[gegl] variable-blur: new op in common-cxx

[Ell <ell src gnome org>]

commit 5f9a19c433752af5a0bf63d4ebee454f8b2618ba
Author: Ell <ell_se yahoo com>
Date:   Thu May 14 21:50:46 2020 +0300

    variable-blur: new op in common-cxx
    
    Add a new gegl:varaible-blur op, which takes an input and a mask,
    and uses the mask as a per-pixel blur factor for the input.  This
    is currently implemened by applying a series of Gaussian blurs to
    the input with increasing radii, and using gegl:piecewise-blend to
    interpolate them using the mask.
    
    The is a C op, but it lives in common-cxx so that it only gets
    built if the rest of the C++ ops are built, since
    gegl:piecewise-blend is one.

 operations/common-cxx/meson.build     |   1 +
 operations/common-cxx/variable-blur.c | 190 ++++++++++++++++++++++++++++++++++
 po/POTFILES.in                        |   1 +
 3 files changed, 192 insertions(+)
---
diff --git a/operations/common-cxx/meson.build b/operations/common-cxx/meson.build
index 0a6ca2cb9..02b63ee8b 100644
--- a/operations/common-cxx/meson.build
+++ b/operations/common-cxx/meson.build
@@ -2,6 +2,7 @@
 gegl_common_cxx_sources = files(
   'distance-transform.cc',
   'piecewise-blend.cc',
+  'variable-blur.c',
   'warp.cc',
 )
 
diff --git a/operations/common-cxx/variable-blur.c b/operations/common-cxx/variable-blur.c
new file mode 100644
index 000000000..42f8ce23e
--- /dev/null
+++ b/operations/common-cxx/variable-blur.c
@@ -0,0 +1,190 @@
+/* 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 2020 Ell
+ */
+
+#include "config.h"
+#include <glib/gi18n-lib.h>
+#include <math.h>
+#include <stdio.h>
+
+#define MAX_LEVELS 16
+
+#ifdef GEGL_PROPERTIES
+
+property_double (radius, _("Radius"), 10.0)
+    description (_("Maximal blur radius"))
+    value_range (0.0, 1500.0)
+    ui_range    (0.0, 100.0)
+    ui_gamma    (2.0)
+    ui_meta     ("unit", "pixel-distance")
+
+property_int (levels, _("Levels"), 8)
+    description (_("Number of blur levels"))
+    value_range (2, MAX_LEVELS)
+
+property_boolean (linear_mask, _("Linear mask"), FALSE)
+    description (_("Use linear mask values"))
+
+#else
+
+#define GEGL_OP_META
+#define GEGL_OP_NAME     variable_blur
+#define GEGL_OP_C_SOURCE variable-blur.c
+
+#include "gegl-op.h"
+
+typedef struct
+{
+  GeglNode *input;
+  GeglNode *aux;
+  GeglNode *output;
+
+  GeglNode *gaussian_blur[MAX_LEVELS];
+
+  GeglNode *piecewise_blend;
+} Nodes;
+
+static void
+update (GeglOperation *operation)
+{
+  GeglProperties *o     = GEGL_PROPERTIES (operation);
+  Nodes          *nodes = o->user_data;
+
+  if (nodes)
+    {
+      gint i;
+
+      for (i = 1; i < o->levels; i++)
+        {
+          gegl_node_link (nodes->input, nodes->gaussian_blur[i]);
+
+          gegl_node_set (nodes->gaussian_blur[i],
+                         "std-dev-x", i * o->radius / (o->levels - 1),
+                         "std-dev-y", i * o->radius / (o->levels - 1),
+                         NULL);
+        }
+
+      for (; i < MAX_LEVELS; i++)
+        gegl_node_disconnect (nodes->gaussian_blur[i], "input");
+    }
+}
+
+static void
+attach (GeglOperation *operation)
+{
+  GeglProperties *o = GEGL_PROPERTIES (operation);
+  Nodes          *nodes;
+  gint            i;
+
+  if (! o->user_data)
+    o->user_data = g_slice_new (Nodes);
+
+  nodes = o->user_data;
+
+  nodes->input  = gegl_node_get_input_proxy  (operation->node, "input");
+  nodes->aux    = gegl_node_get_input_proxy  (operation->node, "aux");
+  nodes->output = gegl_node_get_output_proxy (operation->node, "output");
+
+  nodes->piecewise_blend = gegl_node_new_child (
+    operation->node,
+    "operation", "gegl:piecewise-blend",
+    NULL);
+
+  gegl_operation_meta_redirect (operation,              "levels",
+                                nodes->piecewise_blend, "levels");
+  gegl_operation_meta_redirect (operation,              "linear-mask",
+                                nodes->piecewise_blend, "linear-mask");
+
+  gegl_operation_meta_watch_node (operation, nodes->piecewise_blend);
+
+  gegl_node_connect_to (nodes->input,           "output",
+                        nodes->piecewise_blend, "aux1");
+
+  for (i = 1; i < MAX_LEVELS; i++)
+    {
+      gchar aux_name[32];
+
+      nodes->gaussian_blur[i] = gegl_node_new_child (
+        operation->node,
+        "operation", "gegl:gaussian-blur",
+        NULL);
+
+      gegl_operation_meta_watch_node (operation, nodes->gaussian_blur[i]);
+
+      sprintf (aux_name, "aux%d", i + 1);
+
+      gegl_node_connect_to (nodes->gaussian_blur[i], "output",
+                            nodes->piecewise_blend,  aux_name);
+    }
+
+  gegl_node_link_many (nodes->aux,
+                       nodes->piecewise_blend,
+                       nodes->output,
+                       NULL);
+
+  update (operation);
+}
+
+static void
+my_set_property (GObject      *object,
+                 guint         property_id,
+                 const GValue *value,
+                 GParamSpec   *pspec)
+{
+  set_property (object, property_id, value, pspec);
+
+  update (GEGL_OPERATION (object));
+}
+
+static void
+dispose (GObject *object)
+{
+  GeglProperties *o = GEGL_PROPERTIES (object);
+
+  if (o->user_data)
+    {
+      g_slice_free (Nodes, o->user_data);
+
+      o->user_data = NULL;
+    }
+
+  G_OBJECT_CLASS (gegl_op_parent_class)->dispose (object);
+}
+
+static void
+gegl_op_class_init (GeglOpClass *klass)
+{
+  GObjectClass       *object_class;
+  GeglOperationClass *operation_class;
+
+  object_class    = G_OBJECT_CLASS (klass);
+  operation_class = GEGL_OPERATION_CLASS (klass);
+
+  object_class->dispose      = dispose;
+  object_class->set_property = my_set_property;
+
+  operation_class->attach    = attach;
+
+  gegl_operation_class_set_keys (operation_class,
+    "name",        "gegl:variable-blur",
+    "title",       _("Variable Blur"),
+    "categories",  "blur",
+    "description", _("Blur the image by a varying amount using a mask"),
+    NULL);
+}
+
+#endif
diff --git a/po/POTFILES.in b/po/POTFILES.in
index fe0b95a2c..14653c249 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -127,6 +127,7 @@ operations/common/weighted-blend.c
 operations/common/write-buffer.c
 operations/common-cxx/distance-transform.cc
 operations/common-cxx/piecewise-blend.cc
+operations/common-cxx/variable-blur.c
 operations/common-cxx/warp.cc
 operations/common-gpl3+/antialias.c
 operations/common-gpl3+/apply-lens.c