/*
 * 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-colorize-effect
 * @short_description: A colorization effect
 * @see_also: #ClutterEffect, #ClutterOffscreenEffect
 *
 * #ClutterColorizeEffect is a sub-class of #ClutterEffect that
 * colorizes an actor with the given tint.
 *
 * #ClutterColorizeEffect is available since Clutter 1.4
 */

#define CLUTTER_COLORIZE_EFFECT_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), CLUTTER_TYPE_COLORIZE_EFFECT, ClutterColorizeEffectClass))
#define CLUTTER_IS_COLORIZE_EFFECT_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), CLUTTER_TYPE_COLORIZE_EFFECT))
#define CLUTTER_COLORIZE_EFFECT_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), CLUTTER_TYPE_COLORIZE_EFFECT, ClutterColorizeEffectClass))

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "clutter-colorize-effect.h"

#include "cogl/cogl.h"

#include "clutter-debug.h"
#include "clutter-enum-types.h"
#include "clutter-offscreen-effect.h"
#include "clutter-private.h"

typedef struct _ClutterColorizeEffectClass    ClutterColorizeEffectClass;

struct _ClutterColorizeEffect
{
  ClutterOffscreenEffect parent_instance;

  /* a back pointer to our actor, so that we can query it */
  ClutterActor *actor;

  /* the tint of the colorization */
  ClutterColor tint;

  CoglHandle shader;
  CoglHandle program;

  gint tex_uniform;
  gint tint_uniform;

  guint is_compiled : 1;
};

struct _ClutterColorizeEffectClass
{
  ClutterOffscreenEffectClass 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 *colorize_glsl_shader =
"uniform sampler2D tex;\n"
"uniform vec3 tint;\n"
"\n"
"void main ()\n"
"{\n"
"  vec4 color = gl_Color * texture2D (tex, vec2 (gl_TexCoord[0].xy));\n"
"  float gray = dot (color.rgb, vec3 (0.299, 0.587, 0.114));\n"
"  gl_FragColor = vec4 (gray * tint, color.a);\n"
"}\n";

/* a lame sepia */
static const ClutterColor default_tint = { 255, 204, 153, 255 };

enum
{
  PROP_0,

  PROP_TINT,

  PROP_LAST
};

static GParamSpec *obj_props[PROP_LAST];

G_DEFINE_TYPE (ClutterColorizeEffect,
               clutter_colorize_effect,
               CLUTTER_TYPE_OFFSCREEN_EFFECT);

static gboolean
clutter_colorize_effect_pre_paint (ClutterEffect *effect)
{
  ClutterColorizeEffect *self = CLUTTER_COLORIZE_EFFECT (effect);
  ClutterEffectClass *parent_class;

  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;

  if (!clutter_feature_available (CLUTTER_FEATURE_SHADERS_GLSL))
    {
      /* if we don't have support for GLSL shaders then we
       * forcibly disable the ActorMeta
       */
      g_warning ("Unable to use the ShaderEffect: the graphics hardware "
                 "or the current GL driver does not implement support "
                 "for the GLSL shading language.");
      clutter_actor_meta_set_enabled (CLUTTER_ACTOR_META (effect), FALSE);
      return FALSE;
    }

  if (self->shader == COGL_INVALID_HANDLE)
    {
      self->shader = cogl_create_shader (COGL_SHADER_TYPE_FRAGMENT);
      cogl_shader_source (self->shader, colorize_glsl_shader);

      self->is_compiled = FALSE;
      self->tex_uniform = -1;
      self->tint_uniform = -1;
    }

  if (self->program == COGL_INVALID_HANDLE)
    self->program = cogl_create_program ();

  if (!self->is_compiled)
    {
      g_assert (self->shader != COGL_INVALID_HANDLE);
      g_assert (self->program != COGL_INVALID_HANDLE);

      cogl_shader_compile (self->shader);
      if (!cogl_shader_is_compiled (self->shader))
        {
          gchar *log_buf = cogl_shader_get_info_log (self->shader);

          g_warning (G_STRLOC ": Unable to compile the colorize shader: %s",
                     log_buf);
          g_free (log_buf);

          cogl_handle_unref (self->shader);
          cogl_handle_unref (self->program);

          self->shader = COGL_INVALID_HANDLE;
          self->program = COGL_INVALID_HANDLE;
        }
      else
        {
          cogl_program_attach_shader (self->program, self->shader);
          cogl_program_link (self->program);

          cogl_handle_unref (self->shader);

          self->is_compiled = TRUE;

          self->tex_uniform =
            cogl_program_get_uniform_location (self->program, "tex");
          self->tint_uniform =
            cogl_program_get_uniform_location (self->program, "tint");
        }
    }

  parent_class = CLUTTER_EFFECT_CLASS (clutter_colorize_effect_parent_class);
  return parent_class->pre_paint (effect);
}

static void
clutter_colorize_effect_paint_target (ClutterOffscreenEffect *effect)
{
  ClutterColorizeEffect *self = CLUTTER_COLORIZE_EFFECT (effect);
  ClutterOffscreenEffectClass *parent;
  CoglHandle material;

  if (self->program == COGL_INVALID_HANDLE)
    goto out;

  if (self->tex_uniform > -1)
    cogl_program_set_uniform_1i (self->program, self->tex_uniform, 0);

  if (self->tint_uniform > -1)
    {
      float tint[3] = {
        self->tint.red / 255.0,
        self->tint.green / 255.0,
        self->tint.blue / 255.0
      };

      cogl_program_set_uniform_float (self->program, self->tint_uniform,
                                      3, 1,
                                      tint);
    }

  material = clutter_offscreen_effect_get_target (effect);
  cogl_material_set_user_program (material, self->program);

out:
  parent = CLUTTER_OFFSCREEN_EFFECT_CLASS (clutter_colorize_effect_parent_class);
  parent->paint_target (effect);
}

static void
clutter_colorize_effect_dispose (GObject *gobject)
{
  ClutterColorizeEffect *self = CLUTTER_COLORIZE_EFFECT (gobject);

  if (self->program != COGL_INVALID_HANDLE)
    {
      cogl_handle_unref (self->program);

      self->program = COGL_INVALID_HANDLE;
      self->shader = COGL_INVALID_HANDLE;
    }

  G_OBJECT_CLASS (clutter_colorize_effect_parent_class)->dispose (gobject);
}

static void
clutter_colorize_effect_set_property (GObject      *gobject,
                                      guint         prop_id,
                                      const GValue *value,
                                      GParamSpec   *pspec)
{
  ClutterColorizeEffect *effect = CLUTTER_COLORIZE_EFFECT (gobject);

  switch (prop_id)
    {
    case PROP_TINT:
      clutter_colorize_effect_set_tint (effect,
                                        clutter_value_get_color (value));
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
      break;
    }
}

static void
clutter_colorize_effect_get_property (GObject    *gobject,
                                      guint       prop_id,
                                      GValue     *value,
                                      GParamSpec *pspec)
{
  ClutterColorizeEffect *effect = CLUTTER_COLORIZE_EFFECT (gobject);

  switch (prop_id)
    {
    case PROP_TINT:
      clutter_value_set_color (value, &effect->tint);
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
      break;
    }
}

static void
clutter_colorize_effect_class_init (ClutterColorizeEffectClass *klass)
{
  ClutterEffectClass *effect_class = CLUTTER_EFFECT_CLASS (klass);
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
  ClutterOffscreenEffectClass *offscreen_class;
  GParamSpec *pspec;

  offscreen_class = CLUTTER_OFFSCREEN_EFFECT_CLASS (klass);
  offscreen_class->paint_target = clutter_colorize_effect_paint_target;

  effect_class->pre_paint = clutter_colorize_effect_pre_paint;

  gobject_class->set_property = clutter_colorize_effect_set_property;
  gobject_class->get_property = clutter_colorize_effect_get_property;
  gobject_class->dispose = clutter_colorize_effect_dispose;

  /**
   * ClutterColorizeEffect:tint:
   *
   * The tint to apply to the actor
   *
   * Since: 1.4
   */
  pspec = clutter_param_spec_color ("tint",
                                    P_("Tint"),
                                    P_("The tint to apply"),
                                    &default_tint,
                                    CLUTTER_PARAM_READWRITE);
  obj_props[PROP_TINT] = pspec;
  g_object_class_install_property (gobject_class, PROP_TINT, pspec);
}

static void
clutter_colorize_effect_init (ClutterColorizeEffect *self)
{
  self->tint = default_tint;
}

/**
 * clutter_colorize_effect_new:
 * @tint: the color to be used
 *
 * Creates a new #ClutterColorizeEffect to be used with
 * clutter_actor_add_effect()
 *
 * Return value: the newly created #ClutterColorizeEffect or %NULL
 *
 * Since: 1.4
 */
ClutterEffect *
clutter_colorize_effect_new (const ClutterColor *tint)
{
  return g_object_new (CLUTTER_TYPE_COLORIZE_EFFECT,
                       "tint", tint,
                       NULL);
}

/**
 * clutter_colorize_effect_set_tint:
 * @effect: a #ClutterColorizeEffect
 * @tint: the color to be used
 *
 * Sets the tint to be used when colorizing
 *
 * Since: 1.4
 */
void
clutter_colorize_effect_set_tint (ClutterColorizeEffect *effect,
                                  const ClutterColor    *tint)
{
  g_return_if_fail (CLUTTER_IS_COLORIZE_EFFECT (effect));

  effect->tint = *tint;

  if (effect->actor != NULL)
    clutter_actor_queue_redraw (effect->actor);

  _clutter_notify_by_pspec (G_OBJECT (effect), obj_props[PROP_TINT]);
}

/**
 * clutter_colorize_effect_get_tint:
 * @effect: a #ClutterColorizeEffect
 * @tint: (out): return location for the color used
 *
 * Retrieves the tint used by @effect
 *
 * Since: 1.4
 */
void
clutter_colorize_effect_get_tint (ClutterColorizeEffect *effect,
                                  ClutterColor          *tint)
{
  g_return_if_fail (CLUTTER_IS_COLORIZE_EFFECT (effect));
  g_return_if_fail (tint != NULL);

  *tint = effect->tint;
}