Adding upstream version 2.10.36.upstream/2.10.36

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

1 files changed, 1283 insertions, 0 deletions

diff --git a/app/operations/gimpoperationgradient.c b/app/operations/gimpoperationgradient.c
new file mode 100644
index 0000000..2dbb746
--- /dev/null
+++ b/app/operations/gimpoperationgradient.c
@@ -0,0 +1,1283 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * Largely based on gimpdrawable-gradient.c
+ *
+ * gimpoperationgradient.c
+ * Copyright (C) 2014 Michael Henning <drawoc@darkrefraction.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "operations-types.h"
+
+#include "core/gimpgradient.h"
+
+#include "gimpoperationgradient.h"
+
+
+#define GRADIENT_CACHE_N_SUPERSAMPLES 4
+#define GRADIENT_CACHE_MAX_SIZE       ((1 << 20) / sizeof (GimpRGB))
+
+
+enum
+{
+  PROP_0,
+  PROP_CONTEXT,
+  PROP_GRADIENT,
+  PROP_START_X,
+  PROP_START_Y,
+  PROP_END_X,
+  PROP_END_Y,
+  PROP_GRADIENT_TYPE,
+  PROP_GRADIENT_REPEAT,
+  PROP_OFFSET,
+  PROP_GRADIENT_REVERSE,
+  PROP_GRADIENT_BLEND_COLOR_SPACE,
+  PROP_SUPERSAMPLE,
+  PROP_SUPERSAMPLE_DEPTH,
+  PROP_SUPERSAMPLE_THRESHOLD,
+  PROP_DITHER
+};
+
+typedef struct
+{
+  GimpGradient                *gradient;
+  gboolean                     reverse;
+  GimpGradientBlendColorSpace  blend_color_space;
+  GimpRGB                     *gradient_cache;
+  gint                         gradient_cache_size;
+  GimpGradientSegment         *last_seg;
+  gdouble                      offset;
+  gdouble                      sx, sy;
+  GimpGradientType             gradient_type;
+  gdouble                      dist;
+  gdouble                      vec[2];
+  GimpRepeatMode               repeat;
+  GeglSampler                 *dist_sampler;
+} RenderBlendData;
+
+
+typedef struct
+{
+  gfloat        *data;
+  GeglRectangle  roi;
+  GRand         *dither_rand;
+} PutPixelData;
+
+
+/*  local function prototypes  */
+
+static void            gimp_operation_gradient_dispose           (GObject               *gobject);
+static void            gimp_operation_gradient_finalize          (GObject               *gobject);
+static void            gimp_operation_gradient_get_property      (GObject               *object,
+                                                                  guint                  property_id,
+                                                                  GValue                *value,
+                                                                  GParamSpec            *pspec);
+static void            gimp_operation_gradient_set_property      (GObject               *object,
+                                                                  guint                  property_id,
+                                                                  const GValue          *value,
+                                                                  GParamSpec            *pspec);
+
+static void            gimp_operation_gradient_prepare           (GeglOperation         *operation);
+
+static GeglRectangle   gimp_operation_gradient_get_bounding_box  (GeglOperation         *operation);
+
+static gdouble         gradient_calc_conical_sym_factor          (gdouble                dist,
+                                                                  gdouble               *axis,
+                                                                  gdouble                offset,
+                                                                  gdouble                x,
+                                                                  gdouble                y);
+static gdouble         gradient_calc_conical_asym_factor         (gdouble                dist,
+                                                                  gdouble               *axis,
+                                                                  gdouble                offset,
+                                                                  gdouble                x,
+                                                                  gdouble                y);
+static gdouble         gradient_calc_square_factor               (gdouble                dist,
+                                                                  gdouble                offset,
+                                                                  gdouble                x,
+                                                                  gdouble                y);
+static gdouble         gradient_calc_radial_factor               (gdouble                dist,
+                                                                  gdouble                offset,
+                                                                  gdouble                x,
+                                                                  gdouble                y);
+static gdouble         gradient_calc_linear_factor               (gdouble                dist,
+                                                                  gdouble               *vec,
+                                                                  gdouble                offset,
+                                                                  gdouble                x,
+                                                                  gdouble                y);
+static gdouble         gradient_calc_bilinear_factor             (gdouble                dist,
+                                                                  gdouble               *vec,
+                                                                  gdouble                offset,
+                                                                  gdouble                x,
+                                                                  gdouble                y);
+static gdouble         gradient_calc_spiral_factor               (gdouble                dist,
+                                                                  gdouble               *axis,
+                                                                  gdouble                offset,
+                                                                  gdouble                x,
+                                                                  gdouble                y,
+                                                                  gboolean               clockwise);
+
+static gdouble         gradient_calc_shapeburst_angular_factor   (GeglSampler           *dist_sampler,
+                                                                  gdouble                offset,
+                                                                  gdouble                x,
+                                                                  gdouble                y);
+static gdouble         gradient_calc_shapeburst_spherical_factor (GeglSampler           *dist_sampler,
+                                                                  gdouble                offset,
+                                                                  gdouble                x,
+                                                                  gdouble                y);
+static gdouble         gradient_calc_shapeburst_dimpled_factor   (GeglSampler           *dist_sampler,
+                                                                  gdouble                offset,
+                                                                  gdouble                x,
+                                                                  gdouble                y);
+
+static void            gradient_render_pixel                     (gdouble                x,
+                                                                  gdouble                y,
+                                                                  GimpRGB               *color,
+                                                                  gpointer               render_data);
+
+static void            gradient_put_pixel                        (gint                   x,
+                                                                  gint                   y,
+                                                                  GimpRGB               *color,
+                                                                  gpointer               put_pixel_data);
+
+static void            gradient_dither_pixel                     (GimpRGB               *color,
+                                                                  GRand                 *dither_rand,
+                                                                  gfloat                *dest);
+
+static gboolean        gimp_operation_gradient_process           (GeglOperation         *operation,
+                                                                  GeglBuffer            *input,
+                                                                  GeglBuffer            *output,
+                                                                  const GeglRectangle   *result,
+                                                                  gint                   level);
+
+static void            gimp_operation_gradient_invalidate_cache  (GimpOperationGradient *self);
+static void            gimp_operation_gradient_validate_cache    (GimpOperationGradient *self);
+
+
+G_DEFINE_TYPE (GimpOperationGradient, gimp_operation_gradient,
+               GEGL_TYPE_OPERATION_FILTER)
+
+#define parent_class gimp_operation_gradient_parent_class
+
+
+static void
+gimp_operation_gradient_class_init (GimpOperationGradientClass *klass)
+{
+  GObjectClass             *object_class    = G_OBJECT_CLASS (klass);
+  GeglOperationClass       *operation_class = GEGL_OPERATION_CLASS (klass);
+  GeglOperationFilterClass *filter_class    = GEGL_OPERATION_FILTER_CLASS (klass);
+
+  object_class->dispose             = gimp_operation_gradient_dispose;
+  object_class->finalize            = gimp_operation_gradient_finalize;
+  object_class->set_property        = gimp_operation_gradient_set_property;
+  object_class->get_property        = gimp_operation_gradient_get_property;
+
+  operation_class->prepare          = gimp_operation_gradient_prepare;
+  operation_class->get_bounding_box = gimp_operation_gradient_get_bounding_box;
+
+  filter_class->process             = gimp_operation_gradient_process;
+
+  gegl_operation_class_set_keys (operation_class,
+                                 "name",        "gimp:gradient",
+                                 "categories",  "gimp",
+                                 "description", "GIMP Gradient operation",
+                                 NULL);
+
+  g_object_class_install_property (object_class, PROP_CONTEXT,
+                                   g_param_spec_object ("context",
+                                                        "Context",
+                                                        "A GimpContext",
+                                                        GIMP_TYPE_OBJECT,
+                                                        G_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_GRADIENT,
+                                   g_param_spec_object ("gradient",
+                                                        "Gradient",
+                                                        "A GimpGradient to render",
+                                                        GIMP_TYPE_OBJECT,
+                                                        G_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_START_X,
+                                   g_param_spec_double ("start-x",
+                                                        "Start X",
+                                                        "X coordinate of the first point",
+                                                        -G_MAXDOUBLE, G_MAXDOUBLE, 0,
+                                                        G_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_START_Y,
+                                   g_param_spec_double ("start-y",
+                                                        "Start Y",
+                                                        "Y coordinate of the first point",
+                                                        -G_MAXDOUBLE, G_MAXDOUBLE, 0,
+                                                        G_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_END_X,
+                                   g_param_spec_double ("end-x",
+                                                        "End X",
+                                                        "X coordinate of the second point",
+                                                        -G_MAXDOUBLE, G_MAXDOUBLE, 200,
+                                                        G_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_END_Y,
+                                   g_param_spec_double ("end-y",
+                                                        "End Y",
+                                                        "Y coordinate of the second point",
+                                                        -G_MAXDOUBLE, G_MAXDOUBLE, 200,
+                                                        G_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_GRADIENT_TYPE,
+                                   g_param_spec_enum ("gradient-type",
+                                                      "Gradient Type",
+                                                      "The type of gradient to render",
+                                                      GIMP_TYPE_GRADIENT_TYPE,
+                                                      GIMP_GRADIENT_LINEAR,
+                                                      G_PARAM_READWRITE |
+                                                      G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_GRADIENT_REPEAT,
+                                   g_param_spec_enum ("gradient-repeat",
+                                                      "Repeat mode",
+                                                      "Repeat mode",
+                                                      GIMP_TYPE_REPEAT_MODE,
+                                                      GIMP_REPEAT_NONE,
+                                                      G_PARAM_READWRITE |
+                                                      G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_OFFSET,
+                                   g_param_spec_double ("offset",
+                                                        "Offset",
+                                                        "Offset relates to the starting and ending coordinates "
+                                                        "specified for the blend. This parameter is mode dependent.",
+                                                        0, G_MAXDOUBLE, 0,
+                                                        G_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_GRADIENT_REVERSE,
+                                   g_param_spec_boolean ("gradient-reverse",
+                                                         "Reverse",
+                                                         "Reverse the gradient",
+                                                         FALSE,
+                                                         G_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_GRADIENT_BLEND_COLOR_SPACE,
+                                   g_param_spec_enum ("gradient-blend-color-space",
+                                                      "Blend Color Space",
+                                                      "Which color space to use when blending RGB gradient segments",
+                                                      GIMP_TYPE_GRADIENT_BLEND_COLOR_SPACE,
+                                                      GIMP_GRADIENT_BLEND_RGB_PERCEPTUAL,
+                                                      G_PARAM_READWRITE |
+                                                      G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_SUPERSAMPLE,
+                                   g_param_spec_boolean ("supersample",
+                                                         "Supersample",
+                                                         "Do adaptive supersampling",
+                                                         FALSE,
+                                                         G_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_SUPERSAMPLE_DEPTH,
+                                   g_param_spec_int ("supersample-depth",
+                                                     "Max depth",
+                                                     "Maximum recursion levels for supersampling",
+                                                     1, 9, 3,
+                                                     G_PARAM_READWRITE |
+                                                     G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_SUPERSAMPLE_THRESHOLD,
+                                   g_param_spec_double ("supersample-threshold",
+                                                        "Threshold",
+                                                        "Supersampling threshold",
+                                                        0, 4, 0.20,
+                                                        G_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_DITHER,
+                                   g_param_spec_boolean ("dither",
+                                                         "Dither",
+                                                         "Use dithering to reduce banding",
+                                                         FALSE,
+                                                         G_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT));
+}
+
+static void
+gimp_operation_gradient_init (GimpOperationGradient *self)
+{
+  g_mutex_init (&self->gradient_cache_mutex);
+}
+
+static void
+gimp_operation_gradient_dispose (GObject *object)
+{
+  GimpOperationGradient *self = GIMP_OPERATION_GRADIENT (object);
+
+  gimp_operation_gradient_invalidate_cache (self);
+
+  g_clear_object (&self->gradient);
+  g_clear_object (&self->context);
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_operation_gradient_finalize (GObject *object)
+{
+  GimpOperationGradient *self = GIMP_OPERATION_GRADIENT (object);
+
+  g_mutex_clear (&self->gradient_cache_mutex);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_operation_gradient_get_property (GObject    *object,
+                                      guint       property_id,
+                                      GValue     *value,
+                                      GParamSpec *pspec)
+{
+ GimpOperationGradient *self = GIMP_OPERATION_GRADIENT (object);
+
+  switch (property_id)
+    {
+    case PROP_CONTEXT:
+      g_value_set_object (value, self->context);
+      break;
+
+    case PROP_GRADIENT:
+      g_value_set_object (value, self->gradient);
+      break;
+
+    case PROP_START_X:
+      g_value_set_double (value, self->start_x);
+      break;
+
+    case PROP_START_Y:
+      g_value_set_double (value, self->start_y);
+      break;
+
+    case PROP_END_X:
+      g_value_set_double (value, self->end_x);
+      break;
+
+    case PROP_END_Y:
+      g_value_set_double (value, self->end_y);
+      break;
+
+    case PROP_GRADIENT_TYPE:
+      g_value_set_enum (value, self->gradient_type);
+      break;
+
+    case PROP_GRADIENT_REPEAT:
+      g_value_set_enum (value, self->gradient_repeat);
+      break;
+
+    case PROP_OFFSET:
+      g_value_set_double (value, self->offset);
+      break;
+
+    case PROP_GRADIENT_REVERSE:
+      g_value_set_boolean (value, self->gradient_reverse);
+      break;
+
+    case PROP_GRADIENT_BLEND_COLOR_SPACE:
+      g_value_set_enum (value, self->gradient_blend_color_space);
+      break;
+
+    case PROP_SUPERSAMPLE:
+      g_value_set_boolean (value, self->supersample);
+      break;
+
+    case PROP_SUPERSAMPLE_DEPTH:
+      g_value_set_int (value, self->supersample_depth);
+      break;
+
+    case PROP_SUPERSAMPLE_THRESHOLD:
+      g_value_set_double (value, self->supersample_threshold);
+      break;
+
+    case PROP_DITHER:
+      g_value_set_boolean (value, self->dither);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_operation_gradient_set_property (GObject      *object,
+                                      guint         property_id,
+                                      const GValue *value,
+                                      GParamSpec   *pspec)
+{
+  GimpOperationGradient *self = GIMP_OPERATION_GRADIENT (object);
+
+  switch (property_id)
+    {
+    case PROP_CONTEXT:
+      if (self->context)
+        g_object_unref (self->context);
+
+      self->context = g_value_dup_object (value);
+      break;
+
+    case PROP_GRADIENT:
+      {
+        GimpGradient *gradient = g_value_get_object (value);
+
+        g_clear_object (&self->gradient);
+
+        if (gradient)
+          {
+            if (gimp_gradient_has_fg_bg_segments (gradient))
+              self->gradient = gimp_gradient_flatten (gradient, self->context);
+            else
+              self->gradient = g_object_ref (gradient);
+          }
+
+        gimp_operation_gradient_invalidate_cache (self);
+      }
+      break;
+
+    case PROP_START_X:
+      self->start_x = g_value_get_double (value);
+
+      gimp_operation_gradient_invalidate_cache (self);
+      break;
+
+    case PROP_START_Y:
+      self->start_y = g_value_get_double (value);
+
+      gimp_operation_gradient_invalidate_cache (self);
+      break;
+
+    case PROP_END_X:
+      self->end_x = g_value_get_double (value);
+
+      gimp_operation_gradient_invalidate_cache (self);
+      break;
+
+    case PROP_END_Y:
+      self->end_y = g_value_get_double (value);
+
+      gimp_operation_gradient_invalidate_cache (self);
+      break;
+
+    case PROP_GRADIENT_TYPE:
+      self->gradient_type = g_value_get_enum (value);
+      break;
+
+    case PROP_GRADIENT_REPEAT:
+      self->gradient_repeat = g_value_get_enum (value);
+      break;
+
+    case PROP_OFFSET:
+      self->offset = g_value_get_double (value);
+      break;
+
+    case PROP_GRADIENT_REVERSE:
+      self->gradient_reverse = g_value_get_boolean (value);
+
+      gimp_operation_gradient_invalidate_cache (self);
+      break;
+
+    case PROP_GRADIENT_BLEND_COLOR_SPACE:
+      self->gradient_blend_color_space = g_value_get_enum (value);
+
+      gimp_operation_gradient_invalidate_cache (self);
+      break;
+
+    case PROP_SUPERSAMPLE:
+      self->supersample = g_value_get_boolean (value);
+      break;
+
+    case PROP_SUPERSAMPLE_DEPTH:
+      self->supersample_depth = g_value_get_int (value);
+      break;
+
+    case PROP_SUPERSAMPLE_THRESHOLD:
+      self->supersample_threshold = g_value_get_double (value);
+      break;
+
+    case PROP_DITHER:
+      self->dither = g_value_get_boolean (value);
+      break;
+
+   default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_operation_gradient_prepare (GeglOperation *operation)
+{
+  gegl_operation_set_format (operation, "output", babl_format ("R'G'B'A float"));
+}
+
+static GeglRectangle
+gimp_operation_gradient_get_bounding_box (GeglOperation *operation)
+{
+  return gegl_rectangle_infinite_plane ();
+}
+
+static gdouble
+gradient_calc_conical_sym_factor (gdouble  dist,
+                                  gdouble *axis,
+                                  gdouble  offset,
+                                  gdouble  x,
+                                  gdouble  y)
+{
+  if (dist == 0.0)
+    {
+      return 0.0;
+    }
+  else if ((x != 0) || (y != 0))
+    {
+      gdouble vec[2];
+      gdouble r;
+      gdouble rat;
+
+      /* Calculate offset from the start in pixels */
+
+      r = sqrt (SQR (x) + SQR (y));
+
+      vec[0] = x / r;
+      vec[1] = y / r;
+
+      rat = axis[0] * vec[0] + axis[1] * vec[1]; /* Dot product */
+
+      if (rat > 1.0)
+        rat = 1.0;
+      else if (rat < -1.0)
+        rat = -1.0;
+
+      /* This cool idea is courtesy Josh MacDonald,
+       * Ali Rahimi --- two more XCF losers.  */
+
+      rat = acos (rat) / G_PI;
+      rat = pow (rat, (offset / 10.0) + 1.0);
+
+      return CLAMP (rat, 0.0, 1.0);
+    }
+  else
+    {
+      return 0.5;
+    }
+}
+
+static gdouble
+gradient_calc_conical_asym_factor (gdouble  dist,
+                                   gdouble *axis,
+                                   gdouble  offset,
+                                   gdouble  x,
+                                   gdouble  y)
+{
+  if (dist == 0.0)
+    {
+      return 0.0;
+    }
+  else if (x != 0 || y != 0)
+    {
+      gdouble ang0, ang1;
+      gdouble ang;
+      gdouble rat;
+
+      ang0 = atan2 (axis[0], axis[1]) + G_PI;
+
+      ang1 = atan2 (x, y) + G_PI;
+
+      ang = ang1 - ang0;
+
+      if (ang < 0.0)
+        ang += (2.0 * G_PI);
+
+      rat = ang / (2.0 * G_PI);
+      rat = pow (rat, (offset / 10.0) + 1.0);
+
+      return CLAMP (rat, 0.0, 1.0);
+    }
+  else
+    {
+      return 0.5; /* We are on middle point */
+    }
+}
+
+static gdouble
+gradient_calc_square_factor (gdouble dist,
+                             gdouble offset,
+                             gdouble x,
+                             gdouble y)
+{
+  if (dist == 0.0)
+    {
+      return 0.0;
+    }
+  else
+    {
+      gdouble r;
+      gdouble rat;
+
+      /* Calculate offset from start as a value in [0, 1] */
+
+      offset = offset / 100.0;
+
+      r   = MAX (fabs (x), fabs (y));
+      rat = r / dist;
+
+      if (rat < offset)
+        return 0.0;
+      else if (offset == 1.0)
+        return (rat >= 1.0) ? 1.0 : 0.0;
+      else
+        return (rat - offset) / (1.0 - offset);
+    }
+}
+
+static gdouble
+gradient_calc_radial_factor (gdouble dist,
+                             gdouble offset,
+                             gdouble x,
+                             gdouble y)
+{
+  if (dist == 0.0)
+    {
+      return 0.0;
+    }
+  else
+    {
+      gdouble r;
+      gdouble rat;
+
+      /* Calculate radial offset from start as a value in [0, 1] */
+
+      offset = offset / 100.0;
+
+      r   = sqrt (SQR (x) + SQR (y));
+      rat = r / dist;
+
+      if (rat < offset)
+        return 0.0;
+      else if (offset == 1.0)
+        return (rat >= 1.0) ? 1.0 : 0.0;
+      else
+        return (rat - offset) / (1.0 - offset);
+    }
+}
+
+static gdouble
+gradient_calc_linear_factor (gdouble  dist,
+                             gdouble *vec,
+                             gdouble  offset,
+                             gdouble  x,
+                             gdouble  y)
+{
+  if (dist == 0.0)
+    {
+      return 0.0;
+    }
+  else
+    {
+      gdouble r;
+      gdouble rat;
+
+      offset = offset / 100.0;
+
+      r   = vec[0] * x + vec[1] * y;
+      rat = r / dist;
+
+      if (rat >= 0.0 && rat < offset)
+        return 0.0;
+      else if (offset == 1.0)
+        return (rat >= 1.0) ? 1.0 : 0.0;
+      else if (rat < 0.0)
+        return rat / (1.0 - offset);
+      else
+        return (rat - offset) / (1.0 - offset);
+    }
+}
+
+static gdouble
+gradient_calc_bilinear_factor (gdouble  dist,
+                               gdouble *vec,
+                               gdouble  offset,
+                               gdouble  x,
+                               gdouble  y)
+{
+  if (dist == 0.0)
+    {
+      return 0.0;
+    }
+  else
+    {
+      gdouble r;
+      gdouble rat;
+
+      /* Calculate linear offset from the start line outward */
+
+      offset = offset / 100.0;
+
+      r   = vec[0] * x + vec[1] * y;
+      rat = r / dist;
+
+      if (fabs (rat) < offset)
+        return 0.0;
+      else if (offset == 1.0)
+        return (rat == 1.0) ? 1.0 : 0.0;
+      else
+        return (fabs (rat) - offset) / (1.0 - offset);
+    }
+}
+
+static gdouble
+gradient_calc_spiral_factor (gdouble   dist,
+                             gdouble  *axis,
+                             gdouble   offset,
+                             gdouble   x,
+                             gdouble   y,
+                             gboolean  clockwise)
+{
+  if (dist == 0.0)
+    {
+      return 0.0;
+    }
+  else if (x != 0.0 || y != 0.0)
+    {
+      gdouble ang0, ang1;
+      gdouble ang;
+      double  r;
+
+      offset = offset / 100.0;
+
+      ang0 = atan2 (axis[0], axis[1]) + G_PI;
+      ang1 = atan2 (x, y) + G_PI;
+
+      if (clockwise)
+        ang = ang1 - ang0;
+      else
+        ang = ang0 - ang1;
+
+      if (ang < 0.0)
+        ang += (2.0 * G_PI);
+
+      r = sqrt (SQR (x) + SQR (y)) / dist;
+
+      return fmod (ang / (2.0 * G_PI) + r + offset, 1.0);
+    }
+  else
+    {
+      return 0.5 ; /* We are on the middle point */
+    }
+}
+
+static gdouble
+gradient_calc_shapeburst_angular_factor (GeglSampler *dist_sampler,
+                                         gdouble      offset,
+                                         gdouble      x,
+                                         gdouble      y)
+{
+  gfloat value;
+
+  offset = offset / 100.0;
+
+  gegl_sampler_get (dist_sampler, x, y, NULL, &value, GEGL_ABYSS_NONE);
+
+  value = 1.0 - value;
+
+  if (value < offset)
+    value = 0.0;
+  else if (offset == 1.0)
+    value = (value >= 1.0) ? 1.0 : 0.0;
+  else
+    value = (value - offset) / (1.0 - offset);
+
+  return value;
+}
+
+
+static gdouble
+gradient_calc_shapeburst_spherical_factor (GeglSampler *dist_sampler,
+                                           gdouble      offset,
+                                           gdouble      x,
+                                           gdouble      y)
+{
+  gfloat value;
+
+  offset = 1.0 - offset / 100.0;
+
+  gegl_sampler_get (dist_sampler, x, y, NULL, &value, GEGL_ABYSS_NONE);
+
+  if (value > offset)
+    value = 1.0;
+  else if (offset == 0.0)
+    value = (value <= 0.0) ? 0.0 : 1.0;
+  else
+    value = value / offset;
+
+  value = 1.0 - sin (0.5 * G_PI * value);
+
+  return value;
+}
+
+
+static gdouble
+gradient_calc_shapeburst_dimpled_factor (GeglSampler *dist_sampler,
+                                         gdouble      offset,
+                                         gdouble      x,
+                                         gdouble      y)
+{
+  gfloat value;
+
+  offset = 1.0 - offset / 100.0;
+
+  gegl_sampler_get (dist_sampler, x, y, NULL, &value, GEGL_ABYSS_NONE);
+
+  if (value > offset)
+    value = 1.0;
+  else if (offset == 0.0)
+    value = (value <= 0.0) ? 0.0 : 1.0;
+  else
+    value = value / offset;
+
+  value = cos (0.5 * G_PI * value);
+
+  return value;
+}
+
+static void
+gradient_render_pixel (gdouble   x,
+                       gdouble   y,
+                       GimpRGB  *color,
+                       gpointer  render_data)
+{
+  RenderBlendData *rbd = render_data;
+  gdouble          factor;
+
+  /*  we want to calculate the color at the pixel's center  */
+  x += 0.5;
+  y += 0.5;
+
+  /* Calculate blending factor */
+
+  switch (rbd->gradient_type)
+    {
+    case GIMP_GRADIENT_LINEAR:
+      factor = gradient_calc_linear_factor (rbd->dist,
+                                            rbd->vec, rbd->offset,
+                                            x - rbd->sx, y - rbd->sy);
+      break;
+
+    case GIMP_GRADIENT_BILINEAR:
+      factor = gradient_calc_bilinear_factor (rbd->dist,
+                                              rbd->vec, rbd->offset,
+                                              x - rbd->sx, y - rbd->sy);
+      break;
+
+    case GIMP_GRADIENT_RADIAL:
+      factor = gradient_calc_radial_factor (rbd->dist,
+                                            rbd->offset,
+                                            x - rbd->sx, y - rbd->sy);
+      break;
+
+    case GIMP_GRADIENT_SQUARE:
+      factor = gradient_calc_square_factor (rbd->dist, rbd->offset,
+                                            x - rbd->sx, y - rbd->sy);
+      break;
+
+    case GIMP_GRADIENT_CONICAL_SYMMETRIC:
+      factor = gradient_calc_conical_sym_factor (rbd->dist,
+                                                 rbd->vec, rbd->offset,
+                                                 x - rbd->sx, y - rbd->sy);
+      break;
+
+    case GIMP_GRADIENT_CONICAL_ASYMMETRIC:
+      factor = gradient_calc_conical_asym_factor (rbd->dist,
+                                                  rbd->vec, rbd->offset,
+                                                  x - rbd->sx, y - rbd->sy);
+      break;
+
+    case GIMP_GRADIENT_SHAPEBURST_ANGULAR:
+      factor = gradient_calc_shapeburst_angular_factor (rbd->dist_sampler,
+                                                        rbd->offset,
+                                                        x, y);
+      break;
+
+    case GIMP_GRADIENT_SHAPEBURST_SPHERICAL:
+      factor = gradient_calc_shapeburst_spherical_factor (rbd->dist_sampler,
+                                                          rbd->offset,
+                                                          x, y);
+      break;
+
+    case GIMP_GRADIENT_SHAPEBURST_DIMPLED:
+      factor = gradient_calc_shapeburst_dimpled_factor (rbd->dist_sampler,
+                                                        rbd->offset,
+                                                        x, y);
+      break;
+
+    case GIMP_GRADIENT_SPIRAL_CLOCKWISE:
+      factor = gradient_calc_spiral_factor (rbd->dist,
+                                            rbd->vec, rbd->offset,
+                                            x - rbd->sx, y - rbd->sy, TRUE);
+      break;
+
+    case GIMP_GRADIENT_SPIRAL_ANTICLOCKWISE:
+      factor = gradient_calc_spiral_factor (rbd->dist,
+                                            rbd->vec, rbd->offset,
+                                            x - rbd->sx, y - rbd->sy, FALSE);
+      break;
+
+    default:
+      g_return_if_reached ();
+      break;
+    }
+
+  /* Adjust for repeat */
+
+  switch (rbd->repeat)
+    {
+    case GIMP_REPEAT_NONE:
+      break;
+
+    case GIMP_REPEAT_SAWTOOTH:
+      factor = factor - floor (factor);
+      break;
+
+    case GIMP_REPEAT_TRIANGULAR:
+      {
+        guint ifactor;
+
+        if (factor < 0.0)
+          factor = -factor;
+
+        ifactor = (guint) factor;
+        factor = factor - floor (factor);
+
+        if (ifactor & 1)
+          factor = 1.0 - factor;
+      }
+      break;
+
+    case GIMP_REPEAT_TRUNCATE:
+      if (factor < 0.0 || factor > 1.0)
+        {
+          gimp_rgba_set (color, 0.0, 0.0, 0.0, 0.0);
+          return;
+        }
+      break;
+    }
+
+  /* Blend the colors */
+
+  if (rbd->gradient_cache)
+    {
+      factor = CLAMP (factor, 0.0, 1.0);
+
+      *color =
+        rbd->gradient_cache[ROUND (factor * (rbd->gradient_cache_size - 1))];
+    }
+  else
+    {
+      rbd->last_seg = gimp_gradient_get_color_at (rbd->gradient, NULL,
+                                                  rbd->last_seg, factor,
+                                                  rbd->reverse,
+                                                  rbd->blend_color_space,
+                                                  color);
+    }
+}
+
+static void
+gradient_put_pixel (gint      x,
+                    gint      y,
+                    GimpRGB  *color,
+                    gpointer  put_pixel_data)
+{
+  PutPixelData *ppd   = put_pixel_data;
+  const gint    index = (y - ppd->roi.y) * ppd->roi.width + (x - ppd->roi.x);
+  gfloat       *dest  = ppd->data + 4 * index;
+
+  if (ppd->dither_rand)
+    {
+      gradient_dither_pixel (color, ppd->dither_rand, dest);
+
+      dest += 4;
+    }
+  else
+    {
+      *dest++ = color->r;
+      *dest++ = color->g;
+      *dest++ = color->b;
+      *dest++ = color->a;
+    }
+}
+
+static void
+gradient_dither_pixel (GimpRGB *color,
+                       GRand   *dither_rand,
+                       gfloat  *dest)
+{
+  gfloat r, g, b, a;
+  guint  i;
+
+  i = g_rand_int (dither_rand);
+
+  r = color->r + (gdouble) (i & 0xff) / 256.0 / 256.0 - 0.5 / 256.0; i >>= 8;
+  g = color->g + (gdouble) (i & 0xff) / 256.0 / 256.0 - 0.5 / 256.0; i >>= 8;
+  b = color->b + (gdouble) (i & 0xff) / 256.0 / 256.0 - 0.5 / 256.0; i >>= 8;
+
+  if (color->a > 0.0 && color->a < 1.0)
+    a = color->a + (gdouble) (i & 0xff) / 256.0 / 256.0 - 0.5 / 256.0;
+  else
+    a = color->a;
+
+  *dest++ = CLAMP (r, 0.0, 1.0);
+  *dest++ = CLAMP (g, 0.0, 1.0);
+  *dest++ = CLAMP (b, 0.0, 1.0);
+  *dest++ = CLAMP (a, 0.0, 1.0);
+}
+
+static gboolean
+gimp_operation_gradient_process (GeglOperation       *operation,
+                                 GeglBuffer          *input,
+                                 GeglBuffer          *output,
+                                 const GeglRectangle *result,
+                                 gint                 level)
+{
+  GimpOperationGradient *self = GIMP_OPERATION_GRADIENT (operation);
+
+  const gdouble sx = self->start_x;
+  const gdouble sy = self->start_y;
+  const gdouble ex = self->end_x;
+  const gdouble ey = self->end_y;
+
+  RenderBlendData rbd = { 0, };
+
+  GeglBufferIterator *iter;
+  GeglRectangle      *roi;
+  GRand              *dither_rand = NULL;
+
+  if (! self->gradient)
+    return TRUE;
+
+  gimp_operation_gradient_validate_cache (self);
+
+  rbd.gradient            = self->gradient;
+  rbd.reverse             = self->gradient_reverse;
+  rbd.blend_color_space   = self->gradient_blend_color_space;
+  rbd.gradient_cache      = self->gradient_cache;
+  rbd.gradient_cache_size = self->gradient_cache_size;
+
+  /* Calculate type-specific parameters */
+
+  switch (self->gradient_type)
+    {
+    case GIMP_GRADIENT_RADIAL:
+      rbd.dist = sqrt (SQR (ex - sx) + SQR (ey - sy));
+      break;
+
+    case GIMP_GRADIENT_SQUARE:
+      rbd.dist = MAX (fabs (ex - sx), fabs (ey - sy));
+      break;
+
+    case GIMP_GRADIENT_CONICAL_SYMMETRIC:
+    case GIMP_GRADIENT_CONICAL_ASYMMETRIC:
+    case GIMP_GRADIENT_SPIRAL_CLOCKWISE:
+    case GIMP_GRADIENT_SPIRAL_ANTICLOCKWISE:
+    case GIMP_GRADIENT_LINEAR:
+    case GIMP_GRADIENT_BILINEAR:
+      rbd.dist = sqrt (SQR (ex - sx) + SQR (ey - sy));
+
+      if (rbd.dist > 0.0)
+        {
+          rbd.vec[0] = (ex - sx) / rbd.dist;
+          rbd.vec[1] = (ey - sy) / rbd.dist;
+        }
+
+      break;
+
+    case GIMP_GRADIENT_SHAPEBURST_ANGULAR:
+    case GIMP_GRADIENT_SHAPEBURST_SPHERICAL:
+    case GIMP_GRADIENT_SHAPEBURST_DIMPLED:
+      rbd.dist = sqrt (SQR (ex - sx) + SQR (ey - sy));
+      rbd.dist_sampler = gegl_buffer_sampler_new_at_level (
+        input, babl_format ("Y float"), GEGL_SAMPLER_NEAREST, level);
+      break;
+
+    default:
+      g_return_val_if_reached (FALSE);
+      break;
+    }
+
+  /* Initialize render data */
+
+  rbd.offset        = self->offset;
+  rbd.sx            = self->start_x;
+  rbd.sy            = self->start_y;
+  rbd.gradient_type = self->gradient_type;
+  rbd.repeat        = self->gradient_repeat;
+
+  /* Render the gradient! */
+
+  iter = gegl_buffer_iterator_new (output, result, 0,
+                                   babl_format ("R'G'B'A float"),
+                                   GEGL_ACCESS_WRITE, GEGL_ABYSS_NONE, 1);
+  roi = &iter->items[0].roi;
+
+  if (self->dither)
+    dither_rand = g_rand_new ();
+
+  if (self->supersample)
+    {
+      PutPixelData ppd;
+
+      ppd.dither_rand = dither_rand;
+
+      while (gegl_buffer_iterator_next (iter))
+        {
+          ppd.data = iter->items[0].data;
+          ppd.roi  = *roi;
+
+          gimp_adaptive_supersample_area (roi->x, roi->y,
+                                          roi->x + roi->width  - 1,
+                                          roi->y + roi->height - 1,
+                                          self->supersample_depth,
+                                          self->supersample_threshold,
+                                          gradient_render_pixel, &rbd,
+                                          gradient_put_pixel, &ppd,
+                                          NULL,
+                                          NULL);
+        }
+    }
+  else
+    {
+      while (gegl_buffer_iterator_next (iter))
+        {
+          gfloat *dest = iter->items[0].data;
+          gint    endx = roi->x + roi->width;
+          gint    endy = roi->y + roi->height;
+          gint    x, y;
+
+          if (dither_rand)
+            {
+              for (y = roi->y; y < endy; y++)
+                for (x = roi->x; x < endx; x++)
+                  {
+                    GimpRGB  color = { 0.0, 0.0, 0.0, 1.0 };
+
+                    gradient_render_pixel (x, y, &color, &rbd);
+                    gradient_dither_pixel (&color, dither_rand, dest);
+
+                    dest += 4;
+                  }
+            }
+          else
+            {
+              for (y = roi->y; y < endy; y++)
+                for (x = roi->x; x < endx; x++)
+                  {
+                    GimpRGB  color = { 0.0, 0.0, 0.0, 1.0 };
+
+                    gradient_render_pixel (x, y, &color, &rbd);
+
+                    *dest++ = color.r;
+                    *dest++ = color.g;
+                    *dest++ = color.b;
+                    *dest++ = color.a;
+                  }
+            }
+        }
+    }
+
+  if (self->dither)
+    g_rand_free (dither_rand);
+
+  g_clear_object (&rbd.dist_sampler);
+
+  return TRUE;
+}
+
+static void
+gimp_operation_gradient_invalidate_cache (GimpOperationGradient *self)
+{
+  g_clear_pointer (&self->gradient_cache, g_free);
+}
+
+static void
+gimp_operation_gradient_validate_cache (GimpOperationGradient *self)
+{
+  GimpGradientSegment *last_seg = NULL;
+  gint                 cache_size;
+  gint                 i;
+
+  if (! self->gradient)
+    return;
+
+  g_mutex_lock (&self->gradient_cache_mutex);
+
+  if (self->gradient_cache)
+    {
+      g_mutex_unlock (&self->gradient_cache_mutex);
+
+      return;
+    }
+
+  cache_size = ceil (hypot (self->start_x - self->end_x,
+                            self->start_y - self->end_y)) *
+               GRADIENT_CACHE_N_SUPERSAMPLES;
+
+  /*  have at least two values in the cache  */
+  cache_size = MAX (cache_size, 2);
+
+  /*  don't use a cache if its necessary size is too big  */
+  if (cache_size > GRADIENT_CACHE_MAX_SIZE)
+    {
+      g_mutex_unlock (&self->gradient_cache_mutex);
+
+      return;
+    }
+
+  self->gradient_cache      = g_new0 (GimpRGB, cache_size);
+  self->gradient_cache_size = cache_size;
+
+  for (i = 0; i < self->gradient_cache_size; i++)
+    {
+      gdouble factor = (gdouble) i / (gdouble) (self->gradient_cache_size - 1);
+
+      last_seg = gimp_gradient_get_color_at (self->gradient, NULL, last_seg,
+                                             factor,
+                                             self->gradient_reverse,
+                                             self->gradient_blend_color_space,
+                                             self->gradient_cache + i);
+    }
+
+  g_mutex_unlock (&self->gradient_cache_mutex);
+}