Fixes:

* Preview loading in browser
* Search via bsfs.Graph.sorted to preserve order
* Fixes in parsing.filter.to_string

3 files changed, 48 insertions, 36 deletions

diff --git a/tagit/actions/search.py b/tagit/actions/search.py
index ca36a51..630413f 100644
--- a/tagit/actions/search.py
+++ b/tagit/actions/search.py
@@ -128,7 +128,7 @@ class Search(Action, StorageAwareMixin, ConfigAwareMixin):
             items = Cache.get(self._CACHE_CATEGORY, (query, sort), None)
             if items is None:
                 # FIXME: mb/port: consider sort
-                items = list(session.storage.get(ns.bsfs.File, query))
+                items = list(session.storage.sorted(ns.bsfs.File, query))
                 Cache.append(self._CACHE_CATEGORY, (query, sort), items)
 
             # apply search order because it's cheaper to do it here rather
diff --git a/tagit/parsing/filter/to_string.py b/tagit/parsing/filter/to_string.py
index 0b1a3e1..a2815de 100644
--- a/tagit/parsing/filter/to_string.py
+++ b/tagit/parsing/filter/to_string.py
@@ -206,10 +206,10 @@ class ToString():
             guids = {guid for sub in query for guid in get_guids(sub.value) }
         elif self.matches(query, ast.filter.Not(matcher.Partial(ast.filter.Is))):
             negated = True
-            guids = get_guids(query.value)
+            guids = get_guids(query.expr.value)
         elif self.matches(query, ast.filter.Not(ast.filter.Or(matcher.Rest(matcher.Partial(ast.filter.Is))))):
             negated = True
-            guids = {guid for sub in query for guid in get_guids(sub.value) }
+            guids = {guid for sub in query.expr for guid in get_guids(sub.value) }
 
         if len(guids) == 0:
             # no matches
diff --git a/tagit/widgets/browser.py b/tagit/widgets/browser.py
index bbc3748..28f7440 100644
--- a/tagit/widgets/browser.py
+++ b/tagit/widgets/browser.py
@@ -394,18 +394,30 @@ class Browser(GridLayout, StorageAwareMixin, ConfigAwareMixin):
         if len(items) == 0: # FIXME: mb/port
             return
 
+        resolution = self._cell_resolution()
+        previews = self._fetch_previews(items, resolution)
+        default = resource_find('no_preview.png')
+        for ent, child in zip(reversed(items), childs):
+            if ent in previews:
+                buf = previews[ent]
+            else:
+                buf = open(default, 'rb')
+            child.update(ent, buf, f'{ent}x{resolution}')
+
+    def _fetch_previews(self, items, resolution):
+        """Fetch previews matching *resolution* for *items*.
+        Return a dict with items as key and a BytesIO as value.
+        Items without valid asset are omitted from the dict.
+        """
         # fetch previews
         node_preview = reduce(operator.add, items).get(ns.bse.preview, node=True)
         previews = {p for previews in node_preview.values() for p in previews}
-        previews = reduce(operator.add, previews)
+        previews = reduce(operator.add, previews) # FIXME: empty previews
         # fetch preview resolutions
         res_preview = previews.get(ns.bsp.width, ns.bsp.height, node=True)
-        # get target resolution
-        resolution = self._cell_resolution()
-        # get default preview
-        default = resource_find('no_preview.png')
         # select a preview for each item
-        for ent, child in zip(reversed(items), childs):
+        chosen = {}
+        for ent in items:
             try:
                 # get previews and their resolution for this ent
                 options = []
@@ -416,19 +428,21 @@ class Browser(GridLayout, StorageAwareMixin, ConfigAwareMixin):
                     height = res.get(ns.bsp.height, 0)
                     options.append((preview, Resolution(width, height)))
                 # select the best fitting preview
-                chosen = rmatcher.by_area_min(resolution, options)
-                # open the preview file, default if no asset is available
-                thumb_data = chosen.asset(default=None) # FIXME: get all assets in one call
-                if thumb_data is None:
-                    raise KeyError()
-                thumb = io.BytesIO(thumb_data)
-
+                chosen[ent] = rmatcher.by_area_min(resolution, options)
             except (KeyError, IndexError):
-                # KeyError:
-                # no viable resolution found
-                thumb = open(default, 'rb')
-            # update the image in the child widget
-            child.update(ent, thumb, f'{ent}x{resolution}')
+                # skip objects w/o preview (KeyError in node_preview)
+                # skip objects w/o valid preview (IndexError in rmatcher)
+                pass
+
+        # fetch assets
+        assets = reduce(operator.add, chosen.values()).asset(node=True) # FIXME: empty chosen
+        # build ent -> asset mapping and convert raw data to io buffer
+        return {
+            ent: io.BytesIO(assets[thumb])
+            for ent, thumb
+            in chosen.items()
+            if thumb in assets
+            }
 
     #def _preload_all(self):
     #    # prefer loading from start to end
@@ -436,26 +450,24 @@ class Browser(GridLayout, StorageAwareMixin, ConfigAwareMixin):
 
     def _preload_items(self, items, resolution=None):
         """Load an item into the kivy *Cache* without displaying the image anywhere."""
-        resolution = resolution if resolution is not None else self._cell_resolution()
-
         def _buf_loader(buffer, fname):
             # helper method to load the image from a raw buffer
             with buffer as buf:
                 return ImageLoaderTagit(filename=fname, inline=True, rawdata=buf)
 
-        for obj in items:
-            try:
-                buffer = obj.get('preview').best_match(resolution)
-                source = f'{obj.guid}x{resolution}'
-
-                Loader.image(source,
-                    nocache=False, mipmap=False,
-                    anim_delay=0,
-                    load_callback=partial(_buf_loader, buffer) # mb: pass load_callback
-                    )
-
-            except PredicateNotSet:
-                pass
+        resolution = resolution if resolution is not None else self._cell_resolution()
+        try:
+            foo = self._fetch_previews(items, resolution) # FIXME: _fetch_previews fails on empty previews/chosen
+        except TypeError:
+            return
+        for obj, buffer in foo.items():
+            guid = ','.join(obj.guids)
+            source = f'{guid}x{resolution}'
+            Loader.image(source,
+                nocache=False, mipmap=False,
+                anim_delay=0,
+                load_callback=partial(_buf_loader, buffer) # mb: pass load_callback
+                )
 
 
 class BrowserAwareMixin(object):