Fix #504: Convert corner/smooth for a path selected as a whole with the anchor tools

Reported: Alt-click with the Pen should toggle an anchor between corner and smooth, and the
Control bar had no way to make a corner anchor smooth.

v0.5.0 already has Pen + Alt as the Anchor Point tool (#473) and the Control bar's and the
Properties panel's Convert buttons for direct-selected anchors, the path being drawn included (its
last anchor is selected). The remaining gap: with Direct Selection, the Pen, the Curvature or the
anchor tools, a path selected as a whole shows all its anchors selected, yet the Convert buttons
only appeared once anchors were direct-selected.

- chrome::anchor_controls decides what the Control bar and the Properties panel show: Convert and
  Anchors for direct-selected anchors (as before), Convert alone for paths selected as a whole
  with a tool that edits anchors (path.convertAnchors already converts every anchor of those);
  Remove and Cut still wait for anchors direct-selected, as they act on those only.
- Tests: the Control bar and the Properties panel offer Convert for a whole rectangle with Direct
  Selection and the Pen, not with the Selection tool, and smooth converts every corner; Pen + Alt
  on the path being drawn makes a smooth anchor a corner (click) and a corner smooth (drag), and
  drawing goes on. ROADMAP.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/engine/src/tests_draw2.rs

@@ -766,3 +766,27 @@ fn pen_drag_from_the_first_anchor_closes_the_path() {
     gesture(&mut s, &[(500.0, 500.0)], none);
     assert_eq!(paths(&s).len(), 2);
 }
+
+#[test]
+fn pen_with_alt_converts_the_anchors_of_the_path_being_drawn() {
+    // #504: while drawing, Alt-click on a smooth anchor of the path makes it a corner and Alt-drag
+    // on a corner one pulls out smooth handles; the next click goes on drawing the path.
+    let (none, alt) = (Mods::default(), Mods { alt: true, ..Mods::default() });
+    let v = view();
+    let mut s = session();
+    s.select_tool("pen", v).unwrap();
+    gesture(&mut s, &[(100.0, 300.0)], none);
+    gesture(&mut s, &[(200.0, 300.0), (240.0, 300.0)], none);
+    gesture(&mut s, &[(300.0, 400.0)], none);
+    gesture(&mut s, &[(400.0, 300.0)], none);
+    let id = s.doc().unwrap().selection.objects[0];
+    assert!(smooth(path(&s, id).subpaths[0].anchors[1]));
+    assert_eq!(gesture(&mut s, &[(200.0, 300.0)], alt), 1);
+    let a = path(&s, id).subpaths[0].anchors[1];
+    assert!(!a.has_in() && !a.has_out(), "a corner: {a:?}");
+    assert_eq!(gesture(&mut s, &[(300.0, 400.0), (320.0, 400.0), (340.0, 400.0)], alt), 1);
+    let a = path(&s, id).subpaths[0].anchors[2];
+    assert!(smooth(a) && a.h_out == Point::new(340.0, 400.0), "smooth: {a:?}");
+    gesture(&mut s, &[(500.0, 400.0)], none);
+    assert_eq!((paths(&s).len(), path(&s, id).subpaths[0].anchors.len()), (1, 5));
+}

crates/ui-egui/src/chrome.rs

@@ -108,10 +108,32 @@ pub fn app_bar(app: &mut VectorcraftApp, ui: &mut Ui) {
 /// An anchor button: icon, tooltip, command and the convert command's `to`.
 type AnchorButton<'a> = (&'a str, &'a str, &'a str, Option<&'a str>);
 
-/// What the Control bar and the Properties panel offer for direct-selected anchors: "Convert:"
-/// corner or smooth, then "Anchors:" remove, connect (Join) and cut. Each group is a row of its
-/// own: inline in the Control bar, one under the other in a panel.
-pub fn anchor_buttons(app: &mut VectorcraftApp, ui: &mut Ui) {
+/// The anchor controls the Control bar and the Properties panel show.
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub enum AnchorControls {
+    None,
+    /// Paths selected as a whole with a tool that edits anchors (Direct Selection, the Pen…),
+    /// which shows all their anchors selected: "Convert:" only, as removing or cutting at every
+    /// anchor isn't what they're for.
+    Convert,
+    /// Anchors direct-selected: "Convert:" and "Anchors:".
+    All,
+}
+
+/// Which anchor controls show for the selection and the active tool.
+pub fn anchor_controls(app: &VectorcraftApp) -> AnchorControls {
+    let Some(st) = app.session.active() else { return AnchorControls::None };
+    if !st.selection.anchors.is_empty() {
+        return AnchorControls::All;
+    }
+    let paths = st.selection.objects.iter().any(|id| st.doc.node(*id).is_some_and(|n| matches!(n.kind, NodeKind::Path { .. })));
+    if paths && vectorcraft_tools::catalog::edits_anchors(app.session.tool_id()) { AnchorControls::Convert } else { AnchorControls::None }
+}
+
+/// What the Control bar and the Properties panel offer for selected anchors ([`anchor_controls`]):
+/// "Convert:" corner or smooth, then "Anchors:" remove, connect (Join) and cut. Each group is a
+/// row of its own: inline in the Control bar, one under the other in a panel.
+pub fn anchor_buttons(app: &mut VectorcraftApp, ui: &mut Ui, controls: AnchorControls) {
     let t = Tokens::get(ui.ctx());
     let mut run = None;
     let groups: [(&str, &[AnchorButton]); 2] = [
@@ -131,7 +153,12 @@ pub fn anchor_buttons(app: &mut VectorcraftApp, ui: &mut Ui) {
             ],
         ),
     ];
-    for (label, buttons) in groups {
+    let shown = match controls {
+        AnchorControls::None => 0,
+        AnchorControls::Convert => 1,
+        AnchorControls::All => groups.len(),
+    };
+    for (label, buttons) in groups.into_iter().take(shown) {
         ui.horizontal(|ui| {
             ui.label(egui::RichText::new(label).size(12.0).color(t.text));
             for &(icon, tip, id, to) in buttons {
@@ -166,9 +193,9 @@ pub fn control_bar(app: &mut VectorcraftApp, ui: &mut Ui) {
                 let sel = st.selection.objects.clone();
                 let units = app.session.general_unit();
                 let first = sel.first().and_then(|id| st.doc.node(*id)).cloned();
-                let anchor_mode = !st.selection.anchors.is_empty();
+                let anchors = anchor_controls(app);
                 let label = match &first {
-                    Some(_) if sel.len() == 1 && anchor_mode => tl!("Anchor Point"),
+                    Some(_) if sel.len() == 1 && anchors != AnchorControls::None => tl!("Anchor Point"),
                     Some(vectorcraft_doc::Node { kind: NodeKind::Image(im), .. }) if sel.len() == 1 => {
                         if im.link.is_some() {
                             tl!("Linked File")
@@ -180,8 +207,8 @@ pub fn control_bar(app: &mut VectorcraftApp, ui: &mut Ui) {
                     _ => tl!(crate::panels::appearance::object_label(app)),
                 };
                 ui.label(egui::RichText::new(label).font(theme::semibold(12.0)).color(t.text));
-                if anchor_mode {
-                    anchor_buttons(app, ui);
+                if anchors != AnchorControls::None {
+                    anchor_buttons(app, ui, anchors);
                 }
                 ui.add_space(6.0);
                 // An image or an Image Trace object shows its own controls in place of Fill and Stroke.

crates/ui-egui/src/panels/properties.rs

@@ -16,7 +16,7 @@ pub fn show(app: &mut VectorcraftApp, ui: &mut Ui) {
         return;
     };
     let n_sel = st.selection.len();
-    let anchor_mode = !st.selection.anchors.is_empty();
+    let anchors = crate::chrome::anchor_controls(app);
     let first = first_selected(app);
     let label = match (&first, n_sel) {
         (None, _) => tl!("Document").to_string(),
@@ -85,10 +85,10 @@ pub fn show(app: &mut VectorcraftApp, ui: &mut Ui) {
             }
         });
     }
-    if anchor_mode {
+    if anchors != crate::chrome::AnchorControls::None {
         divider(ui);
         section_header(ui, tl!("Anchor Point"));
-        crate::chrome::anchor_buttons(app, ui);
+        crate::chrome::anchor_buttons(app, ui, anchors);
     }
     divider(ui);
     section_header(ui, tl!("Quick Actions"));

crates/ui-egui/src/tests_removeanchors.rs

@@ -205,3 +205,26 @@ fn the_control_bar_converts_connects_and_cuts_selected_anchors() {
     assert!(app.session.active().unwrap().doc.node(id).unwrap().path_data().unwrap().subpaths[0].closed);
     assert_eq!(anchor_count(&app, id), 4, "the coincident ends merge");
 }
+
+/// #504: with a tool that edits anchors (Direct Selection, the Pen…), a path selected as a whole
+/// shows all its anchors selected, and the Control bar and the Properties panel offer to convert
+/// them; removing and cutting wait for anchors direct-selected. The Selection tool shows neither.
+#[test]
+fn a_whole_path_converts_with_the_tools_that_edit_anchors() {
+    let mut app = app();
+    let id = rect(&mut app);
+    let ctx = egui::Context::default();
+    crate::theme::install_fonts(&ctx);
+    app.select_tool("selection");
+    assert!(!has(&control_frame(&mut app, &ctx, vec![]), "Convert:"));
+    for tool in ["directSelection", "pen"] {
+        app.select_tool(tool);
+        let texts = control_frame(&mut app, &ctx, vec![]);
+        assert!(has(&texts, "Convert:") && !has(&texts, "Anchors:"), "{tool}: {texts:?}");
+        let props = crate::tests_labels::painted_text(&mut app, crate::panels::properties::show);
+        assert!(props.contains("Convert:") && !props.contains("Anchors:"), "{tool}: {props}");
+    }
+    click_button(&mut app, &ctx, "Convert:", 1);
+    let sp = app.session.active().unwrap().doc.node(id).unwrap().path_data().unwrap().subpaths[0].clone();
+    assert!(sp.anchors.iter().all(|a| a.has_in() && a.has_out()), "every corner made smooth: {sp:?}");
+}