Allow scrolling on notebook tabs to change the active page

This is enabled by default but has a setting in the preferences so it can be
disabled.

data/org.x.editor.gschema.xml.in

@@ -126,6 +126,11 @@
       <summary>Bottom Panel is Visible</summary>
       <description>Whether the bottom panel at the bottom of editing windows should be visible.</description>
     </key>
+    <key name="enable-tab-scrolling" type="b">
+      <default>true</default>
+      <summary>Allow changing active tabs by scrolling</summary>
+      <description>Whether you can change active tabs by scrolling.</description>
+    </key>
     <key name="max-recents" type="i">
       <default>5</default>
       <summary>Maximum Recent Files</summary>

xed/dialogs/xed-preferences-dialog.c

@@ -125,6 +125,9 @@ struct _XedPreferencesDialogPrivate
     GtkWidget   *right_margin_position_spinbutton;
     GtkWidget   *right_margin_position_hbox;
 
+    /* Tab scrolling */
+    GtkWidget   *tab_scrolling_checkbutton;
+
     /* Plugins manager */
     GtkWidget   *plugin_manager_place_holder;
 
@@ -234,6 +237,17 @@ auto_save_spinbutton_value_changed (GtkSpinButton        *spin_button,
     xed_prefs_manager_set_auto_save_interval (MAX (1, gtk_spin_button_get_value_as_int (spin_button)));
 }
 
+static void
+tab_scrolling_checkbutton_toggled (GtkToggleButton      *button,
+                                   XedPreferencesDialog *dlg)
+{
+    xed_debug (DEBUG_PREFS);
+
+    g_return_if_fail (button == GTK_TOGGLE_BUTTON (dlg->priv->tab_scrolling_checkbutton));
+
+    xed_prefs_manager_set_enable_tab_scrolling (gtk_toggle_button_get_active (button));
+}
+
 static void
 setup_editor_page (XedPreferencesDialog *dlg)
 {
@@ -251,6 +265,8 @@ setup_editor_page (XedPreferencesDialog *dlg)
                                   xed_prefs_manager_get_auto_indent ());
     gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (dlg->priv->backup_copy_checkbutton),
                                   xed_prefs_manager_get_create_backup_copy ());
+    gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (dlg->priv->tab_scrolling_checkbutton),
+                                  xed_prefs_manager_get_enable_tab_scrolling ());
 
     auto_save = xed_prefs_manager_get_auto_save ();
     gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (dlg->priv->auto_save_checkbutton), auto_save);
@@ -271,6 +287,7 @@ setup_editor_page (XedPreferencesDialog *dlg)
     gtk_widget_set_sensitive (dlg->priv->autosave_hbox, xed_prefs_manager_auto_save_can_set ());
     gtk_widget_set_sensitive (dlg->priv->auto_save_spinbutton,
                               auto_save && xed_prefs_manager_auto_save_interval_can_set ());
+    gtk_widget_set_sensitive (dlg->priv->tab_scrolling_checkbutton, xed_prefs_manager_enable_tab_scrolling_can_set ());
 
     /* Connect signal */
     g_signal_connect (dlg->priv->tabs_width_spinbutton, "value_changed",
@@ -285,6 +302,8 @@ setup_editor_page (XedPreferencesDialog *dlg)
                       G_CALLBACK (backup_copy_checkbutton_toggled), dlg);
     g_signal_connect (dlg->priv->auto_save_spinbutton, "value_changed",
                       G_CALLBACK (auto_save_spinbutton_value_changed), dlg);
+    g_signal_connect (dlg->priv->tab_scrolling_checkbutton, "toggled",
+                      G_CALLBACK (tab_scrolling_checkbutton_toggled), dlg);
 }
 
 static void
@@ -1008,6 +1027,8 @@ xed_preferences_dialog_init (XedPreferencesDialog *dlg)
         "auto_save_checkbutton", &dlg->priv->auto_save_checkbutton,
         "auto_save_spinbutton", &dlg->priv->auto_save_spinbutton,
 
+        "tab_scrolling_checkbutton", &dlg->priv->tab_scrolling_checkbutton,
+
         "default_font_checkbutton", &dlg->priv->default_font_checkbutton,
         "font_button", &dlg->priv->font_button,
         "font_hbox", &dlg->priv->font_hbox,

xed/xed-notebook.c

@@ -64,6 +64,7 @@ struct _XedNotebookPrivate
 	gint	       always_show_tabs : 1;
 	gint           close_buttons_sensitive : 1;
 	gint           tab_drag_and_drop_enabled : 1;
+    gint           tab_scrolling_enabled : 1;
 	guint          destroy_has_run : 1;
 };
 
@@ -643,6 +644,42 @@ button_press_cb (XedNotebook  *notebook,
 	return FALSE;
 }
 
+static gboolean
+notebook_scroll_event_cb (XedNotebook    *notebook,
+                          GdkEventScroll *event,
+                          gpointer        data)
+{
+    GtkWidget *event_widget;
+
+    if (!notebook->priv->tab_scrolling_enabled)
+    {
+        return TRUE;
+    }
+
+    event_widget = gtk_get_event_widget ((GdkEvent *) event);
+
+    if (event_widget == NULL)
+    {
+        return FALSE;
+    }
+
+    switch (event->direction)
+    {
+        case GDK_SCROLL_DOWN:
+        case GDK_SCROLL_RIGHT:
+            gtk_notebook_next_page (GTK_NOTEBOOK (notebook));
+            break;
+        case GDK_SCROLL_UP:
+        case GDK_SCROLL_LEFT:
+            gtk_notebook_prev_page (GTK_NOTEBOOK (notebook));
+            break;
+        default:
+            break;
+    }
+
+    return TRUE;
+}
+
 /**
  * xed_notebook_new:
  *
@@ -711,6 +748,7 @@ xed_notebook_init (XedNotebook *notebook)
 
 	notebook->priv->close_buttons_sensitive = TRUE;
 	notebook->priv->tab_drag_and_drop_enabled = TRUE;
+    notebook->priv->tab_scrolling_enabled = TRUE;
 
 	gtk_notebook_set_scrollable (GTK_NOTEBOOK (notebook), TRUE);
 	gtk_notebook_set_show_border (GTK_NOTEBOOK (notebook), FALSE);
@@ -733,6 +771,10 @@ xed_notebook_init (XedNotebook *notebook)
 				"switch_page",
                                 G_CALLBACK (xed_notebook_switch_page_cb),
                                 NULL);
+
+    gtk_widget_add_events (GTK_WIDGET (notebook), GDK_SCROLL_MASK);
+    g_signal_connect (notebook, "scroll-event",
+                      G_CALLBACK (notebook_scroll_event_cb), NULL);
 }
 
 static void
@@ -1097,3 +1139,41 @@ xed_notebook_get_tab_drag_and_drop_enabled (XedNotebook *nb)
 	return nb->priv->tab_drag_and_drop_enabled;
 }
 
+/**
+ * xed_notebook_set_tab_scrolling_enabled:
+ * @nb: a #XedNotebook
+ * @enable: %TRUE to enable tab scrolling
+ *
+ * Sets whether tab scrolling in the @nb is enabled.
+ */
+void
+xed_notebook_set_tab_scrolling_enabled (XedNotebook *nb,
+                                        gboolean     enable)
+{
+    g_return_if_fail (XED_IS_NOTEBOOK (nb));
+
+    enable = (enable != FALSE);
+
+    if (enable == nb->priv->tab_scrolling_enabled)
+    {
+        return;
+    }
+
+    nb->priv->tab_scrolling_enabled = enable;
+}
+
+/**
+ * xed_notebook_get_tab_scrolling_enabled:
+ * @nb: a #XedNotebook
+ *
+ * Whether notebook tab scrolling is enabled
+ *
+ * Returns: %TRUE if tab scrolling is enabled
+ */
+gboolean
+xed_notebook_get_tab_scrolling_enabled (XedNotebook *nb)
+{
+    g_return_val_if_fail (XED_IS_NOTEBOOK (nb), TRUE);
+
+    return nb->priv->tab_scrolling_enabled;
+}

xed/xed-notebook.h

@@ -138,6 +138,10 @@ void		xed_notebook_set_tab_drag_and_drop_enabled
 gboolean	xed_notebook_get_tab_drag_and_drop_enabled
 						(XedNotebook *nb);
 
+void        xed_notebook_set_tab_scrolling_enabled (XedNotebook *nb,
+                                                    gboolean     enable);
+gboolean    xed_notebook_get_tab_scrolling_enabled (XedNotebook *nb);
+
 G_END_DECLS
 
 #endif /* XED_NOTEBOOK_H */

xed/xed-prefs-manager-app.c

@@ -43,6 +43,7 @@
 #include "xed-debug.h"
 #include "xed-view.h"
 #include "xed-window.h"
+#include "xed-notebook.h"
 #include "xed-window-private.h"
 #include "xed-plugins-engine.h"
 #include "xed-style-scheme-manager.h"
@@ -84,6 +85,10 @@ static void xed_prefs_manager_smart_home_end_changed	(GSettings *settings,
 							 gchar       *key,
 							 gpointer     user_data);
 
+static void xed_prefs_manager_enable_tab_scrolling_changed (GSettings *settings,
+                                                            gchar     *key,
+                                                            gpointer   user_data);
+
 static void xed_prefs_manager_hl_current_line_changed	(GSettings *settings,
 							 gchar       *key,
 							 gpointer     user_data);
@@ -660,6 +665,9 @@ xed_prefs_manager_app_init (void)
 				G_CALLBACK (xed_prefs_manager_smart_home_end_changed),
 				NULL);
 
+        g_signal_connect (xed_prefs_manager->settings, "changed::" GPM_ENABLE_TAB_SCROLLING,
+                          G_CALLBACK (xed_prefs_manager_enable_tab_scrolling_changed), NULL);
+
 		g_signal_connect (xed_prefs_manager->settings,
 				"changed::" GPM_HIGHLIGHT_CURRENT_LINE,
 				G_CALLBACK (xed_prefs_manager_hl_current_line_changed),
@@ -1168,6 +1176,35 @@ xed_prefs_manager_smart_home_end_changed (GSettings *settings,
 	}
 }
 
+static void
+xed_prefs_manager_enable_tab_scrolling_changed (GSettings *settings,
+                                                gchar     *key,
+                                                gpointer   user_data)
+{
+    xed_debug (DEBUG_PREFS);
+
+    g_printerr ("Tab scrolling changed\n");
+
+    if (strcmp (key, GPM_ENABLE_TAB_SCROLLING) == 0)
+    {
+        gboolean enable;
+        const GList *windows;
+
+        enable = g_settings_get_boolean (settings, key);
+
+        windows = xed_app_get_windows (xed_app_get_default ());
+        while (windows != NULL)
+        {
+            XedNotebook *notebook;
+
+            notebook = XED_NOTEBOOK (_xed_window_get_notebook (windows->data));
+            xed_notebook_set_tab_scrolling_enabled (notebook, enable);
+
+            windows = g_list_next (windows);
+        }
+    }
+}
+
 static void
 xed_prefs_manager_syntax_hl_enable_changed (GSettings *settings,
 					      gchar       *key,

xed/xed-prefs-manager.c

@@ -371,6 +371,9 @@ DEFINE_BOOL_PREF (side_pane_visible,
 DEFINE_BOOL_PREF (bottom_panel_visible,
 		  GPM_BOTTOM_PANEL_VISIBLE)
 
+/* Tab scrolling */
+DEFINE_BOOL_PREF (enable_tab_scrolling, GPM_ENABLE_TAB_SCROLLING)
+
 /* Print syntax highlighting */
 DEFINE_BOOL_PREF (print_syntax_hl,
 		  GPM_PRINT_SYNTAX)

xed/xed-prefs-manager.h

@@ -81,6 +81,8 @@
 
 #define GPM_BOTTOM_PANEL_VISIBLE	"bottom-panel-visible"
 
+#define GPM_ENABLE_TAB_SCROLLING    "enable-tab-scrolling"
+
 #define GPM_MAX_RECENTS			"max-recents"
 
 /* Print */
@@ -201,6 +203,12 @@ gboolean		 xed_prefs_manager_side_pane_visible_can_set	(void);
 gboolean		 xed_prefs_manager_get_bottom_panel_visible	(void);
 void			 xed_prefs_manager_set_bottom_panel_visible	(gboolean tv);
 gboolean		 xed_prefs_manager_bottom_panel_visible_can_set(void);
+
+/* Tab scrolling enabled */
+gboolean         xed_prefs_manager_get_enable_tab_scrolling     (void);
+void             xed_prefs_manager_set_enable_tab_scrolling     (gboolean tv);
+gboolean         xed_prefs_manager_enable_tab_scrolling_can_set (void);
+
 /* Print syntax highlighting */
 gboolean		 xed_prefs_manager_get_print_syntax_hl	(void);
 void			 xed_prefs_manager_set_print_syntax_hl	(gboolean ps);

xed/xed-window.c

@@ -3368,6 +3368,9 @@ add_notebook (XedWindow *window,
 {
     gtk_paned_pack1 (GTK_PANED(window->priv->vpaned), notebook, TRUE, TRUE);
     gtk_widget_show (notebook);
+
+    xed_notebook_set_tab_scrolling_enabled (XED_NOTEBOOK (notebook), xed_prefs_manager_get_enable_tab_scrolling ());
+
     connect_notebook_signals (window, notebook);
 }