]> Pileus Git - ~andy/gtk/blobdiff - gtk/gtksizerequest.c
stylecontext: Do invalidation on first resize container
[~andy/gtk] / gtk / gtksizerequest.c
index 0d0bb267cad71f4a43f77ef1e4134de71bdfb3e7..0ce86bd66fc95b849c98347619791f28898604b8 100644 (file)
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
  */
 
-
-/**
- * SECTION:gtksizerequest
- * @Short_Description: Height-for-width geometry management
- * @Title: GtkWidget     
- *
- * The GtkWidget      interface is GTK+'s height-for-width (and width-for-height)
- * geometry management system. Height-for-width means that a widget can
- * change how much vertical space it needs, depending on the amount
- * of horizontal space that it is given (and similar for width-for-height).
- * The most common example is a label that reflows to fill up the available
- * width, wraps to fewer lines, and therefore needs less height.
- *
- * GTK+'s traditional two-pass <link linkend="size-allocation">size-allocation</link>
- * algorithm does not allow this flexibility. #GtkWidget provides a default
- * implementation of the #GtkWidget      interface for existing widgets,
- * which always requests the same height, regardless of the available width.
- *
- * <refsect2>
- * <title>Implementing GtkWidget     </title>
- * <para>
- * Some important things to keep in mind when implementing
- * the GtkWidget      interface and when using it in container
- * implementations.
- *
- * The geometry management system will query a logical hierarchy in
- * only one orientation at a time. When widgets are initially queried
- * for their minimum sizes it is generally done in a dual pass
- * in the direction chosen by the toplevel.
- *
- * For instance when queried in the normal height-for-width mode:
- * First the default minimum and natural width for each widget
- * in the interface will computed and collectively returned to
- * the toplevel by way of gtk_widget_get_preferred_width().
- * Next, the toplevel will use the minimum width to query for the
- * minimum height contextual to that width using
- * gtk_widget_get_preferred_height_for_width(), which will also
- * be a highly recursive operation. This minimum-for-minimum size can
- * be used to set the minimum size constraint on the toplevel.
- *
- * When allocating, each container can use the minimum and natural
- * sizes reported by their children to allocate natural sizes and
- * expose as much content as possible with the given allocation.
- *
- * That means that the request operation at allocation time will
- * usually fire again in contexts of different allocated sizes than
- * the ones originally queried for. #GtkWidget      caches a
- * small number of results to avoid re-querying for the same
- * allocated size in one allocation cycle.
- *
- * A widget that does not actually do height-for-width
- * or width-for-height size negotiations only has to implement
- * get_width() and get_height().
- *
- * If a widget does move content around to smartly use up the
- * allocated size, then it must support the request properly in
- * both orientations; even if the request only makes sense in
- * one orientation.
- *
- * For instance, a GtkLabel that does height-for-width word wrapping
- * will not expect to have get_height() called because that
- * call is specific to a width-for-height request, in this case the
- * label must return the heights contextual to its minimum possible
- * width. By following this rule any widget that handles height-for-width
- * or width-for-height requests will always be allocated at least
- * enough space to fit its own content.
- *
- * Often a widget needs to get its own request during size request or
- * allocation, for example when computing height it may need to also
- * compute width, or when deciding how to use an allocation the widget may
- * need to know its natural size. In these cases, the widget should be
- * careful to call its virtual methods directly, like this:
- * <example>
- *   <title>Widget calling its own size request method.</title>
- *   <programlisting>
- * GTK_SIZE_REQUEST_GET_IFACE(widget)-&gt;get_width(GTK_SIZE_REQUEST(widget), &min, &natural);
- *   </programlisting>
- * </example>
- *
- * It will not work to use the wrapper functions, such as
- * gtk_size_request_get_width(), inside your own size request
- * implementation. These return a request adjusted by #GtkSizeGroup
- * and by the GtkWidgetClass::adjust_size_request virtual method. If a
- * widget used the wrappers inside its virtual method implementations,
- * then the adjustments (such as widget margins) would be applied
- * twice. GTK+ therefore does not allow this and will warn if you try
- * to do it.
- *
- * Of course if you are getting the size request for
- * <emphasis>another</emphasis> widget, such as a child of a
- * container, you <emphasis>must</emphasis> use the wrapper APIs;
- * otherwise, you would not properly consider widget margins,
- * #GtkSizeGroup, and so forth.
- * </para>
- * </refsect2>
- */
-
-
 #include <config.h>
+
 #include "gtksizerequest.h"
-#include "gtksizegroup.h"
+
 #include "gtkdebug.h"
-#include "gtkprivate.h"
 #include "gtkintl.h"
+#include "gtkprivate.h"
+#include "gtksizegroup-private.h"
+#include "gtksizerequestcacheprivate.h"
+#include "gtkwidgetprivate.h"
+#include "deprecated/gtkstyle.h"
 
-/* looks for a cached size request for this for_size. If not
- * found, returns the oldest entry so it can be overwritten
- *
- * Note that this caching code was directly derived from
- * the Clutter toolkit.
- */
-static gboolean
-get_cached_size (SizeRequestCache  *cache,
-                GtkSizeGroupMode   orientation,
-                gint               for_size,
-                SizeRequest      **result)
-{
-  guint i, n_sizes;
-  SizeRequest  *cached_sizes;
-
-  if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
-    {
-      cached_sizes = cache->widths;
-      n_sizes = cache->cached_widths;
-    }
-  else
-    {
-      cached_sizes = cache->heights;
-      n_sizes = cache->cached_widths;
-    }
-
-  /* Search for an already cached size */
-  for (i = 0; i < n_sizes; i++)
-    {
-      if (cached_sizes[i].for_size == for_size)
-       {
-         *result = &cached_sizes[i];
-         return TRUE;
-       }
-    }
-
-  /* If not found, pull a new size from the cache, the returned size cache
-   * will immediately be used to cache the new computed size so we go ahead
-   * and increment the last_cached_width/height right away */
-  if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
-    {
-      if (cache->cached_widths < GTK_SIZE_REQUEST_CACHED_SIZES)
-       {
-         cache->cached_widths++;
-         cache->last_cached_width = cache->cached_widths - 1;
-       }
-      else
-       {
-         if (++cache->last_cached_width == GTK_SIZE_REQUEST_CACHED_SIZES)
-           cache->last_cached_width = 0;
-       }
-
-      *result = &cache->widths[cache->last_cached_width];
-    }
-  else /* GTK_SIZE_GROUP_VERTICAL */
-    {
-      if (cache->cached_heights < GTK_SIZE_REQUEST_CACHED_SIZES)
-       {
-         cache->cached_heights++;
-         cache->last_cached_height = cache->cached_heights - 1;
-       }
-      else
-       {
-         if (++cache->last_cached_height == GTK_SIZE_REQUEST_CACHED_SIZES)
-           cache->last_cached_height = 0;
-       }
-
-      *result = &cache->heights[cache->last_cached_height];
-    }
-
-  return FALSE;
-}
-
-static void
-do_size_request (GtkWidget      *widget,
-                GtkRequisition *requisition)
-{
-  /* Now we dont bother caching the deprecated "size-request" returns,
-   * just unconditionally invoke here just in case we run into legacy stuff */
-  gtk_widget_ensure_style (widget);
-  g_signal_emit_by_name (widget, "size-request", requisition);
-}
 
 #ifndef G_DISABLE_CHECKS
 static GQuark recursion_check_quark = 0;
 #endif /* G_DISABLE_CHECKS */
 
 static void
-push_recursion_check (GtkWidget       *request,
-                      GtkSizeGroupMode orientation,
+push_recursion_check (GtkWidget       *widget,
+                      GtkOrientation   orientation,
                       gint             for_size)
 {
 #ifndef G_DISABLE_CHECKS
@@ -225,9 +48,9 @@ push_recursion_check (GtkWidget       *request,
   if (recursion_check_quark == 0)
     recursion_check_quark = g_quark_from_static_string ("gtk-size-request-in-progress");
 
-  previous_method = g_object_get_qdata (G_OBJECT (request), recursion_check_quark);
+  previous_method = g_object_get_qdata (G_OBJECT (widget), recursion_check_quark);
 
-  if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
+  if (orientation == GTK_ORIENTATION_HORIZONTAL)
     {
       method = for_size < 0 ? "get_width" : "get_width_for_height";
     }
@@ -242,186 +65,249 @@ push_recursion_check (GtkWidget       *request,
                  " GtkWidget     ::%s implementation. "
                  "Should just invoke GTK_WIDGET_GET_CLASS(widget)->%s "
                  "directly rather than using gtk_widget_%s",
-                 G_OBJECT_TYPE_NAME (request), request,
+                 G_OBJECT_TYPE_NAME (widget), widget,
                  method, previous_method,
                  method, method);
     }
 
-  g_object_set_qdata (G_OBJECT (request), recursion_check_quark, (char*) method);
+  g_object_set_qdata (G_OBJECT (widget), recursion_check_quark, (char*) method);
 #endif /* G_DISABLE_CHECKS */
 }
 
 static void
-pop_recursion_check (GtkWidget       *request,
-                     GtkSizeGroupMode orientation)
+pop_recursion_check (GtkWidget       *widget,
+                     GtkOrientation   orientation)
 {
 #ifndef G_DISABLE_CHECKS
-  g_object_set_qdata (G_OBJECT (request), recursion_check_quark, NULL);
+  g_object_set_qdata (G_OBJECT (widget), recursion_check_quark, NULL);
 #endif
 }
 
-static void
-compute_size_for_orientation (GtkWidget         *request,
-                              GtkSizeGroupMode   orientation,
-                              gint               for_size,
-                              gint              *minimum_size,
-                              gint              *natural_size)
+static const char *
+get_vfunc_name (GtkOrientation orientation,
+                gint           for_size)
 {
-  SizeRequestCache *cache;
-  SizeRequest      *cached_size;
-  GtkWidget        *widget;
-  gboolean          found_in_cache = FALSE;
-  int adjusted_min, adjusted_natural;
-
-  g_return_if_fail (GTK_IS_WIDGET (request));
-  g_return_if_fail (minimum_size != NULL || natural_size != NULL);
-
-  widget = GTK_WIDGET (request);
-  cache  = _gtk_widget_peek_request_cache (widget);
-
-  if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
-    {
-      cached_size = &cache->widths[0];
-
-      if (!_gtk_widget_get_width_request_needed (widget))
-        found_in_cache = get_cached_size (cache, orientation, for_size, &cached_size);
-      else
-        {
-          memset (cache->widths, 0, GTK_SIZE_REQUEST_CACHED_SIZES * sizeof (SizeRequest));
-          cache->cached_widths = 1;
-          cache->last_cached_width = 0;
-        }
-    }
+  if (orientation == GTK_ORIENTATION_HORIZONTAL)
+    return for_size < 0 ? "get_preferred_width" : "get_preferred_width_for_height";
   else
-    {
-      cached_size = &cache->heights[0];
-
-      if (!_gtk_widget_get_height_request_needed (widget))
-        found_in_cache = get_cached_size (cache, orientation, for_size, &cached_size);
-      else
-        {
-          memset (cache->heights, 0, GTK_SIZE_REQUEST_CACHED_SIZES * sizeof (SizeRequest));
-          cache->cached_heights = 1;
-          cache->last_cached_height = 0;
-        }
-    }
+    return for_size < 0 ? "get_preferred_height" : "get_preferred_height_for_width";
+}
 
+static void
+gtk_widget_query_size_for_orientation (GtkWidget        *widget,
+                                       GtkOrientation    orientation,
+                                       gint              for_size,
+                                       gint             *minimum_size,
+                                       gint             *natural_size)
+{
+  SizeRequestCache *cache;
+  gint min_size = 0;
+  gint nat_size = 0;
+  gboolean found_in_cache;
+
+  if (gtk_widget_get_request_mode (widget) == GTK_SIZE_REQUEST_CONSTANT_SIZE)
+    for_size = -1;
+
+  cache = _gtk_widget_peek_request_cache (widget);
+  found_in_cache = _gtk_size_request_cache_lookup (cache,
+                                                   orientation,
+                                                   for_size,
+                                                   &min_size,
+                                                   &nat_size);
+  
   if (!found_in_cache)
     {
-      GtkRequisition requisition = { 0, 0 };
-      gint min_size = 0, nat_size = 0;
-      gint requisition_size;
+      gint adjusted_min, adjusted_natural, adjusted_for_size = for_size;
 
-      /* Unconditional size request runs but is often unhandled. */
-      do_size_request (widget, &requisition);
+      gtk_widget_ensure_style (widget);
 
-      push_recursion_check (request, orientation, for_size);
-      if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
+      if (orientation == GTK_ORIENTATION_HORIZONTAL)
         {
-          requisition_size = requisition.width;
-
           if (for_size < 0)
-            GTK_WIDGET_GET_CLASS (request)->get_preferred_width (request, &min_size, &nat_size);
+            {
+             push_recursion_check (widget, orientation, for_size);
+              GTK_WIDGET_GET_CLASS (widget)->get_preferred_width (widget, &min_size, &nat_size);
+             pop_recursion_check (widget, orientation);
+            }
           else
-            GTK_WIDGET_GET_CLASS (request)->get_preferred_width_for_height (request, for_size, 
-                                                                                  &min_size, &nat_size);
+            {
+              gint ignored_position = 0;
+              gint minimum_height;
+              gint natural_height;
+
+             /* Pull the base natural height from the cache as it's needed to adjust
+              * the proposed 'for_size' */
+             gtk_widget_get_preferred_height (widget, &minimum_height, &natural_height);
+
+              /* convert for_size to unadjusted height (for_size is a proposed allocation) */
+              GTK_WIDGET_GET_CLASS (widget)->adjust_size_allocation (widget,
+                                                                     GTK_ORIENTATION_VERTICAL,
+                                                                     &minimum_height,
+                                                                    &natural_height,
+                                                                     &ignored_position,
+                                                                     &adjusted_for_size);
+
+             push_recursion_check (widget, orientation, for_size);
+              GTK_WIDGET_GET_CLASS (widget)->get_preferred_width_for_height (widget, 
+                                                                            MAX (adjusted_for_size, minimum_height),
+                                                                            &min_size, &nat_size);
+             pop_recursion_check (widget, orientation);
+            }
         }
       else
         {
-          requisition_size = requisition.height;
-
           if (for_size < 0)
-            GTK_WIDGET_GET_CLASS (request)->get_preferred_height (request, &min_size, &nat_size);
+            {
+             push_recursion_check (widget, orientation, for_size);
+              GTK_WIDGET_GET_CLASS (widget)->get_preferred_height (widget, &min_size, &nat_size);
+             pop_recursion_check (widget, orientation);
+            }
           else
-            GTK_WIDGET_GET_CLASS (request)->get_preferred_height_for_width (request, for_size, 
-                                                                                  &min_size, &nat_size);
+            {
+              gint ignored_position = 0;
+              gint minimum_width;
+              gint natural_width;
+
+             /* Pull the base natural width from the cache as it's needed to adjust
+              * the proposed 'for_size' */
+             gtk_widget_get_preferred_width (widget, &minimum_width, &natural_width);
+
+              /* convert for_size to unadjusted width (for_size is a proposed allocation) */
+              GTK_WIDGET_GET_CLASS (widget)->adjust_size_allocation (widget,
+                                                                     GTK_ORIENTATION_HORIZONTAL,
+                                                                    &minimum_width,
+                                                                     &natural_width,
+                                                                     &ignored_position,
+                                                                     &adjusted_for_size);
+
+             push_recursion_check (widget, orientation, for_size);
+              GTK_WIDGET_GET_CLASS (widget)->get_preferred_height_for_width (widget, 
+                                                                            MAX (adjusted_for_size, minimum_width),
+                                                                            &min_size, &nat_size);
+             pop_recursion_check (widget, orientation);
+            }
         }
-      pop_recursion_check (request, orientation);
 
       if (min_size > nat_size)
         {
-          g_warning ("%s %p reported min size %d and natural size %d; natural size must be >= min size",
-                     G_OBJECT_TYPE_NAME (request), request, min_size, nat_size);
+          g_warning ("%s %p reported min size %d and natural size %d in %s(); natural size must be >= min size",
+                     G_OBJECT_TYPE_NAME (widget), widget, min_size, nat_size, get_vfunc_name (orientation, for_size));
         }
 
-      /* Support for dangling "size-request" signal implementations on
-       * legacy widgets
-       */
-      min_size = MAX (min_size, requisition_size);
-      nat_size = MAX (nat_size, requisition_size);
-
-      cached_size->minimum_size = min_size;
-      cached_size->natural_size = nat_size;
-      cached_size->for_size     = for_size;
+      adjusted_min     = min_size;
+      adjusted_natural = nat_size;
+      GTK_WIDGET_GET_CLASS (widget)->adjust_size_request (widget,
+                                                          orientation,
+                                                          &adjusted_min,
+                                                          &adjusted_natural);
 
-      if (orientation == GTK_SIZE_GROUP_HORIZONTAL)
-          _gtk_widget_set_width_request_needed (widget, FALSE);
-      else
-          _gtk_widget_set_height_request_needed (widget, FALSE);
-
-      adjusted_min = cached_size->minimum_size;
-      adjusted_natural = cached_size->natural_size;
-      GTK_WIDGET_GET_CLASS (request)->adjust_size_request (GTK_WIDGET (request),
-                                                           orientation == GTK_SIZE_GROUP_HORIZONTAL ?
-                                                           GTK_ORIENTATION_HORIZONTAL :
-                                                           GTK_ORIENTATION_VERTICAL,
-                                                           cached_size->for_size,
-                                                           &adjusted_min,
-                                                           &adjusted_natural);
-
-      if (adjusted_min < cached_size->minimum_size ||
-          adjusted_natural < cached_size->natural_size)
+      if (adjusted_min < min_size ||
+          adjusted_natural < nat_size)
         {
           g_warning ("%s %p adjusted size %s min %d natural %d must not decrease below min %d natural %d",
-                     G_OBJECT_TYPE_NAME (request), request,
-                     orientation == GTK_SIZE_GROUP_VERTICAL ? "vertical" : "horizontal",
+                     G_OBJECT_TYPE_NAME (widget), widget,
+                     orientation == GTK_ORIENTATION_VERTICAL ? "vertical" : "horizontal",
                      adjusted_min, adjusted_natural,
-                     cached_size->minimum_size, cached_size->natural_size);
+                     min_size, nat_size);
           /* don't use the adjustment */
         }
       else if (adjusted_min > adjusted_natural)
         {
           g_warning ("%s %p adjusted size %s min %d natural %d original min %d natural %d has min greater than natural",
-                     G_OBJECT_TYPE_NAME (request), request,
-                     orientation == GTK_SIZE_GROUP_VERTICAL ? "vertical" : "horizontal",
+                     G_OBJECT_TYPE_NAME (widget), widget,
+                     orientation == GTK_ORIENTATION_VERTICAL ? "vertical" : "horizontal",
                      adjusted_min, adjusted_natural,
-                     cached_size->minimum_size, cached_size->natural_size);
+                     min_size, nat_size);
           /* don't use the adjustment */
         }
       else
         {
           /* adjustment looks good */
-          cached_size->minimum_size = adjusted_min;
-          cached_size->natural_size = adjusted_natural;
+          min_size = adjusted_min;
+          nat_size = adjusted_natural;
         }
 
-      /* Update size-groups with our request and update our cached requests 
-       * with the size-group values in a single pass.
-       */
-      _gtk_size_group_bump_requisition (GTK_WIDGET (request),
-                                       orientation, 
-                                       &cached_size->minimum_size,
-                                       &cached_size->natural_size);
+      _gtk_size_request_cache_commit (cache,
+                                      orientation,
+                                      for_size,
+                                      min_size,
+                                      nat_size);
     }
 
   if (minimum_size)
-    *minimum_size = cached_size->minimum_size;
+    *minimum_size = min_size;
 
   if (natural_size)
-    *natural_size = cached_size->natural_size;
+    *natural_size = nat_size;
 
-  g_assert (cached_size->minimum_size <= cached_size->natural_size);
+  g_assert (min_size <= nat_size);
 
   GTK_NOTE (SIZE_REQUEST,
             g_print ("[%p] %s\t%s: %d is minimum %d and natural: %d (hit cache: %s)\n",
-                     request, G_OBJECT_TYPE_NAME (request),
-                     orientation == GTK_SIZE_GROUP_HORIZONTAL ?
+                     widget, G_OBJECT_TYPE_NAME (widget),
+                     orientation == GTK_ORIENTATION_HORIZONTAL ?
                      "width for height" : "height for width" ,
-                     for_size,
-                     cached_size->minimum_size,
-                     cached_size->natural_size,
+                     for_size, min_size, nat_size,
                      found_in_cache ? "yes" : "no"));
+}
 
+/* This is the main function that checks for a cached size and
+ * possibly queries the widget class to compute the size if it's
+ * not cached. If the for_size here is -1, then get_preferred_width()
+ * or get_preferred_height() will be used.
+ */
+void
+_gtk_widget_compute_size_for_orientation (GtkWidget        *widget,
+                                          GtkOrientation    orientation,
+                                          gint              for_size,
+                                          gint             *minimum,
+                                          gint             *natural)
+{
+  GHashTable *widgets;
+  GHashTableIter iter;
+  gpointer key;
+  gint    min_result = 0, nat_result = 0;
+
+  if (!gtk_widget_get_visible (widget) && !gtk_widget_is_toplevel (widget))
+    {
+      if (minimum)
+        *minimum = 0;
+      if (natural)
+        *natural = 0;
+      return;
+    }
+
+  if (G_LIKELY (!_gtk_widget_get_sizegroups (widget)))
+    {
+      gtk_widget_query_size_for_orientation (widget, orientation, for_size, minimum, natural);
+      return;
+    }
+
+  widgets = _gtk_size_group_get_widget_peers (widget, orientation);
+
+  g_hash_table_foreach (widgets, (GHFunc) g_object_ref, NULL);
+  
+  g_hash_table_iter_init (&iter, widgets);
+  while (g_hash_table_iter_next (&iter, &key, NULL))
+    {
+      GtkWidget *tmp_widget = key;
+      gint min_dimension, nat_dimension;
+
+      gtk_widget_query_size_for_orientation (tmp_widget, orientation, for_size, &min_dimension, &nat_dimension);
+
+      min_result = MAX (min_result, min_dimension);
+      nat_result = MAX (nat_result, nat_dimension);
+    }
+
+  g_hash_table_foreach (widgets, (GHFunc) g_object_unref, NULL);
+
+  g_hash_table_destroy (widgets);
+
+  if (minimum)
+    *minimum = min_result;
+
+  if (natural)
+    *natural = nat_result;
 }
 
 /**
@@ -443,16 +329,19 @@ compute_size_for_orientation (GtkWidget         *request,
 GtkSizeRequestMode
 gtk_widget_get_request_mode (GtkWidget *widget)
 {
-  GtkWidgetClass *klass;
+  SizeRequestCache *cache;
+
+  g_return_val_if_fail (GTK_IS_WIDGET (widget), GTK_SIZE_REQUEST_CONSTANT_SIZE);
 
-  g_return_val_if_fail (GTK_IS_WIDGET (widget), GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH);
+  cache = _gtk_widget_peek_request_cache (widget);
 
-  klass = GTK_WIDGET_GET_CLASS (widget);
-  if (klass->get_request_mode)
-    return klass->get_request_mode (widget);
+  if (!cache->request_mode_valid)
+    {
+      cache->request_mode = GTK_WIDGET_GET_CLASS (widget)->get_request_mode (widget);
+      cache->request_mode_valid = TRUE;
+    }
 
-  /* By default widgets are height-for-width. */
-  return GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH;
+  return cache->request_mode;
 }
 
 /**
@@ -468,7 +357,7 @@ gtk_widget_get_request_mode (GtkWidget *widget)
  *
  * The returned request will be modified by the
  * GtkWidgetClass::adjust_size_request virtual method and by any
- * #GtkSizeGroup that have been applied. That is, the returned request
+ * #GtkSizeGroup<!-- -->s that have been applied. That is, the returned request
  * is the one that should be used for layout, not necessarily the one
  * returned by the widget itself.
  *
@@ -479,8 +368,14 @@ gtk_widget_get_preferred_width (GtkWidget *widget,
                                 gint      *minimum_width,
                                 gint      *natural_width)
 {
-  compute_size_for_orientation (widget, GTK_SIZE_GROUP_HORIZONTAL,
-                                -1, minimum_width, natural_width);
+  g_return_if_fail (GTK_IS_WIDGET (widget));
+  g_return_if_fail (minimum_width != NULL || natural_width != NULL);
+
+  _gtk_widget_compute_size_for_orientation (widget,
+                                            GTK_ORIENTATION_HORIZONTAL,
+                                            -1,
+                                            minimum_width,
+                                            natural_width);
 }
 
 
@@ -496,7 +391,7 @@ gtk_widget_get_preferred_width (GtkWidget *widget,
  *
  * The returned request will be modified by the
  * GtkWidgetClass::adjust_size_request virtual method and by any
- * #GtkSizeGroup that have been applied. That is, the returned request
+ * #GtkSizeGroup<!-- -->s that have been applied. That is, the returned request
  * is the one that should be used for layout, not necessarily the one
  * returned by the widget itself.
  *
@@ -507,8 +402,14 @@ gtk_widget_get_preferred_height (GtkWidget *widget,
                                  gint      *minimum_height,
                                  gint      *natural_height)
 {
-  compute_size_for_orientation (widget, GTK_SIZE_GROUP_VERTICAL,
-                                -1, minimum_height, natural_height);
+  g_return_if_fail (GTK_IS_WIDGET (widget));
+  g_return_if_fail (minimum_height != NULL || natural_height != NULL);
+
+  _gtk_widget_compute_size_for_orientation (widget,
+                                            GTK_ORIENTATION_VERTICAL,
+                                            -1,
+                                            minimum_height,
+                                            natural_height);
 }
 
 
@@ -525,7 +426,7 @@ gtk_widget_get_preferred_height (GtkWidget *widget,
  *
  * The returned request will be modified by the
  * GtkWidgetClass::adjust_size_request virtual method and by any
- * #GtkSizeGroup that have been applied. That is, the returned request
+ * #GtkSizeGroup<!-- -->s that have been applied. That is, the returned request
  * is the one that should be used for layout, not necessarily the one
  * returned by the widget itself.
  *
@@ -537,8 +438,15 @@ gtk_widget_get_preferred_width_for_height (GtkWidget *widget,
                                            gint      *minimum_width,
                                            gint      *natural_width)
 {
-  compute_size_for_orientation (widget, GTK_SIZE_GROUP_HORIZONTAL,
-                                height, minimum_width, natural_width);
+  g_return_if_fail (GTK_IS_WIDGET (widget));
+  g_return_if_fail (minimum_width != NULL || natural_width != NULL);
+  g_return_if_fail (height >= 0);
+
+  _gtk_widget_compute_size_for_orientation (widget,
+                                            GTK_ORIENTATION_HORIZONTAL,
+                                            height,
+                                            minimum_width,
+                                            natural_width);
 }
 
 /**
@@ -553,7 +461,7 @@ gtk_widget_get_preferred_width_for_height (GtkWidget *widget,
  *
  * The returned request will be modified by the
  * GtkWidgetClass::adjust_size_request virtual method and by any
- * #GtkSizeGroup that have been applied. That is, the returned request
+ * #GtkSizeGroup<!-- -->s that have been applied. That is, the returned request
  * is the one that should be used for layout, not necessarily the one
  * returned by the widget itself.
  *
@@ -565,8 +473,15 @@ gtk_widget_get_preferred_height_for_width (GtkWidget *widget,
                                            gint      *minimum_height,
                                            gint      *natural_height)
 {
-  compute_size_for_orientation (widget, GTK_SIZE_GROUP_VERTICAL,
-                                width, minimum_height, natural_height);
+  g_return_if_fail (GTK_IS_WIDGET (widget));
+  g_return_if_fail (minimum_height != NULL || natural_height != NULL);
+  g_return_if_fail (width >= 0);
+
+  _gtk_widget_compute_size_for_orientation (widget,
+                                            GTK_ORIENTATION_VERTICAL,
+                                            width,
+                                            minimum_height,
+                                            natural_height);
 }
 
 /**
@@ -575,11 +490,18 @@ gtk_widget_get_preferred_height_for_width (GtkWidget *widget,
  * @minimum_size: (out) (allow-none): location for storing the minimum size, or %NULL
  * @natural_size: (out) (allow-none): location for storing the natural size, or %NULL
  *
- * Retrieves the minimum and natural size of a widget taking
+ * Retrieves the minimum and natural size of a widget, taking
  * into account the widget's preference for height-for-width management.
  *
  * This is used to retrieve a suitable size by container widgets which do
- * not impose any restrictions on the child placement.
+ * not impose any restrictions on the child placement. It can be used
+ * to deduce toplevel window and menu sizes as well as child widgets in
+ * free-form containers such as GtkLayout.
+ *
+ * <note><para>Handle with care. Note that the natural height of a height-for-width
+ * widget will generally be a smaller size than the minimum height, since the required
+ * height for the natural width is generally smaller than the required height for
+ * the minimum width.</para></note>
  *
  * Since: 3.0
  */
@@ -611,7 +533,7 @@ gtk_widget_get_preferred_size (GtkWidget      *widget,
                                                      NULL, &natural_size->height);
        }
     }
-  else /* GTK_SIZE_REQUEST_WIDTH_FOR_HEIGHT */
+  else /* GTK_SIZE_REQUEST_WIDTH_FOR_HEIGHT or CONSTANT_SIZE */
     {
       gtk_widget_get_preferred_height (widget, &min_height, &nat_height);
 
@@ -657,14 +579,14 @@ compare_gap (gconstpointer p1,
 }
 
 /**
- * gtk_distribute_natural_allocation: 
+ * gtk_distribute_natural_allocation:
  * @extra_space: Extra space to redistribute among children after subtracting
  *               minimum sizes and any child padding from the overall allocation
  * @n_requested_sizes: Number of requests to fit into the allocation
  * @sizes: An array of structs with a client pointer and a minimum/natural size
  *         in the orientation of the allocation.
  *
- * Distributes @extra_space to child @sizes by bringing up smaller
+ * Distributes @extra_space to child @sizes by bringing smaller
  * children up to natural size first.
  *
  * The remaining space will be added to the @minimum_size member of the
@@ -674,7 +596,7 @@ compare_gap (gconstpointer p1,
  * Returns: The remainder of @extra_space after redistributing space
  * to @sizes.
  */
-gint 
+gint
 gtk_distribute_natural_allocation (gint              extra_space,
                                   guint             n_requested_sizes,
                                   GtkRequestedSize *sizes)
@@ -705,12 +627,12 @@ gtk_distribute_natural_allocation (gint              extra_space,
    * The following code distributes the additional space by following
    * these rules.
    */
-  
+
   /* Sort descending by gap and position. */
   g_qsort_with_data (spreading,
                     n_requested_sizes, sizeof (guint),
                     compare_gap, sizes);
-  
+
   /* Distribute available space.
    * This master piece of a loop was conceived by Behdad Esfahbod.
    */
@@ -723,14 +645,13 @@ gtk_distribute_natural_allocation (gint              extra_space,
       gint glue = (extra_space + i) / (i + 1);
       gint gap = sizes[(spreading[i])].natural_size
        - sizes[(spreading[i])].minimum_size;
-      
+
       gint extra = MIN (glue, gap);
-      
+
       sizes[spreading[i]].minimum_size += extra;
-      
+
       extra_space -= extra;
     }
 
   return extra_space;
 }
-