Adding upstream version 2.10.36.upstream/2.10.36

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

1 files changed, 1344 insertions, 0 deletions

diff --git a/app/paint/gimpbrushcore.c b/app/paint/gimpbrushcore.c
new file mode 100644
index 0000000..da4f26b
--- /dev/null
+++ b/app/paint/gimpbrushcore.c
@@ -0,0 +1,1344 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * 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 <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "paint-types.h"
+
+#include "operations/layer-modes/gimp-layer-modes.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-loops.h"
+
+#include "core/gimpbrush-header.h"
+#include "core/gimpbrushgenerated.h"
+#include "core/gimpdrawable.h"
+#include "core/gimpdynamics.h"
+#include "core/gimpdynamicsoutput.h"
+#include "core/gimperror.h"
+#include "core/gimpimage.h"
+#include "core/gimpmarshal.h"
+#include "core/gimpsymmetry.h"
+#include "core/gimptempbuf.h"
+
+#include "gimpbrushcore.h"
+#include "gimpbrushcore-loops.h"
+#include "gimpbrushcore-kernels.h"
+
+#include "gimppaintoptions.h"
+
+#include "gimp-intl.h"
+
+
+#define EPSILON  0.00001
+
+enum
+{
+  SET_BRUSH,
+  SET_DYNAMICS,
+  LAST_SIGNAL
+};
+
+
+/*  local function prototypes  */
+
+static void      gimp_brush_core_finalize           (GObject          *object);
+
+static gboolean  gimp_brush_core_start              (GimpPaintCore    *core,
+                                                     GimpDrawable     *drawable,
+                                                     GimpPaintOptions *paint_options,
+                                                     const GimpCoords *coords,
+                                                     GError          **error);
+static gboolean  gimp_brush_core_pre_paint          (GimpPaintCore    *core,
+                                                     GimpDrawable     *drawable,
+                                                     GimpPaintOptions *paint_options,
+                                                     GimpPaintState    paint_state,
+                                                     guint32           time);
+static void      gimp_brush_core_post_paint         (GimpPaintCore    *core,
+                                                     GimpDrawable     *drawable,
+                                                     GimpPaintOptions *paint_options,
+                                                     GimpPaintState    paint_state,
+                                                     guint32           time);
+static void      gimp_brush_core_interpolate        (GimpPaintCore    *core,
+                                                     GimpDrawable     *drawable,
+                                                     GimpPaintOptions *paint_options,
+                                                     guint32           time);
+
+static GeglBuffer * gimp_brush_core_get_paint_buffer(GimpPaintCore    *paint_core,
+                                                     GimpDrawable     *drawable,
+                                                     GimpPaintOptions *paint_options,
+                                                     GimpLayerMode     paint_mode,
+                                                     const GimpCoords *coords,
+                                                     gint             *paint_buffer_x,
+                                                     gint             *paint_buffer_y,
+                                                     gint             *paint_width,
+                                                     gint             *paint_height);
+
+static void      gimp_brush_core_real_set_brush     (GimpBrushCore    *core,
+                                                     GimpBrush        *brush);
+static void      gimp_brush_core_real_set_dynamics  (GimpBrushCore    *core,
+                                                     GimpDynamics     *dynamics);
+
+static gdouble   gimp_brush_core_get_angle          (GimpBrushCore     *core);
+static gboolean  gimp_brush_core_get_reflect        (GimpBrushCore     *core);
+
+static const GimpTempBuf *
+                 gimp_brush_core_transform_mask     (GimpBrushCore     *core,
+                                                     GimpBrush         *brush);
+
+static void      gimp_brush_core_invalidate_cache   (GimpBrush         *brush,
+                                                     GimpBrushCore     *core);
+
+
+G_DEFINE_TYPE (GimpBrushCore, gimp_brush_core, GIMP_TYPE_PAINT_CORE)
+
+#define parent_class gimp_brush_core_parent_class
+
+static guint core_signals[LAST_SIGNAL] = { 0, };
+
+
+static void
+gimp_brush_core_class_init (GimpBrushCoreClass *klass)
+{
+  GObjectClass       *object_class     = G_OBJECT_CLASS (klass);
+  GimpPaintCoreClass *paint_core_class = GIMP_PAINT_CORE_CLASS (klass);
+
+  core_signals[SET_BRUSH] =
+    g_signal_new ("set-brush",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GimpBrushCoreClass, set_brush),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_BRUSH);
+
+  core_signals[SET_DYNAMICS] =
+    g_signal_new ("set-dynamics",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GimpBrushCoreClass, set_dynamics),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_DYNAMICS);
+
+  object_class->finalize                    = gimp_brush_core_finalize;
+
+  paint_core_class->start                   = gimp_brush_core_start;
+  paint_core_class->pre_paint               = gimp_brush_core_pre_paint;
+  paint_core_class->post_paint              = gimp_brush_core_post_paint;
+  paint_core_class->interpolate             = gimp_brush_core_interpolate;
+  paint_core_class->get_paint_buffer        = gimp_brush_core_get_paint_buffer;
+
+  klass->handles_changing_brush             = FALSE;
+  klass->handles_transforming_brush         = TRUE;
+  klass->handles_dynamic_transforming_brush = TRUE;
+
+  klass->set_brush                          = gimp_brush_core_real_set_brush;
+  klass->set_dynamics                       = gimp_brush_core_real_set_dynamics;
+}
+
+static void
+gimp_brush_core_init (GimpBrushCore *core)
+{
+  gint i, j;
+
+  core->main_brush                   = NULL;
+  core->brush                        = NULL;
+  core->dynamics                     = NULL;
+  core->spacing                      = 1.0;
+  core->scale                        = 1.0;
+  core->angle                        = 0.0;
+  core->reflect                      = FALSE;
+  core->hardness                     = 1.0;
+  core->aspect_ratio                 = 0.0;
+
+  core->symmetry_angle               = 0.0;
+  core->symmetry_reflect             = FALSE;
+
+  core->pressure_brush               = NULL;
+
+  core->last_solid_brush_mask        = NULL;
+  core->solid_cache_invalid          = FALSE;
+
+  core->transform_brush              = NULL;
+  core->transform_pixmap             = NULL;
+
+  core->last_subsample_brush_mask    = NULL;
+  core->subsample_cache_invalid      = FALSE;
+
+  core->rand                         = g_rand_new ();
+
+  for (i = 0; i < BRUSH_CORE_SOLID_SUBSAMPLE; i++)
+    {
+      for (j = 0; j < BRUSH_CORE_SOLID_SUBSAMPLE; j++)
+        {
+          core->solid_brushes[i][j] = NULL;
+        }
+    }
+
+  for (i = 0; i < BRUSH_CORE_JITTER_LUTSIZE - 1; ++i)
+    {
+      core->jitter_lut_y[i] = cos (gimp_deg_to_rad (i * 360 /
+                                                    BRUSH_CORE_JITTER_LUTSIZE));
+      core->jitter_lut_x[i] = sin (gimp_deg_to_rad (i * 360 /
+                                                    BRUSH_CORE_JITTER_LUTSIZE));
+    }
+
+  gimp_assert (BRUSH_CORE_SUBSAMPLE == KERNEL_SUBSAMPLE);
+
+  for (i = 0; i < KERNEL_SUBSAMPLE + 1; i++)
+    {
+      for (j = 0; j < KERNEL_SUBSAMPLE + 1; j++)
+        {
+          core->subsample_brushes[i][j] = NULL;
+        }
+    }
+}
+
+static void
+gimp_brush_core_finalize (GObject *object)
+{
+  GimpBrushCore *core = GIMP_BRUSH_CORE (object);
+  gint           i, j;
+
+  g_clear_pointer (&core->pressure_brush, gimp_temp_buf_unref);
+
+  for (i = 0; i < BRUSH_CORE_SOLID_SUBSAMPLE; i++)
+    for (j = 0; j < BRUSH_CORE_SOLID_SUBSAMPLE; j++)
+      g_clear_pointer (&core->solid_brushes[i][j], gimp_temp_buf_unref);
+
+  g_clear_pointer (&core->rand, g_rand_free);
+
+  for (i = 0; i < KERNEL_SUBSAMPLE + 1; i++)
+    for (j = 0; j < KERNEL_SUBSAMPLE + 1; j++)
+      g_clear_pointer (&core->subsample_brushes[i][j], gimp_temp_buf_unref);
+
+  if (core->main_brush)
+    {
+      g_signal_handlers_disconnect_by_func (core->main_brush,
+                                            gimp_brush_core_invalidate_cache,
+                                            core);
+      gimp_brush_end_use (core->main_brush);
+      g_clear_object (&core->main_brush);
+    }
+
+  g_clear_object (&core->dynamics);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gboolean
+gimp_brush_core_pre_paint (GimpPaintCore    *paint_core,
+                           GimpDrawable     *drawable,
+                           GimpPaintOptions *paint_options,
+                           GimpPaintState    paint_state,
+                           guint32           time)
+{
+  GimpBrushCore *core = GIMP_BRUSH_CORE (paint_core);
+
+  if (paint_state == GIMP_PAINT_STATE_MOTION)
+    {
+      GimpCoords last_coords;
+      GimpCoords current_coords;
+      gdouble scale;
+
+      gimp_paint_core_get_last_coords (paint_core, &last_coords);
+      gimp_paint_core_get_current_coords (paint_core, &current_coords);
+
+      /* If we current point == last point, check if the brush
+       * wants to be painted in that case. (Direction dependent
+       * pixmap brush pipes don't, as they don't know which
+       * pixmap to select.)
+       */
+      if (last_coords.x == current_coords.x &&
+          last_coords.y == current_coords.y &&
+          ! gimp_brush_want_null_motion (core->main_brush,
+                                         &last_coords,
+                                         &current_coords))
+        {
+          return FALSE;
+        }
+      /*No drawing anything if the scale is too small*/
+      if (GIMP_BRUSH_CORE_GET_CLASS (core)->handles_transforming_brush)
+        {
+          GimpImage *image = gimp_item_get_image (GIMP_ITEM (drawable));
+          gdouble    fade_point;
+
+          if (GIMP_BRUSH_CORE_GET_CLASS (core)->handles_dynamic_transforming_brush)
+            {
+              gdouble width;
+              gdouble height;
+
+              fade_point = gimp_paint_options_get_fade (paint_options, image,
+                                                        paint_core->pixel_dist);
+              width = gimp_brush_get_width  (core->main_brush);
+              height = gimp_brush_get_height (core->main_brush);
+
+              scale = paint_options->brush_size /
+                      MAX (width, height) *
+                      gimp_dynamics_get_linear_value (core->dynamics,
+                                                      GIMP_DYNAMICS_OUTPUT_SIZE,
+                                                      &current_coords,
+                                                      paint_options,
+                                                      fade_point);
+
+              if (paint_options->brush_lock_to_view &&
+                  MAX (current_coords.xscale, current_coords.yscale) > 0)
+                {
+                  scale /= MAX (current_coords.xscale, current_coords.yscale);
+
+                  /* Cap transform result for brushes or OOM can occur */
+                  if ((scale * MAX (width, height)) > GIMP_BRUSH_MAX_SIZE)
+                    {
+                      scale = GIMP_BRUSH_MAX_SIZE / MAX (width, height);
+                    }
+                }
+
+              if (scale < 0.0000001)
+                return FALSE;
+            }
+        }
+
+      if (GIMP_BRUSH_CORE_GET_CLASS (paint_core)->handles_changing_brush)
+        {
+          core->brush = gimp_brush_select_brush (core->main_brush,
+                                                 &last_coords,
+                                                 &current_coords);
+        }
+      if ((! GIMP_IS_BRUSH_GENERATED(core->main_brush)) &&
+          (paint_options->brush_hardness != gimp_brush_get_blur_hardness(core->main_brush)))
+        {
+          gimp_brush_flush_blur_caches(core->main_brush);
+        }
+    }
+
+  return TRUE;
+}
+
+static void
+gimp_brush_core_post_paint (GimpPaintCore    *paint_core,
+                            GimpDrawable     *drawable,
+                            GimpPaintOptions *paint_options,
+                            GimpPaintState    paint_state,
+                            guint32           time)
+{
+  GimpBrushCore *core = GIMP_BRUSH_CORE (paint_core);
+
+  if (paint_state == GIMP_PAINT_STATE_MOTION)
+    {
+      core->brush = core->main_brush;
+    }
+}
+
+static gboolean
+gimp_brush_core_start (GimpPaintCore     *paint_core,
+                       GimpDrawable      *drawable,
+                       GimpPaintOptions  *paint_options,
+                       const GimpCoords  *coords,
+                       GError           **error)
+{
+  GimpBrushCore *core    = GIMP_BRUSH_CORE (paint_core);
+  GimpContext   *context = GIMP_CONTEXT (paint_options);
+
+  gimp_brush_core_set_brush (core, gimp_context_get_brush (context));
+
+  gimp_brush_core_set_dynamics (core, gimp_context_get_dynamics (context));
+
+  if (! core->main_brush)
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("No brushes available for use with this tool."));
+      return FALSE;
+    }
+
+  if (! core->dynamics)
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("No paint dynamics available for use with this tool."));
+      return FALSE;
+    }
+
+  if (GIMP_BRUSH_CORE_GET_CLASS (core)->handles_transforming_brush)
+    {
+      gimp_brush_core_eval_transform_dynamics (core,
+                                               drawable,
+                                               paint_options,
+                                               coords);
+
+      gimp_brush_core_eval_transform_symmetry (core, NULL, 0);
+    }
+
+  core->spacing = paint_options->brush_spacing;
+
+  core->brush = core->main_brush;
+
+  core->jitter =
+    gimp_paint_options_get_jitter (paint_options,
+                                   gimp_item_get_image (GIMP_ITEM (drawable)));
+
+  return TRUE;
+}
+
+/**
+ * gimp_avoid_exact_integer
+ * @x: points to a gdouble
+ *
+ * Adjusts *x such that it is not too close to an integer. This is used
+ * for decision algorithms that would be vulnerable to rounding glitches
+ * if exact integers were input.
+ *
+ * Side effects: Changes the value of *x
+ **/
+static void
+gimp_avoid_exact_integer (gdouble *x)
+{
+  const gdouble integral   = floor (*x);
+  const gdouble fractional = *x - integral;
+
+  if (fractional < EPSILON)
+    {
+      *x = integral + EPSILON;
+    }
+  else if (fractional > (1 -EPSILON))
+    {
+      *x = integral + (1 - EPSILON);
+    }
+}
+
+static void
+gimp_brush_core_interpolate (GimpPaintCore    *paint_core,
+                             GimpDrawable     *drawable,
+                             GimpPaintOptions *paint_options,
+                             guint32           time)
+{
+  GimpBrushCore      *core  = GIMP_BRUSH_CORE (paint_core);
+  GimpImage          *image = gimp_item_get_image (GIMP_ITEM (drawable));
+  GimpDynamicsOutput *spacing_output;
+  GimpCoords          last_coords;
+  GimpCoords          current_coords;
+  GimpVector2         delta_vec;
+  gdouble             delta_pressure;
+  gdouble             delta_xtilt, delta_ytilt;
+  gdouble             delta_wheel;
+  gdouble             delta_velocity;
+  gdouble             temp_direction;
+  GimpVector2         temp_vec;
+  gint                n, num_points;
+  gdouble             t0, dt, tn;
+  gdouble             st_factor, st_offset;
+  gdouble             initial;
+  gdouble             dist;
+  gdouble             total;
+  gdouble             pixel_dist;
+  gdouble             pixel_initial;
+  gdouble             xd, yd;
+  gdouble             mag;
+  gdouble             dyn_spacing = core->spacing;
+  gdouble             fade_point;
+  gboolean            use_dyn_spacing;
+
+  g_return_if_fail (GIMP_IS_BRUSH (core->brush));
+
+  gimp_paint_core_get_last_coords (paint_core, &last_coords);
+  gimp_paint_core_get_current_coords (paint_core, &current_coords);
+
+  gimp_avoid_exact_integer (&last_coords.x);
+  gimp_avoid_exact_integer (&last_coords.y);
+  gimp_avoid_exact_integer (&current_coords.x);
+  gimp_avoid_exact_integer (&current_coords.y);
+
+  delta_vec.x    = current_coords.x        - last_coords.x;
+  delta_vec.y    = current_coords.y        - last_coords.y;
+  delta_pressure = current_coords.pressure - last_coords.pressure;
+  delta_xtilt    = current_coords.xtilt    - last_coords.xtilt;
+  delta_ytilt    = current_coords.ytilt    - last_coords.ytilt;
+  delta_wheel    = current_coords.wheel    - last_coords.wheel;
+  delta_velocity = current_coords.velocity - last_coords.velocity;
+  temp_direction = current_coords.direction;
+
+  /*  return if there has been no motion  */
+  if (! delta_vec.x    &&
+      ! delta_vec.y    &&
+      ! delta_pressure &&
+      ! delta_xtilt    &&
+      ! delta_ytilt    &&
+      ! delta_wheel    &&
+      ! delta_velocity)
+    return;
+
+  pixel_dist    = gimp_vector2_length (&delta_vec);
+  pixel_initial = paint_core->pixel_dist;
+
+  /*  Zero sized brushes are unfit for interpolate, so we just let
+   *  paint core fail on its own
+   */
+  if (core->scale == 0.0)
+    {
+      gimp_paint_core_set_last_coords (paint_core, &current_coords);
+
+      gimp_paint_core_paint (paint_core, drawable, paint_options,
+                             GIMP_PAINT_STATE_MOTION, time);
+
+      paint_core->pixel_dist = pixel_initial + pixel_dist; /* Don't forget to update pixel distance*/
+
+      return;
+    }
+
+  /* Handle dynamic spacing */
+  spacing_output = gimp_dynamics_get_output (core->dynamics,
+                                             GIMP_DYNAMICS_OUTPUT_SPACING);
+
+  fade_point = gimp_paint_options_get_fade (paint_options, image,
+                                            paint_core->pixel_dist);
+
+  use_dyn_spacing = gimp_dynamics_output_is_enabled (spacing_output);
+
+  if (use_dyn_spacing)
+    {
+      dyn_spacing = gimp_dynamics_output_get_linear_value (spacing_output,
+                                                           &current_coords,
+                                                           paint_options,
+                                                           fade_point);
+
+      /* Dynamic spacing assumes that the value set in core is the min
+       * value and the max is full 200% spacing. This approach differs
+       * from the usual factor from user input approach because making
+       * spacing smaller than the nominal value is unlikely and
+       * spacing has a hard defined max.
+       */
+      dyn_spacing = (core->spacing +
+                     ((2.0 - core->spacing) * (1.0 - dyn_spacing)));
+
+      /*  Limiting spacing to minimum 1%  */
+      dyn_spacing = MAX (core->spacing, dyn_spacing);
+    }
+
+  /* calculate the distance traveled in the coordinate space of the brush */
+  temp_vec = gimp_brush_get_x_axis (core->brush);
+  gimp_vector2_mul (&temp_vec, core->scale);
+  gimp_vector2_rotate (&temp_vec, core->angle * G_PI * 2);
+
+  mag = gimp_vector2_length (&temp_vec);
+  xd  = gimp_vector2_inner_product (&delta_vec, &temp_vec) / (mag * mag);
+
+  temp_vec = gimp_brush_get_y_axis (core->brush);
+  gimp_vector2_mul (&temp_vec, core->scale);
+  gimp_vector2_rotate (&temp_vec, core->angle * G_PI * 2);
+
+  mag = gimp_vector2_length (&temp_vec);
+  yd  = gimp_vector2_inner_product (&delta_vec, &temp_vec) / (mag * mag);
+
+  dist    = 0.5 * sqrt (xd * xd + yd * yd);
+  total   = dist + paint_core->distance;
+  initial = paint_core->distance;
+
+
+  if (delta_vec.x * delta_vec.x > delta_vec.y * delta_vec.y)
+    {
+      st_factor = delta_vec.x;
+      st_offset = last_coords.x - 0.5;
+    }
+  else
+    {
+      st_factor = delta_vec.y;
+      st_offset = last_coords.y - 0.5;
+    }
+
+  if (use_dyn_spacing)
+    {
+      gint s0;
+
+      num_points = dist / dyn_spacing;
+
+      s0 = (gint) floor (st_offset + 0.5);
+      t0 = (s0 - st_offset) / st_factor;
+      dt = dyn_spacing / dist;
+
+      if (num_points == 0)
+        return;
+    }
+  else if (fabs (st_factor) > dist / core->spacing)
+    {
+      /*  The stripe principle leads to brush positions that are spaced
+       *  *closer* than the official brush spacing. Use the official
+       *  spacing instead. This is the common case when the brush spacing
+       *  is large.
+       *  The net effect is then to put a lower bound on the spacing, but
+       *  one that varies with the slope of the line. This is suppose to
+       *  make thin lines (say, with a 1x1 brush) prettier while leaving
+       *  lines with larger brush spacing as they used to look in 1.2.x.
+       */
+
+      dt = core->spacing / dist;
+      n = (gint) (initial / core->spacing + 1.0 + EPSILON);
+      t0 = (n * core->spacing - initial) / dist;
+      num_points = 1 + (gint) floor ((1 + EPSILON - t0) / dt);
+
+      /* if we arnt going to paint anything this time and the brush
+       * has only moved on one axis return without updating the brush
+       * position, distance etc. so that we can more accurately space
+       * brush strokes when curves are supplied to us in single pixel
+       * chunks.
+       */
+
+      if (num_points == 0 && (delta_vec.x == 0 || delta_vec.y == 0))
+        return;
+    }
+  else if (fabs (st_factor) < EPSILON)
+    {
+      /* Hm, we've hardly moved at all. Don't draw anything, but reset the
+       * old coordinates and hope we've gone longer the next time...
+       */
+      current_coords.x = last_coords.x;
+      current_coords.y = last_coords.y;
+
+      gimp_paint_core_set_current_coords (paint_core, &current_coords);
+
+      /* ... but go along with the current pressure, tilt and wheel */
+      return;
+    }
+  else
+    {
+      gint direction = st_factor > 0 ? 1 : -1;
+      gint x, y;
+      gint s0, sn;
+
+      /*  Choose the first and last stripe to paint.
+       *    FIRST PRIORITY is to avoid gaps painting with a 1x1 aliasing
+       *  brush when a horizontalish line segment follows a verticalish
+       *  one or vice versa - no matter what the angle between the two
+       *  lines is. This will also limit the local thinning that a 1x1
+       *  subsampled brush may suffer in the same situation.
+       *    SECOND PRIORITY is to avoid making free-hand drawings
+       *  unpleasantly fat by plotting redundant points.
+       *    These are achieved by the following rules, but it is a little
+       *  tricky to see just why. Do not change this algorithm unless you
+       *  are sure you know what you're doing!
+       */
+
+      /*  Basic case: round the beginning and ending point to nearest
+       *  stripe center.
+       */
+      s0 = (gint) floor (st_offset + 0.5);
+      sn = (gint) floor (st_offset + st_factor + 0.5);
+
+      t0 = (s0 - st_offset) / st_factor;
+      tn = (sn - st_offset) / st_factor;
+
+      x = (gint) floor (last_coords.x + t0 * delta_vec.x);
+      y = (gint) floor (last_coords.y + t0 * delta_vec.y);
+
+      if (t0 < 0.0 && !( x == (gint) floor (last_coords.x) &&
+                         y == (gint) floor (last_coords.y) ))
+        {
+          /*  Exception A: If the first stripe's brush position is
+           *  EXTRApolated into a different pixel square than the
+           *  ideal starting point, don't plot it.
+           */
+          s0 += direction;
+        }
+      else if (x == (gint) floor (paint_core->last_paint.x) &&
+               y == (gint) floor (paint_core->last_paint.y))
+        {
+          /*  Exception B: If first stripe's brush position is within the
+           *  same pixel square as the last plot of the previous line,
+           *  don't plot it either.
+           */
+          s0 += direction;
+        }
+
+      x = (gint) floor (last_coords.x + tn * delta_vec.x);
+      y = (gint) floor (last_coords.y + tn * delta_vec.y);
+
+      if (tn > 1.0 && !( x == (gint) floor (current_coords.x) &&
+                         y == (gint) floor (current_coords.y)))
+        {
+          /*  Exception C: If the last stripe's brush position is
+           *  EXTRApolated into a different pixel square than the
+           *  ideal ending point, don't plot it.
+           */
+          sn -= direction;
+        }
+
+      t0 = (s0 - st_offset) / st_factor;
+      tn = (sn - st_offset) / st_factor;
+      dt         =     direction * 1.0 / st_factor;
+      num_points = 1 + direction * (sn - s0);
+
+      if (num_points >= 1)
+        {
+          /*  Hack the reported total distance such that it looks to the
+           *  next line as if the the last pixel plotted were at an integer
+           *  multiple of the brush spacing. This helps prevent artifacts
+           *  for connected lines when the brush spacing is such that some
+           *  slopes will use the stripe regime and other slopes will use
+           *  the nominal brush spacing.
+           */
+
+          if (tn < 1)
+            total = initial + tn * dist;
+
+          total = core->spacing * (gint) (total / core->spacing + 0.5);
+          total += (1.0 - tn) * dist;
+        }
+    }
+
+  for (n = 0; n < num_points; n++)
+    {
+      gdouble t = t0 + n * dt;
+      gdouble p = (gdouble) n / num_points;
+
+      current_coords.x         = last_coords.x        + t * delta_vec.x;
+      current_coords.y         = last_coords.y        + t * delta_vec.y;
+      current_coords.pressure  = last_coords.pressure + p * delta_pressure;
+      current_coords.xtilt     = last_coords.xtilt    + p * delta_xtilt;
+      current_coords.ytilt     = last_coords.ytilt    + p * delta_ytilt;
+      current_coords.wheel     = last_coords.wheel    + p * delta_wheel;
+      current_coords.velocity  = last_coords.velocity + p * delta_velocity;
+      current_coords.direction = temp_direction;
+      current_coords.xscale    = last_coords.xscale;
+      current_coords.yscale    = last_coords.yscale;
+      current_coords.angle     = last_coords.angle;
+      current_coords.reflect   = last_coords.reflect;
+
+      if (core->jitter > 0.0)
+        {
+          GimpVector2 x_axis;
+          GimpVector2 y_axis;
+          gdouble     dyn_jitter;
+          gdouble     jitter_dist;
+          gint32      jitter_angle;
+
+          x_axis = gimp_brush_get_x_axis (core->brush);
+          y_axis = gimp_brush_get_y_axis (core->brush);
+
+          dyn_jitter = (core->jitter *
+                        gimp_dynamics_get_linear_value (core->dynamics,
+                                                        GIMP_DYNAMICS_OUTPUT_JITTER,
+                                                        &current_coords,
+                                                        paint_options,
+                                                        fade_point));
+
+          jitter_dist  = g_rand_double_range (core->rand, 0, dyn_jitter);
+          jitter_angle = g_rand_int_range (core->rand,
+                                           0, BRUSH_CORE_JITTER_LUTSIZE);
+
+          current_coords.x +=
+            (x_axis.x + y_axis.x) *
+            jitter_dist * core->jitter_lut_x[jitter_angle] * core->scale;
+
+          current_coords.y +=
+            (y_axis.y + x_axis.y) *
+            jitter_dist * core->jitter_lut_y[jitter_angle] * core->scale;
+        }
+
+      gimp_paint_core_set_current_coords (paint_core, &current_coords);
+
+      paint_core->distance   = initial       + t * dist;
+      paint_core->pixel_dist = pixel_initial + t * pixel_dist;
+
+      gimp_paint_core_paint (paint_core, drawable, paint_options,
+                             GIMP_PAINT_STATE_MOTION, time);
+    }
+
+  current_coords.x        = last_coords.x        + delta_vec.x;
+  current_coords.y        = last_coords.y        + delta_vec.y;
+  current_coords.pressure = last_coords.pressure + delta_pressure;
+  current_coords.xtilt    = last_coords.xtilt    + delta_xtilt;
+  current_coords.ytilt    = last_coords.ytilt    + delta_ytilt;
+  current_coords.wheel    = last_coords.wheel    + delta_wheel;
+  current_coords.velocity = last_coords.velocity + delta_velocity;
+  current_coords.xscale   = last_coords.xscale;
+  current_coords.yscale   = last_coords.yscale;
+  current_coords.angle    = last_coords.angle;
+  current_coords.reflect  = last_coords.reflect;
+
+  gimp_paint_core_set_current_coords (paint_core, &current_coords);
+  gimp_paint_core_set_last_coords (paint_core, &current_coords);
+
+  paint_core->distance   = total;
+  paint_core->pixel_dist = pixel_initial + pixel_dist;
+}
+
+static GeglBuffer *
+gimp_brush_core_get_paint_buffer (GimpPaintCore    *paint_core,
+                                  GimpDrawable     *drawable,
+                                  GimpPaintOptions *paint_options,
+                                  GimpLayerMode     paint_mode,
+                                  const GimpCoords *coords,
+                                  gint             *paint_buffer_x,
+                                  gint             *paint_buffer_y,
+                                  gint             *paint_width,
+                                  gint             *paint_height)
+{
+  GimpBrushCore *core = GIMP_BRUSH_CORE (paint_core);
+  gint           x, y;
+  gint           x1, y1, x2, y2;
+  gint           drawable_width, drawable_height;
+  gint           brush_width, brush_height;
+
+  gimp_brush_transform_size (core->brush,
+                             core->scale, core->aspect_ratio,
+                             gimp_brush_core_get_angle (core),
+                             gimp_brush_core_get_reflect (core),
+                             &brush_width, &brush_height);
+
+  if (paint_width)
+    *paint_width  = brush_width;
+  if (paint_height)
+    *paint_height = brush_height;
+
+  /*  adjust the x and y coordinates to the upper left corner of the brush  */
+  x = (gint) floor (coords->x) - (brush_width  / 2);
+  y = (gint) floor (coords->y) - (brush_height / 2);
+
+  drawable_width  = gimp_item_get_width  (GIMP_ITEM (drawable));
+  drawable_height = gimp_item_get_height (GIMP_ITEM (drawable));
+
+  x1 = CLAMP (x - 1, 0, drawable_width);
+  y1 = CLAMP (y - 1, 0, drawable_height);
+  x2 = CLAMP (x + brush_width  + 1, 0, drawable_width);
+  y2 = CLAMP (y + brush_height + 1, 0, drawable_height);
+
+  /*  configure the canvas buffer  */
+  if ((x2 - x1) && (y2 - y1))
+    {
+      GimpTempBuf            *temp_buf;
+      const Babl             *format;
+      GimpLayerCompositeMode  composite_mode;
+
+      composite_mode = gimp_layer_mode_get_paint_composite_mode (paint_mode);
+
+      format = gimp_layer_mode_get_format (paint_mode,
+                                           GIMP_LAYER_COLOR_SPACE_AUTO,
+                                           GIMP_LAYER_COLOR_SPACE_AUTO,
+                                           composite_mode,
+                                           gimp_drawable_get_format (drawable));
+
+      if (paint_core->paint_buffer                                       &&
+          gegl_buffer_get_width  (paint_core->paint_buffer) == (x2 - x1) &&
+          gegl_buffer_get_height (paint_core->paint_buffer) == (y2 - y1) &&
+          gegl_buffer_get_format (paint_core->paint_buffer) == format)
+        {
+          *paint_buffer_x = x1;
+          *paint_buffer_y = y1;
+
+          return paint_core->paint_buffer;
+        }
+
+      g_clear_object (&paint_core->paint_buffer);
+
+      temp_buf = gimp_temp_buf_new ((x2 - x1), (y2 - y1),
+                                    format);
+
+      *paint_buffer_x = x1;
+      *paint_buffer_y = y1;
+
+      paint_core->paint_buffer = gimp_temp_buf_create_buffer (temp_buf);
+
+      gimp_temp_buf_unref (temp_buf);
+
+      return paint_core->paint_buffer;
+    }
+
+  return NULL;
+}
+
+static void
+gimp_brush_core_real_set_brush (GimpBrushCore *core,
+                                GimpBrush     *brush)
+{
+  if (brush == core->main_brush)
+    return;
+
+  if (core->main_brush)
+    {
+      g_signal_handlers_disconnect_by_func (core->main_brush,
+                                            gimp_brush_core_invalidate_cache,
+                                            core);
+      gimp_brush_end_use (core->main_brush);
+    }
+
+  g_set_object (&core->main_brush, brush);
+
+  if (core->main_brush)
+    {
+      gimp_brush_begin_use (core->main_brush);
+      g_signal_connect (core->main_brush, "invalidate-preview",
+                        G_CALLBACK (gimp_brush_core_invalidate_cache),
+                        core);
+    }
+}
+
+static void
+gimp_brush_core_real_set_dynamics (GimpBrushCore *core,
+                                   GimpDynamics  *dynamics)
+{
+  g_set_object (&core->dynamics, dynamics);
+}
+
+void
+gimp_brush_core_set_brush (GimpBrushCore *core,
+                           GimpBrush     *brush)
+{
+  g_return_if_fail (GIMP_IS_BRUSH_CORE (core));
+  g_return_if_fail (brush == NULL || GIMP_IS_BRUSH (brush));
+
+  if (brush != core->main_brush)
+    g_signal_emit (core, core_signals[SET_BRUSH], 0, brush);
+}
+
+void
+gimp_brush_core_set_dynamics (GimpBrushCore *core,
+                              GimpDynamics  *dynamics)
+{
+  g_return_if_fail (GIMP_IS_BRUSH_CORE (core));
+  g_return_if_fail (dynamics == NULL || GIMP_IS_DYNAMICS (dynamics));
+
+  if (dynamics != core->dynamics)
+    g_signal_emit (core, core_signals[SET_DYNAMICS], 0, dynamics);
+}
+
+void
+gimp_brush_core_paste_canvas (GimpBrushCore            *core,
+                              GimpDrawable             *drawable,
+                              const GimpCoords         *coords,
+                              gdouble                   brush_opacity,
+                              gdouble                   image_opacity,
+                              GimpLayerMode             paint_mode,
+                              GimpBrushApplicationMode  brush_hardness,
+                              gdouble                   dynamic_force,
+                              GimpPaintApplicationMode  mode)
+{
+  const GimpTempBuf *brush_mask;
+
+  brush_mask = gimp_brush_core_get_brush_mask (core, coords,
+                                               brush_hardness,
+                                               dynamic_force);
+
+  if (brush_mask)
+    {
+      GimpPaintCore *paint_core = GIMP_PAINT_CORE (core);
+      gint           x;
+      gint           y;
+      gint           off_x;
+      gint           off_y;
+
+      x = (gint) floor (coords->x) - (gimp_temp_buf_get_width  (brush_mask) >> 1);
+      y = (gint) floor (coords->y) - (gimp_temp_buf_get_height (brush_mask) >> 1);
+
+      off_x = (x < 0) ? -x : 0;
+      off_y = (y < 0) ? -y : 0;
+
+      gimp_paint_core_paste (paint_core, brush_mask,
+                             off_x, off_y,
+                             drawable,
+                             brush_opacity,
+                             image_opacity,
+                             paint_mode,
+                             mode);
+    }
+}
+
+/* Similar to gimp_brush_core_paste_canvas, but replaces the alpha channel
+ * rather than using it to composite (i.e. transparent over opaque
+ * becomes transparent rather than opauqe.
+ */
+void
+gimp_brush_core_replace_canvas (GimpBrushCore            *core,
+                                GimpDrawable             *drawable,
+                                const GimpCoords         *coords,
+                                gdouble                   brush_opacity,
+                                gdouble                   image_opacity,
+                                GimpBrushApplicationMode  brush_hardness,
+                                gdouble                   dynamic_force,
+                                GimpPaintApplicationMode  mode)
+{
+  const GimpTempBuf *brush_mask;
+
+  brush_mask = gimp_brush_core_get_brush_mask (core, coords,
+                                               brush_hardness,
+                                               dynamic_force);
+
+  if (brush_mask)
+    {
+      GimpPaintCore *paint_core = GIMP_PAINT_CORE (core);
+      gint           x;
+      gint           y;
+      gint           off_x;
+      gint           off_y;
+
+      x = (gint) floor (coords->x) - (gimp_temp_buf_get_width  (brush_mask) >> 1);
+      y = (gint) floor (coords->y) - (gimp_temp_buf_get_height (brush_mask) >> 1);
+
+      off_x = (x < 0) ? -x : 0;
+      off_y = (y < 0) ? -y : 0;
+
+      gimp_paint_core_replace (paint_core, brush_mask,
+                               off_x, off_y,
+                               drawable,
+                               brush_opacity,
+                               image_opacity,
+                               mode);
+    }
+}
+
+
+static void
+gimp_brush_core_invalidate_cache (GimpBrush     *brush,
+                                  GimpBrushCore *core)
+{
+  /* Make sure we don't cache data for a brush that has changed */
+
+  core->subsample_cache_invalid = TRUE;
+  core->solid_cache_invalid     = TRUE;
+
+  /* Notify of the brush change */
+
+  g_signal_emit (core, core_signals[SET_BRUSH], 0, brush);
+}
+
+
+/************************************************************
+ *             LOCAL FUNCTION DEFINITIONS                   *
+ ************************************************************/
+
+static gdouble
+gimp_brush_core_get_angle (GimpBrushCore *core)
+{
+  gdouble angle = core->angle;
+
+  if (core->reflect)
+    angle -= core->symmetry_angle;
+  else
+    angle += core->symmetry_angle;
+
+  angle = fmod (angle, 1.0);
+
+  if (angle < 0.0)
+    angle += 1.0;
+
+  return angle;
+}
+
+static gboolean
+gimp_brush_core_get_reflect (GimpBrushCore *core)
+{
+  return core->reflect ^ core->symmetry_reflect;
+}
+
+static const GimpTempBuf *
+gimp_brush_core_transform_mask (GimpBrushCore *core,
+                                GimpBrush     *brush)
+{
+  const GimpTempBuf *mask;
+
+  if (core->scale <= 0.0)
+    return NULL;
+
+  mask = gimp_brush_transform_mask (brush,
+                                    core->scale,
+                                    core->aspect_ratio,
+                                    gimp_brush_core_get_angle (core),
+                                    gimp_brush_core_get_reflect (core),
+                                    core->hardness);
+
+  if (mask == core->transform_brush)
+    return mask;
+
+  core->transform_brush         = mask;
+  core->subsample_cache_invalid = TRUE;
+  core->solid_cache_invalid     = TRUE;
+
+  return core->transform_brush;
+}
+
+const GimpTempBuf *
+gimp_brush_core_get_brush_mask (GimpBrushCore            *core,
+                                const GimpCoords         *coords,
+                                GimpBrushApplicationMode  brush_hardness,
+                                gdouble                   dynamic_force)
+{
+  const GimpTempBuf *mask;
+
+  if (dynamic_force <= 0.0)
+    return NULL;
+
+  mask = gimp_brush_core_transform_mask (core, core->brush);
+
+  if (! mask)
+    return NULL;
+
+  switch (brush_hardness)
+    {
+    case GIMP_BRUSH_SOFT:
+      return gimp_brush_core_subsample_mask (core, mask,
+                                             coords->x,
+                                             coords->y);
+      break;
+
+    case GIMP_BRUSH_HARD:
+      return gimp_brush_core_solidify_mask (core, mask,
+                                            coords->x,
+                                            coords->y);
+      break;
+
+    case GIMP_BRUSH_PRESSURE:
+      return gimp_brush_core_pressurize_mask (core, mask,
+                                              coords->x,
+                                              coords->y,
+                                              dynamic_force);
+      break;
+    }
+
+  g_return_val_if_reached (NULL);
+}
+
+const GimpTempBuf *
+gimp_brush_core_get_brush_pixmap (GimpBrushCore *core)
+{
+  const GimpTempBuf *pixmap;
+
+  if (core->scale <= 0.0)
+    return NULL;
+
+  pixmap = gimp_brush_transform_pixmap (core->brush,
+                                        core->scale,
+                                        core->aspect_ratio,
+                                        gimp_brush_core_get_angle (core),
+                                        gimp_brush_core_get_reflect (core),
+                                        core->hardness);
+
+  if (pixmap == core->transform_pixmap)
+    return pixmap;
+
+  core->transform_pixmap        = pixmap;
+  core->subsample_cache_invalid = TRUE;
+
+  return core->transform_pixmap;
+}
+
+void
+gimp_brush_core_eval_transform_dynamics (GimpBrushCore     *core,
+                                         GimpDrawable      *drawable,
+                                         GimpPaintOptions  *paint_options,
+                                         const GimpCoords  *coords)
+{
+  if (core->main_brush)
+    {
+      gdouble max_side;
+
+      max_side = MAX (gimp_brush_get_width  (core->main_brush),
+                      gimp_brush_get_height (core->main_brush));
+
+      core->scale = paint_options->brush_size / max_side;
+
+      if (paint_options->brush_lock_to_view &&
+          MAX (coords->xscale, coords->yscale) > 0)
+        {
+          core->scale /= MAX (coords->xscale, coords->yscale);
+
+          /* Cap transform result for brushes or OOM can occur */
+          if ((core->scale * max_side) > GIMP_BRUSH_MAX_SIZE)
+            {
+              core->scale = GIMP_BRUSH_MAX_SIZE / max_side;
+            }
+        }
+   }
+  else
+    core->scale = -1;
+
+  core->aspect_ratio = paint_options->brush_aspect_ratio;
+  core->angle        = paint_options->brush_angle;
+  core->reflect      = FALSE;
+  core->hardness     = paint_options->brush_hardness;
+
+  if (paint_options->brush_lock_to_view)
+    {
+      core->angle   += coords->angle;
+      core->reflect  = coords->reflect;
+    }
+
+  if (! GIMP_IS_DYNAMICS (core->dynamics))
+    return;
+
+  if (GIMP_BRUSH_CORE_GET_CLASS (core)->handles_dynamic_transforming_brush)
+    {
+      gdouble fade_point = 1.0;
+
+      if (drawable)
+        {
+          GimpImage     *image      = gimp_item_get_image (GIMP_ITEM (drawable));
+          GimpPaintCore *paint_core = GIMP_PAINT_CORE (core);
+
+          fade_point = gimp_paint_options_get_fade (paint_options, image,
+                                                    paint_core->pixel_dist);
+        }
+
+      core->scale *= gimp_dynamics_get_linear_value (core->dynamics,
+                                                     GIMP_DYNAMICS_OUTPUT_SIZE,
+                                                     coords,
+                                                     paint_options,
+                                                     fade_point);
+
+      core->angle += gimp_dynamics_get_angular_value (core->dynamics,
+                                                      GIMP_DYNAMICS_OUTPUT_ANGLE,
+                                                      coords,
+                                                      paint_options,
+                                                      fade_point);
+
+      core->hardness *= gimp_dynamics_get_linear_value (core->dynamics,
+                                                        GIMP_DYNAMICS_OUTPUT_HARDNESS,
+                                                        coords,
+                                                        paint_options,
+                                                        fade_point);
+
+      if (gimp_dynamics_is_output_enabled (core->dynamics,
+                                           GIMP_DYNAMICS_OUTPUT_ASPECT_RATIO))
+        {
+          gdouble dyn_aspect;
+
+          dyn_aspect = gimp_dynamics_get_aspect_value (core->dynamics,
+                                                       GIMP_DYNAMICS_OUTPUT_ASPECT_RATIO,
+                                                       coords,
+                                                       paint_options,
+                                                       fade_point);
+
+          /* Zero aspect ratio is special cased to half of all ar range,
+           * to force dynamics to have any effect. Forcing to full results
+           * in disappearing stamp if applied to maximum.
+           */
+          if (core->aspect_ratio == 0.0)
+            core->aspect_ratio = 10.0 * dyn_aspect;
+          else
+            core->aspect_ratio *= dyn_aspect;
+        }
+    }
+}
+
+void
+gimp_brush_core_eval_transform_symmetry (GimpBrushCore *core,
+                                         GimpSymmetry  *symmetry,
+                                         gint           stroke)
+{
+  g_return_if_fail (GIMP_IS_BRUSH_CORE (core));
+  g_return_if_fail (symmetry == NULL || GIMP_IS_SYMMETRY (symmetry));
+
+  core->symmetry_angle   = 0.0;
+  core->symmetry_reflect = FALSE;
+
+  if (symmetry)
+    {
+      gimp_symmetry_get_transform (symmetry,
+                                   stroke,
+                                   &core->symmetry_angle,
+                                   &core->symmetry_reflect);
+
+      core->symmetry_angle /= 360.0;
+    }
+}
+
+void
+gimp_brush_core_color_area_with_pixmap (GimpBrushCore    *core,
+                                        GimpDrawable     *drawable,
+                                        const GimpCoords *coords,
+                                        GeglBuffer       *area,
+                                        gint              area_x,
+                                        gint              area_y,
+                                        gboolean          apply_mask)
+{
+  const GimpTempBuf *pixmap;
+  GeglBuffer        *pixmap_buffer;
+  const GimpTempBuf *mask;
+  GeglBuffer        *mask_buffer;
+  gint               area_width;
+  gint               area_height;
+  gint               ul_x;
+  gint               ul_y;
+  gint               offset_x;
+  gint               offset_y;
+
+  g_return_if_fail (GIMP_IS_BRUSH (core->brush));
+  g_return_if_fail (gimp_brush_get_pixmap (core->brush) != NULL);
+
+  /*  scale the brush  */
+  pixmap = gimp_brush_core_get_brush_pixmap (core);
+
+  if (! pixmap)
+    return;
+
+  if (apply_mask)
+    mask = gimp_brush_core_transform_mask (core, core->brush);
+  else
+    mask = NULL;
+
+  /*  Calculate upper left corner of brush as in
+   *  gimp_paint_core_get_paint_area.  Ugly to have to do this here, too.
+   */
+  ul_x = (gint) floor (coords->x) - (gimp_temp_buf_get_width  (pixmap) >> 1);
+  ul_y = (gint) floor (coords->y) - (gimp_temp_buf_get_height (pixmap) >> 1);
+
+  /*  Not sure why this is necessary, but empirically the code does
+   *  not work without it for even-sided brushes.  See bug #166622.
+   */
+  if (gimp_temp_buf_get_width (pixmap) % 2 == 0)
+    ul_x += ROUND (coords->x) - floor (coords->x);
+  if (gimp_temp_buf_get_height (pixmap) % 2 == 0)
+    ul_y += ROUND (coords->y) - floor (coords->y);
+
+  offset_x = area_x - ul_x;
+  offset_y = area_y - ul_y;
+
+  area_width  = gegl_buffer_get_width  (area);
+  area_height = gegl_buffer_get_height (area);
+
+  pixmap_buffer = gimp_temp_buf_create_buffer (pixmap);
+
+  gimp_gegl_buffer_copy (pixmap_buffer,
+                         GEGL_RECTANGLE (offset_x,   offset_y,
+                                         area_width, area_height),
+                         GEGL_ABYSS_NONE,
+                         area,
+                         GEGL_RECTANGLE (0,          0,
+                                         area_width, area_height));
+
+  g_object_unref (pixmap_buffer);
+
+  if (mask)
+    {
+      mask_buffer = gimp_temp_buf_create_buffer (mask);
+
+      gimp_gegl_apply_mask (mask_buffer,
+                            GEGL_RECTANGLE (offset_x,   offset_y,
+                                            area_width, area_height),
+                            area,
+                            GEGL_RECTANGLE (0,          0,
+                                            area_width, area_height),
+                            1.0);
+
+      g_object_unref (mask_buffer);
+    }
+}