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

js/ui/magnifier.js

@@ -25,6 +25,7 @@ const SHOW_KEY                  = 'screen-magnifier-enabled';
 const MAGNIFIER_SCHEMA          = 'org.gnome.desktop.a11y.magnifier';
 const SCREEN_POSITION_KEY       = 'screen-position';
 const MAG_FACTOR_KEY            = 'mag-factor';
+const INVERT_LIGHTNESS_KEY      = 'invert-lightness';
 const BRIGHT_RED_KEY            = 'brightness-red';
 const BRIGHT_GREEN_KEY          = 'brightness-green';
 const BRIGHT_BLUE_KEY           = 'brightness-blue';
@@ -451,6 +452,10 @@ const Magnifier = new Lang.Class({
             if (aPref)
                 zoomRegion.setMouseTrackingMode(aPref);
 
+            aPref = this._settings.get_boolean(INVERT_LIGHTNESS_KEY);
+            if (aPref)
+                zoomRegion.setInvertLightness(aPref);
+
             let bc = {};
             bc.r = this._settings.get_double(BRIGHT_RED_KEY);
             bc.g = this._settings.get_double(BRIGHT_GREEN_KEY);
@@ -483,6 +488,9 @@ const Magnifier = new Lang.Class({
         this._settings.connect('changed::' + MOUSE_TRACKING_KEY,
                                Lang.bind(this, this._updateMouseTrackingMode));
 
+        this._settings.connect('changed::' + INVERT_LIGHTNESS_KEY,
+                               Lang.bind(this, this._updateInvertLightness));
+
         this._settings.connect('changed::' + BRIGHT_RED_KEY,
                                Lang.bind(this, this._updateBrightness));
         this._settings.connect('changed::' + BRIGHT_GREEN_KEY,
@@ -574,6 +582,15 @@ const Magnifier = new Lang.Class({
         }
     },
 
+    _updateInvertLightness: function() {
+        // Applies only to the first zoom region.
+        if (this._zoomRegions.length) {
+            this._zoomRegions[0].setInvertLightness(
+                this._settings.get_boolean(INVERT_LIGHTNESS_KEY)
+            );
+        }
+    },
+
     _updateBrightness: function() {
         // Applies only to the first zoom region.
         if (this._zoomRegions.length) {
@@ -608,6 +625,7 @@ const ZoomRegion = new Lang.Class({
         this._clampScrollingAtEdges = false;
         this._lensMode = false;
         this._screenPosition = GDesktopEnums.MagnifierScreenPosition.FULL_SCREEN;
+        this._invertLightness = false;
         this._brightness = { r: NO_CHANGE, g: NO_CHANGE, b: NO_CHANGE };
         this._contrast = { r: NO_CHANGE, g: NO_CHANGE, b: NO_CHANGE };
 
@@ -935,6 +953,26 @@ const ZoomRegion = new Lang.Class({
         }
     },
 
+    /**
+     * setInvertLightness:
+     * Set whether to invert the lightness of the magnified view.
+     * @flag    Boolean to either invert brightness (true), or not (false).
+     */
+    setInvertLightness: function(flag) {
+        this._invertLightness = flag;
+        if (this._magShaderEffects)
+            this._magShaderEffects.setInvertLightness(this._invertLightness);
+    },
+
+    /**
+     * getInvertLightness:
+     * Retrieve whether the lightness is inverted.
+     * @return    Boolean indicating inversion (true), or not (false).
+     */
+    getInvertLightness: function() {
+        return this._invertLightness;
+    },
+
     /**
      * setBrightness:
      * Alter the brightness of the magnified view.
@@ -1036,6 +1074,7 @@ const ZoomRegion = new Lang.Class({
 
         // Contrast and brightness effects.
         this._magShaderEffects = new MagShaderEffects(this._uiGroupClone);
+        this._magShaderEffects.setInvertLightness(this._invertLightness);
         this._magShaderEffects.setBrightness(this._brightness);
         this._magShaderEffects.setContrast(this._contrast);
     },
@@ -1561,10 +1600,13 @@ const MagShaderEffects = new Lang.Class({
     Name: 'MagShaderEffects',
 
     _init: function(uiGroupClone) {
+        this._inverse = new Shell.InvertLightnessEffect();
         this._brightnessContrast = new Clutter.BrightnessContrastEffect();
+        this._inverse.set_enabled(false);
         this._brightnessContrast.set_enabled(false);
 
         this._magView = uiGroupClone;
+        this._magView.add_effect(this._inverse);
         this._magView.add_effect(this._brightnessContrast);
     },
 
@@ -1577,9 +1619,28 @@ const MagShaderEffects = new Lang.Class({
     destroyEffects: function() {
         this._magView.clear_effects();
         this._brightnessContrast = null;
+        this._inverse = null;
         this._magView = null;
     },
 
+    /**
+     * setInvertLightness:
+     * Enable/disable invert lightness effect.
+     * @invertFlag:     Enabled flag.
+     */
+    setInvertLightness: function(invertFlag) {
+        this._inverse.set_enabled(invertFlag);
+    },
+
+    /**
+     * getInvertLightness:
+     * Report whether the inversion effect is enabled.
+     * @return:     Boolean.
+     */
+    getInvertLightness: function() {
+        return this._inverse.get_enabled();
+    },
+
     /**
      * setBrightness:
      * Set the brightness of the magnified view.

src/Makefile.am

@@ -114,6 +114,7 @@ shell_public_headers_h =		\
 	shell-gtk-embed.h		\
 	shell-global.h			\
 	shell-idle-monitor.h		\
+	shell-invert-lightness-effect.h	\
 	shell-mobile-providers.h	\
 	shell-mount-operation.h		\
 	shell-network-agent.h		\
@@ -161,6 +162,7 @@ libgnome_shell_la_SOURCES =		\
 	shell-gtk-embed.c		\
 	shell-global.c			\
 	shell-idle-monitor.c		\
+	shell-invert-lightness-effect.c	\
 	shell-keyring-prompt.h		\
 	shell-keyring-prompt.c		\
 	shell-mobile-providers.c	\

src/shell-invert-lightness-effect.c

@@ -0,0 +1,214 @@
+/* -*- 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);
+}

src/shell-invert-lightness-effect.h

@@ -0,0 +1,42 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+/*
+ * Copyright © 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>
+ */
+#ifndef __SHELL_INVERT_LIGHTNESS_EFFECT_H__
+#define __SHELL_INVERT_LIGHTNESS_EFFECT_H__
+
+#define COGL_ENABLE_EXPERIMENTAL_API
+#include <clutter/clutter.h>
+
+G_BEGIN_DECLS
+
+#define SHELL_TYPE_INVERT_LIGHTNESS_EFFECT        (shell_invert_lightness_effect_get_type ())
+#define SHELL_INVERT_LIGHTNESS_EFFECT(obj)        (G_TYPE_CHECK_INSTANCE_CAST ((obj), SHELL_TYPE_INVERT_LIGHTNESS_EFFECT, ShellInvertLightnessEffect))
+#define SHELL_IS_INVERT_LIGHTNESS_EFFECT(obj)     (G_TYPE_CHECK_INSTANCE_TYPE ((obj), SHELL_TYPE_INVERT_LIGHTNESS_EFFECT))
+
+typedef struct _ShellInvertLightnessEffect        ShellInvertLightnessEffect;
+typedef struct _ShellInvertLightnessEffectClass   ShellInvertLightnessEffectClass;
+
+GType shell_invert_lightness_effect_get_type (void) G_GNUC_CONST;
+
+ClutterEffect *shell_invert_lightness_effect_new (void);
+
+G_END_DECLS
+
+#endif /* __SHELL_INVERT_LIGHTNESS_EFFECT_H__ */