effect: Add DesaturateEffect

A simple shader-based effect that desaturates an actor and its contents
based on a controllable factor.

clutter/Makefile.am

@@ -95,6 +95,7 @@ source_h =					\
 	$(srcdir)/clutter-constraint.h		\
 	$(srcdir)/clutter-container.h		\
 	$(srcdir)/clutter-deprecated.h		\
+	$(srcdir)/clutter-desaturate-effect.h	\
 	$(srcdir)/clutter-device-manager.h	\
 	$(srcdir)/clutter-drag-action.h		\
 	$(srcdir)/clutter-effect.h		\
@@ -180,6 +181,7 @@ source_c = \
 	$(srcdir)/clutter-color.c 		\
 	$(srcdir)/clutter-constraint.c		\
 	$(srcdir)/clutter-container.c		\
+	$(srcdir)/clutter-desaturate-effect.c	\
 	$(srcdir)/clutter-device-manager.c	\
 	$(srcdir)/clutter-drag-action.c		\
 	$(srcdir)/clutter-effect.c		\

clutter/clutter-desaturate-effect.c

@@ -0,0 +1,309 @@
+/*
+ * Clutter.
+ *
+ * An OpenGL based 'interactive canvas' library.
+ *
+ * Copyright (C) 2010  Intel Corporation.
+ *
+ * This library 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 2 of the License, or (at your option) any later version.
+ *
+ * This library 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 this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author:
+ *   Emmanuele Bassi <ebassi@linux.intel.com>
+ */
+
+/**
+ * SECTION:clutter-desaturate-effect
+ * @short_description: A desaturation effect
+ * @see_also: #ClutterEffect, #ClutterOffscreenEffect
+ *
+ * #ClutterDesaturateEffect is a sub-class of #ClutterEffect that
+ * desaturates the color of an actor and its contents. The strenght
+ * of the desaturation effect is controllable and animatable through
+ * the #ClutterDesaturateEffect:factor property.
+ *
+ * #ClutterDesaturateEffect uses the programmable pipeline of the GPU
+ * so it is only available on graphics hardware that supports this
+ * feature.
+ *
+ * #ClutterDesaturateEffect is available since Clutter 1.4
+ */
+
+#define CLUTTER_DESATURATE_EFFECT_CLASS(klass)        (G_TYPE_CHECK_CLASS_CAST ((klass), CLUTTER_TYPE_DESATURATE_EFFECT, ClutterDesaturateEffectClass))
+#define CLUTTER_IS_DESATURATE_EFFECT_CLASS(klass)     (G_TYPE_CHECK_CLASS_TYPE ((klass), CLUTTER_TYPE_DESATURATE_EFFECT))
+#define CLUTTER_DESATURATE_EFFECT_GET_CLASS(obj)      (G_TYPE_INSTANCE_GET_CLASS ((obj), CLUTTER_TYPE_DESATURATE_EFFECT, ClutterDesaturateEffectClass))
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "clutter-desaturate-effect.h"
+
+#include "cogl/cogl.h"
+
+#include "clutter-debug.h"
+#include "clutter-enum-types.h"
+#include "clutter-private.h"
+#include "clutter-shader-effect.h"
+
+typedef struct _ClutterDesaturateEffectClass    ClutterDesaturateEffectClass;
+
+struct _ClutterDesaturateEffect
+{
+  ClutterShaderEffect parent_instance;
+
+  /* a back pointer to our actor, so that we can query it */
+  ClutterActor *actor;
+
+  /* the desaturation factor, also known as "strength" */
+  gdouble factor;
+
+  guint source_set : 1;
+};
+
+struct _ClutterDesaturateEffectClass
+{
+  ClutterShaderEffectClass parent_class;
+};
+
+/* the magic gray vec3 has been taken from the NTSC conversion weights
+ * as defined by:
+ *
+ *   "OpenGL Superbible, 4th edition"
+ *   -- Richard S. Wright Jr, Benjamin Lipchak, Nicholas Haemel
+ *   Addison-Wesley
+ */
+static const gchar *desaturate_glsl_shader =
+"uniform sampler2D tex;\n"
+"uniform float factor;\n"
+"\n"
+"vec3 desaturate (const vec3 color, const float desaturation)\n"
+"{\n"
+"  const vec3 gray_conv = vec3 (0.299, 0.587, 0.114);\n"
+"  vec3 gray = vec3 (dot (gray_conv, color));\n"
+"  return vec3 (mix (color.rgb, gray, desaturation));\n"
+"}\n"
+"\n"
+"void main ()\n"
+"{\n"
+"  vec4 color = gl_Color * texture2D (tex, vec2 (gl_TexCoord[0].xy));\n"
+"  color.rgb = desaturate (color.rgb, factor);\n"
+"  gl_FragColor = color;\n"
+"}\n";
+
+enum
+{
+  PROP_0,
+
+  PROP_FACTOR
+};
+
+G_DEFINE_TYPE (ClutterDesaturateEffect,
+               clutter_desaturate_effect,
+               CLUTTER_TYPE_SHADER_EFFECT);
+
+static gboolean
+clutter_desaturate_effect_pre_paint (ClutterEffect *effect)
+{
+  ClutterDesaturateEffect *self = CLUTTER_DESATURATE_EFFECT (effect);
+  ClutterShaderEffect *shader_effect;
+  ClutterEffectClass *parent_class;
+  float factor;
+
+  if (!clutter_actor_meta_get_enabled (CLUTTER_ACTOR_META (effect)))
+    return FALSE;
+
+  self->actor = clutter_actor_meta_get_actor (CLUTTER_ACTOR_META (effect));
+  if (self->actor == NULL)
+    return FALSE;
+
+  shader_effect = CLUTTER_SHADER_EFFECT (effect);
+
+  if (!self->source_set)
+    {
+      CoglHandle shader;
+
+      /* get the CoglShader handle to set the source */
+      shader = clutter_shader_effect_get_shader (shader_effect);
+      if (shader == COGL_INVALID_HANDLE)
+        return FALSE;
+
+      cogl_shader_source (shader, desaturate_glsl_shader);
+      self->source_set = TRUE;
+    }
+
+  factor = (float) self->factor;
+
+  /* bind the uniforms to the factor property */
+  clutter_shader_effect_set_uniform (shader_effect,
+                                     "tex",
+                                     G_TYPE_INT, 1,
+                                     0);
+  clutter_shader_effect_set_uniform (shader_effect,
+                                     "factor",
+                                     G_TYPE_FLOAT, 1,
+                                     factor);
+
+  parent_class = CLUTTER_EFFECT_CLASS (clutter_desaturate_effect_parent_class);
+  return parent_class->pre_paint (effect);
+}
+
+static void
+clutter_desaturate_effect_finalize (GObject *gobject)
+{
+  G_OBJECT_CLASS (clutter_desaturate_effect_parent_class)->finalize (gobject);
+}
+
+static void
+clutter_desaturate_effect_set_property (GObject      *gobject,
+                                        guint         prop_id,
+                                        const GValue *value,
+                                        GParamSpec   *pspec)
+{
+  ClutterDesaturateEffect *effect = CLUTTER_DESATURATE_EFFECT (gobject);
+
+  switch (prop_id)
+    {
+    case PROP_FACTOR:
+      clutter_desaturate_effect_set_factor (effect,
+                                            g_value_get_double (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+clutter_desaturate_effect_get_property (GObject    *gobject,
+                                        guint       prop_id,
+                                        GValue     *value,
+                                        GParamSpec *pspec)
+{
+  ClutterDesaturateEffect *effect = CLUTTER_DESATURATE_EFFECT (gobject);
+
+  switch (prop_id)
+    {
+    case PROP_FACTOR:
+      g_value_set_double (value, effect->factor);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+clutter_desaturate_effect_class_init (ClutterDesaturateEffectClass *klass)
+{
+  ClutterEffectClass *effect_class = CLUTTER_EFFECT_CLASS (klass);
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+  GParamSpec *pspec;
+
+  effect_class->pre_paint = clutter_desaturate_effect_pre_paint;
+
+  gobject_class->set_property = clutter_desaturate_effect_set_property;
+  gobject_class->get_property = clutter_desaturate_effect_get_property;
+  gobject_class->finalize = clutter_desaturate_effect_finalize;
+
+  /**
+   * ClutterDesaturateEffect:factor:
+   *
+   * The desaturation factor, between 0.0 (no desaturation) and 1.0 (full
+   * desaturation).
+   *
+   * Since: 1.4
+   */
+  pspec = g_param_spec_double ("factor",
+                               "Factor",
+                               "The desaturation factor",
+                               0.0, 1.0,
+                               1.0,
+                               CLUTTER_PARAM_READWRITE);
+  g_object_class_install_property (gobject_class, PROP_FACTOR, pspec);
+}
+
+static void
+clutter_desaturate_effect_init (ClutterDesaturateEffect *self)
+{
+  self->factor = 1.0;
+}
+
+/**
+ * clutter_desaturate_effect_new:
+ * @factor: the desaturation factor, between 0.0 and 1.0
+ *
+ * Creates a new #ClutterDesaturateEffect to be used with
+ * clutter_actor_set_effect()
+ *
+ * Return value: the newly created #ClutterDesaturateEffect or %NULL
+ *
+ * Since: 1.4
+ */
+ClutterEffect *
+clutter_desaturate_effect_new (gdouble factor)
+{
+  g_return_val_if_fail (factor >= 0.0 && factor <= 1.0, NULL);
+
+  return g_object_new (CLUTTER_TYPE_DESATURATE_EFFECT,
+                       "factor", factor,
+                       NULL);
+}
+
+/**
+ * clutter_desaturate_effect_set_factor:
+ * @effect: a #ClutterDesaturateEffect
+ * @factor: the desaturation factor, between 0.0 and 1.0
+ *
+ * Sets the desaturation factor for @effect, with 0.0 being "do not desaturate"
+ * and 1.0 being "fully desaturate"
+ *
+ * Since: 1.4
+ */
+void
+clutter_desaturate_effect_set_factor (ClutterDesaturateEffect *effect,
+                                      gdouble                  factor)
+{
+  g_return_if_fail (CLUTTER_IS_DESATURATE_EFFECT (effect));
+  g_return_if_fail (factor >= 0.0 && factor <= 1.0);
+
+  if (fabsf (effect->factor - factor) >= 0.00001)
+    {
+      effect->factor = factor;
+
+      if (effect->actor != NULL)
+        clutter_actor_queue_redraw (effect->actor);
+
+      g_object_notify (G_OBJECT (effect), "factor");
+    }
+}
+
+/**
+ * clutter_desaturate_effect_get_factor:
+ * @effect: a #ClutterDesaturateEffect
+ *
+ * Retrieves the desaturation factor of @effect
+ *
+ * Return value: the desaturation factor
+ *
+ * Since: 1.4
+ */
+gdouble
+clutter_desaturate_effect_get_factor (ClutterDesaturateEffect *effect)
+{
+  g_return_val_if_fail (CLUTTER_IS_DESATURATE_EFFECT (effect), 0.0);
+
+  return effect->factor;
+}

clutter/clutter-desaturate-effect.h

@@ -0,0 +1,60 @@
+/*
+ * Clutter.
+ *
+ * An OpenGL based 'interactive canvas' library.
+ *
+ * Copyright (C) 2010  Intel Corporation.
+ *
+ * This library 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 2 of the License, or (at your option) any later version.
+ *
+ * This library 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 this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author:
+ *   Emmanuele Bassi <ebassi@linux.intel.com>
+ */
+
+#if !defined(__CLUTTER_H_INSIDE__) && !defined(CLUTTER_COMPILATION)
+#error "Only <clutter/clutter.h> can be included directly."
+#endif
+
+#ifndef __CLUTTER_DESATURATE_EFFECT_H__
+#define __CLUTTER_DESATURATE_EFFECT_H__
+
+#include <clutter/clutter-effect.h>
+
+G_BEGIN_DECLS
+
+#define CLUTTER_TYPE_DESATURATE_EFFECT          (clutter_desaturate_effect_get_type ())
+#define CLUTTER_DESATURATE_EFFECT(obj)          (G_TYPE_CHECK_INSTANCE_CAST ((obj), CLUTTER_TYPE_DESATURATE_EFFECT, ClutterDesaturateEffect))
+#define CLUTTER_IS_DESATURATE_EFFECT(obj)       (G_TYPE_CHECK_INSTANCE_TYPE ((obj), CLUTTER_TYPE_DESATURATE_EFFECT))
+
+/**
+ * ClutterDesaturateEffect:
+ *
+ * <structname>ClutterDesaturateEffect</structname> is an opaque structure
+ * whose members cannot be directly accessed
+ *
+ * Since: 1.4
+ */
+typedef struct _ClutterDesaturateEffect         ClutterDesaturateEffect;
+
+GType clutter_desaturate_effect_get_type (void) G_GNUC_CONST;
+
+ClutterEffect *clutter_desaturate_effect_new        (gdouble                  factor);
+
+void           clutter_desaturate_effect_set_factor (ClutterDesaturateEffect *effect,
+                                                     gdouble                  factor);
+gdouble        clutter_desaturate_effect_get_factor (ClutterDesaturateEffect *effect);
+
+G_END_DECLS
+
+#endif /* __CLUTTER_DESATURATE_EFFECT_H__ */

clutter/clutter.h

@@ -59,6 +59,7 @@
 #include "clutter-color.h"
 #include "clutter-constraint.h"
 #include "clutter-container.h"
+#include "clutter-desaturate-effect.h"
 #include "clutter-device-manager.h"
 #include "clutter-drag-action.h"
 #include "clutter-effect.h"

tests/interactive/test-rotate.c

@@ -35,7 +35,7 @@ test_rotate_main (int argc, char *argv[])
 
   clutter_actor_set_position (hand, 240, 140);
   clutter_actor_show (hand);
-  clutter_container_add_actor (CLUTTER_CONTAINER (stage), hand);
+  clutter_actor_add_effect (hand, clutter_desaturate_effect_new (0.75));
 
   label = clutter_text_new_with_text ("Mono 16",
                                       "The Wonder\n"