[StScrollView] Add support for GtkPolicyType for scrollbars

Previously we were hacking out the vertical scrollbar, this patch
allow us to sanely say in which directions we want to scroll.

Note this patch intentionally changes St to depend on GTK+ in the
API.  I believe this is a correct long term change where we should
view St as co-evolving with GTK+ rather than replacing or paralleling.

https://bugzilla.gnome.org/show_bug.cgi?id=609015

src/Makefile.am

@@ -217,6 +217,7 @@ St-1.0.gir: $(mutter) $(G_IR_SCANNER) libgnome-shell.la libst-1.0.la Makefile
 	        --namespace=St							\
 	        --nsversion=1.0							\
 	        --include=Clutter-1.0						\
+	        --include=Gtk-2.0						\
 		--add-include-path=$(builddir)     				\
 	        --libtool="$(LIBTOOL)"						\
 	        --program=mutter						\

src/st/st-scroll-view.c

@@ -64,6 +64,9 @@ struct _StScrollViewPrivate
   ClutterActor *hscroll;
   ClutterActor *vscroll;
 
+  GtkPolicyType hscroll_policy;
+  GtkPolicyType vscroll_policy;
+
   gfloat        row_size;
   gfloat        column_size;
 
@@ -77,6 +80,8 @@ enum {
 
   PROP_HSCROLL,
   PROP_VSCROLL,
+  PROP_HSCROLLBAR_POLICY,
+  PROP_VSCROLLBAR_POLICY,
   PROP_MOUSE_SCROLL
 };
 
@@ -96,6 +101,12 @@ st_scroll_view_get_property (GObject    *object,
     case PROP_VSCROLL:
       g_value_set_object (value, priv->vscroll);
       break;
+    case PROP_HSCROLLBAR_POLICY:
+      g_value_set_enum (value, priv->hscroll_policy);
+      break;
+    case PROP_VSCROLLBAR_POLICY:
+      g_value_set_enum (value, priv->vscroll_policy);
+      break;
     case PROP_MOUSE_SCROLL:
       g_value_set_boolean (value, priv->mouse_scroll);
       break;
@@ -110,11 +121,25 @@ st_scroll_view_set_property (GObject      *object,
                              const GValue *value,
                              GParamSpec   *pspec)
 {
+  StScrollView *self = ST_SCROLL_VIEW (object);
+  StScrollViewPrivate *priv = self->priv;
+
   switch (property_id)
     {
     case PROP_MOUSE_SCROLL:
-      st_scroll_view_set_mouse_scrolling ((StScrollView *) object,
+      st_scroll_view_set_mouse_scrolling (self,
                                           g_value_get_boolean (value));
+      break;
+    case PROP_HSCROLLBAR_POLICY:
+      st_scroll_view_set_policy (self,
+                                 g_value_get_enum (value),
+                                 priv->vscroll_policy);
+      break;
+    case PROP_VSCROLLBAR_POLICY:
+      st_scroll_view_set_policy (self,
+                                 priv->hscroll_policy,
+                                 g_value_get_enum (value));
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
     }
@@ -474,6 +499,23 @@ st_scroll_view_class_init (StScrollViewClass *klass)
                                                         ST_TYPE_SCROLL_BAR,
                                                         G_PARAM_READABLE));
 
+
+  pspec = g_param_spec_enum ("vscrollbar-policy",
+                             "Vertical Scrollbar Policy",
+                             "When the vertical scrollbar is displayed",
+                             GTK_TYPE_POLICY_TYPE,
+                             GTK_POLICY_ALWAYS,
+                             G_PARAM_READWRITE);
+  g_object_class_install_property (object_class, PROP_VSCROLLBAR_POLICY, pspec);
+
+  pspec = g_param_spec_enum ("hscrollbar-policy",
+                             "Horizontal Scrollbar Policy",
+                             "When the horizontal scrollbar is displayed",
+                             GTK_TYPE_POLICY_TYPE,
+                             GTK_POLICY_ALWAYS,
+                             G_PARAM_READWRITE);
+  g_object_class_install_property (object_class, PROP_HSCROLLBAR_POLICY, pspec);
+
   pspec = g_param_spec_boolean ("enable-mouse-scrolling",
                                 "Enable Mouse Scrolling",
                                 "Enable automatic mouse wheel scrolling",
@@ -525,6 +567,9 @@ child_hadjustment_notify_cb (GObject    *gobject,
                                           child_adjustment_changed_cb,
                                           priv->hscroll);
 
+  if (priv->hscroll_policy == GTK_POLICY_NEVER)
+    return;
+
   st_scrollable_get_adjustments (ST_SCROLLABLE (actor), &hadjust, NULL);
   if (hadjust)
     {
@@ -537,11 +582,15 @@ child_hadjustment_notify_cb (GObject    *gobject,
         }
 
       st_scroll_bar_set_adjustment (ST_SCROLL_BAR(priv->hscroll), hadjust);
+
+      if (priv->hscroll_policy == GTK_POLICY_AUTOMATIC)
+        {
           g_signal_connect (hadjust, "changed", G_CALLBACK (
                            child_adjustment_changed_cb), priv->hscroll);
           child_adjustment_changed_cb (hadjust, priv->hscroll);
         }
     }
+}
 
 static void
 child_vadjustment_notify_cb (GObject    *gobject,
@@ -559,6 +608,9 @@ child_vadjustment_notify_cb (GObject    *gobject,
                                           child_adjustment_changed_cb,
                                           priv->vscroll);
 
+  if (priv->vscroll_policy == GTK_POLICY_NEVER)
+    return;
+
   st_scrollable_get_adjustments (ST_SCROLLABLE(actor), NULL, &vadjust);
   if (vadjust)
     {
@@ -571,17 +623,23 @@ child_vadjustment_notify_cb (GObject    *gobject,
         }
 
       st_scroll_bar_set_adjustment (ST_SCROLL_BAR(priv->vscroll), vadjust);
+      if (priv->vscroll_policy == GTK_POLICY_AUTOMATIC)
+        {
           g_signal_connect (vadjust, "changed", G_CALLBACK (
                             child_adjustment_changed_cb), priv->vscroll);
           child_adjustment_changed_cb (vadjust, priv->vscroll);
         }
     }
+}
 
 static void
 st_scroll_view_init (StScrollView *self)
 {
   StScrollViewPrivate *priv = self->priv = SCROLL_VIEW_PRIVATE (self);
 
+  priv->hscroll_policy = GTK_POLICY_AUTOMATIC;
+  priv->vscroll_policy = GTK_POLICY_AUTOMATIC;
+
   priv->hscroll = CLUTTER_ACTOR (st_scroll_bar_new (NULL));
   priv->vscroll = g_object_new (ST_TYPE_SCROLL_BAR, "vertical", TRUE, NULL);
 
@@ -842,3 +900,73 @@ st_scroll_view_get_mouse_scrolling (StScrollView *scroll)
 
   return priv->mouse_scroll;
 }
+
+/**
+ * st_scroll_view_set_policy:
+ * @scroll: A #StScrollView
+ * @hscroll: Whether to enable horizontal scrolling
+ * @vscroll: Whether to enable vertical scrolling
+ *
+ * Set the scroll policy.
+ */
+void
+st_scroll_view_set_policy (StScrollView   *scroll,
+                           GtkPolicyType   hscroll,
+                           GtkPolicyType   vscroll)
+{
+  StScrollViewPrivate *priv;
+  StAdjustment *hadjust, *vadjust;
+
+  g_return_if_fail (ST_IS_SCROLL_VIEW (scroll));
+  g_return_if_fail (hscroll == GTK_POLICY_ALWAYS || vscroll == GTK_POLICY_ALWAYS);
+
+  priv = ST_SCROLL_VIEW (scroll)->priv;
+
+  if (priv->hscroll_policy == hscroll && priv->vscroll_policy == vscroll)
+    return;
+
+  g_object_freeze_notify ((GObject *) scroll);
+
+  if (priv->hscroll_policy != hscroll)
+    {
+      priv->hscroll_policy = hscroll;
+      g_object_notify ((GObject *) scroll, "hscrollbar-policy");
+    }
+  if (priv->vscroll_policy != vscroll)
+    {
+      priv->vscroll_policy = vscroll;
+      g_object_notify ((GObject *) scroll, "vscrollbar-policy");
+    }
+
+  st_scrollable_get_adjustments (ST_SCROLLABLE (priv->child), &hadjust, &vadjust);
+
+  if (priv->hscroll_policy == GTK_POLICY_NEVER)
+    {
+      hadjust = NULL;
+      clutter_actor_hide (priv->hscroll);
+    }
+  else if (priv->hscroll_policy == GTK_POLICY_AUTOMATIC)
+    {
+      /* We call this function because we need to set up the adjustment
+       * notification hooks, and the _show will queue a reallocate, from which we'll figure
+       * out if we need to really show or hide the scrollbar.
+       */
+      child_hadjustment_notify_cb (G_OBJECT (priv->child), NULL, scroll);
+      clutter_actor_show (priv->hscroll);
+    }
+
+  if (priv->vscroll_policy == GTK_POLICY_NEVER)
+    {
+      vadjust = NULL;
+      clutter_actor_hide (priv->vscroll);
+    }
+  else
+    {
+      child_vadjustment_notify_cb (G_OBJECT (priv->child), NULL, scroll);
+      clutter_actor_show (priv->vscroll);
+    }
+
+  st_scrollable_set_adjustments (ST_SCROLLABLE (priv->child), hadjust, vadjust);
+
+  g_object_thaw_notify ((GObject *) scroll);
+}

src/st/st-scroll-view.h

@@ -84,6 +84,10 @@ void          st_scroll_view_set_mouse_scrolling (StScrollView *scroll,
                                                   gboolean      enabled);
 gboolean      st_scroll_view_get_mouse_scrolling (StScrollView *scroll);
 
+void          st_scroll_view_set_policy          (StScrollView   *scroll,
+                                                  GtkPolicyType   hscroll,
+                                                  GtkPolicyType   vscroll);
+
 G_END_DECLS
 
 #endif /* __ST_SCROLL_VIEW_H__ */

src/st/st-types.h

@@ -34,6 +34,7 @@
 
 #include <glib-object.h>
 #include <clutter/clutter.h>
+#include <gtk/gtk.h>
 
 G_BEGIN_DECLS
 

tests/interactive/scrolling.js

@@ -14,9 +14,19 @@ let vbox = new St.BoxLayout({ vertical: true,
                               style: "padding: 10px;" });
 stage.add_actor(vbox);
 
+let toggle = new St.Button({ label: 'Horizontal Scrolling',
+                         toggle_mode: true });
+vbox.add(toggle);
+
 let v = new St.ScrollView();
 vbox.add(v, { expand: true });
 
+toggle.connect('notify::checked', function () {
+    v.set_policy(toggle.checked ? St.ScrollPolicy.AUTOMATIC
+                                : St.ScrollPolicy.NEVER,
+                 St.ScrollPolicy.AUTOMATIC);
+});
+
 let b = new St.BoxLayout({ vertical: true,
                            style: "border: 2px solid #880000; border-radius: 10px; padding: 0px 5px;" });
 v.add_actor(b);