Automatically expand and scroll the streams tree when focusing on an …

…item (#5494)

### What

- Follow up to #5482
- Fixes #5232 


This PR adds support for expanding and scrolling to the focus item in
the Streams view. It also adds expanding/scrolling the Blueprint tree
when focusing on a component.

- Blocked on emilk/egui#4174

TODO:
- [x] update egui commit once ☝🏻  is merged


https://github.com/rerun-io/rerun/assets/49431240/55c2959f-bb9b-4f67-b20b-06ba82175d71


### 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/5494/index.html)
* Using examples from latest `main` build:
[app.rerun.io](https://app.rerun.io/pr/5494/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/5494/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/5494)
- [Docs
preview](https://rerun.io/preview/e879778c92dd2e50eb05bc6fdefee9ac79b93872/docs)
<!--DOCS-PREVIEW-->
- [Examples
preview](https://rerun.io/preview/e879778c92dd2e50eb05bc6fdefee9ac79b93872/examples)
<!--EXAMPLES-PREVIEW-->
- [Recent benchmark results](https://build.rerun.io/graphs/crates.html)
- [Wasm size tracking](https://build.rerun.io/graphs/sizes.html)

crates/re_time_panel/src/lib.rs

@@ -584,6 +584,18 @@ impl TimePanel {
         clip_rect.max.x = tree_max_y;
         ui.set_clip_rect(clip_rect);
 
+        // expand if children is focused
+        let focused_entity_path = ctx
+            .focused_item
+            .as_ref()
+            .and_then(|item| item.entity_path());
+
+        if focused_entity_path.is_some_and(|entity_path| entity_path.is_descendant_of(&tree.path)) {
+            CollapseScope::StreamsTree
+                .entity(tree.path.clone())
+                .set_open(ui.ctx(), true);
+        }
+
         let re_ui::list_item::ShowCollapsingResponse {
             item_response: response,
             body_response,
@@ -625,6 +637,15 @@ impl TimePanel {
             );
         });
 
+        if Some(&tree.path) == focused_entity_path {
+            // Scroll only if the entity isn't already visible. This is important because that's what
+            // happens when double-clicking an entity _in the blueprint tree_. In such case, it would be
+            // annoying to induce a scroll motion.
+            if !ui.clip_rect().contains_rect(response.rect) {
+                response.scroll_to_me(Some(egui::Align::Center));
+            }
+        }
+
         context_menu_ui_for_item(
             ctx,
             viewport_blueprint,

crates/re_viewport/src/viewport_blueprint_ui.rs

@@ -64,7 +64,10 @@ impl Viewport<'_, '_> {
             .auto_shrink([true, false])
             .show(ui, |ui| {
                 ctx.re_ui.panel_content(ui, |_, ui| {
-                    self.state.blueprint_tree_scroll_to_item = self.handle_focused_item(ctx, ui);
+                    self.state.blueprint_tree_scroll_to_item = ctx
+                        .focused_item
+                        .as_ref()
+                        .and_then(|item| self.handle_focused_item(ctx, ui, item));
 
                     self.root_container_tree_ui(ctx, ui);
 
@@ -86,8 +89,12 @@ impl Viewport<'_, '_> {
     }
 
     /// Expend all required items and compute which item we should scroll to.
-    fn handle_focused_item(&self, ctx: &ViewerContext<'_>, ui: &egui::Ui) -> Option<Item> {
-        let focused_item = ctx.focused_item.as_ref()?;
+    fn handle_focused_item(
+        &self,
+        ctx: &ViewerContext<'_>,
+        ui: &egui::Ui,
+        focused_item: &Item,
+    ) -> Option<Item> {
         match focused_item {
             Item::Container(container_id) => {
                 self.expand_all_contents_until(ui.ctx(), &Contents::Container(*container_id));
@@ -129,8 +136,15 @@ impl Viewport<'_, '_> {
 
                 res
             }
+            Item::ComponentPath(component_path) => self.handle_focused_item(
+                ctx,
+                ui,
+                &Item::InstancePath(InstancePath::entity_splat(
+                    component_path.entity_path.clone(),
+                )),
+            ),
 
-            Item::StoreId(_) | Item::ComponentPath(_) => None,
+            Item::StoreId(_) => None,
         }
     }
 

tests/python/release_checklist/check_focus.py

@@ -19,8 +19,10 @@
 
 ## Checks
 
-- Collapse all in the blueprint tree.
-- Double-click on the box in the first space view, check corresponding space view expands.
+- Collapse all in the blueprint tree and the streams view
+- Double-click on the box in the first space view
+    - check corresponding space view expands and scrolls
+    - check the streams view expands and scrolls
 - Collapse all in the blueprint tree.
 - Double-click on the leaf "boxes3d" entity in the streams view, check both space views expand.
 """