[gtk+/wip/overlay-scrollbar] Introduce a helper function

[Matthias Clasen <matthiasc src gnome org>]

commit ca5e57a6bcc28fd8a12a5d4810f18c36d377f134
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Oct 7 22:59:07 2014 -0400

    Introduce a helper function
    
    Instead of making assumptions about enum value ordering,
    introduce a helper function to determine policy values
    for which the scrollbar may be visible.

 gtk/gtkscrolledwindow.c |   28 ++++++++++++++++------------
 1 files changed, 16 insertions(+), 12 deletions(-)
---
diff --git a/gtk/gtkscrolledwindow.c b/gtk/gtkscrolledwindow.c
index 1fadf01..f8434ec 100644
--- a/gtk/gtkscrolledwindow.c
+++ b/gtk/gtkscrolledwindow.c
@@ -584,6 +584,12 @@ may_vscroll (GtkScrolledWindow *scrolled_window)
   return priv->vscrollbar_visible || priv->vscrollbar_policy == GTK_POLICY_EXTERNAL;
 }
 
+static inline gboolean
+policy_may_be_visible (GtkPolicyType policy)
+{
+  return policy == GTK_POLICY_ALWAYS || policy == GTK_POLICY_AUTOMATIC;
+}
+
 static void
 scrolled_window_drag_begin_cb (GtkScrolledWindow *scrolled_window,
                                gdouble            start_x,
@@ -2158,21 +2164,21 @@ gtk_scrolled_window_size_allocate (GtkWidget     *widget,
                }
              else /* priv->hscrollbar_policy != GTK_POLICY_AUTOMATIC */
                {
-                 priv->hscrollbar_visible = priv->hscrollbar_policy < GTK_POLICY_NEVER;
+                 priv->hscrollbar_visible = policy_may_be_visible (priv->hscrollbar_policy);
                  priv->vscrollbar_visible = child_scroll_height > allocation->height - 
                    (priv->hscrollbar_visible ? sb_height + sb_spacing : 0);
                }
            }
          else /* priv->vscrollbar_policy != GTK_POLICY_AUTOMATIC */
            {
-             priv->vscrollbar_visible = priv->vscrollbar_policy < GTK_POLICY_NEVER;
+             priv->vscrollbar_visible = policy_may_be_visible (priv->vscrollbar_policy);
              
              if (priv->hscrollbar_policy == GTK_POLICY_AUTOMATIC)
                priv->hscrollbar_visible = 
                  child_scroll_width > allocation->width - 
                  (priv->vscrollbar_visible ? 0 : sb_width + sb_spacing);
              else
-               priv->hscrollbar_visible = priv->hscrollbar_policy < GTK_POLICY_NEVER;
+               priv->hscrollbar_visible = policy_may_be_visible (priv->hscrollbar_policy);
            }
        } 
       else /* GTK_SIZE_REQUEST_WIDTH_FOR_HEIGHT */
@@ -2219,21 +2225,21 @@ gtk_scrolled_window_size_allocate (GtkWidget     *widget,
                }
              else /* priv->vscrollbar_policy != GTK_POLICY_AUTOMATIC */
                {
-                 priv->vscrollbar_visible = priv->vscrollbar_policy < GTK_POLICY_NEVER;
+                 priv->vscrollbar_visible = policy_may_be_visible (priv->vscrollbar_policy);
                  priv->hscrollbar_visible = child_scroll_width > allocation->width - 
                    (priv->vscrollbar_visible ? sb_width + sb_spacing : 0);
                }
            }
          else /* priv->hscrollbar_policy != GTK_POLICY_AUTOMATIC */
            {
-             priv->hscrollbar_visible = priv->hscrollbar_policy < GTK_POLICY_NEVER;
+             priv->hscrollbar_visible = policy_may_be_visible (priv->hscrollbar_policy);
              
              if (priv->vscrollbar_policy == GTK_POLICY_AUTOMATIC)
                priv->vscrollbar_visible = 
                  child_scroll_height > allocation->height - 
                  (priv->hscrollbar_visible ? 0 : sb_height + sb_spacing);
              else
-               priv->vscrollbar_visible = priv->vscrollbar_policy < GTK_POLICY_NEVER;
+               priv->vscrollbar_visible = policy_may_be_visible (priv->vscrollbar_policy);
            }
        }
 
@@ -2958,7 +2964,7 @@ gtk_scrolled_window_get_preferred_size (GtkWidget      *widget,
                  natural_req.width = MAX (natural_req.width, min_content_width);
                  extra_width = -1;
                }
-             else if (priv->vscrollbar_policy < GTK_POLICY_NEVER)
+             else if (policy_may_be_visible (priv->vscrollbar_policy))
                {
                  minimum_req.width += vscrollbar_requisition.width;
                  natural_req.width += vscrollbar_requisition.width;
@@ -2986,7 +2992,7 @@ gtk_scrolled_window_get_preferred_size (GtkWidget      *widget,
                  natural_req.height = MAX (natural_req.height, min_content_height);
                  extra_height = -1;
                }
-             else if (priv->vscrollbar_policy < GTK_POLICY_NEVER)
+             else if (policy_may_be_visible (priv->vscrollbar_policy))
                {
                  minimum_req.height += vscrollbar_requisition.height;
                  natural_req.height += vscrollbar_requisition.height;
@@ -2995,8 +3001,7 @@ gtk_scrolled_window_get_preferred_size (GtkWidget      *widget,
        }
     }
 
-  if (priv->hscrollbar_policy == GTK_POLICY_AUTOMATIC ||
-      priv->hscrollbar_policy == GTK_POLICY_ALWAYS)
+  if (policy_may_be_visible (priv->hscrollbar_policy))
     {
       minimum_req.width = MAX (minimum_req.width, hscrollbar_requisition.width);
       natural_req.width = MAX (natural_req.width, hscrollbar_requisition.width);
@@ -3004,8 +3009,7 @@ gtk_scrolled_window_get_preferred_size (GtkWidget      *widget,
        extra_height = scrollbar_spacing + hscrollbar_requisition.height;
     }
 
-  if (priv->vscrollbar_policy == GTK_POLICY_AUTOMATIC ||
-      priv->vscrollbar_policy == GTK_POLICY_ALWAYS)
+  if (policy_may_be_visible (priv->vscrollbar_policy))
     {
       minimum_req.height = MAX (minimum_req.height, vscrollbar_requisition.height);
       natural_req.height = MAX (natural_req.height, vscrollbar_requisition.height);