[gtk+] stack: Don't underallocate child in interpolate-size case

[Timm Bäder <baedert src gnome org>]

commit ee4ba18d5e4b7550fc9fb0cfe5f83b75f6124cb6
Author: Timm Bäder <mail baedert org>
Date:   Fri Oct 28 12:56:36 2016 +0200

    stack: Don't underallocate child in interpolate-size case
    
    In that case, we can't just rely on the stack allocation being big
    enough. Especially, the child can actually be bigger than the current
    stack allocation, so take that into account when positioning it.

 gtk/gtkstack.c |   41 +++++++++++++++++++++++++++--------------
 1 files changed, 27 insertions(+), 14 deletions(-)
---
diff --git a/gtk/gtkstack.c b/gtk/gtkstack.c
index fd23f8a..cf814b7 100644
--- a/gtk/gtkstack.c
+++ b/gtk/gtkstack.c
@@ -2253,22 +2253,35 @@ gtk_stack_allocate (GtkCssGadget        *gadget,
 
   if (priv->visible_child)
     {
-      int min, nat;
-      GtkAlign valign;
+      int min_width;
+      int min_height;
 
-      gtk_widget_get_preferred_height_for_width (priv->visible_child->widget,
-                                                 allocation->width,
-                                                 &min, &nat);
-      if (priv->interpolate_size)
+      gtk_widget_measure (priv->visible_child->widget, GTK_ORIENTATION_HORIZONTAL,
+                          allocation->height, &min_width, NULL, NULL, NULL);
+      child_allocation.width = MAX (child_allocation.width, min_width);
+
+      gtk_widget_measure (priv->visible_child->widget, GTK_ORIENTATION_VERTICAL,
+                          child_allocation.width, &min_height, NULL, NULL, NULL);
+      child_allocation.height = MAX (child_allocation.height, min_height);
+
+      if (child_allocation.width > allocation->width)
         {
-          valign = gtk_widget_get_valign (priv->visible_child->widget);
-          child_allocation.height = MAX (nat, allocation->height);
-          if (valign == GTK_ALIGN_END &&
-              child_allocation.height > allocation->height)
-            child_allocation.y -= nat - allocation->height;
-          else if (valign == GTK_ALIGN_CENTER &&
-                   child_allocation.height > allocation->height)
-            child_allocation.y -= (nat - allocation->height) / 2;
+          GtkAlign halign = gtk_widget_get_halign (priv->visible_child->widget);
+
+          if (halign == GTK_ALIGN_CENTER || halign == GTK_ALIGN_FILL)
+            child_allocation.x = (allocation->width - child_allocation.width) / 2;
+          else if (halign == GTK_ALIGN_END)
+            child_allocation.x = (allocation->width - child_allocation.width);
+        }
+
+      if (child_allocation.height > allocation->height)
+        {
+          GtkAlign valign = gtk_widget_get_valign (priv->visible_child->widget);
+
+          if (valign == GTK_ALIGN_CENTER || valign == GTK_ALIGN_FILL)
+            child_allocation.y = (allocation->height - child_allocation.height) / 2;
+          else if (valign == GTK_ALIGN_END)
+            child_allocation.x = (allocation->height - child_allocation.height);
         }
 
       gtk_widget_size_allocate (priv->visible_child->widget, &child_allocation);