Add support for adjusting wallpaper brightness

2000-12-17  Bradford Hovinen  <hovinen@helixcode.com>

	* capplets/new-background-properties/applier.c
	(renderer_render_wallpaper): Add support for adjusting wallpaper
	brightness

	* capplets/new-background-properties/main.c (ok_cb):
	(cancel_cb): Disconnect ok, cancel handler signals before
	destroying preferences widget
	(setup_capplet_widget): Set signal handler ids for ok, cancel
	signals

	* capplets/new-background-properties/prefs-widget.c
	(prefs_widget_init): Connect signals for adjusting brightness
	(adjust_brightness_toggled_cb):
	(brightness_adjust_changed_cb):
	(set_brightness_controls_sensitive): Implement

	* capplets/new-background-properties/preferences.h (struct
	_Preferences): Add adjust_brightness, brightness_value

	* capplets/new-background-properties/preferences.c (preferences_load):
	(preferences_save):
	(preferences_read_xml):
	(preferences_write_xml): Support adjust_brightness, brightness_value

	* capplets/new-background-properties/prefs-widget.c
	(wallpaper_entry_changed_cb): Don't fail if prefs is NULL, just
	return

	* capplets/new-background-properties/main.c (ok_cb):
	(cancel_cb): Properly destroy the preferences widget

	* capplets/new-background-properties/prefs-widget.c
	(prefs_widget_destroy): Implement

ChangeLog

@@ -1,5 +1,39 @@
 2000-12-17  Bradford Hovinen  <hovinen@helixcode.com>
 
+	* capplets/new-background-properties/applier.c
+	(renderer_render_wallpaper): Add support for adjusting wallpaper
+	brightness
+
+	* capplets/new-background-properties/main.c (ok_cb):
+	(cancel_cb): Disconnect ok, cancel handler signals before
+	destroying preferences widget
+	(setup_capplet_widget): Set signal handler ids for ok, cancel
+	signals
+
+	* capplets/new-background-properties/prefs-widget.c
+	(prefs_widget_init): Connect signals for adjusting brightness
+	(adjust_brightness_toggled_cb): 
+	(brightness_adjust_changed_cb):
+	(set_brightness_controls_sensitive): Implement
+
+	* capplets/new-background-properties/preferences.h (struct
+	_Preferences): Add adjust_brightness, brightness_value
+
+	* capplets/new-background-properties/preferences.c (preferences_load): 
+	(preferences_save): 
+	(preferences_read_xml): 
+	(preferences_write_xml): Support adjust_brightness, brightness_value
+
+	* capplets/new-background-properties/prefs-widget.c
+	(wallpaper_entry_changed_cb): Don't fail if prefs is NULL, just
+	return
+
+	* capplets/new-background-properties/main.c (ok_cb): 
+	(cancel_cb): Properly destroy the preferences widget
+
+	* capplets/new-background-properties/prefs-widget.c
+	(prefs_widget_destroy): Implement
+
 	* capplets/new-background-properties/preferences.c
 	(preferences_changed): Increased delay before autoapply
 	(preferences_load):

capplets/background/applier.c

@@ -537,6 +537,8 @@ run_render_pipeline (Renderer *renderer,
 	    old_prefs->orientation != new_prefs->orientation ||
 	    !gdk_color_equal (old_prefs->color1, new_prefs->color1) ||
 	    !gdk_color_equal (old_prefs->color2, new_prefs->color2) ||
+	    old_prefs->adjust_brightness != new_prefs->adjust_brightness ||
+	    old_prefs->brightness_value != new_prefs->brightness_value ||
 	    ((wallpaper_pixbuf != NULL ||
 	      old_prefs->wallpaper_type != new_prefs->wallpaper_type) &&
 	     render_gradient_p (renderer, new_prefs)))
@@ -703,6 +705,7 @@ static void
 renderer_render_wallpaper (Renderer *renderer) 
 {
 	gint root_width, root_height;
+	gdouble scalex, scaley;
 
 	g_return_if_fail (renderer != NULL);
 	g_return_if_fail (!render_gradient_p (renderer, renderer->prefs) ||
@@ -722,12 +725,49 @@ renderer_render_wallpaper (Renderer *renderer)
 			      &renderer->wwidth, &renderer->wheight,
 			      &renderer->srcx, &renderer->srcy);
 
-		if (renderer->wwidth != renderer->pwidth ||
+		if (renderer->prefs->adjust_brightness) {
-		    renderer->wheight != renderer->pheight) 
+			guint alpha_value;
+			guint32 color;
+
+			alpha_value = ABS (renderer->prefs->brightness_value);
+			alpha_value = 256 - alpha_value * alpha_value / 256;
+			alpha_value = CLAMP (alpha_value, 0, 255);
+			color = (renderer->prefs->brightness_value < 0) ?
+				0 : (guint32) -1;
+
+			if (render_gradient_p (renderer, renderer->prefs)) {
+				scalex = (gdouble) renderer->wwidth / 
+					(gdouble) renderer->pwidth;
+				scaley = (gdouble) renderer->wheight / 
+					(gdouble) renderer->pheight;
+
+				gdk_pixbuf_composite_color
+					(renderer->wallpaper_pixbuf,
+					 renderer->pixbuf,
+					 renderer->wx, renderer->wy,
+					 renderer->wwidth, renderer->wheight,
+					 renderer->wx, renderer->wy,
+					 scalex, scaley,
+					 GDK_INTERP_BILINEAR,
+					 alpha_value, 0, 0, 65536,
+					 color, color);
+			} else {
+				if (renderer->pixbuf != NULL)
+					gdk_pixbuf_unref (renderer->pixbuf);
+
+				renderer->pixbuf =
+					gdk_pixbuf_composite_color_simple 
+					(renderer->wallpaper_pixbuf,
+					 renderer->wwidth, renderer->wheight,
+					 GDK_INTERP_BILINEAR,
+					 alpha_value, 65536,
+					 color, color);
+			}
+		}
+		else if (renderer->wwidth != renderer->pwidth ||
+			 renderer->wheight != renderer->pheight) 
 		{
 			if (render_gradient_p (renderer, renderer->prefs)) {
-				gdouble scalex, scaley;
-
 				scalex = (gdouble) renderer->wwidth / 
 					(gdouble) renderer->pwidth;
 				scaley = (gdouble) renderer->wheight / 
@@ -737,7 +777,8 @@ renderer_render_wallpaper (Renderer *renderer)
 					(renderer->wallpaper_pixbuf,
 					 renderer->pixbuf,
 					 renderer->wx, renderer->wy,
-					 renderer->wwidth, renderer->wheight,
+					 renderer->wwidth, 
+					 renderer->wheight,
 					 renderer->wx, renderer->wy,
 					 scalex, scaley,
 					 GDK_INTERP_BILINEAR);
@@ -748,7 +789,8 @@ renderer_render_wallpaper (Renderer *renderer)
 				renderer->pixbuf =
 					gdk_pixbuf_scale_simple
 					(renderer->wallpaper_pixbuf,
-					 renderer->wwidth, renderer->wheight,
+					 renderer->wwidth,
+					 renderer->wheight,
 					 GDK_INTERP_BILINEAR);
 			}
 		} else {

capplets/background/background-properties.glade

@@ -29,7 +29,7 @@
     <class>GtkTable</class>
     <name>prefs_widget</name>
     <border_width>5</border_width>
-    <rows>4</rows>
+    <rows>5</rows>
     <columns>2</columns>
     <homogeneous>False</homogeneous>
     <row_spacing>5</row_spacing>
@@ -361,6 +361,7 @@
 	<widget>
 	  <class>GnomeFileEntry</class>
 	  <name>wallpaper_entry</name>
+	  <history_id>gnomecc_background_wallpaper_filename</history_id>
 	  <max_saved>10</max_saved>
 	  <directory>False</directory>
 	  <modal>False</modal>
@@ -549,6 +550,140 @@
 	<yfill>False</yfill>
       </child>
     </widget>
+
+    <widget>
+      <class>GtkTable</class>
+      <name>table3</name>
+      <rows>2</rows>
+      <columns>3</columns>
+      <homogeneous>False</homogeneous>
+      <row_spacing>5</row_spacing>
+      <column_spacing>5</column_spacing>
+      <child>
+	<left_attach>0</left_attach>
+	<right_attach>2</right_attach>
+	<top_attach>4</top_attach>
+	<bottom_attach>5</bottom_attach>
+	<xpad>0</xpad>
+	<ypad>0</ypad>
+	<xexpand>False</xexpand>
+	<yexpand>True</yexpand>
+	<xshrink>False</xshrink>
+	<yshrink>False</yshrink>
+	<xfill>True</xfill>
+	<yfill>True</yfill>
+      </child>
+
+      <widget>
+	<class>GtkCheckButton</class>
+	<name>adjust_brightness_toggle</name>
+	<can_focus>True</can_focus>
+	<signal>
+	  <name>toggled</name>
+	  <handler>adjust_brightness_toggled_cb</handler>
+	  <last_modification_time>Sun, 17 Dec 2000 23:15:19 GMT</last_modification_time>
+	</signal>
+	<label>Adjust background's brightness</label>
+	<active>False</active>
+	<draw_indicator>True</draw_indicator>
+	<child>
+	  <left_attach>0</left_attach>
+	  <right_attach>3</right_attach>
+	  <top_attach>0</top_attach>
+	  <bottom_attach>1</bottom_attach>
+	  <xpad>0</xpad>
+	  <ypad>0</ypad>
+	  <xexpand>True</xexpand>
+	  <yexpand>False</yexpand>
+	  <xshrink>False</xshrink>
+	  <yshrink>False</yshrink>
+	  <xfill>True</xfill>
+	  <yfill>False</yfill>
+	</child>
+      </widget>
+
+      <widget>
+	<class>GtkLabel</class>
+	<name>brightness_low_label</name>
+	<label>Dimmer</label>
+	<justify>GTK_JUSTIFY_RIGHT</justify>
+	<wrap>False</wrap>
+	<xalign>1</xalign>
+	<yalign>0.5</yalign>
+	<xpad>0</xpad>
+	<ypad>0</ypad>
+	<child>
+	  <left_attach>0</left_attach>
+	  <right_attach>1</right_attach>
+	  <top_attach>1</top_attach>
+	  <bottom_attach>2</bottom_attach>
+	  <xpad>0</xpad>
+	  <ypad>0</ypad>
+	  <xexpand>False</xexpand>
+	  <yexpand>False</yexpand>
+	  <xshrink>False</xshrink>
+	  <yshrink>False</yshrink>
+	  <xfill>True</xfill>
+	  <yfill>False</yfill>
+	</child>
+      </widget>
+
+      <widget>
+	<class>GtkLabel</class>
+	<name>brightness_high_label</name>
+	<label>Brighter</label>
+	<justify>GTK_JUSTIFY_LEFT</justify>
+	<wrap>False</wrap>
+	<xalign>0</xalign>
+	<yalign>0.5</yalign>
+	<xpad>0</xpad>
+	<ypad>0</ypad>
+	<child>
+	  <left_attach>2</left_attach>
+	  <right_attach>3</right_attach>
+	  <top_attach>1</top_attach>
+	  <bottom_attach>2</bottom_attach>
+	  <xpad>0</xpad>
+	  <ypad>0</ypad>
+	  <xexpand>False</xexpand>
+	  <yexpand>False</yexpand>
+	  <xshrink>False</xshrink>
+	  <yshrink>False</yshrink>
+	  <xfill>True</xfill>
+	  <yfill>False</yfill>
+	</child>
+      </widget>
+
+      <widget>
+	<class>GtkHScale</class>
+	<name>brightness_adjust</name>
+	<can_focus>True</can_focus>
+	<draw_value>False</draw_value>
+	<value_pos>GTK_POS_TOP</value_pos>
+	<digits>1</digits>
+	<policy>GTK_UPDATE_CONTINUOUS</policy>
+	<value>0</value>
+	<lower>-255</lower>
+	<upper>255</upper>
+	<step>0</step>
+	<page>0</page>
+	<page_size>0</page_size>
+	<child>
+	  <left_attach>1</left_attach>
+	  <right_attach>2</right_attach>
+	  <top_attach>1</top_attach>
+	  <bottom_attach>2</bottom_attach>
+	  <xpad>0</xpad>
+	  <ypad>0</ypad>
+	  <xexpand>False</xexpand>
+	  <yexpand>False</yexpand>
+	  <xshrink>False</xshrink>
+	  <yshrink>False</yshrink>
+	  <xfill>True</xfill>
+	  <yfill>True</yfill>
+	</child>
+      </widget>
+    </widget>
   </widget>
 </widget>
 

capplets/background/background-properties.glade.h

@@ -21,3 +21,6 @@ gchar *s = N_("Scaled (keep aspect)");
 gchar *s = N_("Scaled");
 gchar *s = N_("Disable background selection");
 gchar *s = N_("Apply changes automatically");
+gchar *s = N_("Adjust background's brightness");
+gchar *s = N_("Dimmer");
+gchar *s = N_("Brighter");

capplets/background/main.c

@@ -42,11 +42,17 @@ static Preferences *prefs;
 static Preferences *old_prefs;
 static PrefsWidget *prefs_widget;
 
+static guint ok_handler_id;
+static guint cancel_handler_id;
+
 static void
 ok_cb (GtkWidget *widget) 
 {
 	preferences_save (prefs);
 	preferences_apply_now (prefs);
+	gtk_signal_disconnect (GTK_OBJECT (prefs_widget), ok_handler_id);
+	gtk_signal_disconnect (GTK_OBJECT (prefs_widget), cancel_handler_id);
+	gtk_object_destroy (GTK_OBJECT (prefs_widget));
 }
 
 static void
@@ -54,6 +60,9 @@ cancel_cb (GtkWidget *widget)
 {
 	preferences_save (old_prefs);
 	preferences_apply_now (old_prefs);
+	gtk_signal_disconnect (GTK_OBJECT (prefs_widget), ok_handler_id);
+	gtk_signal_disconnect (GTK_OBJECT (prefs_widget), cancel_handler_id);
+	gtk_object_destroy (GTK_OBJECT (prefs_widget));
 }
 
 static void 
@@ -63,10 +72,12 @@ setup_capplet_widget (void)
 
 	prefs_widget = PREFS_WIDGET (prefs_widget_new (prefs));
 
-	gtk_signal_connect (GTK_OBJECT (prefs_widget), "ok", 
+	ok_handler_id =
-			    GTK_SIGNAL_FUNC (ok_cb), NULL);
+		gtk_signal_connect (GTK_OBJECT (prefs_widget), "ok", 
-	gtk_signal_connect (GTK_OBJECT (prefs_widget), "cancel", 
+				    GTK_SIGNAL_FUNC (ok_cb), NULL);
-			    GTK_SIGNAL_FUNC (cancel_cb), NULL);		
+	cancel_handler_id =
+		gtk_signal_connect (GTK_OBJECT (prefs_widget), "cancel", 
+				    GTK_SIGNAL_FUNC (cancel_cb), NULL);		
 
 	gtk_widget_show_all (GTK_WIDGET (prefs_widget));
 

capplets/background/preferences.c

@@ -140,6 +140,10 @@ preferences_clone (Preferences *prefs)
 		new_prefs->wallpaper_sel_path = 
 			g_strdup (prefs->wallpaper_sel_path);;
 
+	new_prefs->auto_apply        = prefs->auto_apply;
+	new_prefs->adjust_brightness = prefs->adjust_brightness;
+	new_prefs->brightness_value  = prefs->brightness_value;
+
 	return object;
 }
 
@@ -231,6 +235,17 @@ preferences_load (Preferences *prefs)
 	} else {
 		prefs->wallpaper_enabled = TRUE;
 	}
+
+	string = gnome_config_get_string
+		("/Background/Default/adjustBrightness=true");
+	if (!g_strcasecmp (string, "true"))
+		prefs->adjust_brightness = TRUE;
+	else if (g_strcasecmp (string, "false"))
+		prefs->adjust_brightness = FALSE;
+	g_free (string);
+
+	prefs->brightness_value = 
+		gnome_config_get_int ("/Background/Default/brightnessValue=0");
 }
 
 void 
@@ -271,6 +286,11 @@ preferences_save (Preferences *prefs)
 	gnome_config_set_string ("/Background/Default/autoApply", 
 				 prefs->auto_apply ? "True" : "False");
 
+	gnome_config_set_string ("/Background/Default/adjustBrightness", 
+				 prefs->adjust_brightness ? "True" : "False");
+	gnome_config_set_int ("/Background/Default/brightnessValue", 
+			      prefs->brightness_value);
+
 	gnome_config_sync ();
 }
 
@@ -284,7 +304,7 @@ preferences_changed (Preferences *prefs)
 
 	if (prefs->auto_apply)
 		prefs->timeout_id = 
-			gtk_timeout_add (5000, (GtkFunction) apply_timeout_cb,
+			gtk_timeout_add (2000, (GtkFunction) apply_timeout_cb,
 					 prefs);
 
 	applier_apply_prefs (applier, prefs, FALSE, TRUE);
@@ -384,6 +404,10 @@ preferences_read_xml (xmlDocPtr xml_doc)
 				g_strdup (xmlNodeGetContent (node));
 		else if (!strcmp (node->name, "auto-apply"))
 			prefs->auto_apply = TRUE;
+		else if (!strcmp (node->name, "adjust-brightness"))
+			prefs->auto_apply = TRUE;
+		else if (!strcmp (node->name, "brightness-value"))
+			prefs->brightness_value = xml_read_int (node, NULL);
 	}
 
 	return prefs;
@@ -436,6 +460,11 @@ preferences_write_xml (Preferences *prefs)
 	if (prefs->auto_apply)
 		xmlNewChild (node, NULL, "auto-apply", NULL);
 
+	if (prefs->adjust_brightness)
+		xmlNewChild (node, NULL, "adjust-brightness", NULL);
+	xmlAddChild (node, xml_write_int ("brightness-value", NULL,
+					  prefs->brightness_value));
+
 	xmlDocSetRootElement (doc, node);
 
 	return doc;

capplets/background/preferences.h

@@ -63,6 +63,9 @@ struct _Preferences
 
 	gchar            *wallpaper_filename;
 	gchar            *wallpaper_sel_path;
+
+	gboolean          adjust_brightness;
+	gint              brightness_value;
 };
 
 struct _PreferencesClass

capplets/background/prefs-widget.c

@@ -48,6 +48,7 @@ static void prefs_widget_set_arg            (GtkObject *object,
 static void prefs_widget_get_arg            (GtkObject *object, 
 					     GtkArg *arg, 
 					     guint arg_id);
+static void prefs_widget_destroy            (GtkObject *object);
 
 static void read_preferences                (PrefsWidget *prefs_widget,
 					     Preferences *prefs);
@@ -87,6 +88,10 @@ static void disable_toggled_cb              (GtkToggleButton *tb,
 					     PrefsWidget *prefs_widget);
 static void auto_apply_toggled_cb           (GtkToggleButton *tb, 
 					     PrefsWidget *prefs_widget);
+static void adjust_brightness_toggled_cb    (GtkToggleButton *tb,
+					     PrefsWidget *prefs_widget);
+static void brightness_adjust_changed_cb    (GtkAdjustment *adjustment,
+					     PrefsWidget *prefs_widget);
 
 static void set_gradient_controls_sensitive   (PrefsWidget *prefs_widget,
 					       gboolean s);
@@ -94,6 +99,8 @@ static void set_wallpaper_controls_sensitive  (PrefsWidget *prefs_widget,
 					       gboolean s);
 static void set_background_controls_sensitive (PrefsWidget *prefs_widget,
 					       gboolean s);
+static void set_brightness_controls_sensitive (PrefsWidget *prefs_widget,
+					       gboolean s);
 
 guint
 prefs_widget_get_type (void)
@@ -123,6 +130,7 @@ static void
 prefs_widget_init (PrefsWidget *prefs_widget)
 {
 	GtkWidget *widget;
+	GtkAdjustment *adjustment;
 
 	prefs_widget->dialog_data = 
 		glade_xml_new (GLADE_DATADIR "/background-properties.glade",
@@ -189,6 +197,20 @@ prefs_widget_init (PrefsWidget *prefs_widget)
 				       "auto_apply_toggled_cb",
 				       auto_apply_toggled_cb,
 				       prefs_widget);
+	glade_xml_signal_connect_data (prefs_widget->dialog_data,
+				       "adjust_brightness_toggled_cb",
+				       adjust_brightness_toggled_cb,
+				       prefs_widget);
+
+	adjustment = gtk_range_get_adjustment
+		(GTK_RANGE (WID ("brightness_adjust")));
+	gtk_signal_connect (GTK_OBJECT (adjustment), "value-changed",
+			    GTK_SIGNAL_FUNC (brightness_adjust_changed_cb),
+			    prefs_widget);
+
+	gnome_entry_load_history
+		(GNOME_ENTRY (gnome_file_entry_gnome_entry 
+			      (GNOME_FILE_ENTRY (WID ("wallpaper_entry")))));
 }
 
 static void
@@ -202,6 +224,7 @@ prefs_widget_class_init (PrefsWidgetClass *class)
 				 ARG_PREFERENCES);
 
 	object_class = GTK_OBJECT_CLASS (class);
+	object_class->destroy = prefs_widget_destroy;
 	object_class->set_arg = prefs_widget_set_arg;
 	object_class->get_arg = prefs_widget_get_arg;
 
@@ -260,6 +283,23 @@ prefs_widget_get_arg (GtkObject *object, GtkArg *arg, guint arg_id)
 	}
 }
 
+static void
+prefs_widget_destroy (GtkObject *object) 
+{
+	PrefsWidget *prefs_widget;
+
+	g_return_if_fail (object != NULL);
+	g_return_if_fail (IS_PREFS_WIDGET (object));
+
+	prefs_widget = PREFS_WIDGET (object);
+
+	gnome_entry_save_history
+		(GNOME_ENTRY (gnome_file_entry_gnome_entry 
+			      (GNOME_FILE_ENTRY (WID ("wallpaper_entry")))));
+
+	GTK_OBJECT_CLASS (parent_class)->destroy (object);
+}
+
 GtkWidget *
 prefs_widget_new (Preferences *prefs) 
 {
@@ -285,6 +325,7 @@ static void
 read_preferences (PrefsWidget *prefs_widget, Preferences *prefs) 
 {
 	GtkWidget *widget, *entry;
+	GtkAdjustment *adjustment;
 
 	g_return_if_fail (prefs_widget != NULL);
 	g_return_if_fail (IS_PREFS_WIDGET (prefs_widget));
@@ -389,6 +430,31 @@ read_preferences (PrefsWidget *prefs_widget, Preferences *prefs)
 					      (WID ("auto_apply")),
 					      FALSE);
 
+	if (prefs->adjust_brightness)
+		gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON 
+					      (WID ("auto_apply")),
+					      TRUE);
+	else
+		gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON 
+					      (WID ("auto_apply")),
+					      FALSE);
+
+	if (prefs->adjust_brightness) {
+		gtk_toggle_button_set_active
+			(GTK_TOGGLE_BUTTON (WID ("adjust_brightness_toggle")),
+			 TRUE);
+		set_brightness_controls_sensitive (prefs_widget, TRUE);
+	} else {
+		gtk_toggle_button_set_active
+			(GTK_TOGGLE_BUTTON (WID ("adjust_brightness_toggle")),
+			 FALSE);
+		set_brightness_controls_sensitive (prefs_widget, FALSE);
+	}
+
+	adjustment = gtk_range_get_adjustment
+		(GTK_RANGE (WID ("brightness_adjust")));
+	gtk_adjustment_set_value (adjustment, prefs->brightness_value);
+
 	preferences_apply_preview (prefs);
 }
 
@@ -507,8 +573,10 @@ wallpaper_entry_changed_cb (GtkEntry *e, PrefsWidget *prefs_widget)
 {
 	g_return_if_fail (prefs_widget != NULL);
 	g_return_if_fail (IS_PREFS_WIDGET (prefs_widget));
-	g_return_if_fail (prefs_widget->prefs != NULL);
+	g_return_if_fail (prefs_widget->prefs == NULL ||
-	g_return_if_fail (IS_PREFERENCES (prefs_widget->prefs));
+			  IS_PREFERENCES (prefs_widget->prefs));
+
+	if (prefs_widget->prefs == NULL) return;
 
 	if (prefs_widget->prefs->wallpaper_filename)
 		g_free (prefs_widget->prefs->wallpaper_filename);
@@ -640,6 +708,41 @@ auto_apply_toggled_cb (GtkToggleButton *tb, PrefsWidget *prefs_widget)
 	capplet_widget_state_changed (CAPPLET_WIDGET (prefs_widget), TRUE);
 }
 
+static void
+adjust_brightness_toggled_cb (GtkToggleButton *tb, PrefsWidget *prefs_widget)
+{
+	g_return_if_fail (prefs_widget != NULL);
+	g_return_if_fail (IS_PREFS_WIDGET (prefs_widget));
+	g_return_if_fail (prefs_widget->prefs != NULL);
+	g_return_if_fail (IS_PREFERENCES (prefs_widget->prefs));
+
+	if (gtk_toggle_button_get_active (tb)) {
+		prefs_widget->prefs->adjust_brightness = TRUE;
+		set_brightness_controls_sensitive (prefs_widget, TRUE);
+	} else {
+		prefs_widget->prefs->adjust_brightness = FALSE;
+		set_brightness_controls_sensitive (prefs_widget, FALSE);
+	}
+
+	preferences_changed (prefs_widget->prefs);
+	capplet_widget_state_changed (CAPPLET_WIDGET (prefs_widget), TRUE);
+}
+
+static void
+brightness_adjust_changed_cb (GtkAdjustment *adjustment,
+			      PrefsWidget *prefs_widget) 
+{
+	g_return_if_fail (prefs_widget != NULL);
+	g_return_if_fail (IS_PREFS_WIDGET (prefs_widget));
+	g_return_if_fail (prefs_widget->prefs != NULL);
+	g_return_if_fail (IS_PREFERENCES (prefs_widget->prefs));
+
+	prefs_widget->prefs->brightness_value = adjustment->value;
+
+	preferences_changed (prefs_widget->prefs);
+	capplet_widget_state_changed (CAPPLET_WIDGET (prefs_widget), TRUE);
+}
+
 static void
 set_gradient_controls_sensitive (PrefsWidget *prefs_widget, gboolean s) 
 {
@@ -665,3 +768,11 @@ set_background_controls_sensitive (PrefsWidget *prefs_widget, gboolean s)
 	gtk_widget_set_sensitive (WID ("wallpaper_frame"), s);
 }
 
+static void
+set_brightness_controls_sensitive (PrefsWidget *prefs_widget, gboolean s)
+{
+	gtk_widget_set_sensitive (WID ("brightness_low_label"), s);
+	gtk_widget_set_sensitive (WID ("brightness_adjust"), s);
+	gtk_widget_set_sensitive (WID ("brightness_high_label"), s);
+}
+