[gimp] Add infrastructure for dragging things between branches of a tree

[Michael Natterer <mitch src gnome org>]

commit b2c7c4f61bd65bf73ea8992ce055255e15d7b3e6
Author: Michael Natterer <mitch gimp org>
Date:   Wed Aug 5 18:57:08 2009 +0200

    Add infrastructure for dragging things between branches of a tree
    
    * app/widgets/gimpcontainertreeview-dnd.c
      (gimp_container_tree_view_real_drop_possible): support DND within a
      tree and make sure a group item is not dropped into itself.
    
    * app/widgets/gimpitemtreeview.c (gimp_item_tree_view_drop_viewable):
      implement intra-container reordering within all branches; print a
      message for inter-container reordering because that's not yet
      implemented in the core.

 app/widgets/gimpcontainertreeview-dnd.c |   72 ++++++++++++++++++++-----------
 app/widgets/gimpitemtreeview.c          |   54 +++++++++++++----------
 2 files changed, 78 insertions(+), 48 deletions(-)
---
diff --git a/app/widgets/gimpcontainertreeview-dnd.c b/app/widgets/gimpcontainertreeview-dnd.c
index db611d1..b2f75b2 100644
--- a/app/widgets/gimpcontainertreeview-dnd.c
+++ b/app/widgets/gimpcontainertreeview-dnd.c
@@ -481,10 +481,38 @@ gimp_container_tree_view_real_drop_possible (GimpContainerTreeView   *tree_view,
                                              GtkTreeViewDropPosition *return_drop_pos,
                                              GdkDragAction           *return_drag_action)
 {
-  GimpContainerView *view       = GIMP_CONTAINER_VIEW (tree_view);
-  GimpContainer     *container  = gimp_container_view_get_container (view);
-  gint               src_index  = -1;
-  gint               dest_index = -1;
+  GimpContainerView *view           = GIMP_CONTAINER_VIEW (tree_view);
+  GimpContainer     *container      = gimp_container_view_get_container (view);
+  GimpContainer     *src_container  = NULL;
+  GimpContainer     *dest_container = NULL;
+  gint               src_index      = -1;
+  gint               dest_index     = -1;
+
+  if (src_viewable)
+    {
+      GimpViewable *parent = gimp_viewable_get_parent (src_viewable);
+
+      if (parent)
+        src_container = gimp_viewable_get_children (parent);
+      else if (gimp_container_have (container, GIMP_OBJECT (src_viewable)))
+        src_container = container;
+
+      src_index = gimp_container_get_child_index (src_container,
+                                                  GIMP_OBJECT (src_viewable));
+    }
+
+  if (dest_viewable)
+    {
+      GimpViewable *parent = gimp_viewable_get_parent (dest_viewable);
+
+      if (parent)
+        dest_container = gimp_viewable_get_children (parent);
+      else if (gimp_container_have (container, GIMP_OBJECT (dest_viewable)))
+        dest_container = container;
+
+      dest_index = gimp_container_get_child_index (dest_container,
+                                                   GIMP_OBJECT (dest_viewable));
+    }
 
   if (src_viewable && g_type_is_a (G_TYPE_FROM_INSTANCE (src_viewable),
                                    gimp_container_get_children_type (container)))
@@ -492,33 +520,27 @@ gimp_container_tree_view_real_drop_possible (GimpContainerTreeView   *tree_view,
       if (src_viewable == dest_viewable)
         return FALSE;
 
-      src_index = gimp_container_get_child_index (container,
-                                                  GIMP_OBJECT (src_viewable));
-
-      if (src_index == -1)
-        return FALSE;
-
-      if (dest_viewable)
-        {
-          dest_index = gimp_container_get_child_index (container,
-                                                       GIMP_OBJECT (dest_viewable));
-          if (dest_index == -1)
-            return FALSE;
-        }
-
       if (src_index == -1 || dest_index == -1)
         return FALSE;
-    }
 
-  if (drop_pos == GTK_TREE_VIEW_DROP_BEFORE)
-    {
-      if (dest_index == (src_index + 1))
+      /*  don't allow dropping a parent node onto one of its descendants
+       */
+      if (gimp_viewable_is_ancestor (src_viewable, dest_viewable))
         return FALSE;
     }
-  else
+
+  if (src_container == dest_container)
     {
-      if (dest_index == (src_index - 1))
-        return FALSE;
+      if (drop_pos == GTK_TREE_VIEW_DROP_BEFORE)
+        {
+          if (dest_index == (src_index + 1))
+            return FALSE;
+        }
+      else
+        {
+          if (dest_index == (src_index - 1))
+            return FALSE;
+        }
     }
 
   if (return_drop_pos)
diff --git a/app/widgets/gimpitemtreeview.c b/app/widgets/gimpitemtreeview.c
index 262c2d7..7d49a36 100644
--- a/app/widgets/gimpitemtreeview.c
+++ b/app/widgets/gimpitemtreeview.c
@@ -784,17 +784,9 @@ gimp_item_tree_view_drop_viewable (GimpContainerTreeView   *tree_view,
                                    GimpViewable            *dest_viewable,
                                    GtkTreeViewDropPosition  drop_pos)
 {
-  GimpContainerView     *container_view = GIMP_CONTAINER_VIEW (tree_view);
-  GimpItemTreeView      *item_view      = GIMP_ITEM_TREE_VIEW (tree_view);
   GimpItemTreeViewClass *item_view_class;
-  GimpContainer         *container;
-  gint                   dest_index     = -1;
-
-  container = gimp_container_view_get_container (container_view);
-
-  if (dest_viewable)
-    dest_index = gimp_container_get_child_index (container,
-                                                 GIMP_OBJECT (dest_viewable));
+  GimpItemTreeView      *item_view  = GIMP_ITEM_TREE_VIEW (tree_view);
+  gint                   dest_index = -1;
 
   item_view_class = GIMP_ITEM_TREE_VIEW_GET_CLASS (item_view);
 
@@ -823,25 +815,41 @@ gimp_item_tree_view_drop_viewable (GimpContainerTreeView   *tree_view,
     }
   else if (dest_viewable)
     {
-      gint src_index;
+      GimpContainer *src_container;
+      GimpContainer *dest_container;
+      gint           src_index;
+      gint           dest_index;
+
+      src_container = gimp_item_get_container (GIMP_ITEM (src_viewable));
+      src_index     = gimp_item_get_index (GIMP_ITEM (src_viewable));
 
-      src_index = gimp_container_get_child_index (container,
-                                                  GIMP_OBJECT (src_viewable));
+      dest_container = gimp_item_get_container (GIMP_ITEM (dest_viewable));
+      dest_index     = gimp_item_get_index (GIMP_ITEM (dest_viewable));
 
-      if (drop_pos == GTK_TREE_VIEW_DROP_AFTER && src_index > dest_index)
+      if (src_container == dest_container)
         {
-          dest_index++;
+          if (drop_pos == GTK_TREE_VIEW_DROP_AFTER &&
+              src_index > dest_index)
+            {
+              dest_index++;
+            }
+          else if (drop_pos == GTK_TREE_VIEW_DROP_BEFORE &&
+                   src_index < dest_index)
+            {
+              dest_index--;
+            }
+
+          item_view_class->reorder_item (item_view->priv->image,
+                                         GIMP_ITEM (src_viewable),
+                                         dest_index,
+                                         TRUE,
+                                         item_view_class->reorder_desc);
         }
-      else if (drop_pos == GTK_TREE_VIEW_DROP_BEFORE && src_index < dest_index)
+      else
         {
-          dest_index--;
+          g_printerr ("%s: dnd between containers (%d -> %d)\n",
+                      G_STRFUNC, src_index, dest_index);
         }
-
-      item_view_class->reorder_item (item_view->priv->image,
-                                     GIMP_ITEM (src_viewable),
-                                     dest_index,
-                                     TRUE,
-                                     item_view_class->reorder_desc);
     }
 
   gimp_image_flush (item_view->priv->image);