Reset state camera and tools only when navigation changes view

crates/oa-desktop/src/app.rs

@@ -642,7 +642,7 @@ impl App {
         if !self.project().contains(id) {
             return;
         }
-        let previous_owner = crate::behavior::selected_owner(self);
+        let previous_state_view = self.state_view_identity();
         self.selected = id;
         self.selected_node = None;
         if let Some(layer) = self.project().layer_of(id)
@@ -656,10 +656,11 @@ impl App {
             && let Some(owner) = crate::behavior::selected_behavior(self.project(), id)
         {
             self.behavior.active_owner = Some(owner);
-            if previous_owner != Some(owner) {
-                self.behavior.diagram = Default::default();
-                self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
-            }
+        }
+        if self.reset_state_view_after_navigation(previous_state_view)
+            && self.page == Page::Behavior
+        {
+            self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
         }
         self.refresh_draft();
     }
@@ -1200,13 +1201,14 @@ impl App {
             Message::Page(page) => {
                 if page != Page::Text || !self.draft_dirty() || self.apply() {
                     if page == Page::Behavior && self.page != Page::Behavior {
+                        let previous_state_view = self.state_view_identity();
                         if let Some(owner) =
                             crate::behavior::selected_behavior(self.project(), self.selected)
                         {
                             self.behavior.active_owner = Some(owner);
                         }
                         self.behavior.active_owner = crate::behavior::selected_owner(self);
-                        self.behavior.diagram.fit = true;
+                        self.reset_state_view_after_navigation(previous_state_view);
                     }
                     self.page = page;
                     self.selected_node = if page == Page::Behavior {
@@ -1360,6 +1362,7 @@ impl App {
             }
             Message::Layer(layer) => {
                 if self.apply() {
+                    let previous_state_view = self.state_view_identity();
                     self.layer = layer;
                     self.create_kind = if layer == Layer::Oa {
                         Kind::Activity
@@ -1375,6 +1378,8 @@ impl App {
                         .map(|d| d.id);
                     self.selected = self.project().id;
                     self.selected_node = None;
+                    self.behavior.active_owner = crate::behavior::selected_owner(self);
+                    self.reset_state_view_after_navigation(previous_state_view);
                     self.refresh_draft();
                     self.fit();
                 }

crates/oa-desktop/src/app/state_diagram.rs

@@ -6,12 +6,35 @@ use crate::behavior::{
 };
 
 impl App {
+    /// The behavior view resolved independently of the current page. Capture
+    /// this before selection/layer changes, while it still identifies the view
+    /// whose camera and tool are retained during navigation.
+    pub(super) fn state_view_identity(&self) -> (Option<Id>, Option<Id>) {
+        let owner = behavior::selected_owner(self);
+        let diagram = owner.and_then(|owner| behavior::state_view::diagram(self, owner));
+        (owner, diagram)
+    }
+
+    pub(super) fn reset_state_view_after_navigation(
+        &mut self,
+        previous: (Option<Id>, Option<Id>),
+    ) -> bool {
+        let current = self.state_view_identity();
+        if current == previous {
+            return false;
+        }
+        self.behavior.diagram = behavior::state_view::State {
+            diagram: current.1,
+            ..Default::default()
+        };
+        true
+    }
+
     pub fn state_context(&self) -> Option<Context> {
         if self.page != Page::Behavior {
             return None;
         }
-        let owner = behavior::selected_owner(self)?;
-        let diagram = behavior::state_view::diagram(self, owner)?;
+        let diagram = self.state_view_identity().1?;
         Some(Context {
             document: self.canvas_document,
             diagram,

crates/oa-desktop/src/app/state_diagram_tests.rs

@@ -89,6 +89,232 @@ fn assert_source_model_agree(app: &App) {
     assert!(!app.source_dirty());
 }
 
+struct NavigationFixture {
+    app: App,
+    machine_a: Id,
+    diagram_a: Id,
+    state_a: Id,
+    transition_a: Id,
+    root_event: Id,
+    machine_b: Id,
+    diagram_b: Id,
+    state_b: Id,
+}
+
+fn navigation_fixture(layer_b: Layer) -> NavigationFixture {
+    let mut project = Project::empty();
+    let mut machine = |layer, name| {
+        let machine = project
+            .add_element(Kind::StateMachine, layer, name, None)
+            .unwrap();
+        let region = project
+            .add_element(Kind::Region, layer, "Main", Some(machine))
+            .unwrap();
+        let state = project
+            .add_element(Kind::State, layer, "Ready", Some(region))
+            .unwrap();
+        (machine, state)
+    };
+    let (machine_a, state_a) = machine(Layer::Sa, "Machine A");
+    let (machine_b, state_b) = machine(layer_b, "Machine B");
+    let root_event = project
+        .add_element(Kind::Event, Layer::Sa, "External event", None)
+        .unwrap();
+    let transition_a = project.relate(RelationKind::StateTransition, "Repeat", state_a, state_a);
+    let plan_a = state_edit::create_view(&project, machine_a).unwrap();
+    project = prepare_command(&project, &plan_a.command).unwrap().project;
+    let plan_b = state_edit::create_view(&project, machine_b).unwrap();
+    project = prepare_command(&project, &plan_b.command).unwrap().project;
+    let mut app = App::with_project(project);
+    send(&mut app, Message::Select(state_a));
+    send(&mut app, Message::Page(Page::Behavior));
+    send(
+        &mut app,
+        Message::BehaviorDiagram(Choice {
+            id: plan_a.diagram,
+            label: "A view".into(),
+        }),
+    );
+    let context = app.state_context().unwrap();
+    event(
+        &mut app,
+        Event::Viewport(context, iced::Size::new(820., 540.)),
+    );
+    event(&mut app, Event::Zoom(context, 0.65));
+    event(
+        &mut app,
+        Event::Pan(context, iced::Vector::new(-1_400., -800.)),
+    );
+    event(
+        &mut app,
+        Event::Choose(Tool::Reconnect {
+            relation: transition_a,
+            endpoint: Endpoint::Target,
+        }),
+    );
+    assert_eq!(app.state_context().unwrap().diagram, plan_a.diagram);
+    assert!(!app.behavior.diagram.fit);
+    NavigationFixture {
+        app,
+        machine_a,
+        diagram_a: plan_a.diagram,
+        state_a,
+        transition_a,
+        root_event,
+        machine_b,
+        diagram_b: plan_b.diagram,
+        state_b,
+    }
+}
+
+fn assert_switched_state_view(f: &mut NavigationFixture) {
+    assert_eq!(behavior::selected_owner(&f.app), Some(f.machine_b));
+    assert_eq!(f.app.state_context().unwrap().diagram, f.diagram_b);
+    let defaults = behavior::state_view::State::default();
+    let state = &f.app.behavior.diagram;
+    assert_eq!(state.diagram, Some(f.diagram_b));
+    assert_eq!(
+        state.tool,
+        Tool::Select,
+        "Reconnect from A must not be armed in B"
+    );
+    assert_eq!(state.pan, defaults.pan);
+    assert_eq!(state.zoom, defaults.zoom);
+    assert!(state.fit);
+    assert!(
+        state.viewport.is_none(),
+        "B needs its own first viewport measurement"
+    );
+    assert!(state.placement.is_none());
+    let context = f.app.state_context().unwrap();
+    event(
+        &mut f.app,
+        Event::Viewport(context, iced::Size::new(820., 540.)),
+    );
+    assert!(
+        f.app.behavior.diagram.pan != defaults.pan || f.app.behavior.diagram.zoom != defaults.zoom,
+        "The unchanged widget size still fits a newly selected view"
+    );
+}
+
+fn catalog_selects_another_machine(layer_b: Layer) {
+    let mut f = navigation_fixture(layer_b);
+    let before = f.app.document.snapshot();
+    send(&mut f.app, Message::Page(Page::Catalog));
+    send(&mut f.app, Message::Select(f.state_b));
+    assert_eq!(f.app.layer, layer_b);
+    send(&mut f.app, Message::Page(Page::Behavior));
+    assert_switched_state_view(&mut f);
+    assert!(Arc::ptr_eq(&before, &f.app.document.snapshot()));
+    assert_source_model_agree(&f.app);
+}
+
+#[test]
+fn state_navigation_catalog_selection_of_another_machine_resets_camera_and_tool() {
+    catalog_selects_another_machine(Layer::Sa);
+}
+
+#[test]
+fn state_navigation_catalog_selection_across_layers_resets_camera_and_tool() {
+    catalog_selects_another_machine(Layer::Oa);
+}
+
+#[test]
+fn state_navigation_layer_change_resets_the_new_machine_at_the_same_viewport_size() {
+    let mut f = navigation_fixture(Layer::Oa);
+    let before = f.app.document.snapshot();
+    send(&mut f.app, Message::Layer(Layer::Oa));
+    assert_switched_state_view(&mut f);
+    assert!(Arc::ptr_eq(&before, &f.app.document.snapshot()));
+    assert_source_model_agree(&f.app);
+}
+
+#[test]
+fn state_navigation_return_to_the_same_view_preserves_camera_tool_and_fit_mode() {
+    for fit in [false, true] {
+        let mut f = navigation_fixture(Layer::Sa);
+        if fit {
+            let context = f.app.state_context().unwrap();
+            event(&mut f.app, Event::Fit(context));
+        }
+        let state = &f.app.behavior.diagram;
+        let retained = (
+            state.diagram,
+            state.pan,
+            state.zoom,
+            state.tool,
+            state.fit,
+            state.viewport,
+        );
+        let before = f.app.document.snapshot();
+        send(&mut f.app, Message::Page(Page::Catalog));
+        send(&mut f.app, Message::Select(f.state_a));
+        send(&mut f.app, Message::Page(Page::Behavior));
+        let context = f.app.state_context().unwrap();
+        event(
+            &mut f.app,
+            Event::Viewport(context, iced::Size::new(820., 540.)),
+        );
+        assert_eq!(behavior::selected_owner(&f.app), Some(f.machine_a));
+        assert_eq!(context.diagram, f.diagram_a);
+        let state = &f.app.behavior.diagram;
+        assert_eq!(
+            (
+                state.diagram,
+                state.pan,
+                state.zoom,
+                state.tool,
+                state.fit,
+                state.viewport
+            ),
+            retained
+        );
+        assert_eq!(
+            state.tool,
+            Tool::Reconnect {
+                relation: f.transition_a,
+                endpoint: Endpoint::Target
+            }
+        );
+        assert!(Arc::ptr_eq(&before, &f.app.document.snapshot()));
+    }
+}
+
+#[test]
+fn state_navigation_root_event_and_same_layer_keep_the_current_camera_and_tool() {
+    let mut f = navigation_fixture(Layer::Sa);
+    let state = &f.app.behavior.diagram;
+    let retained = (
+        state.diagram,
+        state.pan,
+        state.zoom,
+        state.tool,
+        state.fit,
+        state.viewport,
+    );
+    let before = f.app.document.snapshot();
+    send(&mut f.app, Message::Select(f.root_event));
+    assert_eq!(f.app.selected, f.root_event);
+    send(&mut f.app, Message::Page(Page::Catalog));
+    send(&mut f.app, Message::Page(Page::Behavior));
+    send(&mut f.app, Message::Layer(Layer::Sa));
+    assert_eq!(behavior::selected_owner(&f.app), Some(f.machine_a));
+    assert_eq!(f.app.state_context().unwrap().diagram, f.diagram_a);
+    let state = &f.app.behavior.diagram;
+    assert_eq!(
+        (
+            state.diagram,
+            state.pan,
+            state.zoom,
+            state.tool,
+            state.fit,
+            state.viewport
+        ),
+        retained
+    );
+    assert!(Arc::ptr_eq(&before, &f.app.document.snapshot()));
+}
+
 #[test]
 fn create_view_places_only_its_machine_and_restores_exact_source_in_one_undo() {
     let mut f = fixture();