Change when the trace_blendfile() callback is called

Previously the `callback.trace_blendfile()` callback was called just before
tracing its dependencies would start, i.e. after opening it. This is now
changed to before opening it, because that can take a long time (to load
SDNA). this will make any UI (like the Flamenco add-on) report the right
filename when waiting for big files, instead of lingering on the
last-opened (potentially very small) blend file.

CHANGELOG.md

@@ -3,6 +3,10 @@
 This file logs the changes that are actually interesting to users (new features,
 changed functionality, fixed bugs).
 
+# Version 1.14 (in development)
+
+- While tracing dependencies, call the progress callback function before opening a blend file, instead of before iterating over its contents. The opening (and loading of SDNA) takes a significant amount of time, so this will make any UI (like the Flamenco add-on) report the right filename when waiting for big files.
+
 # Version 1.13 (2022-07-14)
 
 - Improve an error message when packing fails. It now not only mentions that something went wrong, but also which file and which operation on that file (copy or move) was involved.

blender_asset_tracer/trace/__init__.py

@@ -49,12 +49,10 @@ def deps(
     :param progress_cb: Progress callback object.
     """
 
-    log.info("opening: %s", bfilepath)
-    bfile = blendfile.open_cached(bfilepath)
-
     bi = file2blocks.BlockIterator()
     if progress_cb:
         bi.progress_cb = progress_cb
+    bfile = bi.open_blendfile(bfilepath)
 
     # Remember which block usages we've reported already, without keeping the
     # blocks themselves in memory.

blender_asset_tracer/trace/file2blocks.py

@@ -65,6 +65,13 @@ class BlockIterator:
 
         self.progress_cb = progress.Callback()
 
+    def open_blendfile(self, bfilepath: pathlib.Path) -> blendfile.BlendFile:
+        """Open a blend file, sending notification about this to the progress callback."""
+
+        log.info("opening: %s", bfilepath)
+        self.progress_cb.trace_blendfile(bfilepath)
+        return blendfile.open_cached(bfilepath)
+
     def iter_blocks(
         self,
         bfile: blendfile.BlendFile,
@@ -72,7 +79,6 @@ class BlockIterator:
     ) -> typing.Iterator[blendfile.BlendFileBlock]:
         """Expand blocks with dependencies from other libraries."""
 
-        self.progress_cb.trace_blendfile(bfile.filepath)
         log.info("inspecting: %s", bfile.filepath)
         if limit_to:
             self._queue_named_blocks(bfile, limit_to)
@@ -127,7 +133,7 @@ class BlockIterator:
                 continue
 
             log.debug("Expanding %d blocks in %s", len(idblocks), lib_path)
-            libfile = blendfile.open_cached(lib_path)
+            libfile = self.open_blendfile(lib_path)
             yield from self.iter_blocks(libfile, idblocks)
 
     def _queue_all_blocks(self, bfile: blendfile.BlendFile):