Asset Catalogs: add catalog filter for the asset browser

Given an "active catalog" (i.e. the one selected in the UI), construct
an `AssetCatalogFilter` instance. This filter can determine whether an
asset should be shown or not. It returns `true` when The asset's catalog
ID is:

- the active catalog,
- an alias of the active catalog (so different UUID that maps to the
  same path),
- a sub-catalog of the active catalog.

Not yet hooked up to the UI.

1 files changed, 37 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/asset_catalog.cc b/source/blender/blenkernel/intern/asset_catalog.cc
index 34bd1fd49db..4973de20fb3 100644
--- a/source/blender/blenkernel/intern/asset_catalog.cc
+++ b/source/blender/blenkernel/intern/asset_catalog.cc
@@ -85,6 +85,33 @@ AssetCatalog *AssetCatalogService::find_catalog_by_path(const AssetCatalogPath &
   return nullptr;
 }
 
+AssetCatalogFilter AssetCatalogService::create_catalog_filter(
+    const CatalogID active_catalog_id) const
+{
+  Set<CatalogID> matching_catalog_ids;
+  matching_catalog_ids.add(active_catalog_id);
+
+  const AssetCatalog *active_catalog = find_catalog(active_catalog_id);
+  if (!active_catalog) {
+    /* If the UUID is unknown (i.e. not mapped to an actual Catalog), it is impossible to determine
+     * its children. The filter can still work on the given UUID. */
+    return AssetCatalogFilter(std::move(matching_catalog_ids));
+  }
+
+  /* This cannot just iterate over tree items to get all the required data, because tree items only
+   * represent single UUIDs. It could be used to get the main UUIDs of the children, though, and
+   * then only do an exact match on the path (instead of the more complex `is_contained_in()`
+   * call). Without an extra indexed-by-path acceleration structure, this is still going to require
+   * a linear search, though. */
+  for (const auto &catalog_uptr : this->catalogs_.values()) {
+    if (catalog_uptr->path.is_contained_in(active_catalog->path)) {
+      matching_catalog_ids.add(catalog_uptr->catalog_id);
+    }
+  }
+
+  return AssetCatalogFilter(std::move(matching_catalog_ids));
+}
+
 void AssetCatalogService::delete_catalog(CatalogID catalog_id)
 {
   std::unique_ptr<AssetCatalog> *catalog_uptr_ptr = this->catalogs_.lookup_ptr(catalog_id);
@@ -754,4 +781,14 @@ std::string AssetCatalog::sensible_simple_name_for_path(const AssetCatalogPath &
   return "..." + name.substr(name.length() - 60);
 }
 
+AssetCatalogFilter::AssetCatalogFilter(Set<CatalogID> &&matching_catalog_ids)
+    : matching_catalog_ids(std::move(matching_catalog_ids))
+{
+}
+
+bool AssetCatalogFilter::contains(const CatalogID asset_catalog_id) const
+{
+  return matching_catalog_ids.contains(asset_catalog_id);
+}
+
 }  // namespace blender::bke