Update UI for static components (#6101)

### What

This PR updates the UI to better display static components, including:
- Components logged as static now have a different icon.
- Components logged as static do not have any event displayed in the
timeline (see below for possible follow-up work).
- The "timeless" gutter in the timeline is gone.
- The hover tooltip in the streams for static component now displays
their content (timeful components have their content displayed on the
corresponding event in the timeline).
- All components now have a "logged time" displayed along their data
(showing the actually logging time that was taken into consideration by
the current LatestAt query). It shows `<static>` for static components.
This appears both in the selection panel and in the hover tooltips.
- In addition, data consistency information is displayed for static
component (both tooltip and selection panel):
- Warning (yellow) if multiple static logs were recorded (the data of
previous logging event is overwritten and not recoverable from the
datastore).
- Error (red) if the static component has timeful stuff logged as well
(albeit that data is not loss, it's not queryable and extremely likely
an indication of user error).

Note: the included release checklist is nice to try the error/warning
cases.

- Fixes #6074
- Possible follow-up #6102

### Screenshots

static + timeful error:
<img width="368" alt="image"
src="https://github.com/rerun-io/rerun/assets/49431240/98c7f1c8-8cf0-4604-95b8-ab7291bd1c20">

multi-static warning:
<img width="334" alt="image"
src="https://github.com/rerun-io/rerun/assets/49431240/4d8e7612-bb3e-4295-bbd1-f9ba0554ac2a">

selection panel:
<img width="295" alt="image"
src="https://github.com/rerun-io/rerun/assets/49431240/a63178ed-adcc-434f-8425-3b22ba88d003">


### 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 examples from latest `main` build:
[rerun.io/viewer](https://rerun.io/viewer/pr/6101?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[rerun.io/viewer](https://rerun.io/viewer/pr/6101?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/6101)
- [Recent benchmark results](https://build.rerun.io/graphs/crates.html)
- [Wasm size tracking](https://build.rerun.io/graphs/sizes.html)

To run all checks from `main`, comment on the PR with `@rerun-bot
full-check`.

crates/re_data_ui/src/component.rs

@@ -52,6 +52,52 @@ impl DataUi for EntityLatestAtResults {
             UiVerbosity::LimitHeight | UiVerbosity::Full => num_instances,
         };
 
+        // Display data time and additional diagnostic information for static components.
+        if verbosity != UiVerbosity::Small {
+            ui.label(format!(
+                "Data time: {}",
+                query
+                    .timeline()
+                    .typ()
+                    .format(self.results.index().0, ctx.app_options.time_zone),
+            ));
+
+            // if the component is static, we display extra diagnostic information
+            if self.results.is_static() {
+                if let Some(histogram) = db
+                    .tree()
+                    .subtree(&self.entity_path)
+                    .and_then(|tree| tree.entity.components.get(&self.component_name))
+                {
+                    if histogram.num_static_messages() > 1 {
+                        ui.label(ctx.re_ui.warning_text(format!(
+                            "Static component value was overridden {} times",
+                            histogram.num_static_messages().saturating_sub(1),
+                        )))
+                        .on_hover_text(
+                            "When a static component is logged multiple times, only the last value \
+                            is stored. Previously logged values are overwritten and not \
+                            recoverable.",
+                        );
+                    }
+
+                    let timeline_message_count = histogram.num_temporal_messages();
+                    if timeline_message_count > 0 {
+                        ui.label(ctx.re_ui.error_text(format!(
+                            "Static component has {} event{} logged on timelines",
+                            timeline_message_count,
+                            if timeline_message_count > 1 { "s" } else { "" }
+                        )))
+                        .on_hover_text(
+                            "Components should be logged either as static or on timelines, but \
+                            never both. Values for static components logged to timelines cannot be \
+                            displayed.",
+                        );
+                    }
+                }
+            }
+        }
+
         // Here we enforce that exactly `max_row` rows are displayed, which means that:
         // - For `num_instances == max_row`, then `max_row` rows are displayed.
         // - For `num_instances == max_row + 1`, then `max_row-1` rows are displayed and "…2 more"

crates/re_data_ui/src/instance_path.rs

@@ -65,6 +65,7 @@ impl DataUi for InstancePath {
                     ctx,
                     ui,
                     &ComponentPath::new(entity_path.clone(), component_name),
+                    db,
                 );
             }
         }
@@ -89,6 +90,7 @@ impl DataUi for InstancePath {
                         ctx,
                         ui,
                         &ComponentPath::new(entity_path.clone(), component_name),
+                        db,
                     );
 
                     if instance_key.is_splat() {

crates/re_data_ui/src/item_ui.rs

@@ -374,12 +374,14 @@ pub fn component_path_button(
     ctx: &ViewerContext<'_>,
     ui: &mut egui::Ui,
     component_path: &ComponentPath,
+    db: &re_entity_db::EntityDb,
 ) -> egui::Response {
     component_path_button_to(
         ctx,
         ui,
         component_path.component_name.short_name(),
         component_path,
+        db,
     )
     .on_hover_text(component_path.component_name.full_name()) // we should show the full name somewhere
 }
@@ -390,11 +392,17 @@ pub fn component_path_button_to(
     ui: &mut egui::Ui,
     text: impl Into<egui::WidgetText>,
     component_path: &ComponentPath,
+    db: &re_entity_db::EntityDb,
 ) -> egui::Response {
     let item = Item::ComponentPath(component_path.clone());
+    let is_component_static = db.is_component_static(component_path).unwrap_or_default();
     let response = ctx.re_ui.selectable_label_with_icon(
         ui,
-        &icons::COMPONENT,
+        if is_component_static {
+            &icons::COMPONENT_STATIC
+        } else {
+            &icons::COMPONENT
+        },
         text,
         ctx.selection().contains_item(&item),
         re_ui::LabelStyle::Normal,

crates/re_entity_db/src/entity_db.rs

@@ -8,9 +8,9 @@ use re_data_store::{
     DataStore, DataStoreConfig, GarbageCollectionOptions, StoreEvent, StoreSubscriber,
 };
 use re_log_types::{
-    ApplicationId, DataCell, DataRow, DataTable, DataTableResult, EntityPath, EntityPathHash,
-    LogMsg, RowId, SetStoreInfo, StoreId, StoreInfo, StoreKind, TimePoint, TimeRange, TimeRangeF,
-    Timeline,
+    ApplicationId, ComponentPath, DataCell, DataRow, DataTable, DataTableResult, EntityPath,
+    EntityPathHash, LogMsg, RowId, SetStoreInfo, StoreId, StoreInfo, StoreKind, TimePoint,
+    TimeRange, TimeRangeF, Timeline,
 };
 use re_query2::PromiseResult;
 use re_types_core::{components::InstanceKey, Archetype, Loggable};
@@ -327,9 +327,22 @@ impl EntityDb {
         self.tree().subtree.time_histogram.get(timeline)
     }
 
-    /// Total number of timeless messages for any entity.
-    pub fn num_timeless_messages(&self) -> u64 {
-        self.tree.num_timeless_messages_recursive()
+    /// Total number of static messages for any entity.
+    pub fn num_static_messages(&self) -> u64 {
+        self.tree.num_static_messages_recursive()
+    }
+
+    /// Returns whether a component is static.
+    pub fn is_component_static(&self, component_path: &ComponentPath) -> Option<bool> {
+        if let Some(entity_tree) = self.tree().subtree(component_path.entity_path()) {
+            entity_tree
+                .entity
+                .components
+                .get(&component_path.component_name)
+                .map(|component_histogram| component_histogram.is_static())
+        } else {
+            None
+        }
     }
 
     pub fn num_rows(&self) -> usize {

crates/re_entity_db/src/entity_tree.rs

@@ -245,8 +245,8 @@ impl EntityTree {
     }
 
     /// Number of timeless messages in this tree, or any child, recursively.
-    pub fn num_timeless_messages_recursive(&self) -> u64 {
-        self.subtree.time_histogram.num_timeless_messages()
+    pub fn num_static_messages_recursive(&self) -> u64 {
+        self.subtree.time_histogram.num_static_messages()
     }
 
     pub fn time_histogram_for_component(

crates/re_entity_db/src/time_histogram_per_timeline.rs

@@ -16,14 +16,19 @@ pub struct TimeHistogramPerTimeline {
     /// When do we have data? Ignores timeless.
     times: BTreeMap<Timeline, TimeHistogram>,
 
-    /// Extra book-keeping used to seed any timelines that include timeless msgs.
-    num_timeless_messages: u64,
+    /// Extra bookkeeping used to seed any timelines that include static msgs.
+    num_static_messages: u64,
 }
 
 impl TimeHistogramPerTimeline {
     #[inline]
     pub fn is_empty(&self) -> bool {
-        self.times.is_empty() && self.num_timeless_messages == 0
+        self.times.is_empty() && self.num_static_messages == 0
+    }
+
+    #[inline]
+    pub fn is_static(&self) -> bool {
+        self.num_static_messages > 0
     }
 
     #[inline]
@@ -47,20 +52,25 @@ impl TimeHistogramPerTimeline {
     }
 
     #[inline]
-    pub fn num_timeless_messages(&self) -> u64 {
-        self.num_timeless_messages
+    pub fn num_static_messages(&self) -> u64 {
+        self.num_static_messages
+    }
+
+    /// Total number of temporal messages over all timelines.
+    pub fn num_temporal_messages(&self) -> u64 {
+        self.times.values().map(|hist| hist.total_count()).sum()
     }
 
     pub fn add(&mut self, times: &[(Timeline, TimeInt)], n: u32) {
         if times.is_empty() {
-            self.num_timeless_messages = self
-                .num_timeless_messages
+            self.num_static_messages = self
+                .num_static_messages
                 .checked_add(n as u64)
                 .unwrap_or_else(|| {
                     re_log::debug!(
-                        current = self.num_timeless_messages,
+                        current = self.num_static_messages,
                         added = n,
-                        "book keeping overflowed"
+                        "bookkeeping overflowed"
                     );
                     u64::MAX
                 });
@@ -76,15 +86,15 @@ impl TimeHistogramPerTimeline {
 
     pub fn remove(&mut self, timepoint: &TimePoint, n: u32) {
         if timepoint.is_static() {
-            self.num_timeless_messages = self
-                .num_timeless_messages
+            self.num_static_messages = self
+                .num_static_messages
                 .checked_sub(n as u64)
                 .unwrap_or_else(|| {
                     // TODO(#4355): hitting this on plots demo
                     re_log::debug!(
-                        current = self.num_timeless_messages,
+                        current = self.num_static_messages,
                         removed = n,
-                        "book keeping underflowed"
+                        "bookkeeping underflowed"
                     );
                     u64::MIN
                 });

crates/re_query_cache2/src/latest_at/results.rs

@@ -157,6 +157,12 @@ impl CachedLatestAtComponentResults {
             _ => None,
         }
     }
+
+    /// Returns whether the resolved data is static.
+    #[inline]
+    pub fn is_static(&self) -> bool {
+        self.index.0 == TimeInt::STATIC
+    }
 }
 
 impl SizeBytes for CachedLatestAtComponentResults {

crates/re_time_panel/Cargo.toml

@@ -23,6 +23,7 @@ re_data_store.workspace = true
 re_data_ui.workspace = true
 re_entity_db.workspace = true
 re_format.workspace = true
+re_log.workspace = true
 re_log_types.workspace = true
 re_tracing.workspace = true
 re_ui.workspace = true

crates/re_time_panel/src/data_density_graph.rs

@@ -10,7 +10,7 @@ use egui::{epaint::Vertex, lerp, pos2, remap, Color32, NumExt as _, Rect, Shape}
 
 use re_data_ui::item_ui;
 use re_entity_db::TimeHistogram;
-use re_log_types::{ComponentPath, TimeInt, TimeRange, TimeReal};
+use re_log_types::{ComponentPath, TimeRange, TimeReal};
 use re_viewer_context::{Item, TimeControl, UiVerbosity, ViewerContext};
 
 use crate::TimePanelItem;
@@ -368,14 +368,13 @@ fn smooth(density: &[f32]) -> Vec<f32> {
 
 #[allow(clippy::too_many_arguments)]
 pub fn data_density_graph_ui(
-    data_dentity_graph_painter: &mut DataDensityGraphPainter,
+    data_density_graph_painter: &mut DataDensityGraphPainter,
     ctx: &ViewerContext<'_>,
     time_ctrl: &mut TimeControl,
     db: &re_entity_db::EntityDb,
     time_area_response: &egui::Response,
     time_area_painter: &egui::Painter,
     ui: &egui::Ui,
-    num_timeless_messages: usize,
     time_histogram: &TimeHistogram,
     row_rect: Rect,
     time_ranges_ui: &TimeRangesUi,
@@ -435,11 +434,6 @@ pub fn data_density_graph_ui(
             }
         };
 
-        add_data_point(
-            TimeRange::point(TimeInt::MIN_TIME_PANEL),
-            num_timeless_messages,
-        );
-
         let visible_time_range = time_ranges_ui
             .time_range_from_x_range((row_rect.left() - MARGIN_X)..=(row_rect.right() + MARGIN_X));
 
@@ -479,7 +473,7 @@ pub fn data_density_graph_ui(
     density_graph.buckets = smooth(&density_graph.buckets);
 
     density_graph.paint(
-        data_dentity_graph_painter,
+        data_density_graph_painter,
         row_rect.y_range(),
         time_area_painter,
         graph_color(ctx, &item.to_item(), ui),
@@ -559,7 +553,7 @@ fn show_row_ids_tooltip(
 
         if let Some(component_name) = component_name {
             let component_path = ComponentPath::new(entity_path.clone(), *component_name);
-            item_ui::component_path_button(ctx, ui, &component_path);
+            item_ui::component_path_button(ctx, ui, &component_path, db);
             ui.add_space(8.0);
             component_path.data_ui(ctx, ui, verbosity, &query, db);
         } else {