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gimp/app/vectors/gimpbezierstroke.c

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/* GIMP - The GNU Image Manipulation Program
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
*
* gimpbezierstroke.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 2 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, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include "config.h"
#include <glib-object.h>
#include "libgimpmath/gimpmath.h"
#include "vectors-types.h"
#include "core/gimpcoords.h"
#include "gimpanchor.h"
#include "gimpbezierstroke.h"
/* local prototypes */
static gdouble
gimp_bezier_stroke_nearest_point_get (const GimpStroke *stroke,
const GimpCoords *coord,
const gdouble precision,
GimpCoords *ret_point,
GimpAnchor **ret_segment_start,
GimpAnchor **ret_segment_end,
gdouble *ret_pos);
static gdouble
gimp_bezier_stroke_segment_nearest_point_get
(const GimpCoords *beziercoords,
const GimpCoords *coord,
const gdouble precision,
GimpCoords *ret_point,
gdouble *ret_pos,
gint depth);
static gdouble
gimp_bezier_stroke_nearest_tangent_get (const GimpStroke *stroke,
const GimpCoords *coord1,
const GimpCoords *coord2,
const gdouble precision,
GimpCoords *nearest,
GimpAnchor **ret_segment_start,
GimpAnchor **ret_segment_end,
gdouble *ret_pos);
static gdouble
gimp_bezier_stroke_segment_nearest_tangent_get
(const GimpCoords *beziercoords,
const GimpCoords *coord1,
const GimpCoords *coord2,
const gdouble precision,
GimpCoords *ret_point,
gdouble *ret_pos);
static void
gimp_bezier_stroke_anchor_move_relative
(GimpStroke *stroke,
GimpAnchor *anchor,
const GimpCoords *deltacoord,
GimpAnchorFeatureType feature);
static void
gimp_bezier_stroke_anchor_move_absolute
(GimpStroke *stroke,
GimpAnchor *anchor,
const GimpCoords *coord,
GimpAnchorFeatureType feature);
static void
gimp_bezier_stroke_anchor_convert (GimpStroke *stroke,
GimpAnchor *anchor,
GimpAnchorFeatureType feature);
static void
gimp_bezier_stroke_anchor_delete (GimpStroke *stroke,
GimpAnchor *anchor);
static gboolean
gimp_bezier_stroke_point_is_movable (GimpStroke *stroke,
GimpAnchor *predec,
gdouble position);
static void
gimp_bezier_stroke_point_move_relative (GimpStroke *stroke,
GimpAnchor *predec,
gdouble position,
const GimpCoords *deltacoord,
GimpAnchorFeatureType feature);
static void
gimp_bezier_stroke_point_move_absolute (GimpStroke *stroke,
GimpAnchor *predec,
gdouble position,
const GimpCoords *coord,
GimpAnchorFeatureType feature);
static void gimp_bezier_stroke_close (GimpStroke *stroke);
static GimpStroke *
gimp_bezier_stroke_open (GimpStroke *stroke,
GimpAnchor *end_anchor);
static gboolean
gimp_bezier_stroke_anchor_is_insertable
(GimpStroke *stroke,
GimpAnchor *predec,
gdouble position);
static GimpAnchor *
gimp_bezier_stroke_anchor_insert (GimpStroke *stroke,
GimpAnchor *predec,
gdouble position);
static gboolean
gimp_bezier_stroke_is_extendable (GimpStroke *stroke,
GimpAnchor *neighbor);
static gboolean
gimp_bezier_stroke_connect_stroke (GimpStroke *stroke,
GimpAnchor *anchor,
GimpStroke *extension,
GimpAnchor *neighbor);
static GArray *
gimp_bezier_stroke_interpolate (const GimpStroke *stroke,
const gdouble precision,
gboolean *closed);
static void gimp_bezier_stroke_finalize (GObject *object);
static GList * gimp_bezier_stroke_get_anchor_listitem
(GList *list);
static void gimp_bezier_coords_subdivide (const GimpCoords *beziercoords,
const gdouble precision,
GArray **ret_coords,
GArray **ret_params);
static void gimp_bezier_coords_subdivide2 (const GimpCoords *beziercoords,
const gdouble start_t,
const gdouble end_t,
const gdouble precision,
GArray **ret_coords,
GArray **ret_params,
gint depth);
static gboolean gimp_bezier_coords_is_straight
(const GimpCoords *beziercoords,
const gdouble precision);
G_DEFINE_TYPE (GimpBezierStroke, gimp_bezier_stroke, GIMP_TYPE_STROKE)
#define parent_class gimp_bezier_stroke_parent_class
static void
gimp_bezier_stroke_class_init (GimpBezierStrokeClass *klass)
{
GObjectClass *object_class = G_OBJECT_CLASS (klass);
GimpStrokeClass *stroke_class = GIMP_STROKE_CLASS (klass);
object_class->finalize = gimp_bezier_stroke_finalize;
stroke_class->nearest_point_get = gimp_bezier_stroke_nearest_point_get;
stroke_class->nearest_tangent_get = gimp_bezier_stroke_nearest_tangent_get;
stroke_class->nearest_intersection_get = NULL;
stroke_class->anchor_move_relative = gimp_bezier_stroke_anchor_move_relative;
stroke_class->anchor_move_absolute = gimp_bezier_stroke_anchor_move_absolute;
stroke_class->anchor_convert = gimp_bezier_stroke_anchor_convert;
stroke_class->anchor_delete = gimp_bezier_stroke_anchor_delete;
stroke_class->point_is_movable = gimp_bezier_stroke_point_is_movable;
stroke_class->point_move_relative = gimp_bezier_stroke_point_move_relative;
stroke_class->point_move_absolute = gimp_bezier_stroke_point_move_absolute;
stroke_class->close = gimp_bezier_stroke_close;
stroke_class->open = gimp_bezier_stroke_open;
stroke_class->anchor_is_insertable = gimp_bezier_stroke_anchor_is_insertable;
stroke_class->anchor_insert = gimp_bezier_stroke_anchor_insert;
stroke_class->is_extendable = gimp_bezier_stroke_is_extendable;
stroke_class->extend = gimp_bezier_stroke_extend;
stroke_class->connect_stroke = gimp_bezier_stroke_connect_stroke;
stroke_class->interpolate = gimp_bezier_stroke_interpolate;
}
static void
gimp_bezier_stroke_init (GimpBezierStroke *stroke)
{
}
static void
gimp_bezier_stroke_finalize (GObject *object)
{
G_OBJECT_CLASS (parent_class)->finalize (object);
}
/* Bezier specific functions */
GimpStroke *
gimp_bezier_stroke_new (void)
{
return g_object_new (GIMP_TYPE_BEZIER_STROKE, NULL);
}
GimpStroke *
gimp_bezier_stroke_new_from_coords (const GimpCoords *coords,
gint n_coords,
gboolean closed)
{
GimpBezierStroke *bezier_stroke;
GimpStroke *stroke;
GimpAnchor *last_anchor;
gint count;
g_return_val_if_fail (coords != NULL, NULL);
g_return_val_if_fail (n_coords >= 3, NULL);
g_return_val_if_fail ((n_coords % 3) == 0, NULL);
stroke = gimp_bezier_stroke_new ();
bezier_stroke = GIMP_BEZIER_STROKE (stroke);
last_anchor = NULL;
for (count = 0; count < n_coords; count++)
last_anchor = gimp_bezier_stroke_extend (stroke,
&coords[count],
last_anchor,
EXTEND_SIMPLE);
if (closed)
gimp_stroke_close (stroke);
return stroke;
}
static void
gimp_bezier_stroke_anchor_delete (GimpStroke *stroke,
GimpAnchor *anchor)
{
GList *list, *list2;
gint i;
/* Anchors always are surrounded by two handles that have to
* be deleted too */
list2 = g_list_find (stroke->anchors, anchor);
list = g_list_previous(list2);
for (i=0; i < 3; i++)
{
g_return_if_fail (list != NULL);
list2 = g_list_next (list);
gimp_anchor_free (GIMP_ANCHOR (list->data));
stroke->anchors = g_list_delete_link (stroke->anchors, list);
list = list2;
}
}
static GimpStroke *
gimp_bezier_stroke_open (GimpStroke *stroke,
GimpAnchor *end_anchor)
{
GList *list, *list2;
GimpStroke *new_stroke = NULL;
list = g_list_find (stroke->anchors, end_anchor);
g_return_val_if_fail (list != NULL && list->next != NULL, NULL);
list = g_list_next (list); /* protect the handle... */
list2 = list->next;
list->next = NULL;
if (list2 != NULL)
{
list2->prev = NULL;
if (stroke->closed)
{
stroke->anchors = g_list_concat (list2, stroke->anchors);
}
else
{
new_stroke = gimp_bezier_stroke_new ();
new_stroke->anchors = list2;
}
}
stroke->closed = FALSE;
g_object_notify (G_OBJECT (stroke), "closed");
return new_stroke;
}
static gboolean
gimp_bezier_stroke_anchor_is_insertable (GimpStroke *stroke,
GimpAnchor *predec,
gdouble position)
{
return (g_list_find (stroke->anchors, predec) != NULL);
}
static GimpAnchor *
gimp_bezier_stroke_anchor_insert (GimpStroke *stroke,
GimpAnchor *predec,
gdouble position)
{
GList *segment_start, *list, *list2;
GimpCoords subdivided[8];
GimpCoords beziercoords[4];
gint i;
segment_start = g_list_find (stroke->anchors, predec);
if (! segment_start)
return NULL;
list = segment_start;
for (i = 0; i <= 3; i++)
{
beziercoords[i] = GIMP_ANCHOR (list->data)->position;
list = g_list_next (list);
if (!list)
list = stroke->anchors;
}
subdivided[0] = beziercoords[0];
subdivided[6] = beziercoords[3];
gimp_coords_mix (1-position, &(beziercoords[0]),
position, &(beziercoords[1]),
&(subdivided[1]));
gimp_coords_mix (1-position, &(beziercoords[1]),
position, &(beziercoords[2]),
&(subdivided[7]));
gimp_coords_mix (1-position, &(beziercoords[2]),
position, &(beziercoords[3]),
&(subdivided[5]));
gimp_coords_mix (1-position, &(subdivided[1]),
position, &(subdivided[7]),
&(subdivided[2]));
gimp_coords_mix (1-position, &(subdivided[7]),
position, &(subdivided[5]),
&(subdivided[4]));
gimp_coords_mix (1-position, &(subdivided[2]),
position, &(subdivided[4]),
&(subdivided[3]));
/* subdivided 0-6 contains the bezier segement subdivided at <position> */
list = segment_start;
for (i = 0; i <= 6; i++)
{
if (i >= 2 && i <= 4)
{
list2 = g_list_append (NULL,
gimp_anchor_new ((i == 3 ?
GIMP_ANCHOR_ANCHOR:
GIMP_ANCHOR_CONTROL),
&(subdivided[i])));
/* insert it *before* list manually. */
list2->next = list;
list2->prev = list->prev;
if (list->prev)
list->prev->next = list2;
list->prev = list2;
list = list2;
if (i == 3)
segment_start = list;
}
else
{
GIMP_ANCHOR (list->data)->position = subdivided[i];
}
list = g_list_next (list);
if (!list)
list = stroke->anchors;
}
stroke->anchors = g_list_first (stroke->anchors);
return GIMP_ANCHOR (segment_start->data);
}
static gboolean
gimp_bezier_stroke_point_is_movable (GimpStroke *stroke,
GimpAnchor *predec,
gdouble position)
{
return (g_list_find (stroke->anchors, predec) != NULL);
}
static void
gimp_bezier_stroke_point_move_relative (GimpStroke *stroke,
GimpAnchor *predec,
gdouble position,
const GimpCoords *deltacoord,
GimpAnchorFeatureType feature)
{
GimpCoords offsetcoords[2];
GList *segment_start, *list;
gint i;
gdouble feel_good;
segment_start = g_list_find (stroke->anchors, predec);
g_return_if_fail (segment_start != NULL);
/* dragging close to endpoints just moves the handle related to
* the endpoint. Just make sure that feel_good is in the range from
* 0 to 1. The 1.0 / 6.0 and 5.0 / 6.0 are duplicated in
* tools/gimpvectortool.c. */
if (position <= 1.0 / 6.0)
feel_good = 0;
else if (position <= 0.5)
feel_good = (pow((6 * position - 1) / 2.0, 3)) / 2;
else if (position <= 5.0 / 6.0)
feel_good = (1 - pow((6 * (1-position) - 1) / 2.0, 3)) / 2 + 0.5;
else
feel_good = 1;
gimp_coords_scale ((1-feel_good)/(3*position*
(1-position)*(1-position)),
deltacoord,
&(offsetcoords[0]));
gimp_coords_scale (feel_good/(3*position*position*(1-position)),
deltacoord,
&(offsetcoords[1]));
list = segment_start;
list = g_list_next (list);
if (!list)
list = stroke->anchors;
for (i = 0; i <= 1; i++)
{
gimp_stroke_anchor_move_relative (stroke, GIMP_ANCHOR (list->data),
&(offsetcoords[i]), feature);
list = g_list_next (list);
if (!list)
list = stroke->anchors;
}
}
static void
gimp_bezier_stroke_point_move_absolute (GimpStroke *stroke,
GimpAnchor *predec,
gdouble position,
const GimpCoords *coord,
GimpAnchorFeatureType feature)
{
GimpCoords deltacoord;
GimpCoords tmp1, tmp2, abs_pos;
GimpCoords beziercoords[4];
GList *segment_start, *list;
gint i;
segment_start = g_list_find (stroke->anchors, predec);
g_return_if_fail (segment_start != NULL);
list = segment_start;
for (i = 0; i <= 3; i++)
{
beziercoords[i] = GIMP_ANCHOR (list->data)->position;
list = g_list_next (list);
if (!list)
list = stroke->anchors;
}
gimp_coords_mix ((1-position)*(1-position)*(1-position), &(beziercoords[0]),
3*(1-position)*(1-position)*position, &(beziercoords[1]),
&tmp1);
gimp_coords_mix (3*(1-position)*position*position, &(beziercoords[2]),
position*position*position, &(beziercoords[3]),
&tmp2);
gimp_coords_add (&tmp1, &tmp2, &abs_pos);
gimp_coords_difference (coord, &abs_pos, &deltacoord);
gimp_bezier_stroke_point_move_relative (stroke, predec, position,
&deltacoord, feature);
}
static void
gimp_bezier_stroke_close (GimpStroke *stroke)
{
GList *start, *end;
GimpAnchor *anchor;
start = g_list_first (stroke->anchors);
end = g_list_last (stroke->anchors);
g_return_if_fail (start->next != NULL && end->prev != NULL);
if (start->next != end->prev)
{
if (gimp_coords_equal (&(GIMP_ANCHOR (start->next->data)->position),
&(GIMP_ANCHOR (start->data)->position)) &&
gimp_coords_equal (&(GIMP_ANCHOR (start->data)->position),
&(GIMP_ANCHOR (end->data)->position)) &&
gimp_coords_equal (&(GIMP_ANCHOR (end->data)->position),
&(GIMP_ANCHOR (end->prev->data)->position)))
{
/* redundant segment */
anchor = GIMP_ANCHOR (stroke->anchors->data);
stroke->anchors = g_list_delete_link (stroke->anchors,
stroke->anchors);
gimp_anchor_free (anchor);
anchor = GIMP_ANCHOR (stroke->anchors->data);
stroke->anchors = g_list_delete_link (stroke->anchors,
stroke->anchors);
gimp_anchor_free (anchor);
anchor = GIMP_ANCHOR (stroke->anchors->data);
stroke->anchors = g_list_delete_link (stroke->anchors,
stroke->anchors);
end = g_list_last (stroke->anchors);
gimp_anchor_free (GIMP_ANCHOR (end->data));
end->data = anchor;
}
}
GIMP_STROKE_CLASS (parent_class)->close (stroke);
}
static gdouble
gimp_bezier_stroke_nearest_point_get (const GimpStroke *stroke,
const GimpCoords *coord,
const gdouble precision,
GimpCoords *ret_point,
GimpAnchor **ret_segment_start,
GimpAnchor **ret_segment_end,
gdouble *ret_pos)
{
gdouble min_dist, dist, pos;
GimpCoords point;
GimpCoords segmentcoords[4];
GList *anchorlist;
GimpAnchor *segment_start, *segment_end = NULL;
GimpAnchor *anchor;
gint count;
if (!stroke->anchors)
return -1.0;
count = 0;
min_dist = -1;
for (anchorlist = stroke->anchors;
anchorlist && GIMP_ANCHOR (anchorlist->data)->type != GIMP_ANCHOR_ANCHOR;
anchorlist = g_list_next (anchorlist));
segment_start = anchorlist->data;
for ( ; anchorlist; anchorlist = g_list_next (anchorlist))
{
anchor = anchorlist->data;
segmentcoords[count] = anchor->position;
count++;
if (count == 4)
{
segment_end = anchorlist->data;
dist = gimp_bezier_stroke_segment_nearest_point_get (segmentcoords,
coord, precision,
&point, &pos,
10);
if (dist < min_dist || min_dist < 0)
{
min_dist = dist;
if (ret_pos)
*ret_pos = pos;
if (ret_point)
*ret_point = point;
if (ret_segment_start)
*ret_segment_start = segment_start;
if (ret_segment_end)
*ret_segment_end = segment_end;
}
segment_start = anchorlist->data;
segmentcoords[0] = segmentcoords[3];
count = 1;
}
}
if (stroke->closed && stroke->anchors)
{
anchorlist = stroke->anchors;
while (count < 3)
{
segmentcoords[count] = GIMP_ANCHOR (anchorlist->data)->position;
count++;
}
anchorlist = g_list_next (anchorlist);
if (anchorlist)
{
segment_end = GIMP_ANCHOR (anchorlist->data);
segmentcoords[3] = segment_end->position;
}
dist = gimp_bezier_stroke_segment_nearest_point_get (segmentcoords,
coord, precision,
&point, &pos,
10);
if (dist < min_dist || min_dist < 0)
{
min_dist = dist;
if (ret_pos)
*ret_pos = pos;
if (ret_point)
*ret_point = point;
if (ret_segment_start)
*ret_segment_start = segment_start;
if (ret_segment_end)
*ret_segment_end = segment_end;
}
}
return min_dist;
}
static gdouble
gimp_bezier_stroke_segment_nearest_point_get (const GimpCoords *beziercoords,
const GimpCoords *coord,
const gdouble precision,
GimpCoords *ret_point,
gdouble *ret_pos,
gint depth)
{
/*
* beziercoords has to contain four GimpCoords with the four control points
* of the bezier segment. We subdivide it at the parameter 0.5.
*/
GimpCoords subdivided[8];
gdouble dist1, dist2;
GimpCoords point1, point2;
gdouble pos1, pos2;
gimp_coords_difference (&beziercoords[1], &beziercoords[0], &point1);
gimp_coords_difference (&beziercoords[3], &beziercoords[2], &point2);
if (!depth || (gimp_bezier_coords_is_straight (beziercoords, precision)
&& gimp_coords_length_squared (&point1) < precision
&& gimp_coords_length_squared (&point2) < precision))
{
GimpCoords line, dcoord;
gdouble length2, scalar;
gint i;
gimp_coords_difference (&(beziercoords[3]),
&(beziercoords[0]),
&line);
gimp_coords_difference (coord,
&(beziercoords[0]),
&dcoord);
length2 = gimp_coords_scalarprod (&line, &line);
scalar = gimp_coords_scalarprod (&line, &dcoord) / length2;
scalar = CLAMP (scalar, 0.0, 1.0);
/* lines look the same as bezier curves where the handles
* sit on the anchors, however, they are parametrized
* differently. Hence we have to do some weird approximation. */
pos1 = pos2 = 0.5;
for (i = 0; i <= 15; i++)
{
pos2 *= 0.5;
if (3*pos1*pos1*(1-pos1) + pos1*pos1*pos1 < scalar)
pos1 += pos2;
else
pos1 -= pos2;
}
*ret_pos = pos1;
gimp_coords_mix (1.0, &(beziercoords[0]),
scalar, &line,
ret_point);
gimp_coords_difference (coord, ret_point, &dcoord);
return gimp_coords_length (&dcoord);
}
/* ok, we have to subdivide */
subdivided[0] = beziercoords[0];
subdivided[6] = beziercoords[3];
/* if (!depth) g_printerr ("Hit recursion depth limit!\n"); */
gimp_coords_average (&(beziercoords[0]), &(beziercoords[1]),
&(subdivided[1]));
gimp_coords_average (&(beziercoords[1]), &(beziercoords[2]),
&(subdivided[7]));
gimp_coords_average (&(beziercoords[2]), &(beziercoords[3]),
&(subdivided[5]));
gimp_coords_average (&(subdivided[1]), &(subdivided[7]),
&(subdivided[2]));
gimp_coords_average (&(subdivided[7]), &(subdivided[5]),
&(subdivided[4]));
gimp_coords_average (&(subdivided[2]), &(subdivided[4]),
&(subdivided[3]));
/*
* We now have the coordinates of the two bezier segments in
* subdivided [0-3] and subdivided [3-6]
*/
dist1 = gimp_bezier_stroke_segment_nearest_point_get (&(subdivided[0]),
coord, precision,
&point1, &pos1,
depth - 1);
dist2 = gimp_bezier_stroke_segment_nearest_point_get (&(subdivided[3]),
coord, precision,
&point2, &pos2,
depth - 1);
if (dist1 <= dist2)
{
*ret_point = point1;
*ret_pos = 0.5 * pos1;
return dist1;
}
else
{
*ret_point = point2;
*ret_pos = 0.5 + 0.5 * pos2;
return dist2;
}
}
static gdouble
gimp_bezier_stroke_nearest_tangent_get (const GimpStroke *stroke,
const GimpCoords *coord1,
const GimpCoords *coord2,
const gdouble precision,
GimpCoords *nearest,
GimpAnchor **ret_segment_start,
GimpAnchor **ret_segment_end,
gdouble *ret_pos)
{
gdouble min_dist, dist, pos;
GimpCoords point;
GimpCoords segmentcoords[4];
GList *anchorlist;
GimpAnchor *segment_start, *segment_end = NULL;
GimpAnchor *anchor;
gint count;
if (!stroke->anchors)
return -1.0;
count = 0;
min_dist = -1;
for (anchorlist = stroke->anchors;
anchorlist && GIMP_ANCHOR (anchorlist->data)->type != GIMP_ANCHOR_ANCHOR;
anchorlist = g_list_next (anchorlist));
segment_start = anchorlist->data;
for ( ; anchorlist; anchorlist = g_list_next (anchorlist))
{
anchor = anchorlist->data;
segmentcoords[count] = anchor->position;
count++;
if (count == 4)
{
segment_end = anchorlist->data;
dist = gimp_bezier_stroke_segment_nearest_tangent_get (segmentcoords,
coord1, coord2,
precision,
&point, &pos);
if (dist >= 0 && (dist < min_dist || min_dist < 0))
{
min_dist = dist;
if (ret_pos)
*ret_pos = pos;
if (nearest)
*nearest = point;
if (ret_segment_start)
*ret_segment_start = segment_start;
if (ret_segment_end)
*ret_segment_end = segment_end;
}
segment_start = anchorlist->data;
segmentcoords[0] = segmentcoords[3];
count = 1;
}
}
if (stroke->closed && stroke->anchors)
{
anchorlist = stroke->anchors;
while (count < 3)
{
segmentcoords[count] = GIMP_ANCHOR (anchorlist->data)->position;
count++;
}
anchorlist = g_list_next (anchorlist);
if (anchorlist)
{
segment_end = GIMP_ANCHOR (anchorlist->data);
segmentcoords[3] = segment_end->position;
}
dist = gimp_bezier_stroke_segment_nearest_tangent_get (segmentcoords,
coord1, coord2,
precision,
&point, &pos);
if (dist >= 0 && (dist < min_dist || min_dist < 0))
{
min_dist = dist;
if (ret_pos)
*ret_pos = pos;
if (nearest)
*nearest = point;
if (ret_segment_start)
*ret_segment_start = segment_start;
if (ret_segment_end)
*ret_segment_end = segment_end;
}
}
return min_dist;
}
static gdouble
gimp_bezier_stroke_segment_nearest_tangent_get (const GimpCoords *beziercoords,
const GimpCoords *coord1,
const GimpCoords *coord2,
const gdouble precision,
GimpCoords *ret_point,
gdouble *ret_pos)
{
GArray *ret_coords, *ret_params;
GimpCoords dir, line, dcoord, min_point;
gdouble min_dist = -1, dist, length2, scalar, ori, ori2;
gint i;
gimp_coords_difference (coord2, coord1, &line);
ret_coords = g_array_new (FALSE, FALSE, sizeof (GimpCoords));
ret_params = g_array_new (FALSE, FALSE, sizeof (gdouble));
g_printerr ("(%.2f, %.2f)-(%.2f,%.2f): ", coord1->x, coord1->y,
coord2->x, coord2->y);
gimp_bezier_coords_subdivide (beziercoords, precision,
&ret_coords, &ret_params);
g_return_val_if_fail (ret_coords->len == ret_params->len, -1.0);
if (ret_coords->len < 2)
return -1;
gimp_coords_difference (&g_array_index (ret_coords, GimpCoords, 1),
&g_array_index (ret_coords, GimpCoords, 0),
&dir);
ori = dir.x * line.y - dir.y * line.x;
for (i = 2; i < ret_coords->len; i++)
{
gimp_coords_difference (&g_array_index (ret_coords, GimpCoords, i),
&g_array_index (ret_coords, GimpCoords, i-1),
&dir);
ori2 = dir.x * line.y - dir.y * line.x;
if (ori * ori2 <= 0)
{
#if 0
if (ori2 == 0)
/* Kandidat finden */;
else
/* ret_coords[i] ist der Kandidat */;
#endif
gimp_coords_difference (&g_array_index (ret_coords, GimpCoords, i),
coord1,
&dcoord);
length2 = gimp_coords_scalarprod (&line, &line);
scalar = gimp_coords_scalarprod (&line, &dcoord) / length2;
if (scalar >= 0 && scalar <= 1)
{
gimp_coords_mix (1.0, coord1,
scalar, &line,
&min_point);
gimp_coords_difference (&min_point,
&g_array_index (ret_coords, GimpCoords, i),
&dcoord);
dist = gimp_coords_length (&dcoord);
if (dist < min_dist || min_dist < 0)
{
min_dist = dist;
*ret_point = g_array_index (ret_coords, GimpCoords, i);
*ret_pos = g_array_index (ret_params, gdouble, i);
}
}
}
ori = ori2;
}
if (min_dist < 0)
g_printerr ("-\n");
else
g_printerr ("%f: (%.2f, %.2f) /%.3f/\n", min_dist,
(*ret_point).x, (*ret_point).y, *ret_pos);
g_array_free (ret_coords, TRUE);
g_array_free (ret_params, TRUE);
return min_dist;
}
static gboolean
gimp_bezier_stroke_is_extendable (GimpStroke *stroke,
GimpAnchor *neighbor)
{
GimpBezierStroke *bezier_stroke;
GList *listneighbor;
gint loose_end;
bezier_stroke = GIMP_BEZIER_STROKE (stroke);
if (stroke->closed)
return FALSE;
if (stroke->anchors == NULL)
return TRUE;
/* assure that there is a neighbor specified */
g_return_val_if_fail (neighbor != NULL, FALSE);
loose_end = 0;
listneighbor = g_list_last (stroke->anchors);
/* Check if the neighbor is at an end of the control points */
if (listneighbor->data == neighbor)
{
loose_end = 1;
}
else
{
listneighbor = g_list_first (stroke->anchors);
if (listneighbor->data == neighbor)
{
loose_end = -1;
}
else
{
/*
* it isnt. if we are on a handle go to the nearest
* anchor and see if we can find an end from it.
* Yes, this is tedious.
*/
listneighbor = g_list_find (stroke->anchors, neighbor);
if (listneighbor && neighbor->type == GIMP_ANCHOR_CONTROL)
{
if (listneighbor->prev &&
GIMP_ANCHOR (listneighbor->prev->data)->type == GIMP_ANCHOR_ANCHOR)
{
listneighbor = listneighbor->prev;
}
else if (listneighbor->next &&
GIMP_ANCHOR (listneighbor->next->data)->type == GIMP_ANCHOR_ANCHOR)
{
listneighbor = listneighbor->next;
}
else
{
loose_end = 0;
listneighbor = NULL;
}
}
if (listneighbor)
/* we found a suitable ANCHOR_ANCHOR now, lets
* search for its loose end.
*/
{
if (listneighbor->prev &&
listneighbor->prev->prev == NULL)
{
loose_end = -1;
listneighbor = listneighbor->prev;
}
else if (listneighbor->next &&
listneighbor->next->next == NULL)
{
loose_end = 1;
listneighbor = listneighbor->next;
}
}
}
}
return (loose_end != 0);
}
GimpAnchor *
gimp_bezier_stroke_extend (GimpStroke *stroke,
const GimpCoords *coords,
GimpAnchor *neighbor,
GimpVectorExtendMode extend_mode)
{
GimpAnchor *anchor = NULL;
GimpBezierStroke *bezier_stroke;
GList *listneighbor;
gint loose_end, control_count;
bezier_stroke = GIMP_BEZIER_STROKE (stroke);
if (stroke->anchors == NULL)
{
/* assure that there is no neighbor specified */
g_return_val_if_fail (neighbor == NULL, NULL);
anchor = gimp_anchor_new (GIMP_ANCHOR_CONTROL, coords);
stroke->anchors = g_list_append (stroke->anchors, anchor);
switch (extend_mode)
{
case EXTEND_SIMPLE:
break;
case EXTEND_EDITABLE:
anchor = gimp_bezier_stroke_extend (stroke,
coords, anchor,
EXTEND_SIMPLE);
/* we return the GIMP_ANCHOR_ANCHOR */
gimp_bezier_stroke_extend (stroke,
coords, anchor,
EXTEND_SIMPLE);
break;
default:
anchor = NULL;
}
return anchor;
}
else
{
/* assure that there is a neighbor specified */
g_return_val_if_fail (neighbor != NULL, NULL);
loose_end = 0;
listneighbor = g_list_last (stroke->anchors);
/* Check if the neighbor is at an end of the control points */
if (listneighbor->data == neighbor)
{
loose_end = 1;
}
else
{
listneighbor = g_list_first (stroke->anchors);
if (listneighbor->data == neighbor)
{
loose_end = -1;
}
else
{
/*
* it isnt. if we are on a handle go to the nearest
* anchor and see if we can find an end from it.
* Yes, this is tedious.
*/
listneighbor = g_list_find (stroke->anchors, neighbor);
if (listneighbor && neighbor->type == GIMP_ANCHOR_CONTROL)
{
if (listneighbor->prev &&
GIMP_ANCHOR (listneighbor->prev->data)->type == GIMP_ANCHOR_ANCHOR)
{
listneighbor = listneighbor->prev;
}
else if (listneighbor->next &&
GIMP_ANCHOR (listneighbor->next->data)->type == GIMP_ANCHOR_ANCHOR)
{
listneighbor = listneighbor->next;
}
else
{
loose_end = 0;
listneighbor = NULL;
}
}
if (listneighbor)
/* we found a suitable ANCHOR_ANCHOR now, lets
* search for its loose end.
*/
{
if (listneighbor->next &&
listneighbor->next->next == NULL)
{
loose_end = 1;
listneighbor = listneighbor->next;
}
else if (listneighbor->prev &&
listneighbor->prev->prev == NULL)
{
loose_end = -1;
listneighbor = listneighbor->prev;
}
}
}
}
if (loose_end)
{
GimpAnchorType type;
/* We have to detect the type of the point to add... */
control_count = 0;
if (loose_end == 1)
{
while (listneighbor &&
GIMP_ANCHOR (listneighbor->data)->type == GIMP_ANCHOR_CONTROL)
{
control_count++;
listneighbor = listneighbor->prev;
}
}
else
{
while (listneighbor &&
GIMP_ANCHOR (listneighbor->data)->type == GIMP_ANCHOR_CONTROL)
{
control_count++;
listneighbor = listneighbor->next;
}
}
switch (extend_mode)
{
case EXTEND_SIMPLE:
switch (control_count)
{
case 0:
type = GIMP_ANCHOR_CONTROL;
break;
case 1:
if (listneighbor) /* only one handle in the path? */
type = GIMP_ANCHOR_CONTROL;
else
type = GIMP_ANCHOR_ANCHOR;
break;
case 2:
type = GIMP_ANCHOR_ANCHOR;
break;
default:
g_warning ("inconsistent bezier curve: "
"%d successive control handles", control_count);
type = GIMP_ANCHOR_ANCHOR;
}
anchor = gimp_anchor_new (type, coords);
if (loose_end == 1)
stroke->anchors = g_list_append (stroke->anchors, anchor);
if (loose_end == -1)
stroke->anchors = g_list_prepend (stroke->anchors, anchor);
break;
case EXTEND_EDITABLE:
switch (control_count)
{
case 0:
neighbor = gimp_bezier_stroke_extend (stroke,
&(neighbor->position),
neighbor,
EXTEND_SIMPLE);
case 1:
neighbor = gimp_bezier_stroke_extend (stroke,
coords,
neighbor,
EXTEND_SIMPLE);
case 2:
anchor = gimp_bezier_stroke_extend (stroke,
coords,
neighbor,
EXTEND_SIMPLE);
neighbor = gimp_bezier_stroke_extend (stroke,
coords,
anchor,
EXTEND_SIMPLE);
break;
default:
g_warning ("inconsistent bezier curve: "
"%d successive control handles", control_count);
}
}
return anchor;
}
return NULL;
}
}
static gboolean
gimp_bezier_stroke_connect_stroke (GimpStroke *stroke,
GimpAnchor *anchor,
GimpStroke *extension,
GimpAnchor *neighbor)
{
GList *list1, *list2;
list1 = g_list_find (stroke->anchors, anchor);
list1 = gimp_bezier_stroke_get_anchor_listitem (list1);
list2 = g_list_find (extension->anchors, neighbor);
list2 = gimp_bezier_stroke_get_anchor_listitem (list2);
g_return_val_if_fail (list1 != NULL && list2 != NULL, FALSE);
if (stroke == extension)
{
g_return_val_if_fail ((list1->prev && list1->prev->prev == NULL &&
list2->next && list2->next->next == NULL) ||
(list1->next && list1->next->next == NULL &&
list2->prev && list2->prev->prev == NULL), FALSE);
gimp_stroke_close (stroke);
return TRUE;
}
if (list1->prev && list1->prev->prev == NULL)
{
stroke->anchors = g_list_reverse (stroke->anchors);
}
g_return_val_if_fail (list1->next && list1->next->next == NULL, FALSE);
if (list2->next && list2->next->next == NULL)
{
extension->anchors = g_list_reverse (extension->anchors);
}
g_return_val_if_fail (list2->prev && list2->prev->prev == NULL, FALSE);
stroke->anchors = g_list_concat (stroke->anchors, extension->anchors);
extension->anchors = NULL;
return TRUE;
}
static void
gimp_bezier_stroke_anchor_move_relative (GimpStroke *stroke,
GimpAnchor *anchor,
const GimpCoords *deltacoord,
GimpAnchorFeatureType feature)
{
GimpCoords delta, coord1, coord2;
GList *anchor_list;
delta = *deltacoord;
delta.pressure = 0;
delta.xtilt = 0;
delta.ytilt = 0;
delta.wheel = 0;
gimp_coords_add (&(anchor->position), &delta, &coord1);
anchor->position = coord1;
anchor_list = g_list_find (stroke->anchors, anchor);
g_return_if_fail (anchor_list != NULL);
if (anchor->type == GIMP_ANCHOR_ANCHOR)
{
if (g_list_previous (anchor_list))
{
coord2 = GIMP_ANCHOR (g_list_previous (anchor_list)->data)->position;
gimp_coords_add (&coord2, &delta, &coord1);
GIMP_ANCHOR (g_list_previous (anchor_list)->data)->position = coord1;
}
if (g_list_next (anchor_list))
{
coord2 = GIMP_ANCHOR (g_list_next (anchor_list)->data)->position;
gimp_coords_add (&coord2, &delta, &coord1);
GIMP_ANCHOR (g_list_next (anchor_list)->data)->position = coord1;
}
}
else
{
if (feature == GIMP_ANCHOR_FEATURE_SYMMETRIC)
{
GList *neighbour = NULL, *opposite = NULL;
/* search for opposite control point. Sigh. */
neighbour = g_list_previous (anchor_list);
if (neighbour &&
GIMP_ANCHOR (neighbour->data)->type == GIMP_ANCHOR_ANCHOR)
{
opposite = g_list_previous (neighbour);
}
else
{
neighbour = g_list_next (anchor_list);
if (neighbour &&
GIMP_ANCHOR (neighbour->data)->type == GIMP_ANCHOR_ANCHOR)
{
opposite = g_list_next (neighbour);
}
}
if (opposite &&
GIMP_ANCHOR (opposite->data)->type == GIMP_ANCHOR_CONTROL)
{
gimp_coords_difference (&(GIMP_ANCHOR (neighbour->data)->position),
&(anchor->position), &delta);
gimp_coords_add (&(GIMP_ANCHOR (neighbour->data)->position),
&delta, &coord1);
GIMP_ANCHOR (opposite->data)->position = coord1;
}
}
}
}
static void
gimp_bezier_stroke_anchor_move_absolute (GimpStroke *stroke,
GimpAnchor *anchor,
const GimpCoords *coord,
GimpAnchorFeatureType feature)
{
GimpCoords deltacoord;
gimp_coords_difference (coord, &anchor->position, &deltacoord);
gimp_bezier_stroke_anchor_move_relative (stroke, anchor,
&deltacoord, feature);
}
static void
gimp_bezier_stroke_anchor_convert (GimpStroke *stroke,
GimpAnchor *anchor,
GimpAnchorFeatureType feature)
{
GList *anchor_list;
anchor_list = g_list_find (stroke->anchors, anchor);
g_return_if_fail (anchor_list != NULL);
switch (feature)
{
case GIMP_ANCHOR_FEATURE_EDGE:
if (anchor->type == GIMP_ANCHOR_ANCHOR)
{
if (g_list_previous (anchor_list))
GIMP_ANCHOR (g_list_previous (anchor_list)->data)->position =
anchor->position;
if (g_list_next (anchor_list))
GIMP_ANCHOR (g_list_next (anchor_list)->data)->position =
anchor->position;
}
else
{
if (g_list_previous (anchor_list) &&
GIMP_ANCHOR (g_list_previous (anchor_list)->data)->type == GIMP_ANCHOR_ANCHOR)
anchor->position = GIMP_ANCHOR (g_list_previous (anchor_list)->data)->position;
if (g_list_next (anchor_list) &&
GIMP_ANCHOR (g_list_next (anchor_list)->data)->type == GIMP_ANCHOR_ANCHOR)
anchor->position = GIMP_ANCHOR (g_list_next (anchor_list)->data)->position;
}
break;
default:
g_warning ("gimp_bezier_stroke_anchor_convert: "
"unimplemented anchor conversion %d\n", feature);
}
}
static GArray *
gimp_bezier_stroke_interpolate (const GimpStroke *stroke,
gdouble precision,
gboolean *ret_closed)
{
GArray *ret_coords;
GimpAnchor *anchor;
GList *anchorlist;
GimpCoords segmentcoords[4];
gint count;
gboolean need_endpoint = FALSE;
if (!stroke->anchors)
{
if (ret_closed)
*ret_closed = FALSE;
return NULL;
}
ret_coords = g_array_new (FALSE, FALSE, sizeof (GimpCoords));
count = 0;
for (anchorlist = stroke->anchors;
anchorlist && GIMP_ANCHOR (anchorlist->data)->type != GIMP_ANCHOR_ANCHOR;
anchorlist = g_list_next (anchorlist));
for ( ; anchorlist; anchorlist = g_list_next (anchorlist))
{
anchor = anchorlist->data;
segmentcoords[count] = anchor->position;
count++;
if (count == 4)
{
gimp_bezier_coords_subdivide (segmentcoords, precision,
&ret_coords, NULL);
segmentcoords[0] = segmentcoords[3];
count = 1;
need_endpoint = TRUE;
}
}
if (stroke->closed && stroke->anchors)
{
anchorlist = stroke->anchors;
while (count < 3)
{
segmentcoords[count] = GIMP_ANCHOR (anchorlist->data)->position;
count++;
}
anchorlist = g_list_next (anchorlist);
if (anchorlist)
segmentcoords[3] = GIMP_ANCHOR (anchorlist->data)->position;
gimp_bezier_coords_subdivide (segmentcoords, precision,
&ret_coords, NULL);
need_endpoint = TRUE;
}
if (need_endpoint)
ret_coords = g_array_append_val (ret_coords, segmentcoords[3]);
if (ret_closed)
*ret_closed = stroke->closed;
if (ret_coords->len == 0)
{
g_array_free (ret_coords, TRUE);
ret_coords = NULL;
}
return ret_coords;
}
GimpStroke *
gimp_bezier_stroke_new_moveto (const GimpCoords *start)
{
GimpStroke *stroke;
stroke = gimp_bezier_stroke_new ();
stroke->anchors = g_list_prepend (stroke->anchors,
gimp_anchor_new (GIMP_ANCHOR_CONTROL,
start));
stroke->anchors = g_list_prepend (stroke->anchors,
gimp_anchor_new (GIMP_ANCHOR_ANCHOR,
start));
stroke->anchors = g_list_prepend (stroke->anchors,
gimp_anchor_new (GIMP_ANCHOR_CONTROL,
start));
return stroke;
}
void
gimp_bezier_stroke_lineto (GimpStroke *stroke,
const GimpCoords *end)
{
g_return_if_fail (GIMP_IS_BEZIER_STROKE (stroke));
g_return_if_fail (stroke->closed == FALSE);
g_return_if_fail (stroke->anchors != NULL);
stroke->anchors = g_list_prepend (stroke->anchors,
gimp_anchor_new (GIMP_ANCHOR_CONTROL,
end));
stroke->anchors = g_list_prepend (stroke->anchors,
gimp_anchor_new (GIMP_ANCHOR_ANCHOR,
end));
stroke->anchors = g_list_prepend (stroke->anchors,
gimp_anchor_new (GIMP_ANCHOR_CONTROL,
end));
}
void
gimp_bezier_stroke_conicto (GimpStroke *stroke,
const GimpCoords *control,
const GimpCoords *end)
{
GimpCoords start, coords;
g_return_if_fail (GIMP_IS_BEZIER_STROKE (stroke));
g_return_if_fail (stroke->closed == FALSE);
g_return_if_fail (stroke->anchors != NULL);
g_return_if_fail (stroke->anchors->next != NULL);
start = GIMP_ANCHOR (stroke->anchors->next->data)->position;
gimp_coords_mix (2.0 / 3.0, control, 1.0 / 3.0, &start, &coords);
GIMP_ANCHOR (stroke->anchors->data)->position = coords;
gimp_coords_mix (2.0 / 3.0, control, 1.0 / 3.0, end, &coords);
stroke->anchors = g_list_prepend (stroke->anchors,
gimp_anchor_new (GIMP_ANCHOR_CONTROL,
&coords));
stroke->anchors = g_list_prepend (stroke->anchors,
gimp_anchor_new (GIMP_ANCHOR_ANCHOR,
end));
stroke->anchors = g_list_prepend (stroke->anchors,
gimp_anchor_new (GIMP_ANCHOR_CONTROL,
end));
}
void
gimp_bezier_stroke_cubicto (GimpStroke *stroke,
const GimpCoords *control1,
const GimpCoords *control2,
const GimpCoords *end)
{
g_return_if_fail (GIMP_IS_BEZIER_STROKE (stroke));
g_return_if_fail (stroke->closed == FALSE);
g_return_if_fail (stroke->anchors != NULL);
GIMP_ANCHOR (stroke->anchors->data)->position = *control1;
stroke->anchors = g_list_prepend (stroke->anchors,
gimp_anchor_new (GIMP_ANCHOR_CONTROL,
control2));
stroke->anchors = g_list_prepend (stroke->anchors,
gimp_anchor_new (GIMP_ANCHOR_ANCHOR,
end));
stroke->anchors = g_list_prepend (stroke->anchors,
gimp_anchor_new (GIMP_ANCHOR_CONTROL,
end));
}
static gdouble
arcto_circleparam (gdouble h, gdouble *y)
{
gdouble t0 = 0.5;
gdouble dt = 0.25;
gdouble pt0;
gdouble y01, y12, y23, y012, y123, y0123; /* subdividing y[] */
while (dt >= 0.00001)
{
pt0 = ( y[0]*(1-t0)*(1-t0)*(1-t0) +
3*y[1]*(1-t0)*(1-t0)*t0 +
3*y[2]*(1-t0)*t0*t0 +
y[3]*t0*t0*t0 );
if (pt0 > h)
t0 = t0 - dt;
else if (pt0 < h)
t0 = t0 + dt;
else
break;
dt = dt/2;
}
y01 = y[0] * (1-t0) + y[1] * t0;
y12 = y[1] * (1-t0) + y[2] * t0;
y23 = y[2] * (1-t0) + y[3] * t0;
y012 = y01 * (1-t0) + y12 * t0;
y123 = y12 * (1-t0) + y23 * t0;
y0123 = y012 * (1-t0) + y123 * t0;
y[0] = y0123; y[1] = y123; y[2] = y23; /* y[3] unchanged */
return t0;
}
static void
arcto_subdivide (gdouble t, gint part, GimpCoords *p)
{
GimpCoords p01, p12, p23, p012, p123, p0123;
gimp_coords_mix (1-t, &(p[0]), t, &(p[1]), &p01 );
gimp_coords_mix (1-t, &(p[1]), t, &(p[2]), &p12 );
gimp_coords_mix (1-t, &(p[2]), t, &(p[3]), &p23 );
gimp_coords_mix (1-t, &p01 , t, &p12 , &p012 );
gimp_coords_mix (1-t, &p12 , t, &p23 , &p123 );
gimp_coords_mix (1-t, &p012 , t, &p123 , &p0123);
if (part == 0)
{
/* p[0] unchanged */
p[1] = p01;
p[2] = p012;
p[3] = p0123;
}
else
{
p[0] = p0123;
p[1] = p123;
p[2] = p23;
/* p[3] unchanged */
}
}
static void
arcto_ellipsesegment (gdouble radius_x,
gdouble radius_y,
gdouble phi0,
gdouble phi1,
GimpCoords *ellips)
{
gdouble phi_s, phi_e;
GimpCoords template = GIMP_COORDS_DEFAULT_VALUES;
const gdouble circlemagic = 4.0 * (G_SQRT2 - 1.0) / 3.0;
gdouble y[4];
gdouble h0, h1;
gdouble t0, t1;
g_return_if_fail (ellips != NULL);
y[0] = 0.0;
y[1] = circlemagic;
y[2] = 1.0;
y[3] = 1.0;
ellips[0] = template;
ellips[1] = template;
ellips[2] = template;
ellips[3] = template;
if (phi0 < phi1)
{
phi_s = floor (phi0 / G_PI_2) * G_PI_2;
while (phi_s < 0) phi_s += 2 * G_PI;
phi_e = phi_s + G_PI_2;
}
else
{
phi_e = floor (phi1 / G_PI_2) * G_PI_2;
while (phi_e < 0) phi_e += 2 * G_PI;
phi_s = phi_e + G_PI_2;
}
h0 = sin (fabs (phi0-phi_s));
h1 = sin (fabs (phi1-phi_s));
ellips[0].x = cos (phi_s); ellips[0].y = sin (phi_s);
ellips[3].x = cos (phi_e); ellips[3].y = sin (phi_e);
gimp_coords_mix (1, &(ellips[0]), circlemagic, &(ellips[3]),
&(ellips[1]));
gimp_coords_mix (circlemagic, &(ellips[0]), 1, &(ellips[3]),
&(ellips[2]));
if (h0 > y[0])
{
t0 = arcto_circleparam (h0, y); /* also subdivides y[] at t0 */
arcto_subdivide (t0, 1, ellips);
}
if (h1 < y[3])
{
t1 = arcto_circleparam (h1, y);
arcto_subdivide (t1, 0, ellips);
}
ellips[0].x *= radius_x ; ellips[0].y *= radius_y;
ellips[1].x *= radius_x ; ellips[1].y *= radius_y;
ellips[2].x *= radius_x ; ellips[2].y *= radius_y;
ellips[3].x *= radius_x ; ellips[3].y *= radius_y;
}
void
gimp_bezier_stroke_arcto (GimpStroke *bez_stroke,
gdouble radius_x,
gdouble radius_y,
gdouble angle_rad,
gboolean large_arc,
gboolean sweep,
const GimpCoords *end)
{
GimpCoords start;
GimpCoords middle; /* between start and end */
GimpCoords trans_delta;
GimpCoords trans_center;
GimpCoords tmp_center;
GimpCoords center;
GimpCoords ellips[4]; /* control points of untransformed ellipse segment */
GimpCoords ctrl[4]; /* control points of next bezier segment */
GimpMatrix3 anglerot;
gdouble lambda;
gdouble phi0, phi1, phi2;
gdouble tmpx, tmpy;
g_return_if_fail (GIMP_IS_BEZIER_STROKE (bez_stroke));
g_return_if_fail (bez_stroke->closed == FALSE);
g_return_if_fail (bez_stroke->anchors != NULL);
g_return_if_fail (bez_stroke->anchors->next != NULL);
if (radius_x == 0 || radius_y == 0)
{
gimp_bezier_stroke_lineto (bez_stroke, end);
return;
}
start = GIMP_ANCHOR (bez_stroke->anchors->next->data)->position;
gimp_matrix3_identity (&anglerot);
gimp_matrix3_rotate (&anglerot, -angle_rad);
gimp_coords_mix (0.5, &start, -0.5, end, &trans_delta);
gimp_matrix3_transform_point (&anglerot,
trans_delta.x, trans_delta.y,
&tmpx, &tmpy);
trans_delta.x = tmpx;
trans_delta.y = tmpy;
lambda = (SQR (trans_delta.x) / SQR (radius_x) +
SQR (trans_delta.y) / SQR (radius_y));
if (lambda < 0.00001)
{
/* dont bother with it - endpoint is too close to startpoint */
return;
}
trans_center = trans_delta;
if (lambda > 1.0)
{
/* The radii are too small for a matching ellipse. We expand them
* so that they fit exactly (center of the ellipse between the
* start- and endpoint
*/
radius_x *= sqrt (lambda);
radius_y *= sqrt (lambda);
trans_center.x = 0.0;
trans_center.y = 0.0;
}
else
{
gdouble factor = sqrt ((1.0 - lambda) / lambda);
trans_center.x = trans_delta.y * radius_x / radius_y * factor;
trans_center.y = - trans_delta.x * radius_y / radius_x * factor;
}
if ((large_arc && sweep) || (!large_arc && !sweep))
{
trans_center.x *= -1;
trans_center.y *= -1;
}
gimp_matrix3_identity (&anglerot);
gimp_matrix3_rotate (&anglerot, angle_rad);
tmp_center = trans_center;
gimp_matrix3_transform_point (&anglerot,
tmp_center.x, tmp_center.y,
&tmpx, &tmpy);
tmp_center.x = tmpx;
tmp_center.y = tmpy;
gimp_coords_mix (0.5, &start, 0.5, end, &middle);
gimp_coords_add (&tmp_center, &middle, &center);
phi1 = atan2 ((trans_delta.y - trans_center.y) / radius_y,
(trans_delta.x - trans_center.x) / radius_x);
phi2 = atan2 ((- trans_delta.y - trans_center.y) / radius_y,
(- trans_delta.x - trans_center.x) / radius_x);
if (phi1 < 0)
phi1 += 2 * G_PI;
if (phi2 < 0)
phi2 += 2 * G_PI;
if (sweep)
{
while (phi2 < phi1)
phi2 += 2 * G_PI;
phi0 = floor (phi1 / G_PI_2) * G_PI_2;
while (phi0 < phi2)
{
arcto_ellipsesegment (radius_x, radius_y,
MAX (phi0, phi1), MIN (phi0 + G_PI_2, phi2),
ellips);
gimp_matrix3_transform_point (&anglerot, ellips[0].x, ellips[0].y,
&tmpx, &tmpy);
ellips[0].x = tmpx; ellips[0].y = tmpy;
gimp_matrix3_transform_point (&anglerot, ellips[1].x, ellips[1].y,
&tmpx, &tmpy);
ellips[1].x = tmpx; ellips[1].y = tmpy;
gimp_matrix3_transform_point (&anglerot, ellips[2].x, ellips[2].y,
&tmpx, &tmpy);
ellips[2].x = tmpx; ellips[2].y = tmpy;
gimp_matrix3_transform_point (&anglerot, ellips[3].x, ellips[3].y,
&tmpx, &tmpy);
ellips[3].x = tmpx; ellips[3].y = tmpy;
gimp_coords_add (&center, &(ellips[1]), &(ctrl[1]));
gimp_coords_add (&center, &(ellips[2]), &(ctrl[2]));
gimp_coords_add (&center, &(ellips[3]), &(ctrl[3]));
gimp_bezier_stroke_cubicto (bez_stroke,
&(ctrl[1]), &(ctrl[2]), &(ctrl[3]));
phi0 += G_PI_2;
}
}
else
{
while (phi1 < phi2)
phi1 += 2 * G_PI;
phi0 = ceil (phi1 / G_PI_2) * G_PI_2;
while (phi0 > phi2)
{
arcto_ellipsesegment (radius_x, radius_y,
MIN (phi0, phi1), MAX (phi0 - G_PI_2, phi2),
ellips);
gimp_matrix3_transform_point (&anglerot, ellips[0].x, ellips[0].y,
&tmpx, &tmpy);
ellips[0].x = tmpx; ellips[0].y = tmpy;
gimp_matrix3_transform_point (&anglerot, ellips[1].x, ellips[1].y,
&tmpx, &tmpy);
ellips[1].x = tmpx; ellips[1].y = tmpy;
gimp_matrix3_transform_point (&anglerot, ellips[2].x, ellips[2].y,
&tmpx, &tmpy);
ellips[2].x = tmpx; ellips[2].y = tmpy;
gimp_matrix3_transform_point (&anglerot, ellips[3].x, ellips[3].y,
&tmpx, &tmpy);
ellips[3].x = tmpx; ellips[3].y = tmpy;
gimp_coords_add (&center, &(ellips[1]), &(ctrl[1]));
gimp_coords_add (&center, &(ellips[2]), &(ctrl[2]));
gimp_coords_add (&center, &(ellips[3]), &(ctrl[3]));
gimp_bezier_stroke_cubicto (bez_stroke,
&(ctrl[1]), &(ctrl[2]), &(ctrl[3]));
phi0 -= G_PI_2;
}
}
}
GimpStroke *
gimp_bezier_stroke_new_ellipse (const GimpCoords *center,
gdouble radius_x,
gdouble radius_y,
gdouble angle)
{
GimpStroke *stroke;
GimpCoords p1 = *center;
GimpCoords p2 = *center;
GimpCoords p3 = *center;
GimpCoords dx = *center;
GimpCoords dy = *center;
const gdouble circlemagic = 4.0 * (G_SQRT2 - 1.0) / 3.0;
GimpAnchor *handle;
dx.x = radius_x * cos (angle);
dx.y = - radius_x * sin (angle);
dy.x = radius_y * sin (angle);
dy.y = radius_y * cos (angle);
gimp_coords_mix (1.0, center, 1.0, &dx, &p1);
stroke = gimp_bezier_stroke_new_moveto (&p1);
handle = g_list_last (GIMP_STROKE (stroke)->anchors)->data;
gimp_coords_mix (1.0, &p1, -circlemagic, &dy, &handle->position);
gimp_coords_mix (1.0, &p1, circlemagic, &dy, &p1);
gimp_coords_mix (1.0, center, 1.0, &dy, &p3);
gimp_coords_mix (1.0, &p3, circlemagic, &dx, &p2);
gimp_bezier_stroke_cubicto (stroke, &p1, &p2, &p3);
gimp_coords_mix (1.0, &p3, -circlemagic, &dx, &p1);
gimp_coords_mix (1.0, center, -1.0, &dx, &p3);
gimp_coords_mix (1.0, &p3, circlemagic, &dy, &p2);
gimp_bezier_stroke_cubicto (stroke, &p1, &p2, &p3);
gimp_coords_mix (1.0, &p3, -circlemagic, &dy, &p1);
gimp_coords_mix (1.0, center, -1.0, &dy, &p3);
gimp_coords_mix (1.0, &p3, -circlemagic, &dx, &p2);
gimp_bezier_stroke_cubicto (stroke, &p1, &p2, &p3);
handle = g_list_first (GIMP_STROKE (stroke)->anchors)->data;
gimp_coords_mix (1.0, &p3, circlemagic, &dx, &handle->position);
gimp_stroke_close (stroke);
return stroke;
}
/* helper function to get the associated anchor of a listitem */
static GList *
gimp_bezier_stroke_get_anchor_listitem (GList *list)
{
if (!list)
return NULL;
if (GIMP_ANCHOR (list->data)->type == GIMP_ANCHOR_ANCHOR)
return list;
if (list->prev && GIMP_ANCHOR (list->prev->data)->type == GIMP_ANCHOR_ANCHOR)
return list->prev;
if (list->next && GIMP_ANCHOR (list->next->data)->type == GIMP_ANCHOR_ANCHOR)
return list->next;
g_return_val_if_fail (/* bezier stroke inconsistent! */ FALSE, NULL);
return NULL;
}
/*
* a helper function that determines if a bezier segment is "straight
* enough" to be approximated by a line.
*
* To be more exact, it also checks for the control points to be distributed
* evenly along the line. This makes it easier to reconstruct parameters for
* a given point along the segment.
*
* Needs four GimpCoords in an array.
*/
static gboolean
gimp_bezier_coords_is_straight (const GimpCoords *beziercoords,
gdouble precision)
{
GimpCoords pt1, pt2;
/* calculate the "ideal" positions for the control points */
gimp_coords_mix (2.0 / 3.0, &(beziercoords[0]),
1.0 / 3.0, &(beziercoords[3]),
&pt1);
gimp_coords_mix (1.0 / 3.0, &(beziercoords[0]),
2.0 / 3.0, &(beziercoords[3]),
&pt2);
/* calculate the deviation of the actual control points */
return (gimp_coords_manhattan_dist (&(beziercoords[1]), &pt1) < precision &&
gimp_coords_manhattan_dist (&(beziercoords[2]), &pt2) < precision);
}
/* local helper functions for bezier subdivision */
static void
gimp_bezier_coords_subdivide (const GimpCoords *beziercoords,
const gdouble precision,
GArray **ret_coords,
GArray **ret_params)
{
gimp_bezier_coords_subdivide2 (beziercoords, 0.0, 1.0,
precision, ret_coords, ret_params, 10);
}
static void
gimp_bezier_coords_subdivide2 (const GimpCoords *beziercoords,
const gdouble start_t,
const gdouble end_t,
const gdouble precision,
GArray **ret_coords,
GArray **ret_params,
gint depth)
{
/*
* beziercoords has to contain four GimpCoords with the four control points
* of the bezier segment. We subdivide it at the parameter 0.5.
*/
GimpCoords subdivided[8];
gdouble middle_t = (start_t + end_t) / 2;
subdivided[0] = beziercoords[0];
subdivided[6] = beziercoords[3];
/* if (!depth) g_printerr ("Hit recursion depth limit!\n"); */
gimp_coords_average (&(beziercoords[0]), &(beziercoords[1]),
&(subdivided[1]));
gimp_coords_average (&(beziercoords[1]), &(beziercoords[2]),
&(subdivided[7]));
gimp_coords_average (&(beziercoords[2]), &(beziercoords[3]),
&(subdivided[5]));
gimp_coords_average (&(subdivided[1]), &(subdivided[7]),
&(subdivided[2]));
gimp_coords_average (&(subdivided[7]), &(subdivided[5]),
&(subdivided[4]));
gimp_coords_average (&(subdivided[2]), &(subdivided[4]),
&(subdivided[3]));
/*
* We now have the coordinates of the two bezier segments in
* subdivided [0-3] and subdivided [3-6]
*/
/*
* Here we need to check, if we have sufficiently subdivided, i.e.
* if the stroke is sufficiently close to a straight line.
*/
if (!depth || gimp_bezier_coords_is_straight (&(subdivided[0]),
precision)) /* 1st half */
{
*ret_coords = g_array_append_vals (*ret_coords, &(subdivided[0]), 3);
if (ret_params)
{
gdouble params[3];
params[0] = start_t;
params[1] = (2 * start_t + middle_t) / 3;
params[2] = (start_t + 2 * middle_t) / 3;
*ret_params = g_array_append_vals (*ret_params, &(params[0]), 3);
}
}
else
{
gimp_bezier_coords_subdivide2 (&(subdivided[0]),
start_t, (start_t + end_t) / 2,
precision,
ret_coords, ret_params, depth-1);
}
if (!depth || gimp_bezier_coords_is_straight (&(subdivided[3]),
precision)) /* 2nd half */
{
*ret_coords = g_array_append_vals (*ret_coords, &(subdivided[3]), 3);
if (ret_params)
{
gdouble params[3];
params[0] = middle_t;
params[1] = (2 * middle_t + end_t) / 3;
params[2] = (middle_t + 2 * end_t) / 3;
*ret_params = g_array_append_vals (*ret_params, &(params[0]), 3);
}
}
else
{
gimp_bezier_coords_subdivide2 (&(subdivided[3]),
(start_t + end_t) / 2, end_t,
precision,
ret_coords, ret_params, depth-1);
}
}
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