GtkOverlay: Don't allocate child except in size_allocate

We were calling gtk_overlay_child_allocate() both in realize
and in add as we wanted to create and position the child windows
for the widgets. However, this call also actually called
gtk_widget_size_allocate() on the child, which it shouldn't. In some
cases the overlay is realized before being allocated, and thus it
will allocate the child at 0x0 which is an invalid size for it to be in.
In particular, if the child has margins set this will result in negative
allocations and warnings.

This fix splits out the allocation computation so that
gtk_overlay_create_child_window can use it without callers
having to call gtk_overlay_child_allocate() to move the windows.

https://bugzilla.gnome.org/show_bug.cgi?id=696623

1 files changed, 55 insertions, 44 deletions

diff --git a/gtk/gtkoverlay.c b/gtk/gtkoverlay.c
index de80637d07..d87e9774b4 100644
--- a/gtk/gtkoverlay.c
+++ b/gtk/gtkoverlay.c
@@ -82,9 +82,52 @@ G_DEFINE_TYPE_WITH_CODE (GtkOverlay, gtk_overlay, GTK_TYPE_BIN,
                          G_IMPLEMENT_INTERFACE (GTK_TYPE_BUILDABLE,
                                                 gtk_overlay_buildable_init))
 
+static void
+gtk_overlay_compute_child_allocation (GtkOverlay      *overlay,
+				      GtkOverlayChild *child,
+				      GtkAllocation *window_allocation,
+				      GtkAllocation *widget_allocation)
+{
+  gint left, right, top, bottom;
+  GtkAllocation allocation, overlay_allocation;
+  gboolean result;
+
+  g_signal_emit (overlay, signals[GET_CHILD_POSITION],
+                 0, child->widget, &allocation, &result);
+
+  gtk_widget_get_allocation (GTK_WIDGET (overlay), &overlay_allocation);
+
+  allocation.x += overlay_allocation.x;
+  allocation.y += overlay_allocation.y;
+
+  /* put the margins outside the window; also arrange things
+   * so that the adjusted child allocation still ends up at 0, 0
+   */
+  left = gtk_widget_get_margin_left (child->widget);
+  right = gtk_widget_get_margin_right (child->widget);
+  top = gtk_widget_get_margin_top (child->widget);
+  bottom = gtk_widget_get_margin_bottom (child->widget);
+
+  if (widget_allocation)
+    {
+      widget_allocation->x = - left;
+      widget_allocation->y = - top;
+      widget_allocation->width = allocation.width;
+      widget_allocation->height = allocation.height;
+    }
+
+  if (window_allocation)
+    {
+      window_allocation->x = allocation.x + left;
+      window_allocation->y = allocation.y + top;
+      window_allocation->width = allocation.width - (left + right);
+      window_allocation->height = allocation.height - (top + bottom);
+    }
+}
+
 static GdkWindow *
 gtk_overlay_create_child_window (GtkOverlay *overlay,
-                                 GtkWidget  *child)
+                                 GtkOverlayChild *child)
 {
   GtkWidget *widget = GTK_WIDGET (overlay);
   GtkAllocation allocation;
@@ -92,7 +135,7 @@ gtk_overlay_create_child_window (GtkOverlay *overlay,
   GdkWindowAttr attributes;
   gint attributes_mask;
 
-  gtk_widget_get_allocation (child, &allocation);
+  gtk_overlay_compute_child_allocation (overlay, child, &allocation, NULL);
 
   attributes.window_type = GDK_WINDOW_CHILD;
   attributes.wclass = GDK_INPUT_OUTPUT;
@@ -108,8 +151,8 @@ gtk_overlay_create_child_window (GtkOverlay *overlay,
   gtk_widget_register_window (widget, window);
   gtk_style_context_set_background (gtk_widget_get_style_context (widget), window);
 
-  gtk_widget_set_parent_window (child, window);
-
+  gtk_widget_set_parent_window (child->widget, window);
+  
   return window;
 }
 
@@ -240,9 +283,7 @@ static void
 gtk_overlay_child_allocate (GtkOverlay      *overlay,
                             GtkOverlayChild *child)
 {
-  gint left, right, top, bottom;
-  GtkAllocation allocation, child_allocation, overlay_allocation;
-  gboolean result;
+  GtkAllocation window_allocation, child_allocation;
 
   if (gtk_widget_get_mapped (GTK_WIDGET (overlay)))
     {
@@ -255,38 +296,14 @@ gtk_overlay_child_allocate (GtkOverlay      *overlay,
   if (!gtk_widget_get_visible (child->widget))
     return;
 
-  g_signal_emit (overlay, signals[GET_CHILD_POSITION],
-                 0, child->widget, &allocation, &result);
-
-  gtk_widget_get_allocation (GTK_WIDGET (overlay), &overlay_allocation);
-
-  allocation.x += overlay_allocation.x;
-  allocation.y += overlay_allocation.y;
-
-  /* put the margins outside the window; also arrange things
-   * so that the adjusted child allocation still ends up at 0, 0
-   */
-  left = gtk_widget_get_margin_left (child->widget);
-  right = gtk_widget_get_margin_right (child->widget);
-  top = gtk_widget_get_margin_top (child->widget);
-  bottom = gtk_widget_get_margin_bottom (child->widget);
-
-  child_allocation.x = - left;
-  child_allocation.y = - top;
-  child_allocation.width = allocation.width;
-  child_allocation.height = allocation.height;
-
-  allocation.x += left;
-  allocation.y += top;
-  allocation.width -= left + right;
-  allocation.height -= top + bottom;
+  gtk_overlay_compute_child_allocation (overlay, child, &window_allocation, &child_allocation);
 
   if (child->window)
     gdk_window_move_resize (child->window,
-                            allocation.x, allocation.y,
-                            allocation.width, allocation.height);
+                            window_allocation.x, window_allocation.y,
+                            window_allocation.width, window_allocation.height);
 
-  gtk_overlay_child_update_style_classes (overlay, child->widget, &allocation);
+  gtk_overlay_child_update_style_classes (overlay, child->widget, &window_allocation);
   gtk_widget_size_allocate (child->widget, &child_allocation);
 }
 
@@ -346,9 +363,7 @@ gtk_overlay_size_allocate (GtkWidget     *widget,
   gtk_widget_size_allocate (main_widget, allocation);
 
   for (children = priv->children; children; children = children->next)
-    {
-      gtk_overlay_child_allocate (overlay, children->data);
-    }
+    gtk_overlay_child_allocate (overlay, children->data);
 }
 
 static gboolean
@@ -423,10 +438,7 @@ gtk_overlay_realize (GtkWidget *widget)
       child = children->data;
 
       if (child->window == NULL)
-	{
-	  child->window = gtk_overlay_create_child_window (overlay, child->widget);
-	  gtk_overlay_child_allocate (overlay, child);
-	}
+	child->window = gtk_overlay_create_child_window (overlay, child);
     }
 }
 
@@ -712,9 +724,8 @@ gtk_overlay_add_overlay (GtkOverlay *overlay,
 
   if (gtk_widget_get_realized (GTK_WIDGET (overlay)))
     {
-      child->window = gtk_overlay_create_child_window (overlay, widget);
+      child->window = gtk_overlay_create_child_window (overlay, child);
       gtk_widget_set_parent (widget, GTK_WIDGET (overlay));
-      gtk_overlay_child_allocate (overlay, child);
     }
   else
     gtk_widget_set_parent (widget, GTK_WIDGET (overlay));