Added GtkScrollablePolicy property to scrollable interface

This patch adds the GtkScrollablePolicy type property to GtkScrollable
and implements it in all subclasses. GtkScrolledWindow observes this
property to make a good guess about when to show/hide scrollbars for
height-for-width content.

Most scrollable children do not do height-for-width *yet* but
most certainly will (toolpalette, treeview, iconview, textview
widgets all TODO), for scrollable widgets that do have a minimum
and natural size, it's important for them to observe the state
of this property in order to properly drive the scroll adjustments
according to the desired GtkScrollablePolicy. This patch makes
GtkViewport do this.

Patch also adds tests/testscrolledwindow.c to display the effects
of this property.

1 files changed, 52 insertions, 12 deletions

diff --git a/gtk/gtkviewport.c b/gtk/gtkviewport.c
index 4389646325..573910dcdc 100644
--- a/gtk/gtkviewport.c
+++ b/gtk/gtkviewport.c
@@ -66,14 +66,19 @@ struct _GtkViewportPrivate
 
   GdkWindow      *bin_window;
   GdkWindow      *view_window;
+
+  /* GtkScrollablePolicy needs to be checked when
+   * driving the scrollable adjustment values */
+  guint hscroll_policy : 1;
+  guint vscroll_policy : 1;
 };
 
 enum {
   PROP_0,
   PROP_HADJUSTMENT,
   PROP_VADJUSTMENT,
-  PROP_MIN_DISPLAY_WIDTH,
-  PROP_MIN_DISPLAY_HEIGHT,
+  PROP_HSCROLL_POLICY,
+  PROP_VSCROLL_POLICY,
   PROP_SHADOW_TYPE
 };
 
@@ -139,8 +144,10 @@ gtk_viewport_class_init (GtkViewportClass *class)
   container_class->add = gtk_viewport_add;
 
   /* GtkScrollable implementation */
-  g_object_class_override_property (gobject_class, PROP_HADJUSTMENT, "hadjustment");
-  g_object_class_override_property (gobject_class, PROP_VADJUSTMENT, "vadjustment");
+  g_object_class_override_property (gobject_class, PROP_HADJUSTMENT,    "hadjustment");
+  g_object_class_override_property (gobject_class, PROP_VADJUSTMENT,    "vadjustment");
+  g_object_class_override_property (gobject_class, PROP_HSCROLL_POLICY, "hscroll-policy");
+  g_object_class_override_property (gobject_class, PROP_VSCROLL_POLICY, "vscroll-policy");
 
   g_object_class_install_property (gobject_class,
                                    PROP_SHADOW_TYPE,
@@ -172,6 +179,14 @@ gtk_viewport_set_property (GObject         *object,
     case PROP_VADJUSTMENT:
       gtk_viewport_set_vadjustment (viewport, g_value_get_object (value));
       break;
+    case PROP_HSCROLL_POLICY:
+      viewport->priv->hscroll_policy = g_value_get_enum (value);
+      gtk_widget_queue_resize (GTK_WIDGET (viewport));
+      break;
+    case PROP_VSCROLL_POLICY:
+      viewport->priv->vscroll_policy = g_value_get_enum (value);
+      gtk_widget_queue_resize (GTK_WIDGET (viewport));
+      break;
     case PROP_SHADOW_TYPE:
       gtk_viewport_set_shadow_type (viewport, g_value_get_enum (value));
       break;
@@ -198,6 +213,12 @@ gtk_viewport_get_property (GObject         *object,
     case PROP_VADJUSTMENT:
       g_value_set_object (value, priv->vadjustment);
       break;
+    case PROP_HSCROLL_POLICY:
+      g_value_set_enum (value, priv->hscroll_policy);
+      break;
+    case PROP_VSCROLL_POLICY:
+      g_value_set_enum (value, priv->vscroll_policy);
+      break;
     case PROP_SHADOW_TYPE:
       g_value_set_enum (value, priv->shadow_type);
       break;
@@ -414,13 +435,23 @@ viewport_set_hadjustment_values (GtkViewport *viewport,
   child = gtk_bin_get_child (bin);
   if (child && gtk_widget_get_visible (child))
     {
-      gint minimum_width;
+      gint minimum_width, natural_width;
+      gint scroll_height;
+      
+      if (viewport->priv->vscroll_policy == GTK_SCROLL_MINIMUM)
+	gtk_widget_get_preferred_height (child, &scroll_height, NULL);
+      else
+	gtk_widget_get_preferred_height (child, NULL, &scroll_height);
 
       gtk_widget_get_preferred_width_for_height (child,
-                                                 view_allocation.height,
+                                                 MAX (view_allocation.height, scroll_height),
                                                  &minimum_width,
-                                                 NULL);
-      hadjustment->upper = MAX (minimum_width, view_allocation.width);
+                                                 &natural_width);
+
+      if (viewport->priv->hscroll_policy == GTK_SCROLL_MINIMUM)
+	hadjustment->upper = MAX (minimum_width, view_allocation.width);
+      else
+	hadjustment->upper = MAX (natural_width, view_allocation.width);
     }
   else
     hadjustment->upper = view_allocation.width;
@@ -456,14 +487,23 @@ viewport_set_vadjustment_values (GtkViewport *viewport,
   child = gtk_bin_get_child (bin);
   if (child && gtk_widget_get_visible (child))
     {
-      gint minimum_height;
+      gint minimum_height, natural_height;
+      gint scroll_width;
+
+      if (viewport->priv->hscroll_policy == GTK_SCROLL_MINIMUM)
+	gtk_widget_get_preferred_width (child, &scroll_width, NULL);
+      else
+	gtk_widget_get_preferred_width (child, NULL, &scroll_width);
 
       gtk_widget_get_preferred_height_for_width (child,
-                                                 view_allocation.width,
+                                                 MAX (view_allocation.width, scroll_width),
                                                  &minimum_height,
-                                                 NULL);
+                                                 &natural_height);
 
-      vadjustment->upper = MAX (minimum_height, view_allocation.height);
+      if (viewport->priv->vscroll_policy == GTK_SCROLL_MINIMUM)
+	vadjustment->upper = MAX (minimum_height, view_allocation.height);
+      else
+	vadjustment->upper = MAX (natural_height, view_allocation.height);
     }
   else
     vadjustment->upper = view_allocation.height;