Run the fill-handle double-click fill before the handle press returns (#507)

crates/ui-egui/src/grid.rs

@@ -1743,6 +1743,29 @@ fn interact(app: &mut SheetApp, ui: &mut egui::Ui, resp: &egui::Response, geo: &
         }
     }
 
+    // Double-click the fill handle: a double-click is also a click, so run it before the handle press returns.
+    if resp.double_clicked()
+        && let Some(p) = pos
+        && on_handle(p)
+    {
+        // Fill down as far as the neighbouring column goes.
+        let src = sel.current();
+        let neighbour = if src.start.col > 0 { src.start.col - 1 } else { src.end.col + 1 };
+        let mut last = src.end.row;
+        while last + 1 < MAX_ROWS && sh.value_ref(CellRef::new(last + 1, neighbour)).is_some_and(|v| !v.is_empty()) && last - src.end.row < 1_000_000
+        {
+            last += 1;
+        }
+        if last > src.end.row {
+            let target = RangeRef::new(src.start, CellRef::new(last, src.end.col));
+            let _ = app.run("edit.autoFill", json!({"source": src.a1(), "target": target.a1()}));
+        }
+        app.grid.drag = Drag::None;
+        app.grid.drag_select = false;
+        resp.request_focus();
+        return;
+    }
+
     // Press: decide the drag mode.
     if resp.drag_started() || (primary_clicked && app.grid.drag == Drag::None) {
         // Where the press began (a drag is only recognised after the pointer has moved).
@@ -2046,25 +2069,6 @@ fn interact(app: &mut SheetApp, ui: &mut egui::Ui, resp: &egui::Response, geo: &
         app.grid.drag_select = false;
     }
 
-    // Double-click the fill handle.
-    if resp.double_clicked()
-        && let Some(p) = pos
-        && on_handle(p)
-    {
-        // Fill down as far as the neighbouring column goes.
-        let src = sel.current();
-        let neighbour = if src.start.col > 0 { src.start.col - 1 } else { src.end.col + 1 };
-        let mut last = src.end.row;
-        while last + 1 < MAX_ROWS && sh.value_ref(CellRef::new(last + 1, neighbour)).is_some_and(|v| !v.is_empty()) && last - src.end.row < 1_000_000
-        {
-            last += 1;
-        }
-        if last > src.end.row {
-            let target = RangeRef::new(src.start, CellRef::new(last, src.end.col));
-            let _ = app.run("edit.autoFill", json!({"source": src.a1(), "target": target.a1()}));
-        }
-    }
-
     // Right-click: context menu.
     if resp.secondary_clicked()
         && let Some(p) = pos

crates/ui-egui/tests/fill_handle_double_click.rs

@@ -0,0 +1,59 @@
+//! Double-clicking the fill handle fills down to the neighbouring column's last used row,
+//! even with the pointer up for a frame between the two clicks.
+
+use egui::{Event, Modifiers, PointerButton, Pos2, vec2};
+use gridcraft_engine::Session;
+use gridcraft_engine::core::{CellRef, Value};
+use gridcraft_ui_egui::{SheetApp, grid::Geo};
+use serde_json::json;
+
+fn harness() -> egui_kittest::Harness<'static, SheetApp> {
+    let mut session = Session::new();
+    session.new_workbook();
+    session.execute("range.setValues", json!({"range": "A1", "values": [[1], [2], [3], [4], [5], [6]]})).unwrap();
+    session.execute("range.setValues", json!({"range": "B1", "values": [[10], [20], [30]]})).unwrap();
+    session.execute("selection.set", json!({"range": "B1:B3"})).unwrap();
+    let mut h = egui_kittest::Harness::builder().with_step_dt(1.0 / 60.0).with_size(vec2(1200.0, 800.0)).build_ui_state(
+        |ui, app: &mut SheetApp| {
+            app.logic(ui.ctx());
+            app.ui(ui);
+        },
+        SheetApp::new(session, Default::default()),
+    );
+    h.run_steps(4);
+    h
+}
+
+fn handle(h: &egui_kittest::Harness<'_, SheetApp>) -> Pos2 {
+    let app = h.state();
+    let sheet = app.session.active().unwrap().wb.active().unwrap();
+    let geo = Geo::new(sheet, app.grid.rect.unwrap(), app.view().scroll);
+    geo.cell_rect(sheet, CellRef::new(2, 1)).right_bottom() - vec2(1.0, 1.0)
+}
+
+fn button(h: &mut egui_kittest::Harness<'_, SheetApp>, pos: Pos2, pressed: bool) {
+    h.input_mut()
+        .events
+        .extend([Event::PointerMoved(pos), Event::PointerButton { pos, button: PointerButton::Primary, pressed, modifiers: Modifiers::NONE }]);
+    h.step();
+}
+
+fn number(h: &egui_kittest::Harness<'_, SheetApp>, row: u32) -> Value {
+    h.state().session.active().unwrap().wb.active().unwrap().value(CellRef::new(row, 1))
+}
+
+#[test]
+fn double_click_on_the_fill_handle_fills_down_with_a_frame_between_the_clicks() {
+    let mut h = harness();
+    let pos = handle(&h);
+    button(&mut h, pos, true);
+    button(&mut h, pos, false);
+    h.step(); // One idle frame between the clicks, well inside the double-click interval.
+    button(&mut h, pos, true);
+    button(&mut h, pos, false);
+    h.run_steps(2);
+
+    assert_eq!([number(&h, 3), number(&h, 4), number(&h, 5)], [Value::Number(40.0), Value::Number(50.0), Value::Number(60.0)]);
+    assert_eq!(h.state().session.active().unwrap().selection.a1(), "B1:B6");
+    assert_eq!(h.state().session.journal.iter().filter(|(id, _)| id == "edit.autoFill").count(), 1);
+}