M4.89: Slice and Slice Selection tools draw, pick, move, resize and delete slices

The Slice tool (Shift+K) drags out a user slice (Shift square, Alt from the
centre, snapping to ruler guides) as one undo step through
object.slice.create. The Slice Selection tool selects slices (Shift
toggles, object.slice.select), moves them (object.slice.move; object
slices move their objects), resizes a user slice by its handles
(object.slice.setRect), opens Slice Options on a double click and deletes
with Delete (object.slice.delete). Hidden or locked slices can't be
picked. Both tools have cursors drawn in code.

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

crates/engine/src/cmd/slices.rs

@@ -129,6 +129,51 @@ pub fn specs() -> Vec<CommandSpec> {
             list
         ),
         cmd!("select.object.slices", "Slices", ["Select", "Object"], None, "{} select every user and object slice → {count}", has_doc, select_all),
+        cmd!(
+            "object.slice.create",
+            "Create Slice",
+            [],
+            None,
+            "{x, y, width, height} a user slice over that rectangle, selected (the Slice tool's drag) → {id}",
+            has_doc,
+            create
+        ),
+        cmd!(
+            "object.slice.setRect",
+            "Set Slice Rectangle",
+            [],
+            None,
+            "{id: user slice, x, y, width, height} move or resize a user slice (an object slice follows its object) → {id}",
+            has_doc,
+            set_rect
+        ),
+        cmd!(
+            "object.slice.move",
+            "Move Slices",
+            [],
+            None,
+            "{slices?: [id…] (default: the selected slices), dx, dy} move the slices: user slices move, object slices move their objects → {ids}",
+            has_doc,
+            move_slices
+        ),
+        cmd!(
+            "object.slice.delete",
+            "Delete Slices",
+            [],
+            None,
+            "{slices?: [id…] (default: the selected slices)} delete the user slices and release the object slices (their objects stay) → {count}",
+            has_doc,
+            delete
+        ),
+        cmd!(
+            "object.slice.select",
+            "Select Slices",
+            [],
+            None,
+            "{slices?: [id…] (user slice ids or ids of objects with an object slice; none: deselect the slices), toggle?: bool (Shift: add the unselected ones, drop the selected ones)} select slices as the Slice Selection tool does; the objects are deselected → {selected: [id…]}",
+            has_doc,
+            select
+        ),
     ]
 }
 
@@ -145,6 +190,18 @@ impl Session {
 
 // ---------- targets and params ----------
 
+/// The slices a command acts on: `slices` (ids that must all be slices), else the selected ones.
+fn slice_targets(s: &Session, p: &Value, cmd: &str) -> Result<Vec<NodeId>> {
+    let st = s.doc()?;
+    match ids_param(p, "slices") {
+        Some(ids) => match ids.iter().find(|id| !st.doc.is_slice(**id)) {
+            Some(id) => Err(bad(cmd, format!("{id} is not a slice"))),
+            None => Ok(dedup(ids)),
+        },
+        None => Ok(selected_slices(&st.doc, &st.selection)),
+    }
+}
+
 /// The selected slices: those the Slice Selection tool selected and the selected objects that are
 /// object slices.
 fn selected(s: &Session) -> Result<Vec<NodeId>> {
@@ -565,3 +622,96 @@ fn select_all(s: &mut Session, _: &Value) -> Result<Value> {
     s.select(|_, sel| sel.set_slices(ids))?;
     Ok(json!({ "count": n }))
 }
+
+// ---------- the Slice and Slice Selection tools ----------
+
+/// `{x, y, width, height}` as a rectangle a slice can have.
+fn rect_param(p: &Value, cmd: &str) -> Result<Rect> {
+    let (x, y) = (f64_req(p, "x", cmd)?, f64_req(p, "y", cmd)?);
+    let r = Rect::new(x, y, x + f64_req(p, "width", cmd)?, y + f64_req(p, "height", cmd)?).abs();
+    if slice_rect_ok(r) { Ok(r) } else { Err(bad(cmd, "the rectangle needs a size and must lie on the canvas")) }
+}
+
+fn create(s: &mut Session, p: &Value) -> Result<Value> {
+    let r = rect_param(p, "object.slice.create")?;
+    let id = s.edit("Slice", |d, sel| {
+        let id = add_slice(d, r, SliceOptions::default());
+        sel.set_slices([id]);
+        Ok(id)
+    })?;
+    Ok(json!({ "id": id.0 }))
+}
+
+fn set_rect(s: &mut Session, p: &Value) -> Result<Value> {
+    const C: &str = "object.slice.setRect";
+    let id = id_param(p, "id").ok_or_else(|| bad(C, "missing `id`"))?;
+    let r = rect_param(p, C)?;
+    let d = &s.doc()?.doc;
+    if d.slice(id).is_none() {
+        return Err(bad(C, if d.is_slice(id) { format!("{id} is an object slice: it follows its object") } else { format!("{id} is not a slice") }));
+    }
+    s.edit("Resize Slice", |d, _| {
+        if let Some(sl) = d.slice_mut(id) {
+            sl.rect = r;
+        }
+        Ok(())
+    })?;
+    Ok(json!({ "id": id.0 }))
+}
+
+fn move_slices(s: &mut Session, p: &Value) -> Result<Value> {
+    const C: &str = "object.slice.move";
+    let targets = slice_targets(s, p, C)?;
+    let v = vectorcraft_geom::Vec2::new(f64_req(p, "dx", C)?, f64_req(p, "dy", C)?);
+    if !(v.x.is_finite() && v.y.is_finite()) {
+        return Err(bad(C, "dx and dy must be numbers"));
+    }
+    s.edit("Move Slice", |d, _| {
+        for id in &targets {
+            match d.slice_mut(*id) {
+                Some(sl) if slice_rect_ok(sl.rect + v) => sl.rect = sl.rect + v,
+                Some(_) => return Err(bad(C, "the slice would leave the canvas")),
+                None => {
+                    if let Some(n) = d.node_mut(*id) {
+                        n.transform(vectorcraft_geom::Affine::translate(v), vectorcraft_doc::Scaling::default());
+                    }
+                }
+            }
+        }
+        Ok(())
+    })?;
+    Ok(json!({ "ids": ids_json(&targets) }))
+}
+
+fn delete(s: &mut Session, p: &Value) -> Result<Value> {
+    let targets = slice_targets(s, p, "object.slice.delete")?;
+    if targets.is_empty() {
+        return Ok(json!({ "count": 0 }));
+    }
+    s.edit("Delete Slice", |d, _| {
+        for id in &targets {
+            remove_slice(d, *id);
+        }
+        Ok(())
+    })?;
+    Ok(json!({ "count": targets.len() }))
+}
+
+fn select(s: &mut Session, p: &Value) -> Result<Value> {
+    let ids = slice_targets(s, &json!({ "slices": p.get("slices").cloned().unwrap_or(json!([])) }), "object.slice.select")?;
+    let toggle = bool_or(p, "toggle", false);
+    s.select(|_, sel| {
+        let mut now = if toggle { sel.slices.clone() } else { vec![] };
+        for id in ids {
+            match now.iter().position(|x| *x == id) {
+                Some(i) if toggle => {
+                    now.remove(i);
+                }
+                Some(_) => {}
+                None => now.push(id),
+            }
+        }
+        sel.set_slices(now);
+    })?;
+    Ok(json!({ "selected": ids_json(&s.doc()?.selection.slices) }))
+}

crates/engine/src/tests_slices.rs

@@ -250,3 +250,80 @@ fn slices_survive_a_native_round_trip() {
     run(&mut s, "edit.duplicate", json!({}));
     assert_eq!(s.doc().unwrap().doc.object_slices().len(), 2);
 }
+
+#[test]
+fn slice_tool_gestures_are_one_undo_step_each() {
+    use vectorcraft_tools::{Mods, PointerEvent, PointerKind as K, ToolKey};
+    let mut s = session();
+    let view = ViewInfo { smart_guides: false, ..Default::default() };
+    let undo = |s: &Session| s.doc().unwrap().history.undo.len();
+    let gesture = |s: &mut Session, pts: &[(K, f64, f64)]| {
+        for (k, x, y) in pts {
+            s.pointer(&PointerEvent::new(*k, *x, *y), view).unwrap();
+        }
+    };
+    s.select_tool("slice", view).unwrap();
+    let n = undo(&s);
+    gesture(&mut s, &[(K::Down, 10.0, 10.0), (K::Drag, 50.0, 30.0), (K::Drag, 110.0, 60.0), (K::Up, 110.0, 60.0)]);
+    assert_eq!(undo(&s), n + 1);
+    let id = s.doc().unwrap().doc.slices[0].id;
+    assert_eq!(s.doc().unwrap().doc.slices.len(), 1, "the previews left one slice");
+    assert_eq!(rect_of(&mut s, id.0), [10.0, 10.0, 100.0, 50.0]);
+    assert_eq!(s.doc().unwrap().selection.slices, vec![id]);
+
+    // Slice Selection: drag the slice, then its bottom-right handle, then Delete.
+    s.select_tool("sliceSelection", view).unwrap();
+    gesture(&mut s, &[(K::Down, 20.0, 20.0), (K::Drag, 30.0, 40.0), (K::Drag, 40.0, 50.0), (K::Up, 40.0, 50.0)]);
+    assert_eq!(undo(&s), n + 2);
+    assert_eq!(rect_of(&mut s, id.0), [30.0, 40.0, 100.0, 50.0]);
+    gesture(&mut s, &[(K::Down, 130.0, 90.0), (K::Drag, 140.0, 95.0), (K::Drag, 150.0, 100.0), (K::Up, 150.0, 100.0)]);
+    assert_eq!(undo(&s), n + 3);
+    assert_eq!(rect_of(&mut s, id.0), [30.0, 40.0, 120.0, 60.0]);
+    assert!(s.tool_claims_key(ToolKey::Delete, view));
+    s.tool_key(ToolKey::Delete, Mods::default(), view).unwrap();
+    assert!(s.doc().unwrap().doc.slices.is_empty());
+    assert_eq!(undo(&s), n + 4);
+    // Undo walks the gestures back one at a time.
+    run(&mut s, "edit.undo", json!({}));
+    assert_eq!(rect_of(&mut s, id.0), [30.0, 40.0, 120.0, 60.0]);
+    run(&mut s, "edit.undo", json!({}));
+    assert_eq!(rect_of(&mut s, id.0), [30.0, 40.0, 100.0, 50.0]);
+
+    // An object slice moves its object; locked slices stay put.
+    let a = rect(&mut s, 200.0, 200.0, 40.0, 40.0);
+    run(&mut s, "object.slice.make", json!({}));
+    gesture(&mut s, &[(K::Down, 220.0, 220.0), (K::Drag, 230.0, 220.0), (K::Drag, 240.0, 230.0), (K::Up, 240.0, 230.0)]);
+    assert_eq!(s.doc().unwrap().doc.node(NodeId(a)).unwrap().geometric_bounds().unwrap().x0, 220.0);
+    run(&mut s, "view.slices.lock", json!({"locked": true}));
+    let before = undo(&s);
+    gesture(&mut s, &[(K::Down, 250.0, 240.0), (K::Drag, 280.0, 260.0), (K::Up, 280.0, 260.0)]);
+    assert_eq!(undo(&s), before);
+    // The journal replays the gestures as commands.
+    let journal: Vec<String> = s.journal.iter().map(|(c, _)| c.clone()).collect();
+    for c in ["object.slice.create", "object.slice.move", "object.slice.setRect", "object.slice.delete", "object.slice.select"] {
+        assert!(journal.iter().any(|j| j == c), "{c} journaled: {journal:?}");
+    }
+}
+
+#[test]
+fn slice_commands_check_their_params() {
+    let mut s = session();
+    assert!(s.execute("object.slice.create", &json!({"x": 0, "y": 0, "width": 0, "height": 10})).is_err(), "no area");
+    assert!(s.execute("object.slice.create", &json!({"x": 1e9, "y": 0, "width": 10, "height": 10})).is_err(), "off the canvas");
+    let id = run(&mut s, "object.slice.create", json!({"x": 50, "y": 60, "width": -20, "height": 10}))["id"].as_u64().unwrap();
+    assert_eq!(rect_of(&mut s, id), [30.0, 60.0, 20.0, 10.0], "a negative size draws the other way");
+    run(&mut s, "object.slice.setRect", json!({"id": id, "x": 0, "y": 0, "width": 5, "height": 5}));
+    assert_eq!(rect_of(&mut s, id), [0.0, 0.0, 5.0, 5.0]);
+    let a = rect(&mut s, 100.0, 100.0, 10.0, 10.0);
+    run(&mut s, "object.slice.make", json!({}));
+    assert!(
+        s.execute("object.slice.setRect", &json!({"id": a, "x": 0, "y": 0, "width": 5, "height": 5})).is_err(),
+        "object slices follow their object"
+    );
+    assert!(s.execute("object.slice.move", &json!({"slices": [12345], "dx": 1, "dy": 1})).is_err(), "not a slice");
+    assert_eq!(run(&mut s, "object.slice.select", json!({"slices": [id, a]}))["selected"], json!([id, a]));
+    assert_eq!(run(&mut s, "object.slice.select", json!({"slices": [a], "toggle": true}))["selected"], json!([id]));
+    assert_eq!(run(&mut s, "object.slice.delete", json!({"slices": [a]}))["count"], 1);
+    assert!(s.doc().unwrap().doc.node(NodeId(a)).is_some(), "deleting an object slice keeps its object");
+    assert_eq!(run(&mut s, "object.slice.select", json!({}))["selected"], json!([]));
+}

crates/engine/src/tooling.rs

@@ -89,6 +89,8 @@ impl Session {
             unit,
             stroke_unit,
             paste_plain_text: self.prefs.paste_text_formatting == "plain",
+            slices_hidden: self.menu.slices_hidden,
+            slices_locked: self.menu.slices_locked,
         };
         let tool = &mut self.tool;
         match crate::guard::catch_panic(|| f(tool.as_mut(), &cx)) {

crates/tools/src/lib.rs

@@ -22,6 +22,7 @@ pub mod pen;
 pub mod place;
 pub mod select;
 pub mod shape;
+pub mod slice;
 pub mod symbolism;
 pub mod text;
 pub mod xform;
@@ -209,6 +210,10 @@ pub struct ToolContext<'a> {
     /// Clipboard Handling → When pasting text: Keep Plain Text. Text pasted while typing takes
     /// the style at the caret, even the text the Type tool copied with its formatting.
     pub paste_plain_text: bool,
+    /// View → Hide Slices: the Slice Selection tool can't pick hidden slices.
+    pub slices_hidden: bool,
+    /// View → Lock Slices: the Slice Selection tool leaves locked slices alone.
+    pub slices_locked: bool,
 }
 
 impl ToolContext<'_> {
@@ -286,6 +291,10 @@ pub enum Cursor {
     AddStop,
     /// A gradient stop dragged off the bar: releasing deletes it.
     RemoveStop,
+    /// The Slice tool: a crosshair with a blade.
+    Slice,
+    /// The Slice Selection tool: the arrow with a slice badge.
+    SliceSelect,
 }
 
 /// A tool state machine.
@@ -347,6 +356,7 @@ pub fn create(id: &str) -> Box<dyn Tool> {
             .or_else(|| meshblend::create(other))
             .or_else(|| distort::create(other))
             .or_else(|| extra::create(other))
+            .or_else(|| slice::create(other))
             .unwrap_or_else(|| Box::new(NoopTool(tool_info(other).map(|t| t.id).unwrap_or("selection")))),
     }
 }
@@ -409,6 +419,8 @@ pub(crate) mod testutil {
             unit: Unit::Points,
             stroke_unit: Unit::Points,
             paste_plain_text: false,
+            slices_hidden: false,
+            slices_locked: false,
         }
     }
 }

crates/tools/src/shape.rs

@@ -80,12 +80,7 @@ impl ShapeTool {
                 ("shape.line".into(), json!({ "x1": a.x, "y1": a.y, "x2": b.x, "y2": b.y }))
             }
             _ => {
-                let mut d = p - start;
+                let r = drag_rect(start, p, m);
-                if m.shift {
-                    let s = d.x.abs().max(d.y.abs());
-                    d = vectorcraft_geom::Vec2::new(s * d.x.signum(), s * d.y.signum());
-                }
-                let r = if m.alt { Rect::from_points(start - d, start + d) } else { Rect::from_points(start, start + d) };
                 let cmd = if self.id == "ellipse" { "shape.ellipse" } else { "shape.rectangle" };
                 let mut v = json!({ "x": r.x0, "y": r.y0, "width": r.width(), "height": r.height() });
                 if self.id == "roundedRectangle" {
@@ -97,6 +92,17 @@ impl ShapeTool {
     }
 }
 
+/// The rectangle a drag from `start` to `p` draws: Shift makes it a square, Alt draws it from its
+/// centre.
+pub(crate) fn drag_rect(start: Point, p: Point, m: Mods) -> Rect {
+    let mut d = p - start;
+    if m.shift {
+        let s = d.x.abs().max(d.y.abs());
+        d = vectorcraft_geom::Vec2::new(s * d.x.signum(), s * d.y.signum());
+    }
+    if m.alt { Rect::from_points(start - d, start + d) } else { Rect::from_points(start, start + d) }
+}
+
 impl Tool for ShapeTool {
     fn id(&self) -> &'static str {
         self.id

crates/tools/src/slice.rs

@@ -0,0 +1,432 @@
+//! Slice tool (Shift+K) and Slice Selection tool.
+//!
+//! The Slice tool drags out a user slice (Shift: a square, Alt: from its centre), snapping to the
+//! ruler guides and, like the drawing tools, to art: the drag previews `object.slice.create` and
+//! commits it as one undo step. The Slice Selection tool clicks a slice to select it (Shift adds or
+//! drops it), drags the selected slices to move them (`object.slice.move`: an object slice moves
+//! its object), drags a selected user slice's edge or corner handle to resize it
+//! (`object.slice.setRect`), opens Slice Options on a double click and deletes the selected slices
+//! with Delete. Hidden or locked slices (View menu) can't be picked.
+
+use serde_json::{Value, json};
+use vectorcraft_doc::{NodeId, SliceSource};
+use vectorcraft_geom::{Point, Rect, Vec2};
+
+use crate::bbox::{Handle, hit_handle, move_delta, scale_for_drag};
+use crate::shape::drag_rect;
+use crate::xform::{BLUE, polygon, rect_corners};
+use crate::{Action, Cursor, Mods, Overlay, PointerEvent, PointerKind, Tool, ToolContext, ToolKey, json_ids};
+
+/// Create a slice tool by id (None = not one of ours).
+pub fn create(id: &str) -> Option<Box<dyn Tool>> {
+    Some(match id {
+        "slice" => Box::new(SliceTool::default()),
+        "sliceSelection" => Box::new(SliceSelectionTool::default()),
+        _ => return None,
+    })
+}
+
+fn rect_json(r: Rect) -> Value {
+    json!({ "x": r.x0, "y": r.y0, "width": r.width(), "height": r.height() })
+}
+
+/// A rectangle with a size (a drag along one axis has none).
+fn has_area(r: Rect) -> bool {
+    r.width() > 1e-6 && r.height() > 1e-6
+}
+
+/// Snap `p` as the drawing tools do, then to the nearest ruler guide within reach (guides win).
+fn snap(cx: &ToolContext, p: Point) -> (Point, Vec<Overlay>) {
+    let (mut q, ov) = crate::guides::snap_draw(cx, p, &[]);
+    let tol = cx.tol(5.0);
+    let nearest = |vertical: bool, v: f64| {
+        cx.doc
+            .guides
+            .iter()
+            .filter(|g| g.vertical == vertical && (g.pos - v).abs() <= tol)
+            .min_by(|a, b| (a.pos - v).abs().total_cmp(&(b.pos - v).abs()))
+    };
+    if let Some(g) = nearest(true, p.x) {
+        q.x = g.pos;
+    }
+    if let Some(g) = nearest(false, p.y) {
+        q.y = g.pos;
+    }
+    (q, ov)
+}
+
+/// The Slice tool: drag to make a user slice.
+#[derive(Default)]
+pub struct SliceTool {
+    start: Option<Point>,
+    last: Point,
+    began: bool,
+    guides: Vec<Overlay>,
+}
+
+impl Tool for SliceTool {
+    fn id(&self) -> &'static str {
+        "slice"
+    }
+
+    fn busy(&self) -> bool {
+        self.start.is_some()
+    }
+
+    fn pointer(&mut self, cx: &ToolContext, ev: &PointerEvent) -> Vec<Action> {
+        match ev.kind {
+            PointerKind::Down => {
+                let (p, _) = snap(cx, ev.pos);
+                (self.start, self.last, self.began) = (Some(p), p, false);
+                vec![]
+            }
+            PointerKind::Drag => {
+                let Some(start) = self.start else { return vec![] };
+                let (p, guides) = snap(cx, ev.pos);
+                (self.last, self.guides) = (p, guides);
+                let mut out = vec![];
+                if !self.began {
+                    if p.distance(start) < cx.tol(2.0) {
+                        return out;
+                    }
+                    self.began = true;
+                    out.push(Action::Begin("Slice".into()));
+                }
+                let r = drag_rect(start, p, ev.mods);
+                if has_area(r) {
+                    out.push(Action::Preview("object.slice.create".into(), rect_json(r)));
+                }
+                out
+            }
+            PointerKind::Up => {
+                self.guides.clear();
+                let began = std::mem::take(&mut self.began);
+                if self.start.take().is_some() && began { vec![Action::Commit] } else { vec![] }
+            }
+            _ => vec![],
+        }
+    }
+
+    fn key(&mut self, _cx: &ToolContext, key: ToolKey, _mods: Mods) -> Vec<Action> {
+        if key == ToolKey::Escape && self.began { self.deactivate(_cx) } else { vec![] }
+    }
+
+    fn overlays(&self, cx: &ToolContext) -> Vec<Overlay> {
+        match self.start {
+            Some(s) if self.began => {
+                let d = self.last - s;
+                let mut o = self.guides.clone();
+                o.push(Overlay::Measure { p: self.last, text: cx.size_label(d.x.abs(), d.y.abs()) });
+                o
+            }
+            _ => vec![],
+        }
+    }
+
+    fn cursor(&self, _cx: &ToolContext, _p: Point, _m: Mods) -> Cursor {
+        Cursor::Slice
+    }
+
+    fn deactivate(&mut self, _cx: &ToolContext) -> Vec<Action> {
+        self.start = None;
+        self.guides.clear();
+        if std::mem::take(&mut self.began) { vec![Action::Cancel] } else { vec![] }
+    }
+}
+
+#[derive(Clone, Debug)]
+enum Drag {
+    Move { start: Point, ids: Vec<NodeId>, began: bool },
+    Resize { id: NodeId, handle: Handle, rect: Rect, began: bool },
+}
+
+impl Drag {
+    fn began(&self) -> bool {
+        match self {
+            Drag::Move { began, .. } | Drag::Resize { began, .. } => *began,
+        }
+    }
+}
+
+/// The Slice Selection tool: select, move, resize and delete slices.
+#[derive(Default)]
+pub struct SliceSelectionTool {
+    drag: Option<Drag>,
+}
+
+/// Can the slices be picked (not hidden or locked)?
+fn pickable(cx: &ToolContext) -> bool {
+    !cx.slices_hidden && !cx.slices_locked
+}
+
+/// The user or object slice under `p` (the smallest one where several overlap).
+fn slice_at(cx: &ToolContext, p: Point) -> Option<NodeId> {
+    let lay = cx.doc.slice_layout();
+    let hit = lay.iter().filter(|a| a.source != SliceSource::Auto && a.rect.contains(p));
+    hit.min_by(|a, b| a.rect.area().total_cmp(&b.rect.area())).and_then(|a| a.id)
+}
+
+/// A handle of a selected user slice under `p`: (slice, handle, its rectangle).
+fn handle_at(cx: &ToolContext, p: Point) -> Option<(NodeId, Handle, Rect)> {
+    cx.selection.slices.iter().filter_map(|id| cx.doc.slice(*id)).find_map(|s| hit_handle(s.rect, p, cx.tol(5.0)).map(|h| (s.id, h, s.rect)))
+}
+
+impl SliceSelectionTool {
+    /// Select `ids` only.
+    fn select(ids: &[NodeId]) -> Action {
+        Action::Exec("object.slice.select".into(), json!({ "slices": json_ids(ids) }))
+    }
+}
+
+impl Tool for SliceSelectionTool {
+    fn id(&self) -> &'static str {
+        "sliceSelection"
+    }
+
+    fn busy(&self) -> bool {
+        self.drag.is_some()
+    }
+
+    fn pointer(&mut self, cx: &ToolContext, ev: &PointerEvent) -> Vec<Action> {
+        let (p, m) = (ev.pos, ev.mods);
+        match (ev.kind, self.drag.clone()) {
+            (PointerKind::Down, _) => {
+                self.drag = None;
+                if !pickable(cx) {
+                    return vec![];
+                }
+                if let Some((id, handle, rect)) = handle_at(cx, p) {
+                    self.drag = Some(Drag::Resize { id, handle, rect, began: false });
+                    return vec![];
+                }
+                let selected = &cx.selection.slices;
+                match slice_at(cx, p) {
+                    Some(id) if m.shift => vec![Action::Exec("object.slice.select".into(), json!({ "slices": [id.0], "toggle": true }))],
+                    Some(id) if selected.contains(&id) => {
+                        self.drag = Some(Drag::Move { start: p, ids: selected.clone(), began: false });
+                        vec![]
+                    }
+                    Some(id) => {
+                        self.drag = Some(Drag::Move { start: p, ids: vec![id], began: false });
+                        vec![Self::select(&[id])]
+                    }
+                    None if !m.shift && !selected.is_empty() => vec![Self::select(&[])],
+                    None => vec![],
+                }
+            }
+            (PointerKind::Drag, Some(Drag::Move { start, ids, began })) => {
+                let mut out = vec![];
+                if !began {
+                    if p.distance(start) < cx.tol(3.0) {
+                        return out;
+                    }
+                    out.push(Action::Begin("Move Slice".into()));
+                }
+                let d = move_delta(start, p, m.shift);
+                out.push(Action::Preview("object.slice.move".into(), json!({ "slices": json_ids(&ids), "dx": d.x, "dy": d.y })));
+                self.drag = Some(Drag::Move { start, ids, began: true });
+                out
+            }
+            (PointerKind::Drag, Some(Drag::Resize { id, handle, rect, began })) => {
+                let mut out = vec![];
+                if !began {
+                    out.push(Action::Begin("Resize Slice".into()));
+                }
+                self.drag = Some(Drag::Resize { id, handle, rect, began: true });
+                let r = scale_for_drag(rect, handle, p, m.shift, m.alt).transform_rect_bbox(rect);
+                if has_area(r) {
+                    let mut v = rect_json(r);
+                    v["id"] = json!(id.0);
+                    out.push(Action::Preview("object.slice.setRect".into(), v));
+                }
+                out
+            }
+            (PointerKind::Up, Some(d)) => {
+                self.drag = None;
+                if d.began() { vec![Action::Commit] } else { vec![] }
+            }
+            (PointerKind::DoubleClick, _) => {
+                self.drag = None;
+                match slice_at(cx, p).filter(|_| pickable(cx)) {
+                    Some(id) if cx.selection.slices == [id] => vec![Action::Dialog("sliceOptions".into(), json!({}))],
+                    Some(id) => vec![Self::select(&[id]), Action::Dialog("sliceOptions".into(), json!({}))],
+                    None => vec![],
+                }
+            }
+            _ => vec![],
+        }
+    }
+
+    fn claims_key(&self, cx: &ToolContext, key: ToolKey) -> bool {
+        matches!(key, ToolKey::Delete | ToolKey::Backspace) && !cx.selection.slices.is_empty() && pickable(cx)
+    }
+
+    fn key(&mut self, cx: &ToolContext, key: ToolKey, _mods: Mods) -> Vec<Action> {
+        match key {
+            ToolKey::Delete | ToolKey::Backspace if self.drag.is_none() && self.claims_key(cx, key) => {
+                vec![Action::Exec("object.slice.delete".into(), json!({}))]
+            }
+            ToolKey::Escape => self.deactivate(cx),
+            _ => vec![],
+        }
+    }
+
+    fn overlays(&self, cx: &ToolContext) -> Vec<Overlay> {
+        let mut o = vec![];
+        for id in &cx.selection.slices {
+            let Some(r) = cx.doc.slice_bounds(*id) else { continue };
+            o.push(Overlay::Path { path: polygon(&rect_corners(r), true), color: BLUE, width: 1.0, dashed: false });
+            if cx.doc.slice(*id).is_some() && pickable(cx) {
+                o.extend(Handle::ALL.iter().map(|h| Overlay::Anchor { p: h.pos(r), color: BLUE, filled: false, size: 7.0 }));
+            }
+        }
+        match &self.drag {
+            Some(Drag::Resize { id, began: true, .. }) => {
+                if let Some(r) = cx.doc.slice_bounds(*id) {
+                    o.push(Overlay::Measure {
+                        p: Point::new(r.x1, r.y1) + Vec2::new(cx.tol(12.0), cx.tol(12.0)),
+                        text: cx.size_label(r.width(), r.height()),
+                    });
+                }
+            }
+            Some(Drag::Move { ids, began: true, .. }) => {
+                if let Some(r) = ids.iter().filter_map(|id| cx.doc.slice_bounds(*id)).reduce(|a, b| a.union(b)) {
+                    o.push(Overlay::Measure {
+                        p: Point::new(r.x1, r.y1) + Vec2::new(cx.tol(12.0), cx.tol(12.0)),
+                        text: cx.size_label(r.width(), r.height()),
+                    });
+                }
+            }
+            _ => {}
+        }
+        o
+    }
+
+    fn cursor(&self, cx: &ToolContext, p: Point, _m: Mods) -> Cursor {
+        match handle_at(cx, p).filter(|_| pickable(cx)).map(|(_, h, _)| h) {
+            Some(Handle::Top | Handle::Bottom) => Cursor::ResizeV,
+            Some(Handle::Left | Handle::Right) => Cursor::ResizeH,
+            Some(Handle::TopLeft | Handle::BottomRight) => Cursor::ResizeNwSe,
+            Some(Handle::TopRight | Handle::BottomLeft) => Cursor::ResizeNeSw,
+            None => Cursor::SliceSelect,
+        }
+    }
+
+    fn deactivate(&mut self, _cx: &ToolContext) -> Vec<Action> {
+        if self.drag.take().is_some_and(|d| d.began()) { vec![Action::Cancel] } else { vec![] }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::testutil::*;
+    use vectorcraft_doc::{Document, Guide, Selection, Slice};
+
+    fn ev(kind: PointerKind, x: f64, y: f64) -> PointerEvent {
+        PointerEvent::new(kind, x, y)
+    }
+
+    fn with(kind: PointerKind, x: f64, y: f64, m: Mods) -> PointerEvent {
+        ev(kind, x, y).with_mods(m)
+    }
+
+    fn create_preview(a: &[Action]) -> Option<Value> {
+        a.iter().find_map(|a| match a {
+            Action::Preview(c, v) if c == "object.slice.create" => Some(v.clone()),
+            _ => None,
+        })
+    }
+
+    #[test]
+    fn the_slice_tool_drags_out_a_slice_in_one_undo_step() {
+        let (mut d, _) = doc_with_rect();
+        d.guides.push(Guide { vertical: true, pos: 403.0 });
+        let s = Selection::default();
+        let p = paint();
+        let mut c = cx(&d, &s, &p);
+        c.smart_guides = false;
+        let mut t = SliceTool::default();
+        assert!(t.pointer(&c, &ev(PointerKind::Down, 300.0, 300.0)).is_empty());
+        assert!(t.pointer(&c, &ev(PointerKind::Drag, 300.5, 300.0)).is_empty(), "a jitter is no drag");
+        let a = t.pointer(&c, &ev(PointerKind::Drag, 350.0, 320.0));
+        assert_eq!(a[0], Action::Begin("Slice".into()));
+        assert_eq!(create_preview(&a), Some(json!({"x": 300.0, "y": 300.0, "width": 50.0, "height": 20.0})));
+        assert!(matches!(t.overlays(&c).last(), Some(Overlay::Measure { .. })));
+        // Shift: a square; Alt: from the centre.
+        let sq = t.pointer(&c, &with(PointerKind::Drag, 350.0, 320.0, Mods { shift: true, ..Default::default() }));
+        assert_eq!(create_preview(&sq), Some(json!({"x": 300.0, "y": 300.0, "width": 50.0, "height": 50.0})));
+        let mid = t.pointer(&c, &with(PointerKind::Drag, 350.0, 320.0, Mods { alt: true, ..Default::default() }));
+        assert_eq!(create_preview(&mid), Some(json!({"x": 250.0, "y": 280.0, "width": 100.0, "height": 40.0})));
+        // The edge near a guide snaps to it.
+        let g = t.pointer(&c, &ev(PointerKind::Drag, 401.0, 320.0));
+        assert_eq!(create_preview(&g), Some(json!({"x": 300.0, "y": 300.0, "width": 103.0, "height": 20.0})));
+        // A drag along one axis has no area: no preview.
+        assert_eq!(create_preview(&t.pointer(&c, &ev(PointerKind::Drag, 350.0, 300.0))), None);
+        assert_eq!(t.pointer(&c, &ev(PointerKind::Up, 350.0, 320.0)), vec![Action::Commit]);
+        assert!(!t.busy());
+        // A click makes nothing; Escape cancels a drag.
+        t.pointer(&c, &ev(PointerKind::Down, 10.0, 10.0));
+        assert!(t.pointer(&c, &ev(PointerKind::Up, 10.0, 10.0)).is_empty());
+        t.pointer(&c, &ev(PointerKind::Down, 10.0, 10.0));
+        t.pointer(&c, &ev(PointerKind::Drag, 40.0, 40.0));
+        assert_eq!(t.key(&c, ToolKey::Escape, Mods::default()), vec![Action::Cancel]);
+        assert_eq!(t.cursor(&c, Point::ZERO, Mods::default()), Cursor::Slice);
+    }
+
+    fn doc_with_slices() -> (Document, NodeId, NodeId) {
+        let (mut d, _) = doc_with_rect();
+        let a = d.alloc_id();
+        d.slices.push(Slice { id: a, rect: Rect::new(10.0, 10.0, 60.0, 40.0), options: Default::default() });
+        let b = d.alloc_id();
+        d.slices.push(Slice { id: b, rect: Rect::new(300.0, 300.0, 400.0, 400.0), options: Default::default() });
+        (d, a, b)
+    }
+
+    #[test]
+    fn the_slice_selection_tool_selects_moves_resizes_and_deletes() {
+        let (d, a, b) = doc_with_slices();
+        let p = paint();
+        let none = Selection::default();
+        let c = cx(&d, &none, &p);
+        let mut t = SliceSelectionTool::default();
+        // A click selects the slice under the pointer; a drag moves it as one gesture.
+        assert_eq!(t.pointer(&c, &ev(PointerKind::Down, 20.0, 20.0)), vec![Action::Exec("object.slice.select".into(), json!({"slices": [a.0]}))]);
+        let mut sel = Selection::default();
+        sel.set_slices([a]);
+        let c = cx(&d, &sel, &p);
+        let m = t.pointer(&c, &ev(PointerKind::Drag, 30.0, 25.0));
+        assert_eq!(
+            m,
+            vec![Action::Begin("Move Slice".into()), Action::Preview("object.slice.move".into(), json!({"slices": [a.0], "dx": 10.0, "dy": 5.0}))]
+        );
+        assert_eq!(t.pointer(&c, &ev(PointerKind::Up, 30.0, 25.0)), vec![Action::Commit]);
+        // Shift-click toggles another slice.
+        let shift = Mods { shift: true, ..Default::default() };
+        assert_eq!(
+            t.pointer(&c, &with(PointerKind::Down, 350.0, 350.0, shift)),
+            vec![Action::Exec("object.slice.select".into(), json!({"slices": [b.0], "toggle": true}))]
+        );
+        t.pointer(&c, &ev(PointerKind::Up, 350.0, 350.0));
+        // A corner handle of the selected user slice resizes it.
+        assert_eq!(t.cursor(&c, Point::new(60.0, 40.0), Mods::default()), Cursor::ResizeNwSe);
+        assert!(t.pointer(&c, &ev(PointerKind::Down, 60.0, 40.0)).is_empty());
+        let r = t.pointer(&c, &ev(PointerKind::Drag, 80.0, 50.0));
+        assert_eq!(r[0], Action::Begin("Resize Slice".into()));
+        assert_eq!(r[1], Action::Preview("object.slice.setRect".into(), json!({"id": a.0, "x": 10.0, "y": 10.0, "width": 70.0, "height": 40.0})));
+        assert_eq!(t.pointer(&c, &ev(PointerKind::Up, 80.0, 50.0)), vec![Action::Commit]);
+        assert!(t.overlays(&c).iter().filter(|o| matches!(o, Overlay::Anchor { .. })).count() == 8);
+        // A double click opens Slice Options; Delete deletes the selected slices.
+        assert_eq!(t.pointer(&c, &ev(PointerKind::DoubleClick, 20.0, 20.0)), vec![Action::Dialog("sliceOptions".into(), json!({}))]);
+        assert!(t.claims_key(&c, ToolKey::Delete));
+        assert_eq!(t.key(&c, ToolKey::Delete, Mods::default()), vec![Action::Exec("object.slice.delete".into(), json!({}))]);
+        // A click on no slice deselects.
+        assert_eq!(t.pointer(&c, &ev(PointerKind::Down, 200.0, 5.0)), vec![Action::Exec("object.slice.select".into(), json!({"slices": []}))]);
+        // Locked slices can't be picked.
+        let mut locked = cx(&d, &sel, &p);
+        locked.slices_locked = true;
+        assert!(t.pointer(&locked, &ev(PointerKind::Down, 20.0, 20.0)).is_empty());
+        assert!(!t.claims_key(&locked, ToolKey::Delete));
+        assert_eq!(t.cursor(&locked, Point::new(60.0, 40.0), Mods::default()), Cursor::SliceSelect);
+    }
+}

crates/ui-egui/src/canvas.rs

@@ -369,6 +369,8 @@ fn cursor_icon(c: Cursor) -> egui::CursorIcon {
         Cursor::NotAllowed => C::NotAllowed,
         Cursor::AddStop => C::Copy,
         Cursor::RemoveStop => C::NotAllowed,
+        Cursor::Slice => C::Crosshair,
+        Cursor::SliceSelect => C::Default,
     }
 }
 

crates/ui-egui/src/cursors.rs

@@ -118,6 +118,21 @@ fn stop_badge(p: &Painter, o: Pos2, add: bool) {
     }
 }
 
+/// A slice badge: a small rectangle cut by a line, at `b` (its top left).
+fn slice_badge(p: &Painter, b: Pos2) {
+    let pts = vec![b, b + vec2(8.0, 0.0), b + vec2(8.0, 6.0), b + vec2(0.0, 6.0)];
+    poly(p, pts, HALO, INK);
+    line(p, b + vec2(4.0, 0.0), b + vec2(4.0, 6.0));
+}
+
+/// The Slice tool: a crosshair with a blade below right of the hotspot.
+fn slice(p: &Painter, o: Pos2) {
+    crosshair(p, o);
+    let b = o + vec2(7.0, 7.0);
+    poly(p, vec![b, b + vec2(9.0, 4.0), b + vec2(10.0, 7.0), b + vec2(3.0, 6.0)], HALO, INK);
+    line(p, b + vec2(8.0, 6.0), b + vec2(12.0, 12.0));
+}
+
 fn ibeam(p: &Painter, o: Pos2) {
     line(p, o + vec2(0.0, -8.0), o + vec2(0.0, 8.0));
     line(p, o + vec2(-3.0, -8.0), o + vec2(3.0, -8.0));
@@ -150,6 +165,11 @@ pub fn paint(painter: &Painter, c: Cursor, p: Pos2) -> bool {
         Cursor::Text => ibeam(painter, p),
         Cursor::AddStop => stop_badge(painter, p, true),
         Cursor::RemoveStop => stop_badge(painter, p, false),
+        Cursor::Slice => slice(painter, p),
+        Cursor::SliceSelect => {
+            arrow(painter, p, false);
+            slice_badge(painter, p + vec2(11.0, 14.0));
+        }
         _ => return false,
     }
     let _ = pos2;

crates/ui-egui/src/tests_slices.rs

@@ -72,3 +72,31 @@ fn slice_menu_items_follow_the_state() {
     app.run("view.slices.lock", json!({})).unwrap();
     assert_eq!(crate::menus::checked(&app, "view.slices.lock", &json!({})), Some(true));
 }
+
+#[test]
+fn slice_tool_cursors_are_drawn_in_code() {
+    let ctx = egui::Context::default();
+    let mut out = ctx.run_ui(Default::default(), |ui| {
+        for c in [vectorcraft_tools::Cursor::Slice, vectorcraft_tools::Cursor::SliceSelect] {
+            assert!(crate::cursors::paint(ui.painter(), c, egui::pos2(50.0, 50.0)), "{c:?}");
+        }
+    });
+    out.textures_delta.clear();
+    assert!(!out.shapes.is_empty());
+}
+
+#[test]
+fn the_slice_tools_are_real_tools() {
+    let mut app = app();
+    for t in ["slice", "sliceSelection"] {
+        app.run("tool.select", json!({"tool": t})).unwrap();
+        assert_eq!(app.session.tool_id(), t);
+    }
+    // Double-clicking a slice opens Slice Options.
+    let id = app.run("object.slice.create", json!({"x": 10, "y": 10, "width": 50, "height": 50})).unwrap()["id"].as_u64().unwrap();
+    let view = app.view_info();
+    let ev = vectorcraft_tools::PointerEvent::new(vectorcraft_tools::PointerKind::DoubleClick, 20.0, 20.0);
+    crate::canvas::dispatch(&mut app, &ev, view);
+    assert_eq!(app.ui.dialog.as_ref().map(|d| d.kind.as_str()), Some(crate::dialogs::slices::OPTIONS));
+    assert_eq!(app.session.active().unwrap().selection.slices, vec![vectorcraft_doc::NodeId(id)]);
+}

docs/control-protocol.md

@@ -325,3 +325,8 @@ selected slices. `sliceOptions` (fields `kind`: `image`/`noImage`/`htmlText`, `n
 runs `object.slice.options` on `ui.dialog.confirm`; `divideSlices` (fields `divideRows`, `rows`, `rowMode`:
 `count`/`size`, `rowHeight`, and `divideColumns`, `columns`, `columnMode`, `columnWidth`) runs `object.slice.divide`.
 Read slice options with `slice.list`.
+
+The Slice tools: `ui.pointer` drags with the `slice` tool make a user slice (Shift square, Alt from the centre; one
+undo step). With `sliceSelection` a click selects a slice (Shift toggles), a drag moves the selected slices, a drag on
+a selected user slice's handle resizes it, a double click opens `sliceOptions` and `ui.key` Delete deletes the
+selected slices. Hidden or locked slices (`view.slices.hide`, `view.slices.lock`) can't be picked.

docs/mcp.md

@@ -1138,3 +1138,14 @@ the `sliceLineColor` preference, numbered while `showSliceNumbers` is on.
 {"name":"run_command","arguments":{"command":"object.slice.options","params":{"name":"logo","url":"https://example.com","alt":"Logo"}}}
 {"name":"run_command","arguments":{"command":"slice.list","params":{}}}
 ```
+
+The Slice tool (`slice`, Shift+K) and the Slice Selection tool (`sliceSelection`) reduce to commands:
+`object.slice.create {x, y, width, height}` (the Slice tool's drag; it snaps to ruler guides), `object.slice.select
+{slices?, toggle?}`, `object.slice.move {slices?, dx, dy}` (an object slice moves its object),
+`object.slice.setRect {id, x, y, width, height}` (user slices) and `object.slice.delete {slices?}`. Slice ids are user
+slice ids and the ids of objects with an object slice.
+
+```json
+{"name":"run_command","arguments":{"command":"object.slice.create","params":{"x":0,"y":0,"width":200,"height":80}}}
+{"name":"run_command","arguments":{"command":"object.slice.move","params":{"dx":10,"dy":0}}}
+```