Asset Browser: Support dragging catalogs into top level

This was an oversight when I added catalog drag & drop support. I forgot
to add this for dragging catalogs into the top level by dragging into to
the "All" item as well. This made the drag & drop support rather broken
because it wouldn't work for a basic case.

source/blender/editors/asset/ED_asset_catalog.hh

@@ -20,6 +20,8 @@
 
 #pragma once
 
+#include <optional>
+
 #include "BKE_asset_catalog.hh"
 
 #include "BLI_string_ref.hh"
@@ -37,6 +39,18 @@ void ED_asset_catalog_remove(AssetLibrary *library, const blender::bke::CatalogI
 void ED_asset_catalog_rename(AssetLibrary *library,
                              blender::bke::CatalogID catalog_id,
                              blender::StringRefNull new_name);
-void ED_asset_catalog_move(AssetLibrary *library,
-                           blender::bke::CatalogID src_catalog_id,
-                           blender::bke::CatalogID dst_parent_catalog_id);
+/**
+ * Reinsert catalog identified by \a src_catalog_id as child to catalog identified by \a
+ * dst_parent_catalog_id. If \a dst_parent_catalog_id is not set, the catalog is moved to the root
+ * level of the tree.
+ * The name of the reinserted catalog is made unique within the parent. Note that moving a catalog
+ * to the same level it was before will also change its name, since the name uniqueness check isn't
+ * smart enough to ignore the item to be reinserted. So the caller is expected to handle this case
+ * to avoid unwanted renames.
+ *
+ * Nothing is done (debug builds run into an assert) if the given catalog IDs can't be identified.
+ */
+void ED_asset_catalog_move(
+    AssetLibrary *library,
+    blender::bke::CatalogID src_catalog_id,
+    std::optional<blender::bke::CatalogID> dst_parent_catalog_id = std::nullopt);

source/blender/editors/asset/intern/asset_catalog.cc

@@ -123,7 +123,7 @@ void ED_asset_catalog_rename(::AssetLibrary *library,
 
 void ED_asset_catalog_move(::AssetLibrary *library,
                            const CatalogID src_catalog_id,
-                           const CatalogID dst_parent_catalog_id)
+                           const std::optional<CatalogID> dst_parent_catalog_id)
 {
   bke::AssetCatalogService *catalog_service = BKE_asset_library_get_catalog_service(library);
   if (!catalog_service) {
@@ -132,9 +132,24 @@ void ED_asset_catalog_move(::AssetLibrary *library,
   }
 
   AssetCatalog *src_catalog = catalog_service->find_catalog(src_catalog_id);
-  AssetCatalog *dst_catalog = catalog_service->find_catalog(dst_parent_catalog_id);
+  if (!src_catalog) {
+    BLI_assert_unreachable();
+    return;
+  }
+  AssetCatalog *dst_catalog = dst_parent_catalog_id ?
+                                  catalog_service->find_catalog(*dst_parent_catalog_id) :
+                                  nullptr;
+  if (!dst_catalog && dst_parent_catalog_id) {
+    BLI_assert_unreachable();
+    return;
+  }
 
-  const AssetCatalogPath new_path = dst_catalog->path / StringRef(src_catalog->path.name());
+  std::string unique_name = catalog_name_ensure_unique(
+      *catalog_service, src_catalog->path.name(), dst_catalog ? dst_catalog->path.c_str() : "");
+  /* If a destination catalog was given, construct the path using that. Otherwise, the path is just
+   * the name of the catalog to be moved, which means it ends up at the root level. */
+  const AssetCatalogPath new_path = dst_catalog ? (dst_catalog->path / unique_name) :
+                                                  AssetCatalogPath{unique_name};
   const AssetCatalogPath clean_new_path = new_path.cleanup();
 
   if (new_path == src_catalog->path || clean_new_path == src_catalog->path) {

source/blender/editors/space_file/asset_catalog_tree_view.cc

@@ -52,6 +52,8 @@ using namespace blender::bke;
 
 namespace blender::ed::asset_browser {
 
+class AssetCatalogTreeViewAllItem;
+
 class AssetCatalogTreeView : public ui::AbstractTreeView {
   ::AssetLibrary *asset_library_;
   /** The asset catalog tree this tree-view represents. */
@@ -61,6 +63,7 @@ class AssetCatalogTreeView : public ui::AbstractTreeView {
 
   friend class AssetCatalogTreeViewItem;
   friend class AssetCatalogDropController;
+  friend class AssetCatalogTreeViewAllItem;
 
  public:
   AssetCatalogTreeView(::AssetLibrary *library,
@@ -69,6 +72,8 @@ class AssetCatalogTreeView : public ui::AbstractTreeView {
 
   void build_tree() override;
 
+  void activate_catalog_by_id(CatalogID catalog_id);
+
  private:
   ui::BasicTreeViewItem &build_catalog_items_recursive(ui::TreeViewItemContainer &view_parent_item,
                                                        AssetCatalogTreeItem &catalog);
@@ -122,16 +127,22 @@ class AssetCatalogDropController : public ui::AbstractTreeViewItemDropController
   bool on_drop(const wmDrag &drag) override;
 
   ::AssetLibrary &get_asset_library() const;
-  AssetCatalog *get_drag_catalog(const wmDrag &drag) const;
 
+  static AssetCatalog *get_drag_catalog(const wmDrag &drag, const ::AssetLibrary &asset_library);
   static bool has_droppable_asset(const wmDrag &drag, const char **r_disabled_hint);
   static bool drop_assets_into_catalog(const AssetCatalogTreeView &tree_view,
                                        const wmDrag &drag,
                                        CatalogID catalog_id,
                                        StringRefNull simple_name = "");
+  /**
+   * \param drop_catalog_id: Can be unset to drop into the root level of the tree.
+   */
+  static bool drop_asset_catalog_into_catalog(
+      const wmDrag &drag,
+      AssetCatalogTreeView &tree_view,
+      const std::optional<CatalogID> drop_catalog_id = std::nullopt);
 
  private:
-  bool drop_asset_catalog_into_catalog(const wmDrag &drag);
   std::string drop_tooltip_asset_list(const wmDrag &drag) const;
   std::string drop_tooltip_asset_catalog(const wmDrag &drag) const;
 };
@@ -142,6 +153,16 @@ class AssetCatalogTreeViewAllItem : public ui::BasicTreeViewItem {
   using BasicTreeViewItem::BasicTreeViewItem;
 
   void build_row(uiLayout &row) override;
+
+  struct DropController : public ui::AbstractTreeViewItemDropController {
+    DropController(AssetCatalogTreeView &tree_view);
+
+    bool can_drop(const wmDrag &drag, const char **r_disabled_hint) const override;
+    std::string drop_tooltip(const wmDrag &drag) const override;
+    bool on_drop(const wmDrag &drag) override;
+  };
+
+  std::unique_ptr<ui::AbstractTreeViewItemDropController> create_drop_controller() const override;
 };
 
 class AssetCatalogTreeViewUnassignedItem : public ui::BasicTreeViewItem {
@@ -228,6 +249,13 @@ void AssetCatalogTreeView::add_unassigned_item()
       [params]() { return params->asset_catalog_visibility == FILE_SHOW_ASSETS_WITHOUT_CATALOG; });
 }
 
+void AssetCatalogTreeView::activate_catalog_by_id(CatalogID catalog_id)
+{
+  params_->asset_catalog_visibility = FILE_SHOW_ASSETS_FROM_CATALOG;
+  params_->catalog_id = catalog_id;
+  WM_main_add_notifier(NC_SPACE | ND_SPACE_ASSET_PARAMS, nullptr);
+}
+
 bool AssetCatalogTreeView::is_active_catalog(CatalogID catalog_id) const
 {
   return (params_->asset_catalog_visibility == FILE_SHOW_ASSETS_FROM_CATALOG) &&
@@ -243,11 +271,8 @@ AssetCatalogTreeViewItem::AssetCatalogTreeViewItem(AssetCatalogTreeItem *catalog
 
 void AssetCatalogTreeViewItem::on_activate()
 {
-  const AssetCatalogTreeView &tree_view = static_cast<const AssetCatalogTreeView &>(
-      get_tree_view());
-  tree_view.params_->asset_catalog_visibility = FILE_SHOW_ASSETS_FROM_CATALOG;
-  tree_view.params_->catalog_id = catalog_item_.get_catalog_id();
-  WM_main_add_notifier(NC_SPACE | ND_SPACE_ASSET_PARAMS, nullptr);
+  AssetCatalogTreeView &tree_view = static_cast<AssetCatalogTreeView &>(get_tree_view());
+  tree_view.activate_catalog_by_id(catalog_item_.get_catalog_id());
 }
 
 void AssetCatalogTreeViewItem::build_row(uiLayout &row)
@@ -344,7 +369,7 @@ AssetCatalogDropController::AssetCatalogDropController(AssetCatalogTreeView &tre
 bool AssetCatalogDropController::can_drop(const wmDrag &drag, const char **r_disabled_hint) const
 {
   if (drag.type == WM_DRAG_ASSET_CATALOG) {
-    const AssetCatalog *drag_catalog = get_drag_catalog(drag);
+    const AssetCatalog *drag_catalog = get_drag_catalog(drag, get_asset_library());
     /* Note: Technically it's not an issue to allow this (the catalog will just receive a new
      * path and the catalog system will generate missing parents from the path). But it does
      * appear broken to users, so disabling entirely. */
@@ -371,7 +396,7 @@ std::string AssetCatalogDropController::drop_tooltip(const wmDrag &drag) const
 std::string AssetCatalogDropController::drop_tooltip_asset_catalog(const wmDrag &drag) const
 {
   BLI_assert(drag.type == WM_DRAG_ASSET_CATALOG);
-  const AssetCatalog *src_catalog = get_drag_catalog(drag);
+  const AssetCatalog *src_catalog = get_drag_catalog(drag, get_asset_library());
 
   return std::string(TIP_("Move Catalog")) + " '" + src_catalog->path.name() + "' " +
          TIP_("into") + " '" + catalog_item_.get_name() + "'";
@@ -396,7 +421,8 @@ std::string AssetCatalogDropController::drop_tooltip_asset_list(const wmDrag &dr
 bool AssetCatalogDropController::on_drop(const wmDrag &drag)
 {
   if (drag.type == WM_DRAG_ASSET_CATALOG) {
-    return drop_asset_catalog_into_catalog(drag);
+    return drop_asset_catalog_into_catalog(
+        drag, tree_view<AssetCatalogTreeView>(), catalog_item_.get_catalog_id());
   }
   return drop_assets_into_catalog(tree_view<AssetCatalogTreeView>(),
                                   drag,
@@ -404,12 +430,15 @@ bool AssetCatalogDropController::on_drop(const wmDrag &drag)
                                   catalog_item_.get_simple_name());
 }
 
-bool AssetCatalogDropController::drop_asset_catalog_into_catalog(const wmDrag &drag)
+bool AssetCatalogDropController::drop_asset_catalog_into_catalog(
+    const wmDrag &drag,
+    AssetCatalogTreeView &tree_view,
+    const std::optional<CatalogID> drop_catalog_id)
 {
   BLI_assert(drag.type == WM_DRAG_ASSET_CATALOG);
   wmDragAssetCatalog *catalog_drag = WM_drag_get_asset_catalog_data(&drag);
-  ED_asset_catalog_move(
-      &get_asset_library(), catalog_drag->drag_catalog_id, catalog_item_.get_catalog_id());
+  ED_asset_catalog_move(tree_view.asset_library_, catalog_drag->drag_catalog_id, drop_catalog_id);
+  tree_view.activate_catalog_by_id(catalog_drag->drag_catalog_id);
 
   WM_main_add_notifier(NC_ASSET | ND_ASSET_CATALOGS, nullptr);
   return true;
@@ -443,13 +472,14 @@ bool AssetCatalogDropController::drop_assets_into_catalog(const AssetCatalogTree
   return true;
 }
 
-AssetCatalog *AssetCatalogDropController::get_drag_catalog(const wmDrag &drag) const
+AssetCatalog *AssetCatalogDropController::get_drag_catalog(const wmDrag &drag,
+                                                           const ::AssetLibrary &asset_library)
 {
   if (drag.type != WM_DRAG_ASSET_CATALOG) {
     return nullptr;
   }
   const bke::AssetCatalogService *catalog_service = BKE_asset_library_get_catalog_service(
-      &get_asset_library());
+      &asset_library);
   const wmDragAssetCatalog *catalog_drag = WM_drag_get_asset_catalog_data(&drag);
 
   return catalog_service->find_catalog(catalog_drag->drag_catalog_id);
@@ -514,6 +544,55 @@ void AssetCatalogTreeViewAllItem::build_row(uiLayout &row)
   RNA_string_set(props, "parent_path", nullptr);
 }
 
+std::unique_ptr<ui::AbstractTreeViewItemDropController> AssetCatalogTreeViewAllItem::
+    create_drop_controller() const
+{
+  return std::make_unique<AssetCatalogTreeViewAllItem::DropController>(
+      static_cast<AssetCatalogTreeView &>(get_tree_view()));
+}
+
+AssetCatalogTreeViewAllItem::DropController::DropController(AssetCatalogTreeView &tree_view)
+    : ui::AbstractTreeViewItemDropController(tree_view)
+{
+}
+
+bool AssetCatalogTreeViewAllItem::DropController::can_drop(const wmDrag &drag,
+                                                           const char **r_disabled_hint) const
+{
+  if (drag.type != WM_DRAG_ASSET_CATALOG) {
+    return false;
+  }
+
+  const AssetCatalog *drag_catalog = AssetCatalogDropController::get_drag_catalog(
+      drag, *tree_view<AssetCatalogTreeView>().asset_library_);
+  if (drag_catalog->path.parent() == "") {
+    *r_disabled_hint = "Catalog is already placed at the highest level";
+    return false;
+  }
+
+  return true;
+}
+
+std::string AssetCatalogTreeViewAllItem::DropController::drop_tooltip(const wmDrag &drag) const
+{
+  BLI_assert(drag.type == WM_DRAG_ASSET_CATALOG);
+  const AssetCatalog *drag_catalog = AssetCatalogDropController::get_drag_catalog(
+      drag, *tree_view<AssetCatalogTreeView>().asset_library_);
+
+  return std::string(TIP_("Move Catalog")) + " '" + drag_catalog->path.name() + "' " +
+         TIP_("to the top level of the tree");
+}
+
+bool AssetCatalogTreeViewAllItem::DropController::on_drop(const wmDrag &drag)
+{
+  BLI_assert(drag.type == WM_DRAG_ASSET_CATALOG);
+  return AssetCatalogDropController::drop_asset_catalog_into_catalog(
+      drag,
+      tree_view<AssetCatalogTreeView>(),
+      /* No value to drop into the root level. */
+      std::nullopt);
+}
+
 /* ---------------------------------------------------------------------- */
 
 std::unique_ptr<ui::AbstractTreeViewItemDropController> AssetCatalogTreeViewUnassignedItem::