app: Generalize gimp_dock_add/remove_book()

Move the GtkPaned management code into gimp_widgets_add_paned_widget()
and gimp_widgets_remove_paned_widget() in gimpwidgets-utils.[ch] so we
can share this code for GimpDockColumns later.

app/widgets/gimpwidgets-utils.c

@@ -54,6 +54,7 @@
 
 #include "widgets-types.h"
 
+#include "gimpdockseparator.h"
 #include "gimperrordialog.h"
 #include "gimpwidgets-utils.h"
 
@@ -1159,3 +1160,174 @@ gimp_pango_layout_set_weight (PangoLayout *layout,
   pango_layout_set_attributes (layout, attrs);
   pango_attr_list_unref (attrs);
 }
+
+/**
+ * gimp_widgets_add_paned_widget:
+ * @box:                  A #GtkBox
+ * @box_widget_list:      List of current widgets in the @box
+ * @box_widget_keep_last: The widget to keep last in the @box
+ * @widget:               The #GtkWidget to add
+ * @index:                Where to add the @widget
+ *
+ * Add a #GtkWidget to a #GtkBox in a hierarchy of #GtkPaned:s so the
+ * space can be manually distributed between the widgets.
+ **/
+void
+gimp_widgets_add_paned_widget (GtkBox     *box,
+                               GList     **box_widget_list,
+                               GtkWidget  *box_widget_keep_last,
+                               GtkWidget  *widget,
+                               gint        index)
+{
+  gint old_length = 0;
+
+  g_return_if_fail (GTK_IS_BOX (box));
+  g_return_if_fail (box_widget_list != NULL);
+  g_return_if_fail (GTK_IS_WIDGET (box_widget_keep_last) ||
+                    box_widget_keep_last == NULL);
+  g_return_if_fail (GTK_IS_WIDGET (widget));
+
+  /* Calculate length */
+  old_length = g_list_length (*box_widget_list);
+
+  /* If index is invalid append at the end */
+  if (index >= old_length || index < 0)
+    {
+      index = old_length;
+    }
+
+  /* Insert into the list */
+  *box_widget_list = g_list_insert (*box_widget_list, widget, index);
+
+  /* Insert into the GtkPaned hierarchy */
+  if (old_length == 0)
+    {
+      gtk_box_pack_start (box, widget, TRUE, TRUE, 0);
+
+      /* Keep the desired widget at the end */
+      if (box_widget_keep_last)
+        gtk_box_reorder_child (box, box_widget_keep_last, -1);
+    }
+  else
+    {
+      GtkWidget *old_widget;
+      GtkWidget *parent;
+      GtkWidget *paned;
+
+      /* Figure out what widget to detach */
+      if (index == 0)
+        {
+          old_widget = g_list_nth_data (*box_widget_list, index + 1);
+        }
+      else
+        {
+          old_widget = g_list_nth_data (*box_widget_list, index - 1);
+        }
+
+      parent = gtk_widget_get_parent (old_widget);
+
+      if (old_length > 1 && index > 0)
+        {
+          GtkWidget *grandparent = gtk_widget_get_parent (parent);
+
+          old_widget = parent;
+          parent     = grandparent;
+        }
+
+      /* Deatch the widget and bulid up a new hierarchy */
+      g_object_ref (old_widget);
+      gtk_container_remove (GTK_CONTAINER (parent), old_widget);
+
+      paned = gtk_vpaned_new ();
+      if (GTK_IS_VPANED (parent))
+        {
+          gtk_paned_pack1 (GTK_PANED (parent), paned, TRUE, FALSE);
+        }
+      else
+        {
+          gtk_box_pack_start (GTK_BOX (parent), paned, TRUE, TRUE, 0);
+        }
+      gtk_widget_show (paned);
+
+      if (index == 0)
+        {
+          gtk_paned_pack1 (GTK_PANED (paned), widget,
+                           TRUE, FALSE);
+          gtk_paned_pack2 (GTK_PANED (paned), old_widget,
+                           TRUE, FALSE);
+        }
+      else
+        {
+          gtk_paned_pack1 (GTK_PANED (paned), old_widget,
+                           TRUE, FALSE);
+          gtk_paned_pack2 (GTK_PANED (paned), widget,
+                           TRUE, FALSE);
+        }
+
+      g_object_unref (old_widget);
+    }
+}
+
+/**
+ * gimp_widgets_remove_paned_widget:
+ * @box:             A #GtkBox
+ * @box_widget_list: Pointer to list of current widgets in the @box
+ * @widget:          The #GtkWidget to remove
+ *
+ * Remove a #GtkWidget from a #GtkBox added with
+ * gimp_widgets_add_paned_widget().
+ **/
+void
+gimp_widgets_remove_paned_widget (GtkBox     *box,
+                                  GList     **box_widget_list,
+                                  GtkWidget  *widget)
+{
+  gint       old_length   = 0;
+  gint       index        = 0;
+  GtkWidget *other_widget = NULL;
+  GtkWidget *parent       = NULL;
+  GtkWidget *grandparent  = NULL;
+
+  g_return_if_fail (GTK_IS_BOX (box));
+  g_return_if_fail (GTK_IS_WIDGET (widget));
+  g_return_if_fail (box_widget_list);
+
+  /* Calculate length and index */
+  old_length = g_list_length (*box_widget_list);
+  index      = g_list_index (*box_widget_list, widget);
+
+  /* Remove from list */
+  *box_widget_list = g_list_remove (*box_widget_list, widget);
+
+  /* Remove from widget hierarchy */
+  if (old_length == 1)
+    {
+      gtk_container_remove (GTK_CONTAINER (box), widget);
+    }
+  else
+    {
+      g_object_ref (widget);
+
+      parent      = gtk_widget_get_parent (GTK_WIDGET (widget));
+      grandparent = gtk_widget_get_parent (parent);
+
+      if (index == 0)
+        other_widget = gtk_paned_get_child2 (GTK_PANED (parent));
+      else
+        other_widget = gtk_paned_get_child1 (GTK_PANED (parent));
+
+      g_object_ref (other_widget);
+
+      gtk_container_remove (GTK_CONTAINER (parent), other_widget);
+      gtk_container_remove (GTK_CONTAINER (parent), GTK_WIDGET (widget));
+
+      gtk_container_remove (GTK_CONTAINER (grandparent), parent);
+
+      if (GTK_IS_VPANED (grandparent))
+        gtk_paned_pack1 (GTK_PANED (grandparent), other_widget, TRUE, FALSE);
+      else
+        gtk_box_pack_start (box, other_widget, TRUE, TRUE, 0);
+
+      g_object_unref (other_widget);
+    }
+}