords1,
+                                                                coords2,
+                                                                precision,
+                                                                nearest,
+                                                                ret_segment_start,
+                                                                ret_segment_end,
+                                                                ret_pos);
+  return -1;
+}
+
+gdouble
+gimp_stroke_nearest_intersection_get (GimpStroke        *stroke,
+                                      const GimpCoords  *coords1,
+                                      const GimpCoords  *direction,
+                                      gdouble            precision,
+                                      GimpCoords        *nearest,
+                                      GimpAnchor       **ret_segment_start,
+                                      GimpAnchor       **ret_segment_end,
+                                      gdouble           *ret_pos)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), FALSE);
+  g_return_val_if_fail (coords1 != NULL, FALSE);
+  g_return_val_if_fail (direction != NULL, FALSE);
+
+  if (GIMP_STROKE_GET_CLASS (stroke)->nearest_intersection_get)
+    return GIMP_STROKE_GET_CLASS (stroke)->nearest_intersection_get (stroke,
+                                                                     coords1,
+                                                                     direction,
+                                                                     precision,
+                                                                     nearest,
+                                                                     ret_segment_start,
+                                                                     ret_segment_end,
+                                                                     ret_pos);
+  return -1;
+}
+
+static GimpAnchor *
+gimp_stroke_real_anchor_get (GimpStroke       *stroke,
+                             const GimpCoords *coord)
+{
+  gdouble     dx, dy;
+  gdouble     mindist = -1;
+  GList      *anchors;
+  GList      *list;
+  GimpAnchor *anchor = NULL;
+
+  anchors = gimp_stroke_get_draw_controls (stroke);
+
+  for (list = anchors; list; list = g_list_next (list))
+    {
+      dx = coord->x - GIMP_ANCHOR (list->data)->position.x;
+      dy = coord->y - GIMP_ANCHOR (list->data)->position.y;
+
+      if (mindist < 0 || mindist > dx * dx + dy * dy)
+        {
+          mindist = dx * dx + dy * dy;
+          anchor = GIMP_ANCHOR (list->data);
+        }
+    }
+
+  g_list_free (anchors);
+
+  anchors = gimp_stroke_get_draw_anchors (stroke);
+
+  for (list = anchors; list; list = g_list_next (list))
+    {
+      dx = coord->x - GIMP_ANCHOR (list->data)->position.x;
+      dy = coord->y - GIMP_ANCHOR (list->data)->position.y;
+
+      if (mindist < 0 || mindist > dx * dx + dy * dy)
+        {
+          mindist = dx * dx + dy * dy;
+          anchor = GIMP_ANCHOR (list->data);
+        }
+    }
+
+  g_list_free (anchors);
+
+  return anchor;
+}
+
+
+GimpAnchor *
+gimp_stroke_anchor_get_next (GimpStroke       *stroke,
+                             const GimpAnchor *prev)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), NULL);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->anchor_get_next (stroke, prev);
+}
+
+static GimpAnchor *
+gimp_stroke_real_anchor_get_next (GimpStroke       *stroke,
+                                  const GimpAnchor *prev)
+{
+  GList *list;
+
+  if (prev)
+    {
+      list = g_queue_find (stroke->anchors, prev);
+      if (list)
+        list = g_list_next (list);
+    }
+  else
+    {
+      list = stroke->anchors->head;
+    }
+
+  if (list)
+    return GIMP_ANCHOR (list->data);
+
+  return NULL;
+}
+
+
+void
+gimp_stroke_anchor_select (GimpStroke *stroke,
+                           GimpAnchor *anchor,
+                           gboolean    selected,
+                           gboolean    exclusive)
+{
+  g_return_if_fail (GIMP_IS_STROKE (stroke));
+
+  GIMP_STROKE_GET_CLASS (stroke)->anchor_select (stroke, anchor,
+                                                 selected, exclusive);
+}
+
+static void
+gimp_stroke_real_anchor_select (GimpStroke *stroke,
+                                GimpAnchor *anchor,
+                                gboolean    selected,
+                                gboolean    exclusive)
+{
+  GList *list = stroke->anchors->head;
+
+  if (exclusive)
+    {
+      while (list)
+        {
+          GIMP_ANCHOR (list->data)->selected = FALSE;
+          list = g_list_next (list);
+        }
+    }
+
+  list = g_queue_find (stroke->anchors, anchor);
+
+  if (list)
+    GIMP_ANCHOR (list->data)->selected = selected;
+}
+
+
+void
+gimp_stroke_anchor_move_relative (GimpStroke            *stroke,
+                                  GimpAnchor            *anchor,
+                                  const GimpCoords      *delta,
+                                  GimpAnchorFeatureType  feature)
+{
+  g_return_if_fail (GIMP_IS_STROKE (stroke));
+  g_return_if_fail (anchor != NULL);
+  g_return_if_fail (g_queue_find (stroke->anchors, anchor));
+
+  GIMP_STROKE_GET_CLASS (stroke)->anchor_move_relative (stroke, anchor,
+                                                        delta, feature);
+}
+
+static void
+gimp_stroke_real_anchor_move_relative (GimpStroke            *stroke,
+                                       GimpAnchor            *anchor,
+                                       const GimpCoords      *delta,
+                                       GimpAnchorFeatureType  feature)
+{
+  anchor->position.x += delta->x;
+  anchor->position.y += delta->y;
+}
+
+
+void
+gimp_stroke_anchor_move_absolute (GimpStroke            *stroke,
+                                  GimpAnchor            *anchor,
+                                  const GimpCoords      *coord,
+                                  GimpAnchorFeatureType  feature)
+{
+  g_return_if_fail (GIMP_IS_STROKE (stroke));
+  g_return_if_fail (anchor != NULL);
+  g_return_if_fail (g_queue_find (stroke->anchors, anchor));
+
+  GIMP_STROKE_GET_CLASS (stroke)->anchor_move_absolute (stroke, anchor,
+                                                        coord, feature);
+}
+
+static void
+gimp_stroke_real_anchor_move_absolute (GimpStroke            *stroke,
+                                       GimpAnchor            *anchor,
+                                       const GimpCoords      *coord,
+                                       GimpAnchorFeatureType  feature)
+{
+  anchor->position.x = coord->x;
+  anchor->position.y = coord->y;
+}
+
+gboolean
+gimp_stroke_point_is_movable (GimpStroke *stroke,
+                              GimpAnchor *predec,
+                              gdouble     position)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), FALSE);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->point_is_movable (stroke, predec,
+                                                           position);
+}
+
+
+static gboolean
+gimp_stroke_real_point_is_movable (GimpStroke *stroke,
+                                   GimpAnchor *predec,
+                                   gdouble     position)
+{
+  return FALSE;
+}
+
+
+void
+gimp_stroke_point_move_relative (GimpStroke            *stroke,
+                                 GimpAnchor            *predec,
+                                 gdouble                position,
+                                 const GimpCoords      *deltacoord,
+                                 GimpAnchorFeatureType  feature)
+{
+  g_return_if_fail (GIMP_IS_STROKE (stroke));
+
+  GIMP_STROKE_GET_CLASS (stroke)->point_move_relative (stroke, predec,
+                                                       position, deltacoord,
+                                                       feature);
+}
+
+
+static void
+gimp_stroke_real_point_move_relative (GimpStroke           *stroke,
+                                      GimpAnchor           *predec,
+                                      gdouble               position,
+                                      const GimpCoords     *deltacoord,
+                                      GimpAnchorFeatureType feature)
+{
+  g_printerr ("gimp_stroke_point_move_relative: default implementation\n");
+}
+
+
+void
+gimp_stroke_point_move_absolute (GimpStroke            *stroke,
+                                 GimpAnchor            *predec,
+                                 gdouble                position,
+                                 const GimpCoords      *coord,
+                                 GimpAnchorFeatureType  feature)
+{
+  g_return_if_fail (GIMP_IS_STROKE (stroke));
+
+  GIMP_STROKE_GET_CLASS (stroke)->point_move_absolute (stroke, predec,
+                                                       position, coord,
+                                                       feature);
+}
+
+static void
+gimp_stroke_real_point_move_absolute (GimpStroke           *stroke,
+                                      GimpAnchor           *predec,
+                                      gdouble               position,
+                                      const GimpCoords     *coord,
+                                      GimpAnchorFeatureType feature)
+{
+  g_printerr ("gimp_stroke_point_move_absolute: default implementation\n");
+}
+
+
+void
+gimp_stroke_close (GimpStroke *stroke)
+{
+  g_return_if_fail (GIMP_IS_STROKE (stroke));
+  g_return_if_fail (g_queue_is_empty (stroke->anchors) == FALSE);
+
+  GIMP_STROKE_GET_CLASS (stroke)->close (stroke);
+}
+
+static void
+gimp_stroke_real_close (GimpStroke *stroke)
+{
+  stroke->closed = TRUE;
+  g_object_notify (G_OBJECT (stroke), "closed");
+}
+
+
+void
+gimp_stroke_anchor_convert (GimpStroke            *stroke,
+                            GimpAnchor            *anchor,
+                            GimpAnchorFeatureType  feature)
+{
+  g_return_if_fail (GIMP_IS_STROKE (stroke));
+
+  GIMP_STROKE_GET_CLASS (stroke)->anchor_convert (stroke, anchor, feature);
+}
+
+static void
+gimp_stroke_real_anchor_convert (GimpStroke            *stroke,
+                                 GimpAnchor            *anchor,
+                                 GimpAnchorFeatureType  feature)
+{
+  g_printerr ("gimp_stroke_anchor_convert: default implementation\n");
+}
+
+
+void
+gimp_stroke_anchor_delete (GimpStroke *stroke,
+                           GimpAnchor *anchor)
+{
+  g_return_if_fail (GIMP_IS_STROKE (stroke));
+  g_return_if_fail (anchor && anchor->type == GIMP_ANCHOR_ANCHOR);
+
+  GIMP_STROKE_GET_CLASS (stroke)->anchor_delete (stroke, anchor);
+}
+
+static void
+gimp_stroke_real_anchor_delete (GimpStroke *stroke,
+                                GimpAnchor *anchor)
+{
+  g_printerr ("gimp_stroke_anchor_delete: default implementation\n");
+}
+
+GimpStroke *
+gimp_stroke_open (GimpStroke *stroke,
+                  GimpAnchor *end_anchor)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), NULL);
+  g_return_val_if_fail (end_anchor &&
+                        end_anchor->type == GIMP_ANCHOR_ANCHOR, NULL);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->open (stroke, end_anchor);
+}
+
+static GimpStroke *
+gimp_stroke_real_open (GimpStroke *stroke,
+                       GimpAnchor *end_anchor)
+{
+  g_printerr ("gimp_stroke_open: default implementation\n");
+  return NULL;
+}
+
+gboolean
+gimp_stroke_anchor_is_insertable (GimpStroke *stroke,
+                                  GimpAnchor *predec,
+                                  gdouble     position)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), FALSE);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->anchor_is_insertable (stroke,
+                                                               predec,
+                                                               position);
+}
+
+static gboolean
+gimp_stroke_real_anchor_is_insertable (GimpStroke *stroke,
+                                       GimpAnchor *predec,
+                                       gdouble     position)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), FALSE);
+
+  return FALSE;
+}
+
+GimpAnchor *
+gimp_stroke_anchor_insert (GimpStroke *stroke,
+                           GimpAnchor *predec,
+                           gdouble     position)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), NULL);
+  g_return_val_if_fail (predec->type == GIMP_ANCHOR_ANCHOR, NULL);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->anchor_insert (stroke,
+                                                        predec, position);
+}
+
+static GimpAnchor *
+gimp_stroke_real_anchor_insert (GimpStroke *stroke,
+                                GimpAnchor *predec,
+                                gdouble     position)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), NULL);
+
+  return NULL;
+}
+
+
+gboolean
+gimp_stroke_is_extendable (GimpStroke *stroke,
+                           GimpAnchor *neighbor)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), FALSE);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->is_extendable (stroke, neighbor);
+}
+
+static gboolean
+gimp_stroke_real_is_extendable (GimpStroke *stroke,
+                                GimpAnchor *neighbor)
+{
+  return FALSE;
+}
+
+
+GimpAnchor *
+gimp_stroke_extend (GimpStroke           *stroke,
+                    const GimpCoords     *coords,
+                    GimpAnchor           *neighbor,
+                    GimpVectorExtendMode  extend_mode)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), NULL);
+  g_return_val_if_fail (!stroke->closed, NULL);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->extend (stroke, coords,
+                                                 neighbor, extend_mode);
+}
+
+static GimpAnchor *
+gimp_stroke_real_extend (GimpStroke           *stroke,
+                         const GimpCoords     *coords,
+                         GimpAnchor           *neighbor,
+                         GimpVectorExtendMode  extend_mode)
+{
+  g_printerr ("gimp_stroke_extend: default implementation\n");
+  return NULL;
+}
+
+gboolean
+gimp_stroke_connect_stroke (GimpStroke *stroke,
+                            GimpAnchor *anchor,
+                            GimpStroke *extension,
+                            GimpAnchor *neighbor)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), FALSE);
+  g_return_val_if_fail (GIMP_IS_STROKE (extension), FALSE);
+  g_return_val_if_fail (stroke->closed == FALSE &&
+                        extension->closed == FALSE, FALSE);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->connect_stroke (stroke, anchor,
+                                                         extension, neighbor);
+}
+
+gboolean
+gimp_stroke_real_connect_stroke (GimpStroke *stroke,
+                                 GimpAnchor *anchor,
+                                 GimpStroke *extension,
+                                 GimpAnchor *neighbor)
+{
+  g_printerr ("gimp_stroke_connect_stroke: default implementation\n");
+  return FALSE;
+}
+
+gboolean
+gimp_stroke_is_empty (GimpStroke *stroke)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), FALSE);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->is_empty (stroke);
+}
+
+static gboolean
+gimp_stroke_real_is_empty (GimpStroke *stroke)
+{
+  return g_queue_is_empty (stroke->anchors);
+}
+
+
+gdouble
+gimp_stroke_get_length (GimpStroke *stroke,
+                        gdouble     precision)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), 0.0);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->get_length (stroke, precision);
+}
+
+static gdouble
+gimp_stroke_real_get_length (GimpStroke *stroke,
+                             gdouble     precision)
+{
+  GArray     *points;
+  gint        i;
+  gdouble     length;
+  GimpCoords  difference;
+
+  if (g_queue_is_empty (stroke->anchors))
+    return -1;
+
+  points = gimp_stroke_interpolate (stroke, precision, NULL);
+  if (points == NULL)
+    return -1;
+
+  length = 0;
+
+  for (i = 0; i < points->len - 1; i++ )
+    {
+       gimp_coords_difference (&(g_array_index (points, GimpCoords, i)),
+                               &(g_array_index (points, GimpCoords, i+1)),
+                               &difference);
+       length += gimp_coords_length (&difference);
+    }
+
+  g_array_free(points, TRUE);
+
+  return length;
+}
+
+
+gdouble
+gimp_stroke_get_distance (GimpStroke       *stroke,
+                          const GimpCoords *coord)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), 0.0);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->get_distance (stroke, coord);
+}
+
+static gdouble
+gimp_stroke_real_get_distance (GimpStroke       *stroke,
+                               const GimpCoords *coord)
+{
+  g_printerr ("gimp_stroke_get_distance: default implementation\n");
+
+  return 0.0;
+}
+
+
+GArray *
+gimp_stroke_interpolate (GimpStroke *stroke,
+                         gdouble     precision,
+                         gboolean   *ret_closed)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), NULL);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->interpolate (stroke, precision,
+                                                      ret_closed);
+}
+
+static GArray *
+gimp_stroke_real_interpolate (GimpStroke *stroke,
+                              gdouble     precision,
+                              gboolean   *ret_closed)
+{
+  g_printerr ("gimp_stroke_interpolate: default implementation\n");
+
+  return NULL;
+}
+
+GimpStroke *
+gimp_stroke_duplicate (GimpStroke *stroke)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), NULL);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->duplicate (stroke);
+}
+
+static GimpStroke *
+gimp_stroke_real_duplicate (GimpStroke *stroke)
+{
+  GimpStroke *new_stroke;
+  GList      *list;
+
+  new_stroke = g_object_new (G_TYPE_FROM_INSTANCE (stroke),
+                             "name", gimp_object_get_name (stroke),
+                             NULL);
+
+  g_queue_free_full (new_stroke->anchors, (GDestroyNotify) gimp_anchor_free);
+  new_stroke->anchors = g_queue_copy (stroke->anchors);
+
+  for (list = new_stroke->anchors->head; list; list = g_list_next (list))
+    {
+      list->data = gimp_anchor_copy (GIMP_ANCHOR (list->data));
+    }
+
+  new_stroke->closed = stroke->closed;
+  /* we do *not* copy the ID! */
+
+  return new_stroke;
+}
+
+
+GimpBezierDesc *
+gimp_stroke_make_bezier (GimpStroke *stroke)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), NULL);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->make_bezier (stroke);
+}
+
+static GimpBezierDesc *
+gimp_stroke_real_make_bezier (GimpStroke *stroke)
+{
+  g_printerr ("gimp_stroke_make_bezier: default implementation\n");
+
+  return NULL;
+}
+
+
+void
+gimp_stroke_translate (GimpStroke *stroke,
+                       gdouble     offset_x,
+                       gdouble     offset_y)
+{
+  g_return_if_fail (GIMP_IS_STROKE (stroke));
+
+  GIMP_STROKE_GET_CLASS (stroke)->translate (stroke, offset_x, offset_y);
+}
+
+static void
+gimp_stroke_real_translate (GimpStroke *stroke,
+                            gdouble     offset_x,
+                            gdouble     offset_y)
+{
+  GList *list;
+
+  for (list = stroke->anchors->head; list; list = g_list_next (list))
+    {
+      GimpAnchor *anchor = list->data;
+
+      anchor->position.x += offset_x;
+      anchor->position.y += offset_y;
+    }
+}
+
+
+void
+gimp_stroke_scale (GimpStroke *stroke,
+                   gdouble     scale_x,
+                   gdouble     scale_y)
+{
+  g_return_if_fail (GIMP_IS_STROKE (stroke));
+
+  GIMP_STROKE_GET_CLASS (stroke)->scale (stroke, scale_x, scale_y);
+}
+
+static void
+gimp_stroke_real_scale (GimpStroke *stroke,
+                        gdouble     scale_x,
+                        gdouble     scale_y)
+{
+  GList *list;
+
+  for (list = stroke->anchors->head; list; list = g_list_next (list))
+    {
+      GimpAnchor *anchor = list->data;
+
+      anchor->position.x *= scale_x;
+      anchor->position.y *= scale_y;
+    }
+}
+
+void
+gimp_stroke_rotate (GimpStroke *stroke,
+                    gdouble     center_x,
+                    gdouble     center_y,
+                    gdouble     angle)
+{
+  g_return_if_fail (GIMP_IS_STROKE (stroke));
+
+  GIMP_STROKE_GET_CLASS (stroke)->rotate (stroke, center_x, center_y, angle);
+}
+
+static void
+gimp_stroke_real_rotate (GimpStroke *stroke,
+                         gdouble     center_x,
+                         gdouble     center_y,
+                         gdouble     angle)
+{
+  GimpMatrix3  matrix;
+
+  angle = angle / 180.0 * G_PI;
+  gimp_matrix3_identity (&matrix);
+  gimp_transform_matrix_rotate_center (&matrix, center_x, center_y, angle);
+
+  gimp_stroke_transform (stroke, &matrix, NULL);
+}
+
+void
+gimp_stroke_flip (GimpStroke          *stroke,
+                  GimpOrientationType  flip_type,
+                  gdouble              axis)
+{
+  g_return_if_fail (GIMP_IS_STROKE (stroke));
+
+  GIMP_STROKE_GET_CLASS (stroke)->flip (stroke, flip_type, axis);
+}
+
+static void
+gimp_stroke_real_flip (GimpStroke          *stroke,
+                       GimpOrientationType  flip_type,
+                       gdouble              axis)
+{
+  GimpMatrix3  matrix;
+
+  gimp_matrix3_identity (&matrix);
+  gimp_transform_matrix_flip (&matrix, flip_type, axis);
+  gimp_stroke_transform (stroke, &matrix, NULL);
+}
+
+void
+gimp_stroke_flip_free (GimpStroke *stroke,
+                       gdouble     x1,
+                       gdouble     y1,
+                       gdouble     x2,
+                       gdouble     y2)
+{
+  g_return_if_fail (GIMP_IS_STROKE (stroke));
+
+  GIMP_STROKE_GET_CLASS (stroke)->flip_free (stroke, x1, y1, x2, y2);
+}
+
+static void
+gimp_stroke_real_flip_free (GimpStroke *stroke,
+                            gdouble     x1,
+                            gdouble     y1,
+                            gdouble     x2,
+                            gdouble     y2)
+{
+  /* x, y, width and height parameter in gimp_transform_matrix_flip_free are unused */
+  GimpMatrix3  matrix;
+
+  gimp_matrix3_identity (&matrix);
+  gimp_transform_matrix_flip_free (&matrix, x1, y1, x2, y2);
+
+  gimp_stroke_transform (stroke, &matrix, NULL);
+}
+
+/* transforms 'stroke' by 'matrix'.  due to clipping, the transformation may
+ * result in multiple strokes.
+ *
+ * if 'ret_strokes' is not NULL, the transformed strokes are appended to the
+ * queue, and 'stroke' is left in an unspecified state.  one of the resulting
+ * strokes may alias 'stroke'.
+ *
+ * if 'ret_strokes' is NULL, the transformation is performed in-place.  if the
+ * transformation results in multiple strokes (which, atm, can only happen for
+ * non-affine transformation), the result is undefined.
+ */
+void
+gimp_stroke_transform (GimpStroke        *stroke,
+                       const GimpMatrix3 *matrix,
+                       GQueue            *ret_strokes)
+{
+  g_return_if_fail (GIMP_IS_STROKE (stroke));
+
+  GIMP_STROKE_GET_CLASS (stroke)->transform (stroke, matrix, ret_strokes);
+}
+
+static void
+gimp_stroke_real_transform (GimpStroke        *stroke,
+                            const GimpMatrix3 *matrix,
+                            GQueue            *ret_strokes)
+{
+  GList *list;
+
+  for (list = stroke->anchors->head; list; list = g_list_next (list))
+    {
+      GimpAnchor *anchor = list->data;
+
+      gimp_matrix3_transform_point (matrix,
+                                    anchor->position.x,
+                                    anchor->position.y,
+                                    &anchor->position.x,
+                                    &anchor->position.y);
+    }
+
+  if (ret_strokes)
+    {
+      stroke->ID = 0;
+
+      g_queue_push_tail (ret_strokes, g_object_ref (stroke));
+    }
+}
+
+
+GList *
+gimp_stroke_get_draw_anchors (GimpStroke *stroke)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), NULL);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->get_draw_anchors (stroke);
+}
+
+static GList *
+gimp_stroke_real_get_draw_anchors (GimpStroke *stroke)
+{
+  GList *list;
+  GList *ret_list = NULL;
+
+  for (list = stroke->anchors->head; list; list = g_list_next (list))
+    {
+      if (GIMP_ANCHOR (list->data)->type == GIMP_ANCHOR_ANCHOR)
+        ret_list = g_list_prepend (ret_list, list->data);
+    }
+
+  return g_list_reverse (ret_list);
+}
+
+
+GList *
+gimp_stroke_get_draw_controls (GimpStroke *stroke)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), NULL);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->get_draw_controls (stroke);
+}
+
+static GList *
+gimp_stroke_real_get_draw_controls (GimpStroke *stroke)
+{
+  GList *list;
+  GList *ret_list = NULL;
+
+  for (list = stroke->anchors->head; list; list = g_list_next (list))
+    {
+      GimpAnchor *anchor = list->data;
+
+      if (anchor->type == GIMP_ANCHOR_CONTROL)
+        {
+          GimpAnchor *next = list->next ? list->next->data : NULL;
+          GimpAnchor *prev = list->prev ? list->prev->data : NULL;
+
+          if (next && next->type == GIMP_ANCHOR_ANCHOR && next->selected)
+            {
+              /* Ok, this is a hack.
+               * The idea is to give control points at the end of a
+               * stroke a higher priority for the interactive tool.
+               */
+              if (prev)
+                ret_list = g_list_prepend (ret_list, anchor);
+              else
+                ret_list = g_list_append (ret_list, anchor);
+            }
+          else if (prev && prev->type == GIMP_ANCHOR_ANCHOR && prev->selected)
+            {
+              /* same here... */
+              if (next)
+                ret_list = g_list_prepend (ret_list, anchor);
+              else
+                ret_list = g_list_append (ret_list, anchor);
+            }
+        }
+    }
+
+  return g_list_reverse (ret_list);
+}
+
+
+GArray *
+gimp_stroke_get_draw_lines (GimpStroke *stroke)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), NULL);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->get_draw_lines (stroke);
+}
+
+static GArray *
+gimp_stroke_real_get_draw_lines (GimpStroke *stroke)
+{
+  GList  *list;
+  GArray *ret_lines = NULL;
+  gint    count = 0;
+
+  for (list = stroke->anchors->head; list; list = g_list_next (list))
+    {
+      GimpAnchor *anchor = list->data;
+
+      if (anchor->type == GIMP_ANCHOR_ANCHOR && anchor->selected)
+        {
+          if (list->next)
+            {
+              GimpAnchor *next = list->next->data;
+
+              if (count == 0)
+                ret_lines = g_array_new (FALSE, FALSE, sizeof (GimpCoords));
+
+              ret_lines = g_array_append_val (ret_lines, anchor->position);
+              ret_lines = g_array_append_val (ret_lines, next->position);
+              count += 1;
+            }
+
+          if (list->prev)
+            {
+              GimpAnchor *prev = list->prev->data;
+
+              if (count == 0)
+                ret_lines = g_array_new (FALSE, FALSE, sizeof (GimpCoords));
+
+              ret_lines = g_array_append_val (ret_lines, anchor->position);
+              ret_lines = g_array_append_val (ret_lines, prev->position);
+              count += 1;
+            }
+        }
+    }
+
+  return ret_lines;
+}
+
+GArray *
+gimp_stroke_control_points_get (GimpStroke *stroke,
+                                gboolean   *ret_closed)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), NULL);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->control_points_get (stroke,
+                                                             ret_closed);
+}
+
+static GArray *
+gimp_stroke_real_control_points_get (GimpStroke *stroke,
+                                     gboolean   *ret_closed)
+{
+  guint   num_anchors;
+  GArray *ret_array;
+  GList  *list;
+
+  num_anchors = g_queue_get_length (stroke->anchors);
+  ret_array = g_array_sized_new (FALSE, FALSE,
+                                 sizeof (GimpAnchor), num_anchors);
+
+  for (list = stroke->anchors->head; list; list = g_list_next (list))
+    {
+      g_array_append_vals (ret_array, list->data, 1);
+    }
+
+  if (ret_closed)
+    *ret_closed = stroke->closed;
+
+  return ret_array;
+}
+
+gboolean
+gimp_stroke_get_point_at_dist (GimpStroke *stroke,
+                               gdouble     dist,
+                               gdouble     precision,
+                               GimpCoords *position,
+                               gdouble    *slope)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE (stroke), FALSE);
+
+  return GIMP_STROKE_GET_CLASS (stroke)->get_point_at_dist (stroke,
+                                                            dist,
+                                                            precision,
+                                                            position,
+                                                            slope);
+}
+
+
+static gboolean
+gimp_stroke_real_get_point_at_dist (GimpStroke *stroke,
+                                    gdouble     dist,
+                                    gdouble     precision,
+                                    GimpCoords *position,
+                                    gdouble    *slope)
+{
+  GArray     *points;
+  gint        i;
+  gdouble     length;
+  gdouble     segment_length;
+  gboolean    ret = FALSE;
+  GimpCoords  difference;
+
+  points = gimp_stroke_interpolate (stroke, precision, NULL);
+  if (points == NULL)
+    return ret;
+
+  length = 0;
+  for (i=0; i < points->len - 1; i++)
+    {
+      gimp_coords_difference (&(g_array_index (points, GimpCoords , i)),
+                              &(g_array_index (points, GimpCoords , i+1)),
+                              &difference);
+      segment_length = gimp_coords_length (&difference);
+
+      if (segment_length == 0 || length + segment_length < dist )
+        {
+          length += segment_length;
+        }
+      else
+        {
+          /* x = x1 + (x2 - x1 ) u  */
+          /* x   = x1 (1-u) + u x2  */
+
+          gdouble u = (dist - length) / segment_length;
+
+          gimp_coords_mix (1 - u, &(g_array_index (points, GimpCoords , i)),
+                               u, &(g_array_index (points, GimpCoords , i+1)),
+                           position);
+
+          if (difference.x == 0)
+            *slope = G_MAXDOUBLE;
+          else
+            *slope = difference.y / difference.x;
+
+          ret = TRUE;
+          break;
+        }
+    }
+
+  g_array_free (points, TRUE);
+
+  return ret;
+}