gnome-shell/src/shell-invert-lightness-effect.c
Joseph Scheuhammer 61a17d7fab Magnifier: Add brightness and contrast functionality
Added clutter effects class that does lightness inversion.
Modified the magnifier to use this inversion effect.

https://bugzilla.gnome.org/show_bug.cgi?id=639851
2012-05-16 18:59:33 -04:00

215 lines
7.0 KiB
C

/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/*
* Copyright (C) 2010-2012 Inclusive Design Research Centre, OCAD University.
*
* This program 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:
* Joseph Scheuhammer <clown@alum.mit.edu>
*/
/**
* SECTION:shell-invert-lightness-effect
* @short_description: A colorization effect where lightness is inverted but
* color is not.
* @see_also: #ClutterEffect, #ClutterOffscreenEffect
*
* #ShellInvertLightnessEffect is a sub-class of #ClutterEffect that enhances
* the appearance of a clutter actor. Specifically it inverts the lightness
* of a #ClutterActor (e.g., darker colors become lighter, white becomes black,
* and white, black).
*/
#define SHELL_INVERT_LIGHTNESS_EFFECT_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST ((klass), SHELL_TYPE_INVERT_LIGHTNESS_EFFECT, ShellInvertLightnessEffectClass))
#define SHELL_IS_INVERT_EFFECT_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), SHELL_TYPE_INVERT_LIGHTNESS_EFFECT))
#define SHELL_INVERT_LIGHTNESS_EFFECT_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS ((obj), SHELL_TYPE_INVERT_LIGHTNESS_EFFEC, ShellInvertLightnessEffectClass))
#define CLUTTER_ENABLE_EXPERIMENTAL_API
#include "shell-invert-lightness-effect.h"
#include <cogl/cogl.h>
struct _ShellInvertLightnessEffect
{
ClutterOffscreenEffect parent_instance;
gint tex_width;
gint tex_height;
CoglPipeline *pipeline;
};
struct _ShellInvertLightnessEffectClass
{
ClutterOffscreenEffectClass parent_class;
CoglPipeline *base_pipeline;
};
/* Lightness inversion in GLSL.
*/
static const gchar *invert_lightness_source =
"cogl_texel = texture2D (cogl_sampler, cogl_tex_coord.st);\n"
"vec3 effect = vec3 (cogl_texel);\n"
"\n"
"float maxColor = max (cogl_texel.r, max (cogl_texel.g, cogl_texel.b));\n"
"float minColor = min (cogl_texel.r, min (cogl_texel.g, cogl_texel.b));\n"
"float lightness = (maxColor + minColor) / 2.0;\n"
"\n"
"float delta = (1.0 - lightness) - lightness;\n"
"effect.rgb = (effect.rgb + delta);\n"
"\n"
"cogl_texel = vec4 (effect, cogl_texel.a);\n";
G_DEFINE_TYPE (ShellInvertLightnessEffect,
shell_invert_lightness_effect,
CLUTTER_TYPE_OFFSCREEN_EFFECT);
static gboolean
shell_invert_lightness_effect_pre_paint (ClutterEffect *effect)
{
ShellInvertLightnessEffect *self = SHELL_INVERT_LIGHTNESS_EFFECT (effect);
ClutterEffectClass *parent_class;
if (!clutter_actor_meta_get_enabled (CLUTTER_ACTOR_META (effect)))
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 ShellInvertLightnessEffect: 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 (self), FALSE);
return FALSE;
}
parent_class =
CLUTTER_EFFECT_CLASS (shell_invert_lightness_effect_parent_class);
if (parent_class->pre_paint (effect))
{
ClutterOffscreenEffect *offscreen_effect =
CLUTTER_OFFSCREEN_EFFECT (effect);
CoglHandle texture;
texture = clutter_offscreen_effect_get_texture (offscreen_effect);
self->tex_width = cogl_texture_get_width (texture);
self->tex_height = cogl_texture_get_height (texture);
cogl_pipeline_set_layer_texture (self->pipeline, 0, texture);
return TRUE;
}
else
return FALSE;
}
static void
shell_invert_lightness_effect_paint_target (ClutterOffscreenEffect *effect)
{
ShellInvertLightnessEffect *self = SHELL_INVERT_LIGHTNESS_EFFECT (effect);
ClutterActor *actor;
guint8 paint_opacity;
actor = clutter_actor_meta_get_actor (CLUTTER_ACTOR_META (effect));
paint_opacity = clutter_actor_get_paint_opacity (actor);
cogl_pipeline_set_color4ub (self->pipeline,
paint_opacity,
paint_opacity,
paint_opacity,
paint_opacity);
cogl_push_source (self->pipeline);
cogl_rectangle (0, 0, self->tex_width, self->tex_height);
cogl_pop_source ();
}
static void
shell_invert_lightness_effect_dispose (GObject *gobject)
{
ShellInvertLightnessEffect *self = SHELL_INVERT_LIGHTNESS_EFFECT (gobject);
if (self->pipeline != NULL)
{
cogl_object_unref (self->pipeline);
self->pipeline = NULL;
}
G_OBJECT_CLASS (shell_invert_lightness_effect_parent_class)->dispose (gobject);
}
static void
shell_invert_lightness_effect_class_init (ShellInvertLightnessEffectClass *klass)
{
ClutterEffectClass *effect_class = CLUTTER_EFFECT_CLASS (klass);
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
ClutterOffscreenEffectClass *offscreen_class;
offscreen_class = CLUTTER_OFFSCREEN_EFFECT_CLASS (klass);
offscreen_class->paint_target = shell_invert_lightness_effect_paint_target;
effect_class->pre_paint = shell_invert_lightness_effect_pre_paint;
gobject_class->dispose = shell_invert_lightness_effect_dispose;
}
static void
shell_invert_lightness_effect_init (ShellInvertLightnessEffect *self)
{
ShellInvertLightnessEffectClass *klass;
klass = SHELL_INVERT_LIGHTNESS_EFFECT_GET_CLASS (self);
if (G_UNLIKELY (klass->base_pipeline == NULL))
{
CoglSnippet *snippet;
CoglContext *ctx =
clutter_backend_get_cogl_context (clutter_get_default_backend ());
klass->base_pipeline = cogl_pipeline_new (ctx);
snippet = cogl_snippet_new (COGL_SNIPPET_HOOK_TEXTURE_LOOKUP,
NULL,
NULL);
cogl_snippet_set_replace (snippet, invert_lightness_source);
cogl_pipeline_add_layer_snippet (klass->base_pipeline, 0, snippet);
cogl_object_unref (snippet);
cogl_pipeline_set_layer_null_texture (klass->base_pipeline,
0, /* layer number */
COGL_TEXTURE_TYPE_2D);
}
self->pipeline = cogl_pipeline_copy (klass->base_pipeline);
}
/**
* shell_invert_lightness_effect_new:
*
* Creates a new #ShellInvertLightnessEffect to be used with
* clutter_actor_add_effect()
*
* Return value: (transfer full): the newly created
* #ShellInvertLightnessEffect or %NULL. Use g_object_unref() when done.
*/
ClutterEffect *
shell_invert_lightness_effect_new (void)
{
return g_object_new (SHELL_TYPE_INVERT_LIGHTNESS_EFFECT, NULL);
}