R8.3: sheet tab strip scrolls the chosen sheet in (Gitea #8)

Co-Authored-By: Claude <noreply@anthropic.com>

apps/ely-table/src/sheets.rs

@@ -109,18 +109,12 @@ impl Book {
         let Some(tab) = self.active_tab() else {
             return div().into_any_element();
         };
-        let Some(choices) = visible(&tab.extra.sheets) else {
+        let Some(tabs) = strip(tab.id, &tab.extra.sheets) else {
             return div().into_any_element();
         };
         let this = cx.entity();
         let picked = this.clone();
-        let tabs = SheetTabs::new(
-            "table-sheets",
-            choices,
-            tab.extra.sheets.current.to_string(),
-        )
-        .placement(TabPlacement::Bottom)
-        .on_change(move |value, _, cx| {
+        let tabs = tabs.on_change(move |value, _, cx| {
             let index: usize = value.parse().expect("sheet tabs are indexes");
             picked.update(cx, |book, cx| book.show_sheet(index, cx));
         })
@@ -310,6 +304,15 @@ impl Book {
     }
 }
 
+/// Workbook `id`'s sheet tabs; each workbook keeps its own scroll.
+fn strip(id: u64, sheets: &ely_lok::Sheets) -> Option<SheetTabs> {
+    let choices = visible(sheets)?;
+    Some(
+        SheetTabs::new(("table-sheets", id), choices, sheets.current.to_string())
+            .placement(TabPlacement::Bottom),
+    )
+}
+
 /// Visible sheets as tabs, once the shown one is known.
 fn visible(sheets: &ely_lok::Sheets) -> Option<Vec<Choice>> {
     let shown = sheets.list.get(sheets.current)?;
@@ -327,6 +330,10 @@ fn visible(sheets: &ely_lok::Sheets) -> Option<Vec<Choice>> {
     )
 }
 
+#[cfg(test)]
+#[path = "tests/strip.rs"]
+mod strip_tests;
+
 #[cfg(test)]
 mod tests {
     use super::*;

apps/ely-table/src/tests/strip.rs

@@ -0,0 +1,96 @@
+//! Each workbook's strip shows its own chosen sheet.
+
+use ely_lok::{Sheet, Sheets};
+use gpui::{
+    Bounds, Context, IntoElement, Modifiers, ParentElement as _, Pixels, Render, RenderOnce as _,
+    ScrollDelta, ScrollHandle, ScrollWheelEvent, Styled as _, TestAppContext, TouchPhase,
+    VisualTestContext, Window, div, point, px,
+};
+
+use super::strip;
+
+struct Books {
+    book: u64,
+    sheets: Sheets,
+    scroll: Option<ScrollHandle>,
+}
+
+impl Render for Books {
+    fn render(&mut self, window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
+        let tabs = strip(self.book, &self.sheets)
+            .expect("tabs")
+            .render(window, cx)
+            .into_any_element();
+        let id = gpui::ElementId::from(("table-sheets", self.book));
+        let handle = window.use_keyed_state((id, "scroll"), cx, |_, _| ScrollHandle::new());
+        self.scroll = Some(handle.read(cx).clone());
+        div()
+            .w(px(640.))
+            .child(div().flex().items_center().px_2().child(tabs))
+    }
+}
+
+fn settle(cx: &mut VisualTestContext) {
+    for _ in 0..5 {
+        cx.run_until_parked();
+        cx.update(|window, _| window.refresh());
+    }
+    cx.run_until_parked();
+}
+
+/// The strip's viewport and the chosen tab in it.
+fn place(
+    view: &gpui::Entity<Books>,
+    cx: &mut VisualTestContext,
+) -> (Bounds<Pixels>, Bounds<Pixels>) {
+    view.read_with(cx, |view, _| {
+        let scroll = view.scroll.as_ref().expect("drawn");
+        let mut chosen = scroll
+            .bounds_for_item(view.sheets.current)
+            .expect("chosen tab");
+        chosen.origin += scroll.offset();
+        (scroll.bounds(), chosen)
+    })
+}
+
+fn shown(view: &gpui::Entity<Books>, cx: &mut VisualTestContext) -> bool {
+    let (viewport, chosen) = place(view, cx);
+    chosen.left() >= viewport.left() && chosen.right() <= viewport.right()
+}
+
+#[gpui::test]
+fn a_switched_workbook_shows_its_chosen_sheet(cx: &mut TestAppContext) {
+    cx.update(ely_gpui_component::init_for_tests);
+    let sheets = Sheets {
+        current: 29,
+        list: (0..30)
+            .map(|n| Sheet {
+                name: format!("Sheet {n}"),
+                visible: true,
+            })
+            .collect(),
+    };
+    let (view, cx) = cx.add_window_view(|_, _| Books {
+        book: 1,
+        sheets,
+        scroll: None,
+    });
+    settle(cx);
+    assert!(shown(&view, cx), "the first draw shows the chosen sheet");
+    for book in [2, 1, 2] {
+        cx.simulate_event(ScrollWheelEvent {
+            position: point(px(60.), px(16.)),
+            delta: ScrollDelta::Pixels(point(px(0.), px(50_000.))),
+            modifiers: Modifiers::none(),
+            touch_phase: TouchPhase::Moved,
+        });
+        settle(cx);
+        assert!(!shown(&view, cx), "the wheel moves the chosen sheet away");
+        view.update(cx, |view, cx| {
+            view.book = book;
+            cx.notify();
+        });
+        settle(cx);
+        assert!(shown(&view, cx), "workbook {book} shows its chosen sheet");
+    }
+}