Entity path query now shows simple statistics and warns if nothing is…

… displayed (#5693)

### What

* Fixes  #5669


https://github.com/rerun-io/rerun/assets/1220815/91c63fbb-4b6e-4eb9-a5b5-3d14ea41d412

a small step towards making it easy to debug why no data might be shown


### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using newly built examples:
[app.rerun.io](https://app.rerun.io/pr/5693/index.html)
* Using examples from latest `main` build:
[app.rerun.io](https://app.rerun.io/pr/5693/index.html?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[app.rerun.io](https://app.rerun.io/pr/5693/index.html?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG
* [x] If applicable, add a new check to the [release
checklist](https://github.com/rerun-io/rerun/blob/main/tests/python/release_checklist)!

- [PR Build Summary](https://build.rerun.io/pr/5693)
- [Docs
preview](https://rerun.io/preview/b9425379e1b41bf8f1891ffada4e6e0d15edc3cc/docs)
<!--DOCS-PREVIEW-->
- [Examples
preview](https://rerun.io/preview/b9425379e1b41bf8f1891ffada4e6e0d15edc3cc/examples)
<!--EXAMPLES-PREVIEW-->
- [Recent benchmark results](https://build.rerun.io/graphs/crates.html)
- [Wasm size tracking](https://build.rerun.io/graphs/sizes.html)

---------

Co-authored-by: Emil Ernerfeldt <[email protected]>

crates/re_space_view/src/space_view_contents.rs

@@ -223,14 +223,22 @@ impl DataQuery for SpaceViewContents {
         let executor =
             QueryExpressionEvaluator::new(self, visualizable_entities_for_visualizer_systems);
 
+        let mut num_matching_entities = 0;
+        let mut num_visualized_entities = 0;
         let root_handle = {
             re_tracing::profile_scope!("add_entity_tree_to_data_results_recursive");
-            executor
-                .add_entity_tree_to_data_results_recursive(ctx.recording.tree(), &mut data_results)
+            executor.add_entity_tree_to_data_results_recursive(
+                ctx.recording.tree(),
+                &mut data_results,
+                &mut num_matching_entities,
+                &mut num_visualized_entities,
+            )
         };
 
         DataQueryResult {
             tree: DataResultTree::new(data_results, root_handle),
+            num_matching_entities,
+            num_visualized_entities,
         }
     }
 }
@@ -262,6 +270,8 @@ impl<'a> QueryExpressionEvaluator<'a> {
         &self,
         tree: &EntityTree,
         data_results: &mut SlotMap<DataResultHandle, DataResultNode>,
+        num_matching_entities: &mut usize,
+        num_visualized_entities: &mut usize,
     ) -> Option<DataResultHandle> {
         // Early-out optimization
         if !self
@@ -275,27 +285,34 @@ impl<'a> QueryExpressionEvaluator<'a> {
 
         let entity_path = &tree.path;
 
-        let tree_prefix_only = !self.entity_path_filter.is_included(entity_path);
+        let matches_filter = self.entity_path_filter.is_included(entity_path);
+        *num_matching_entities += matches_filter as usize;
 
         // TODO(#5067): For now, we always start by setting visualizers to the full list of available visualizers.
         // This is currently important for evaluating auto-properties during the space-view `on_frame_start`, which
         // is called before the property-overrider has a chance to update this list.
         // This list will be updated below during `update_overrides_recursive` by calling `choose_default_visualizers`
         // on the space view.
-        let visualizers: SmallVec<[_; 4]> = if tree_prefix_only {
-            Default::default()
-        } else {
+        let visualizers: SmallVec<[_; 4]> = if matches_filter {
             self.visualizable_entities_for_visualizer_systems
                 .iter()
                 .filter_map(|(visualizer, ents)| ents.contains(entity_path).then_some(*visualizer))
                 .collect()
+        } else {
+            Default::default()
         };
+        *num_visualized_entities += !visualizers.is_empty() as usize;
 
         let children: SmallVec<[_; 4]> = tree
             .children
             .values()
             .filter_map(|subtree| {
-                self.add_entity_tree_to_data_results_recursive(subtree, data_results)
+                self.add_entity_tree_to_data_results_recursive(
+                    subtree,
+                    data_results,
+                    num_matching_entities,
+                    num_visualized_entities,
+                )
             })
             .collect();
 
@@ -308,7 +325,7 @@ impl<'a> QueryExpressionEvaluator<'a> {
                 data_result: DataResult {
                     entity_path: entity_path.clone(),
                     visualizers,
-                    tree_prefix_only,
+                    tree_prefix_only: !matches_filter,
                     property_overrides: None,
                 },
                 children,

crates/re_viewer/src/ui/selection_panel.rs

@@ -819,11 +819,11 @@ fn blueprint_ui(
 ) {
     match item {
         Item::SpaceView(space_view_id) => {
-            blueprint_ui_for_space_view(ui, ctx, viewport, space_view_id);
+            blueprint_ui_for_space_view(ui, ctx, viewport, *space_view_id);
         }
 
         Item::DataResult(space_view_id, instance_path) => {
-            blueprint_ui_for_data_result(ui, ctx, viewport, space_view_id, instance_path);
+            blueprint_ui_for_data_result(ui, ctx, viewport, *space_view_id, instance_path);
         }
 
         Item::DataSource(_)
@@ -838,14 +838,16 @@ fn blueprint_ui_for_space_view(
     ui: &mut Ui,
     ctx: &ViewerContext<'_>,
     viewport: &mut Viewport<'_, '_>,
-    space_view_id: &SpaceViewId,
+    space_view_id: SpaceViewId,
 ) {
-    if let Some(space_view) = viewport.blueprint.space_view(space_view_id) {
+    if let Some(space_view) = viewport.blueprint.space_view(&space_view_id) {
         if let Some(new_entity_path_filter) = entity_path_filter_ui(
             ui,
+            ctx,
             viewport,
             space_view_id,
             &space_view.contents.entity_path_filter,
+            &space_view.space_origin,
         ) {
             space_view
                 .contents
@@ -862,7 +864,8 @@ fn blueprint_ui_for_space_view(
         )
         .clicked()
     {
-        if let Some(new_space_view_id) = viewport.blueprint.duplicate_space_view(space_view_id, ctx)
+        if let Some(new_space_view_id) =
+            viewport.blueprint.duplicate_space_view(&space_view_id, ctx)
         {
             ctx.selection_state()
                 .set_selection(Item::SpaceView(new_space_view_id));
@@ -874,7 +877,7 @@ fn blueprint_ui_for_space_view(
     ReUi::full_span_separator(ui);
     ui.add_space(ui.spacing().item_spacing.y / 2.0);
 
-    if let Some(space_view) = viewport.blueprint.space_view(space_view_id) {
+    if let Some(space_view) = viewport.blueprint.space_view(&space_view_id) {
         let class_identifier = *space_view.class_identifier();
 
         let space_view_state = viewport.state.space_view_state_mut(
@@ -925,10 +928,10 @@ fn blueprint_ui_for_data_result(
     ui: &mut Ui,
     ctx: &ViewerContext<'_>,
     viewport: &Viewport<'_, '_>,
-    space_view_id: &SpaceViewId,
+    space_view_id: SpaceViewId,
     instance_path: &InstancePath,
 ) {
-    if let Some(space_view) = viewport.blueprint.space_view(space_view_id) {
+    if let Some(space_view) = viewport.blueprint.space_view(&space_view_id) {
         if instance_path.instance_key.is_splat() {
             // splat - the whole entity
             let space_view_class = *space_view.class_identifier();
@@ -948,7 +951,7 @@ fn blueprint_ui_for_data_result(
                 entity_props_ui(
                     ctx,
                     ui,
-                    ctx.lookup_query_result(*space_view_id),
+                    ctx.lookup_query_result(space_view_id),
                     &space_view_class,
                     entity_path,
                     &mut props,
@@ -962,9 +965,11 @@ fn blueprint_ui_for_data_result(
 /// Returns a new filter when the editing is done, and there has been a change.
 fn entity_path_filter_ui(
     ui: &mut egui::Ui,
+    ctx: &ViewerContext<'_>,
     viewport: &mut Viewport<'_, '_>,
-    space_view_id: &SpaceViewId,
+    space_view_id: SpaceViewId,
     filter: &EntityPathFilter,
+    origin: &EntityPath,
 ) -> Option<EntityPathFilter> {
     fn entity_path_filter_help_ui(ui: &mut egui::Ui) {
         let markdown = r#"
@@ -1077,7 +1082,7 @@ The last rule matching `/world/house` is `+ /world/**`, so it is included.
                     .on_hover_text("Modify the entity query using the editor")
                     .clicked()
                 {
-                    viewport.show_add_remove_entities_modal(*space_view_id);
+                    viewport.show_add_remove_entities_modal(space_view_id);
                 }
             },
         );
@@ -1093,6 +1098,22 @@ The last rule matching `/world/house` is `+ /world/**`, so it is included.
         ui.data_mut(|data| data.remove::<String>(filter_text_id));
     }
 
+    // Show some statistics about the query, print a warning text if something seems off.
+    let query = ctx.lookup_query_result(space_view_id);
+    if query.num_matching_entities == 0 {
+        ui.label(ctx.re_ui.warning_text("Does not match any entity"));
+    } else if query.num_matching_entities == 1 {
+        ui.label("Matches 1 entity");
+    } else {
+        ui.label(format!("Matches {} entities", query.num_matching_entities));
+    }
+    if query.num_matching_entities != 0 && query.num_visualized_entities == 0 {
+        // TODO(andreas): Talk about this root bit only if it's a spatial view.
+        ui.label(ctx.re_ui.warning_text(
+            format!("This space view is not able to visualize any of the matched entities using the current root \"{origin:?}\"."),
+        ));
+    }
+
     // Apply the edit.
     let new_filter = EntityPathFilter::parse_forgiving(&filter_string, &Default::default());
     if &new_filter == filter {

crates/re_viewer_context/src/query_context.rs

@@ -17,6 +17,15 @@ slotmap::new_key_type! {
 pub struct DataQueryResult {
     /// The [`DataResultTree`] for the query
     pub tree: DataResultTree,
+
+    /// The number of entities that matched the query, including those that are not visualizable.
+    pub num_matching_entities: usize,
+
+    /// Of the matched queries, the number of entities that are visualizable by any given visualizer.
+    ///
+    /// This does *not* take into account the actual selection of visualizers
+    /// which may be an explicit none for any given entity.
+    pub num_visualized_entities: usize,
 }
 
 impl DataQueryResult {
@@ -38,6 +47,8 @@ impl Clone for DataQueryResult {
         re_tracing::profile_function!();
         Self {
             tree: self.tree.clone(),
+            num_matching_entities: self.num_matching_entities,
+            num_visualized_entities: self.num_visualized_entities,
         }
     }
 }