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-rw-r--r--app/vectors/gimpvectors-warp.c210
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diff --git a/app/vectors/gimpvectors-warp.c b/app/vectors/gimpvectors-warp.c
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+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpvectors-warp.c
+ * Copyright (C) 2005 Bill Skaggs <weskaggs@primate.ucdavis.edu>
+ *
+ * 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 <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "vectors-types.h"
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core/gimp-utils.h"
+#include "core/gimpcoords.h"
+
+#include "gimpanchor.h"
+#include "gimpstroke.h"
+#include "gimpvectors.h"
+#include "gimpvectors-warp.h"
+
+
+#define EPSILON 0.2
+#define DX 2.0
+
+
+static void gimp_stroke_warp_point (GimpStroke *stroke,
+ gdouble x,
+ gdouble y,
+ GimpCoords *point_warped,
+ gdouble y_offset,
+ gdouble x_len);
+
+static void gimp_vectors_warp_stroke (GimpVectors *vectors,
+ GimpStroke *stroke,
+ gdouble y_offset);
+
+
+void
+gimp_vectors_warp_point (GimpVectors *vectors,
+ GimpCoords *point,
+ GimpCoords *point_warped,
+ gdouble y_offset)
+{
+ gdouble x = point->x;
+ gdouble y = point->y;
+ gdouble len;
+ GList *list;
+ GimpStroke *stroke;
+
+ for (list = vectors->strokes->head;
+ list;
+ list = g_list_next (list))
+ {
+ stroke = list->data;
+
+ len = gimp_vectors_stroke_get_length (vectors, stroke);
+
+ if (x < len || ! list->next)
+ break;
+
+ x -= len;
+ }
+
+ if (! list)
+ {
+ point_warped->x = 0;
+ point_warped->y = 0;
+ return;
+ }
+
+ gimp_stroke_warp_point (stroke, x, y, point_warped, y_offset, len);
+}
+
+static void
+gimp_stroke_warp_point (GimpStroke *stroke,
+ gdouble x,
+ gdouble y,
+ GimpCoords *point_warped,
+ gdouble y_offset,
+ gdouble x_len)
+{
+ GimpCoords point_zero = { 0, };
+ GimpCoords point_minus = { 0, };
+ GimpCoords point_plus = { 0, };
+ gdouble slope;
+ gdouble dx, dy, nx, ny, len;
+
+ if (x + DX >= x_len)
+ {
+ gdouble tx, ty;
+
+ if (! gimp_stroke_get_point_at_dist (stroke, x_len, EPSILON,
+ &point_zero, &slope))
+ {
+ point_warped->x = 0;
+ point_warped->y = 0;
+ return;
+ }
+
+ point_warped->x = point_zero.x;
+ point_warped->y = point_zero.y;
+
+ if (! gimp_stroke_get_point_at_dist (stroke, x_len - DX, EPSILON,
+ &point_minus, &slope))
+ return;
+
+ dx = point_zero.x - point_minus.x;
+ dy = point_zero.y - point_minus.y;
+
+ len = hypot (dx, dy);
+
+ if (len < 0.01)
+ return;
+
+ tx = dx / len;
+ ty = dy / len;
+
+ nx = - dy / len;
+ ny = dx / len;
+
+ point_warped->x += tx * (x - x_len) + nx * (y - y_offset);
+ point_warped->y += ty * (x - x_len) + ny * (y - y_offset);
+
+ return;
+ }
+
+ if (! gimp_stroke_get_point_at_dist (stroke, x, EPSILON,
+ &point_zero, &slope))
+ {
+ point_warped->x = 0;
+ point_warped->y = 0;
+ return;
+ }
+
+ point_warped->x = point_zero.x;
+ point_warped->y = point_zero.y;
+
+ if (! gimp_stroke_get_point_at_dist (stroke, x - DX, EPSILON,
+ &point_minus, &slope))
+ return;
+
+ if (! gimp_stroke_get_point_at_dist (stroke, x + DX, EPSILON,
+ &point_plus, &slope))
+ return;
+
+ dx = point_plus.x - point_minus.x;
+ dy = point_plus.y - point_minus.y;
+
+ len = hypot (dx, dy);
+
+ if (len < 0.01)
+ return;
+
+ nx = - dy / len;
+ ny = dx / len;
+
+ point_warped->x = point_zero.x + nx * (y - y_offset);
+ point_warped->y = point_zero.y + ny * (y - y_offset);
+}
+
+static void
+gimp_vectors_warp_stroke (GimpVectors *vectors,
+ GimpStroke *stroke,
+ gdouble y_offset)
+{
+ GList *list;
+
+ for (list = stroke->anchors->head; list; list = g_list_next (list))
+ {
+ GimpAnchor *anchor = list->data;
+
+ gimp_vectors_warp_point (vectors,
+ &anchor->position, &anchor->position,
+ y_offset);
+ }
+}
+
+void
+gimp_vectors_warp_vectors (GimpVectors *vectors,
+ GimpVectors *vectors_in,
+ gdouble y_offset)
+{
+ GList *list;
+
+ for (list = vectors_in->strokes->head;
+ list;
+ list = g_list_next (list))
+ {
+ GimpStroke *stroke = list->data;
+
+ gimp_vectors_warp_stroke (vectors, stroke, y_offset);
+ }
+}