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[gegl] Add Spyrograph operations.

commit b8c7faa2ba4a44007e0dfc8730e4c93931a1728f
Author: elad <dawn ever gmail com>
Date:   Mon Oct 22 02:27:26 2018 +0300

    Add Spyrograph operations.

 operations/external/Makefile.am  |   5 +-
 operations/external/spyrograph.c | 621 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 625 insertions(+), 1 deletion(-)
---
diff --git a/operations/external/Makefile.am b/operations/external/Makefile.am
index bfc337d32..c18c072e9 100644
--- a/operations/external/Makefile.am
+++ b/operations/external/Makefile.am
@@ -17,7 +17,7 @@ gif_load_la_LIBADD = $(op_libs)
 gif_load_la_CFLAGS = $(AM_CFLAGS)
 
 if HAVE_CAIRO
-ops += path.la vector-fill.la vector-stroke.la
+ops += path.la vector-fill.la vector-stroke.la spyrograph.la
 path_la_SOURCES = path.c
 path_la_LIBADD = $(op_libs) $(CAIRO_LIBS)
 path_la_CFLAGS = $(AM_CFLAGS) $(CAIRO_CFLAGS)
@@ -27,6 +27,9 @@ vector_fill_la_CFLAGS = $(AM_CFLAGS) $(CAIRO_CFLAGS)
 vector_stroke_la_SOURCES = vector-stroke.c
 vector_stroke_la_LIBADD = $(op_libs) $(CAIRO_LIBS)
 vector_stroke_la_CFLAGS = $(AM_CFLAGS) $(CAIRO_CFLAGS)
+spyrograph_la_SOURCES = spyrograph.c
+spyrograph_la_LIBADD = $(op_libs) $(CAIRO_LIBS)
+spyrograph_la_CFLAGS = $(AM_CFLAGS) $(CAIRO_CFLAGS)
 endif
 
 if HAVE_PNG
diff --git a/operations/external/spyrograph.c b/operations/external/spyrograph.c
new file mode 100644
index 000000000..143ee05cb
--- /dev/null
+++ b/operations/external/spyrograph.c
@@ -0,0 +1,621 @@
+/* This file is an image processing operation for GEGL
+ *
+ * GEGL is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * GEGL 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with GEGL; if not, see <https://www.gnu.org/licenses/>.
+ *
+ * Copyright 2018 Øyvind Kolås <pippin gimp org>
+ */
+
+
+#include "config.h"
+#include <glib/gi18n-lib.h>
+
+
+#ifdef GEGL_PROPERTIES
+
+enum_start (gegl_curve_type)
+  enum_value (GEGL_CURVE_TYPE_SPYROGRAPH,   "spyrograph",      N_("Spyrograph"))
+  enum_value (GEGL_CURVE_TYPE_EPITROCHOID, "epitrochoid", N_("EPITROCHOID"))
+enum_end (GeglCurveType)
+
+property_enum (curve_type, _("Curve Type"),
+               GeglCurveType, gegl_curve_type,
+               GEGL_CURVE_TYPE_SPYROGRAPH)
+  description (_("Curve type"))
+
+property_int   (fixed_gear_teeth, _("Fixed Gear Teeth"), 96)
+   description (_("Number of teeth in fixed gear."))
+   value_range (10, 180)
+
+property_int   (moving_gear_teeth, _("Moving Gear Teeth"), 36)
+   description (_("Number of teeth in moving gear. Radius of moving gear,"
+                  " relative to radius of fixed gear, is determined by the "
+                  "proportion between the number of teeth in gears."))
+   value_range (10, 100)
+
+property_double (hole_percent, _("Hole Percent"), 100.0)
+  description (_("How far the hole is from the center of the moving gear. "
+                 "100 means that the hole is at the gear's edge."))
+  value_range (0.0, 100.0)
+
+property_double (x, _("X"), 0.5)
+  description (_("X coordinate of pattern center"))
+  ui_range    (0.0, 1.0)
+  ui_meta     ("unit", "relative-coordinate")
+  ui_meta     ("axis", "x")
+
+property_double (y, _("Y"), 0.5)
+  description (_("Y coordinate of pattern center"))
+  ui_range    (0.0, 1.0)
+  ui_meta     ("unit", "relative-coordinate")
+  ui_meta     ("axis", "y")
+
+property_double (radius, _("Radius"), 100.0)
+  description (_("Radius of fixed gear"))
+  value_range (1.0, G_MAXDOUBLE)
+  ui_range    (1.0, 1000.0)
+  ui_meta     ("unit", "pixel-distance")
+
+property_double (rotation, _("Rotation"), 0.0)
+  description (_("Pattern rotation"))
+  value_range (0.0, 360.0)
+  ui_meta     ("unit", "degree")
+
+property_color  (stroke, _("Stroke Color"), "rgba(0.0,0.0,0.0,0.0)")
+  description(_("Color of paint to use for stroking"))
+
+property_double (stroke_width,_("Stroke width"), 2.0)
+  description (_("The width of the brush used to stroke the path"))
+  value_range (0.0, 200.0)
+
+property_double (stroke_opacity, _("Stroke opacity"), 1.0)
+  description (_("Opacity of stroke, note, does not behave like SVG since at the moment stroking is done 
using an airbrush tool"))
+  value_range (-2.0, 2.0)
+
+property_double (stroke_hardness, _("Hardness"), 0.6)
+  description (_("Hardness of the brush, 0.0 for a soft brush, 1.0 for a hard brush"))
+  value_range (0.0, 1.0)
+
+#else
+
+#define GEGL_OP_FILTER
+#define GEGL_OP_NAME     spyrograph
+#define GEGL_OP_C_SOURCE spyrograph.c
+
+#include "gegl-plugin.h"
+#include "gegl-path.h"
+#include "gegl-op.h"
+#include <cairo.h>
+#include <math.h>
+
+typedef struct StampStatic {
+  gboolean    valid;
+  const Babl *format;
+  gfloat     *buf;
+  gdouble     radius;
+}StampStatic;
+
+static void gegl_path_stroke  (GeglBuffer *buffer,
+                               const GeglRectangle *clip_rect,
+                               GeglPath *vector,
+                               GeglColor  *color,
+                               gdouble     linewidth,
+                               gdouble     hardness,
+                               gdouble     opacity);
+
+static void gegl_path_stamp   (GeglBuffer *buffer,
+                               const GeglRectangle *clip_rect,
+                               gdouble     x,
+                               gdouble     y,
+                               gdouble     radius,
+                               gdouble     hardness,
+                               GeglColor  *color,
+                               gdouble     opacity);
+
+static void
+gegl_path_stroke (GeglBuffer *buffer,
+                  const GeglRectangle *clip_rect,
+                  GeglPath *vector,
+                  GeglColor  *color,
+                  gdouble     linewidth,
+                  gdouble     hardness,
+                  gdouble     opacity)
+{
+  gfloat traveled_length = 0;
+  gfloat need_to_travel = 0;
+  gfloat x = 0,y = 0;
+  GeglPathList *iter;
+  gdouble       xmin, xmax, ymin, ymax;
+  GeglRectangle extent;
+
+  if (!vector)
+    return;
+
+  if (!clip_rect)
+    {
+      g_print ("using buffer extent\n");
+      clip_rect = gegl_buffer_get_extent (buffer);
+    }
+
+  iter = gegl_path_get_flat_path (vector);
+  gegl_path_get_bounds (vector, &xmin, &xmax, &ymin, &ymax);
+  extent.x = floor (xmin);
+  extent.y = floor (ymin);
+  extent.width = ceil (xmax) - extent.x;
+  extent.height = ceil (ymax) - extent.y;
+
+  if (!gegl_rectangle_intersect (&extent, &extent, clip_rect))
+   {
+     return;
+   }
+
+  while (iter)
+    {
+      /*fprintf (stderr, "%c, %i %i\n", iter->d.type, iter->d.point[0].x, iter->d.point[0].y);*/
+      switch (iter->d.type)
+        {
+          case 'M':
+            x = iter->d.point[0].x;
+            y = iter->d.point[0].y;
+            need_to_travel = 0;
+            traveled_length = 0;
+            break;
+          case 'L':
+            {
+              GeglPathPoint a,b;
+
+              gfloat spacing;
+              gfloat local_pos;
+              gfloat distance;
+              gfloat offset;
+              gfloat leftover;
+              gfloat radius = linewidth / 2.0;
+
+              a.x = x;
+              a.y = y;
+
+              b.x = iter->d.point[0].x;
+              b.y = iter->d.point[0].y;
+
+              spacing = 0.2 * radius;
+
+              distance = gegl_path_point_dist (&a, &b);
+
+              leftover = need_to_travel - traveled_length;
+              offset = spacing - leftover;
+
+              local_pos = offset;
+
+              if (distance > 0)
+                for (;
+                     local_pos <= distance;
+                     local_pos += spacing)
+                  {
+                    GeglPathPoint spot;
+                    gfloat ratio = local_pos / distance;
+                    gfloat radius = linewidth/2;
+
+                    gegl_path_point_lerp (&spot, &a, &b, ratio);
+
+                    gegl_path_stamp (buffer, clip_rect,
+                      spot.x, spot.y, radius, hardness, color, opacity);
+
+                    traveled_length += spacing;
+                  }
+
+              need_to_travel += distance;
+
+              x = b.x;
+              y = b.y;
+            }
+
+            break;
+          case 'u':
+            g_error ("stroking uninitialized path\n");
+            break;
+          case 's':
+            break;
+          default:
+            g_error ("can't stroke for instruction: %i\n", iter->d.type);
+            break;
+        }
+      iter=iter->next;
+    }
+}
+
+static void
+gegl_path_stamp (GeglBuffer *buffer,
+                 const GeglRectangle *clip_rect,
+                 gdouble     x,
+                 gdouble     y,
+                 gdouble     radius,
+                 gdouble     hardness,
+                 GeglColor  *color,
+                 gdouble     opacity)
+{
+  gfloat col[4];
+  StampStatic s = {FALSE,}; /* there should be a cache of stamps,
+                               note that stamps are accessed in multiple threads
+                             */
+
+  GeglRectangle temp;
+  GeglRectangle roi;
+
+  roi.x = floor(x-radius);
+  roi.y = floor(y-radius);
+  roi.width = ceil (x+radius) - floor (x-radius);
+  roi.height = ceil (y+radius) - floor (y-radius);
+
+  gegl_color_get_pixel (color, babl_format ("RGBA float"), col);
+
+  /* bail out if we wouldn't leave a mark on the buffer */
+  if (!gegl_rectangle_intersect (&temp, &roi, clip_rect))
+    {
+      return;
+    }
+
+  if (s.format == NULL)
+    s.format = babl_format ("RaGaBaA float");
+
+  if (s.buf == NULL ||
+      s.radius != radius)
+    {
+      g_free (s.buf);
+      /* allocate a little bit more, just in case due to rounding errors and
+       * such */
+      s.buf = g_malloc (4*4* (roi.width + 2 ) * (roi.height + 2));
+      s.radius = radius;
+      s.valid = TRUE;
+    }
+  g_assert (s.buf);
+
+  gegl_buffer_get (buffer, &roi, 1.0, s.format, s.buf, 0, GEGL_ABYSS_NONE);
+
+  {
+    gint u, v;
+    gint i=0;
+
+    gfloat radius_squared = radius * radius;
+    gfloat inner_radius_squared = (radius * hardness)*(radius * hardness);
+    gfloat soft_range = radius_squared - inner_radius_squared;
+
+    for (v= roi.y; v < roi.y + roi.height ; v++)
+    {
+      gfloat vy2 = (v-y)*(v-y);
+      for (u= roi.x; u < roi.x + roi.width; u++)
+        {
+          gfloat o = (u-x) * (u-x) + vy2;
+
+          if (o < inner_radius_squared)
+             o = col[3];
+          else if (o < radius_squared)
+            {
+              o = (1.0 - (o-inner_radius_squared) / (soft_range)) * col[3];
+            }
+          else
+            {
+              o=0.0;
+            }
+         if (o!=0.0)
+           {
+             gint c;
+             o = o*opacity;
+             for (c=0;c<4;c++)
+               s.buf[i*4+c] = (s.buf[i*4+c] * (1.0-o) + col[c] * o);
+           }
+         i++;
+        }
+    }
+  }
+  gegl_buffer_set (buffer, &roi, 0, s.format, s.buf, 0);
+  g_free (s.buf);
+}
+
+static int 
+findGCD(int num1, int num2) {
+    if (num2 == 0) {
+        return num1;
+    }
+    if (num1 % num2 == 0) {
+        return num2;
+    }
+    return findGCD(num2, num1 % num2);
+}
+
+
+static GeglPath *
+gegl_path_curve(GeglProperties *o)
+{
+  GeglPath *path = gegl_path_new();
+  GeglPathItem gegl_path_item;
+
+  double TWO_PI = 2 * G_PI; 
+
+  int least_common_mult = o->fixed_gear_teeth * o->moving_gear_teeth /
+    findGCD(o->fixed_gear_teeth, o-> moving_gear_teeth);
+  int steps = least_common_mult + 1;
+
+  // Extract paramters.
+  gfloat hole_percent = o->hole_percent;
+  gfloat x_center = o->x;
+  gfloat y_center = o->y;
+  gfloat fixed_gear_radius = o->radius;
+  gfloat pattern_rotation = o->rotation * G_PI / 180.0;
+
+  // Variables used in loop.
+  int i; 
+  gfloat x, y;
+  gfloat fixed_gear_angle, moving_gear_angle;
+
+  // Computations.
+  gfloat fixed_angle_factor = TWO_PI / o-> fixed_gear_teeth;
+  gfloat moving_gear_radius = fixed_gear_radius * o->moving_gear_teeth / o->fixed_gear_teeth ;
+  gfloat hole_dist_from_center = hole_percent / 100.0 * moving_gear_radius;
+
+  gfloat moving_angle_factor; 
+  if (o->curve_type == GEGL_CURVE_TYPE_SPYROGRAPH) {
+    moving_angle_factor = fixed_angle_factor * -1 * 
+      (o->fixed_gear_teeth - o->moving_gear_teeth) / o->moving_gear_teeth;
+  }
+  else {
+    moving_angle_factor = fixed_angle_factor *  
+      (o->fixed_gear_teeth + o->moving_gear_teeth) / o->moving_gear_teeth;
+  }
+
+  // Compute points of pattern.
+  for (i=0; i<steps; i++) {
+    moving_gear_angle = i * moving_angle_factor;
+    fixed_gear_angle = fmod(i * fixed_angle_factor + pattern_rotation, TWO_PI);
+
+    x = x_center + (fixed_gear_radius - moving_gear_radius) * cos(fixed_gear_angle) +
+        hole_dist_from_center * cos(moving_gear_angle);
+    y = y_center + ( fixed_gear_radius - moving_gear_radius) * sin(fixed_gear_angle) +
+        hole_dist_from_center * sin(moving_gear_angle);
+
+    gegl_path_append (path, 'L', x, y);
+  }
+
+  // Replace first node from an 'L' type to an 'M' type
+  gegl_path_get_node(path, 0, &gegl_path_item);
+  gegl_path_item.type = 'M';
+  gegl_path_replace_node(path, 0, &gegl_path_item);
+
+  return path;
+}
+
+static void
+prepare (GeglOperation *operation)
+{
+  GeglProperties *o = GEGL_PROPERTIES (operation);
+
+  // Compute vector of curve, and store it on the operation.
+  GeglPath *d = gegl_path_curve(o);
+  g_object_set_data (G_OBJECT (operation), "d", d);
+
+  gegl_operation_set_format (operation, "output", babl_format ("R'aG'aB'aA float"));
+}
+
+static GeglRectangle
+get_bounding_box (GeglOperation *operation)
+{
+  GeglProperties    *o       = GEGL_PROPERTIES (operation);
+  GeglRectangle  defined = { 0, 0, 512, 512 };
+  GeglRectangle *in_rect;
+  gdouble        x0, x1, y0, y1;
+  GeglPath *d = g_object_get_data (G_OBJECT (operation), "d");
+
+  in_rect =  gegl_operation_source_get_bounding_box (operation, "input");
+
+  gegl_path_get_bounds (d, &x0, &x1, &y0, &y1);
+  defined.x      = x0 - o->stroke_width/2;
+  defined.y      = y0 - o->stroke_width/2;
+  defined.width  = x1 - x0 + o->stroke_width;
+  defined.height = y1 - y0 + o->stroke_width;
+
+  if (in_rect)
+    {
+      gegl_rectangle_bounding_box (&defined, &defined, in_rect);
+    }
+
+  return defined;
+}
+
+static void gegl_path_cairo_play (GeglPath *path,
+                                    cairo_t *cr);
+
+static gboolean
+process (GeglOperation       *operation,
+         GeglBuffer          *input,
+         GeglBuffer          *output,
+         const GeglRectangle *result,
+         gint                 level)
+{
+  GeglProperties *o = GEGL_PROPERTIES (operation);
+  GeglPath *d = g_object_get_data (G_OBJECT (operation), "d");
+
+  if (input)
+    {
+      gegl_buffer_copy (input, result, GEGL_ABYSS_NONE,
+                        output, result);
+    }
+  else
+    {
+      gegl_buffer_clear (output, result);
+    }
+
+  // For small stroke size, use Cairo to draw.
+  if (o->stroke_width <= 1.0)
+    {
+      gdouble color[4] = {0, 0, 0, 0};
+      gegl_color_get_pixel (o->stroke, babl_format ("R'G'B'A double"), color);
+      color[3] *= o->stroke_opacity;
+
+      if (color[3] > 0.001)
+        {
+          static GMutex mutex = { 0, };
+          cairo_t *cr;
+          cairo_surface_t *surface;
+          guchar *data;
+
+          g_mutex_lock (&mutex);
+          data = gegl_buffer_linear_open (output, result, NULL, babl_format ("cairo-ARGB32"));
+          surface = cairo_image_surface_create_for_data (data,
+                                                         CAIRO_FORMAT_ARGB32,
+                                                         result->width,
+                                                         result->height,
+                                                         result->width * 4);
+          cr = cairo_create (surface);
+          cairo_translate (cr, -result->x, -result->y);
+          gegl_path_cairo_play (d, cr);
+          cairo_set_source_rgba (cr, color[0], color[1], color[2], color[3]);
+          cairo_set_line_width (cr, o->stroke_width);
+          cairo_stroke (cr);
+
+          g_mutex_unlock (&mutex);
+          gegl_buffer_linear_close (output, data);
+        }
+
+      return TRUE;
+    }
+
+
+  g_object_set_data (G_OBJECT (operation), "path-radius", GINT_TO_POINTER((gint)(o->stroke_width+1)/2));
+
+  if (o->stroke_width > 0.1 && o->stroke_opacity > 0.0001)
+    {
+      gegl_path_stroke (output, result,
+                                d,
+                                o->stroke,
+                                o->stroke_width,
+                                o->stroke_hardness,
+                                o->stroke_opacity);
+    }
+
+  return  TRUE;
+}
+
+
+static void foreach_cairo (const GeglPathItem *knot,
+                           gpointer              cr)
+{
+  switch (knot->type)
+    {
+      case 'M':
+        cairo_move_to (cr, knot->point[0].x, knot->point[0].y);
+        break;
+      case 'L':
+        cairo_line_to (cr, knot->point[0].x, knot->point[0].y);
+        break;
+      case 'z':
+        cairo_close_path (cr);
+        break;
+      default:
+        g_print ("%s uh?:%c\n", G_STRLOC, knot->type);
+    }
+}
+
+static void gegl_path_cairo_play (GeglPath *path,
+                                    cairo_t *cr)
+{
+  gegl_path_foreach_flat (path, foreach_cairo, cr);
+}
+
+static GeglNode *detect (GeglOperation *operation,
+                         gint           x,
+                         gint           y)
+{
+  GeglProperties *o = GEGL_PROPERTIES (operation);
+  cairo_t *cr;
+  cairo_surface_t *surface;
+  gchar *data = "     ";
+  gboolean result = FALSE;
+  GeglPath *d = g_object_get_data (G_OBJECT (operation), "d");
+
+  surface = cairo_image_surface_create_for_data ((guchar*)data,
+                                                 CAIRO_FORMAT_ARGB32,
+                                                 1,1,4);
+  cr = cairo_create (surface);
+  gegl_path_cairo_play (d, cr);
+  cairo_set_line_width (cr, o->stroke_width);
+
+  if (o->stroke_width > 0.1 && o->stroke_opacity > 0.0001)
+    result = cairo_in_stroke (cr, x, y);
+
+  cairo_destroy (cr);
+
+  if (result)
+    return operation->node;
+
+  return NULL;
+}
+
+static void
+finalize (GObject *object)
+{
+  GeglPath *d = g_object_get_data (object, "d");
+  if (d) {
+     gegl_path_clear(d);
+  }
+
+  G_OBJECT_CLASS (gegl_op_parent_class)->finalize (object);
+}
+
+static void
+gegl_op_class_init (GeglOpClass *klass)
+{
+  GObjectClass             *object_class;
+  GeglOperationClass       *operation_class;
+  GeglOperationFilterClass *filter_class;
+  const gchar *composition =
+    "<gegl>"
+    "<node operation='gegl:crop' width='200' height='200'/>"
+    "<node operation='gegl:over'>"
+    "<node operation='gegl:spyrograph'>"
+    "  <params>"
+    "    <param name='fixed-gear-teeth'>96</param>"
+    "    <param name='moving-gear-teeth'>36</param>"
+    "    <param name='x'>100</param>"
+    "    <param name='y'>100</param>"
+    "    <param name='radius'>90</param>"
+    "    <param name='stroke'>rgba(0,0,1,0.9)</param>"
+    "    <param name='stroke-hardness'>1.0</param>"
+    "    <param name='stroke-width'>8.0</param>"
+    "  </params>"
+    "</node>"
+    "</node>"
+    "<node operation='gegl:checkerboard' color1='rgb(0.25,0.25,0.25)' color2='rgb(0.75,0.75,0.75)'/>"
+    "</gegl>";
+
+  object_class    = G_OBJECT_CLASS (klass);
+  operation_class = GEGL_OPERATION_CLASS (klass);
+  filter_class    = GEGL_OPERATION_FILTER_CLASS (klass);
+
+  object_class->finalize = finalize;
+  filter_class->process = process;
+  operation_class->get_bounding_box = get_bounding_box;
+  operation_class->prepare = prepare;
+  operation_class->detect = detect;
+  /*operation_class->no_cache = TRUE;*/
+
+  gegl_operation_class_set_keys (operation_class,
+    "name",           "gegl:spyrograph",
+    "title",          _("Render Spyrograph"),
+    "categories",     "render",
+    "reference-hash", "73276d276ac18bc1f32404e258f7b9ee",
+    "reference-composition", composition,
+    "description" , _("Renders a Spyrograph pattern"),
+    NULL);
+}
+
+
+#endif
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