Refresh scenario viewport measurement when its identity changes

crates/oa-desktop/src/behavior/scenario/workspace.rs

@@ -649,6 +649,8 @@ fn canvas_pane<'a, R: iced::advanced::text::Renderer + 'a>(
                 .width(Fill)
                 .height(Fill),
         ))
+        // A new owner/document needs its first measurement even at the same size.
+        .key((context.document, context.scenario))
         .on_show(move |size| Message::ScenarioCanvas(CanvasEvent::Viewport(context, size)))
         .on_resize(move |size| Message::ScenarioCanvas(CanvasEvent::Viewport(context, size))),
     )

crates/oa-desktop/src/behavior/scenario/workspace/tests.rs

@@ -341,6 +341,85 @@ fn scenario_workspace_fit_uses_measured_inner_viewport_and_rejects_nonfinite_inp
     );
 }
 
+#[test]
+fn scenario_workspace_fit_reobserves_same_sized_owner_and_document_changes() {
+    use super::super::direct_tests::{navigation_event, navigation_fixture};
+    let (project, [a, b, _], [reference, _, _]) = navigation_fixture();
+    let mut app = App::with_project(project.clone());
+    let _ = app.update(Message::Select(a));
+    let _ = app.update(Message::Page(crate::app::Page::Behavior));
+    let size = Size::new(500., 570.);
+    let graph = Size::new(1800., 2400.);
+    let mut view = fixture_view(
+        &app.behavior.scenario,
+        app.scenario_context().unwrap(),
+        false,
+        68.,
+    );
+    let mut tree = widget::Tree::new(view.as_widget());
+    redraw(&mut view, &mut tree, size, &mut app);
+    let (_, first) = geometry(&mut view, &mut tree, size);
+    let measured = first.scrolls["scenario-canvas"].0.size();
+    assert_eq!(app.behavior.scenario.presentation.viewport, Some(measured));
+
+    let accepted = app.document.snapshot();
+    navigation_event(&mut app, |ctx| CanvasEvent::OpenUse(ctx, reference));
+    assert_eq!(app.scenario_context().unwrap().scenario, b);
+    assert_eq!(app.behavior.scenario.presentation.viewport, None);
+    view = fixture_view(
+        &app.behavior.scenario,
+        app.scenario_context().unwrap(),
+        false,
+        68.,
+    );
+    tree.diff(view.as_widget());
+    redraw(&mut view, &mut tree, size, &mut app);
+    let (_, second) = geometry(&mut view, &mut tree, size);
+    assert_eq!(second.scrolls["scenario-canvas"].0.size(), measured);
+    assert_eq!(app.behavior.scenario.presentation.viewport, Some(measured));
+    navigation_event(&mut app, |ctx| CanvasEvent::Zoom(ctx, None));
+    let fitted = app.behavior.scenario.presentation.scale(graph);
+    assert!(
+        fitted < 1.
+            && graph.width * fitted <= measured.width - 16.
+            && graph.height * fitted <= measured.height - 16.
+    );
+    assert!(std::sync::Arc::ptr_eq(&accepted, &app.document.snapshot()));
+    assert!(!app.document.can_undo());
+
+    let document = app.scenario_context().unwrap().document;
+    let mut replacement = App::with_project(project);
+    let _ = replacement.update(Message::Select(b));
+    let _ = replacement.update(Message::Page(crate::app::Page::Behavior));
+    assert_ne!(replacement.scenario_context().unwrap().document, document);
+    assert_eq!(replacement.behavior.scenario.presentation.viewport, None);
+    let accepted = replacement.document.snapshot();
+    view = fixture_view(
+        &replacement.behavior.scenario,
+        replacement.scenario_context().unwrap(),
+        false,
+        68.,
+    );
+    tree.diff(view.as_widget());
+    redraw(&mut view, &mut tree, size, &mut replacement);
+    let (_, replaced) = geometry(&mut view, &mut tree, size);
+    assert_eq!(replaced.scrolls["scenario-canvas"].0.size(), measured);
+    assert_eq!(
+        replacement.behavior.scenario.presentation.viewport,
+        Some(measured)
+    );
+    navigation_event(&mut replacement, |ctx| CanvasEvent::Zoom(ctx, None));
+    assert_eq!(
+        replacement.behavior.scenario.presentation.scale(graph),
+        fitted
+    );
+    assert!(std::sync::Arc::ptr_eq(
+        &accepted,
+        &replacement.document.snapshot()
+    ));
+    assert!(!replacement.document.can_undo());
+}
+
 #[test]
 fn scenario_workspace_open_and_back_restore_owner_and_mounted_scroll_after_preselection() {
     use super::super::direct_tests::{navigation_event, navigation_fixture};
@@ -694,10 +773,9 @@ fn scenario_workspace_scaled_and_scrolled_scene_keeps_clicked_slots_and_message_
                     &canvas::Event::Mouse(event),
                     bounds,
                     mouse::Cursor::Available(cursor + scene.scroll_offset),
-                ) {
-                    if let Some(message) = action.into_inner().0 {
-                        messages.push(message);
-                    }
+                ) && let Some(message) = action.into_inner().0
+                {
+                    messages.push(message);
                 }
             }
             assert!(