Refactor BKE_bpath module.

The main goal of this refactor is to make BPath module use `IDTypeInfo`,
and move each ID-specific part of the `foreach_path` looper into their
own IDTypeInfo struct, using a new `foreach_path` callback.

Additionally, following improvements/cleanups are included:
* Attempt to get better, more consistent namings.
** In particular, move from `path_visitor` to more standard `foreach_path`.
* Update and extend documentation.
** API doc was moved to header, according to recent discussions on this
   topic.
* Remove `BKE_bpath_relocate_visitor` from API, this is specific
  callback that belongs in `lib_id.c` user code.

NOTE: This commit is expected to be 100% non-behavioral-change. This
implies that several potential further changes were only noted as
comments (like using a more generic solution for
`lib_id_library_local_paths`, addressing inconsistencies like path of
packed libraries always being skipped, regardless of the
`BKE_BPATH_FOREACH_PATH_SKIP_PACKED` `eBPathForeachFlag` flag value,
etc.).

NOTE: basic unittests were added to master already in
rBdcc500e5a265093bc9cc.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D13381

1 files changed, 13 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/volume.cc b/source/blender/blenkernel/intern/volume.cc
index 75f23ca0598..c79d4e8cd87 100644
--- a/source/blender/blenkernel/intern/volume.cc
+++ b/source/blender/blenkernel/intern/volume.cc
@@ -41,6 +41,7 @@
 #include "BLI_utildefines.h"
 
 #include "BKE_anim_data.h"
+#include "BKE_bpath.h"
 #include "BKE_geometry_set.hh"
 #include "BKE_global.h"
 #include "BKE_idtype.h"
@@ -576,6 +577,17 @@ static void volume_foreach_cache(ID *id,
   function_callback(id, &key, (void **)&volume->runtime.grids, 0, user_data);
 }
 
+static void volume_foreach_path(ID *id, BPathForeachPathData *bpath_data)
+{
+  Volume *volume = reinterpret_cast<Volume *>(id);
+
+  if (volume->packedfile != nullptr && (bpath_data->flag & BKE_BPATH_FOREACH_PATH_SKIP_PACKED) != 0) {
+    return;
+  }
+
+  BKE_bpath_foreach_path_fixed_process(bpath_data, volume->filepath);
+}
+
 static void volume_blend_write(BlendWriter *writer, ID *id, const void *id_address)
 {
   Volume *volume = (Volume *)id;
@@ -653,6 +665,7 @@ IDTypeInfo IDType_ID_VO = {
     /* make_local */ nullptr,
     /* foreach_id */ volume_foreach_id,
     /* foreach_cache */ volume_foreach_cache,
+    /* foreach_path */ volume_foreach_path,
     /* owner_get */ nullptr,
 
     /* blend_write */ volume_blend_write,