From 245d217e06be3b84aae877aea50c1737732e0c15 Mon Sep 17 00:00:00 2001
From: Benjamin Otte <otte@gnome.org>
Date: Sat, 27 Feb 2016 03:56:07 +0100
Subject: [PATCH] boxgadget: Add ability to draw children in reverse

This is necessary for GtkNotebook so that the stack is always drawn
before the header.
And that is necessary so that the active tab can use negative
margins to overdraw the border of the stack to create a gap and
simulate old GTK2-style visuals for notebooks.
---
 gtk/gtkboxgadget.c        | 18 +++++++++++++++---
 gtk/gtkboxgadgetprivate.h |  2 ++
 gtk/gtknotebook.c         |  5 +++++
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/gtk/gtkboxgadget.c b/gtk/gtkboxgadget.c
index c5657a9261..e47f64b03a 100644
--- a/gtk/gtkboxgadget.c
+++ b/gtk/gtkboxgadget.c
@@ -36,8 +36,10 @@
 typedef struct _GtkBoxGadgetPrivate GtkBoxGadgetPrivate;
 struct _GtkBoxGadgetPrivate {
   GtkOrientation orientation;
-  gboolean draw_focus;
   GArray *children;
+
+  guint draw_focus : 1;
+  guint draw_reverse : 1;
 };
 
 typedef gboolean (* ComputeExpandFunc) (GObject *object, GtkOrientation orientation);
@@ -452,9 +454,10 @@ gtk_box_gadget_draw (GtkCssGadget *gadget,
   GtkWidget *owner = gtk_css_gadget_get_owner (gadget);
   guint i;
 
-  for (i = 0 ; i < priv->children->len; i++)
+  for (i = 0; i < priv->children->len; i++)
     {
-      GtkBoxGadgetChild *child = &g_array_index (priv->children, GtkBoxGadgetChild, i);
+      guint draw_index = priv->draw_reverse ? priv->children->len - 1 - i : i;
+      GtkBoxGadgetChild *child = &g_array_index (priv->children, GtkBoxGadgetChild, draw_index);
 
       if (GTK_IS_WIDGET (child->object))
         gtk_container_propagate_draw (GTK_CONTAINER (owner), GTK_WIDGET (child->object), cr);
@@ -559,6 +562,15 @@ gtk_box_gadget_set_draw_focus (GtkBoxGadget *gadget,
   priv->draw_focus = draw_focus;
 }
 
+void
+gtk_box_gadget_set_draw_reverse (GtkBoxGadget *gadget,
+                                 gboolean      draw_reverse)
+{
+  GtkBoxGadgetPrivate *priv = gtk_box_gadget_get_instance_private (gadget);
+
+  priv->draw_reverse = draw_reverse;
+}
+
 static GtkCssNode *
 get_css_node (GObject *child)
 {
diff --git a/gtk/gtkboxgadgetprivate.h b/gtk/gtkboxgadgetprivate.h
index e59ab9afd9..2fd224010d 100644
--- a/gtk/gtkboxgadgetprivate.h
+++ b/gtk/gtkboxgadgetprivate.h
@@ -58,6 +58,8 @@ void                    gtk_box_gadget_set_orientation          (GtkBoxGadget
                                                                  GtkOrientation          orientation);
 void                    gtk_box_gadget_set_draw_focus           (GtkBoxGadget           *gadget,
                                                                  gboolean                draw_focus);
+void                    gtk_box_gadget_set_draw_reverse         (GtkBoxGadget           *gadget,
+                                                                 gboolean                draw_reverse);
 
 void                    gtk_box_gadget_insert_widget            (GtkBoxGadget           *gadget,
                                                                  int                     pos,
diff --git a/gtk/gtknotebook.c b/gtk/gtknotebook.c
index abd62b2e77..4b2a75b6b5 100644
--- a/gtk/gtknotebook.c
+++ b/gtk/gtknotebook.c
@@ -1304,6 +1304,7 @@ gtk_notebook_init (GtkNotebook *notebook)
                                               GTK_WIDGET (notebook));
   gtk_css_gadget_add_class (priv->gadget, GTK_STYLE_CLASS_FRAME);
   gtk_box_gadget_set_orientation (GTK_BOX_GADGET (priv->gadget), GTK_ORIENTATION_VERTICAL);
+  gtk_box_gadget_set_draw_reverse (GTK_BOX_GADGET (priv->gadget), TRUE);
 
   priv->stack_gadget = gtk_css_custom_gadget_new ("stack",
                                                   GTK_WIDGET (notebook),
@@ -6995,6 +6996,7 @@ gtk_notebook_update_tab_pos (GtkNotebook *notebook)
     case GTK_POS_TOP:
       if (priv->show_tabs)
         gtk_box_gadget_insert_gadget (GTK_BOX_GADGET (priv->gadget), 0, priv->header_gadget, FALSE, FALSE, GTK_ALIGN_FILL);
+      gtk_box_gadget_set_draw_reverse (GTK_BOX_GADGET (priv->gadget), TRUE);
       gtk_box_gadget_set_orientation (GTK_BOX_GADGET (priv->gadget), GTK_ORIENTATION_VERTICAL);
       gtk_box_gadget_set_orientation (GTK_BOX_GADGET (priv->header_gadget), GTK_ORIENTATION_HORIZONTAL);
       break;
@@ -7002,6 +7004,7 @@ gtk_notebook_update_tab_pos (GtkNotebook *notebook)
     case GTK_POS_BOTTOM:
       if (priv->show_tabs)
         gtk_box_gadget_insert_gadget (GTK_BOX_GADGET (priv->gadget), 1, priv->header_gadget, FALSE, FALSE, GTK_ALIGN_FILL);
+      gtk_box_gadget_set_draw_reverse (GTK_BOX_GADGET (priv->gadget), FALSE);
       gtk_box_gadget_set_orientation (GTK_BOX_GADGET (priv->gadget), GTK_ORIENTATION_VERTICAL);
       gtk_box_gadget_set_orientation (GTK_BOX_GADGET (priv->header_gadget), GTK_ORIENTATION_HORIZONTAL);
       break;
@@ -7009,6 +7012,7 @@ gtk_notebook_update_tab_pos (GtkNotebook *notebook)
     case GTK_POS_LEFT:
       if (priv->show_tabs)
         gtk_box_gadget_insert_gadget (GTK_BOX_GADGET (priv->gadget), 0, priv->header_gadget, FALSE, FALSE, GTK_ALIGN_FILL);
+      gtk_box_gadget_set_draw_reverse (GTK_BOX_GADGET (priv->gadget), TRUE);
       gtk_box_gadget_set_orientation (GTK_BOX_GADGET (priv->gadget), GTK_ORIENTATION_HORIZONTAL);
       gtk_box_gadget_set_orientation (GTK_BOX_GADGET (priv->header_gadget), GTK_ORIENTATION_VERTICAL);
       break;
@@ -7016,6 +7020,7 @@ gtk_notebook_update_tab_pos (GtkNotebook *notebook)
     case GTK_POS_RIGHT:
       if (priv->show_tabs)
         gtk_box_gadget_insert_gadget (GTK_BOX_GADGET (priv->gadget), 1, priv->header_gadget, FALSE, FALSE, GTK_ALIGN_FILL);
+      gtk_box_gadget_set_draw_reverse (GTK_BOX_GADGET (priv->gadget), FALSE);
       gtk_box_gadget_set_orientation (GTK_BOX_GADGET (priv->gadget), GTK_ORIENTATION_HORIZONTAL);
       gtk_box_gadget_set_orientation (GTK_BOX_GADGET (priv->header_gadget), GTK_ORIENTATION_VERTICAL);
       break;