refactor: split complex input, explode, sweep, cache and options code into helpers

Pure extraction, no behaviour change: same order of side effects, same
early returns and error values. Clears cognitive-complexity findings on
AreaM::input, explode_kind, hatch sweep, the COMPARE overlay paint and
the Files options tab (S3776).

crates/engine/src/cmd/inquiry.rs

@@ -963,6 +963,57 @@ impl AreaM {
             AreaMode::Subtract => self.total - v,
         }
     }
+    /// Input while a height is pending: typed, or given by two points (their distance).
+    fn height_input(&mut self, s: &mut Session, i: Input) -> Step {
+        match (i, self.height_from) {
+            (Input::Point(p), None) => self.height_from = Some(p),
+            (Input::Point(p), Some(from)) => {
+                self.height_from = None;
+                return self.height(s, p.dist(from));
+            }
+            (Input::Text(t), None) => match crate::units::parse_distance(&t).filter(|v| v.is_finite()) {
+                Some(h) => return self.height(s, h),
+                None => s.echo("Requires a distance."),
+            },
+            (Input::Enter, None) => s.echo("Requires a height."),
+            (Input::Enter, Some(_)) => s.echo("Requires a second point."),
+            (Input::Text(_), Some(_)) => s.echo("Requires a point."),
+            _ => {}
+        }
+        Step::Continue
+    }
+
+    /// Input while the objects to measure are picked.
+    fn object_input(&mut self, s: &mut Session, i: Input) -> Step {
+        match i {
+            Input::Pick(hs) => {
+                for h in hs {
+                    match object_area(s, h) {
+                        Ok((a, per)) => {
+                            if self.measured(s, a, per) == Step::Done {
+                                return Step::Done;
+                            }
+                            // A single volume takes the first object with an area.
+                            if self.volume && self.mode == AreaMode::Single {
+                                break;
+                            }
+                        }
+                        Err(_) => s.echo("The selected object has no area."),
+                    }
+                }
+            }
+            Input::Enter => {
+                self.object = false;
+                if self.mode == AreaMode::Single {
+                    return Step::Done;
+                }
+            }
+            Input::Text(_) | Input::Keyword(_) => s.echo("*Invalid selection*"),
+            _ => {}
+        }
+        Step::Continue
+    }
+
     /// Measure the oldest pending area's volume with height `h`.
     fn height(&mut self, s: &mut Session, h: f64) -> Step {
         match self.pending.first().map(|a| a * h.abs()) {
@@ -1042,52 +1093,10 @@ impl Interactive for AreaM {
     }
     fn input(&mut self, s: &mut Session, i: Input) -> Result<Step> {
         if !self.pending.is_empty() {
-            // A height is typed, or given by two points (their distance).
+            return Ok(self.height_input(s, i));
-            match (i, self.height_from) {
-                (Input::Point(p), None) => self.height_from = Some(p),
-                (Input::Point(p), Some(from)) => {
-                    self.height_from = None;
-                    return Ok(self.height(s, p.dist(from)));
-                }
-                (Input::Text(t), None) => match crate::units::parse_distance(&t).filter(|v| v.is_finite()) {
-                    Some(h) => return Ok(self.height(s, h)),
-                    None => s.echo("Requires a distance."),
-                },
-                (Input::Enter, None) => s.echo("Requires a height."),
-                (Input::Enter, Some(_)) => s.echo("Requires a second point."),
-                (Input::Text(_), Some(_)) => s.echo("Requires a point."),
-                _ => {}
-            }
-            return Ok(Step::Continue);
         }
         if self.object {
-            match i {
+            return Ok(self.object_input(s, i));
-                Input::Pick(hs) => {
-                    for h in hs {
-                        match object_area(s, h) {
-                            Ok((a, per)) => {
-                                if self.measured(s, a, per) == Step::Done {
-                                    return Ok(Step::Done);
-                                }
-                                // A single volume takes the first object with an area.
-                                if self.volume && self.mode == AreaMode::Single {
-                                    break;
-                                }
-                            }
-                            Err(_) => s.echo("The selected object has no area."),
-                        }
-                    }
-                }
-                Input::Enter => {
-                    self.object = false;
-                    if self.mode == AreaMode::Single {
-                        return Ok(Step::Done);
-                    }
-                }
-                Input::Text(_) | Input::Keyword(_) => s.echo("*Invalid selection*"),
-                _ => {}
-            }
-            return Ok(Step::Continue);
         }
         if self.length {
             if let Some(p) = length_input(&self.pts, i)? {

crates/engine/src/cmd/modify.rs

@@ -1296,33 +1296,7 @@ fn run_chamfer(s: &mut Session, p: &Value) -> Result<Value> {
 
 // ---------------- explode / array / order / break / join ----------------
 
-pub(crate) fn explode_kind(d: &cadcraft_doc::Drawing, e: &Entity) -> Option<Vec<Entity>> {
+fn explode_block_ref(d: &cadcraft_doc::Drawing, e: &Entity, ins: &cadcraft_doc::Insert) -> Option<Vec<Entity>> {
-    // An annotative object explodes into plain objects as it draws at the current annotation scale.
-    if cadcraft_doc::is_annotative(e) {
-        let mut se = match d.anno_draw(e) {
-            cadcraft_doc::AnnoDraw::Scaled(f) => cadcraft_doc::anno_scaled(e, f),
-            _ => e.clone(),
-        };
-        se.common.anno_scales.clear();
-        return explode_kind(d, &se);
-    }
-    match &e.kind {
-        EntityKind::LwPolyline(p) => {
-            let pl = Polyline { vertices: p.vertices.clone(), closed: p.closed };
-            Some(
-                pl.segments()
-                    .into_iter()
-                    .map(|s| {
-                        let k = match s {
-                            Segment::Line(l) => line(l.a, l.b),
-                            Segment::Arc { arc: a, .. } => arc(&a),
-                        };
-                        Entity { handle: Handle(0), common: e.common.clone(), kind: k }
-                    })
-                    .collect(),
-            )
-        }
-        EntityKind::Insert(ins) => {
     if let Some(items) = super::array::explode_array(d, e) {
         return Some(items);
     }
@@ -1345,19 +1319,8 @@ pub(crate) fn explode_kind(d: &cadcraft_doc::Drawing, e: &Entity) -> Option<Vec<
             .collect(),
     )
 }
-        // A helix explodes into its spline (seen from above).
+
-        EntityKind::Helix(h) => Some(vec![Entity { handle: Handle(0), common: e.common.clone(), kind: EntityKind::Spline(h.spline()) }]),
+fn explode_mtext(e: &Entity, m: &cadcraft_doc::MText) -> Vec<Entity> {
-        EntityKind::Polyline3d(p) => Some(
-            p.points
-                .windows(2)
-                .filter_map(|w| {
-                    let kind = EntityKind::Line(cadcraft_doc::Line { a: *w.first()?, b: *w.get(1)? });
-                    Some(Entity { handle: Handle(0), common: e.common.clone(), kind })
-                })
-                .collect(),
-        ),
-        EntityKind::MLine(m) => Some(super::draw2::mline::explode(e, m)),
-        EntityKind::MText(m) => Some(
     cadcraft_fonts::plain_mtext(&m.contents)
         .split('\n')
         .enumerate()
@@ -1380,12 +1343,12 @@ pub(crate) fn explode_kind(d: &cadcraft_doc::Drawing, e: &Entity) -> Option<Vec<
                 }),
             }
         })
-                .collect(),
+        .collect()
-        ),
+}
-        // A region explodes into its boundary's lines and arcs.
+
-        EntityKind::Region(r) => Some(
+/// The entities of a boundary's lines and arcs, on the object's layer and style.
-            r.segments()
+fn segment_entities(e: &Entity, segs: impl IntoIterator<Item = Segment>) -> Vec<Entity> {
-                .into_iter()
+    segs.into_iter()
         .map(|s| {
             let k = match s {
                 Segment::Line(l) => line(l.a, l.b),
@@ -1393,9 +1356,10 @@ pub(crate) fn explode_kind(d: &cadcraft_doc::Drawing, e: &Entity) -> Option<Vec<
             };
             Entity { handle: Handle(0), common: e.common.clone(), kind: k }
         })
-                .collect(),
+        .collect()
-        ),
+}
-        EntityKind::Dimension(dm) => {
+
+fn explode_dimension(d: &cadcraft_doc::Drawing, e: &Entity, dm: &cadcraft_doc::Dimension) -> Vec<Entity> {
     // The dimension as drawn: its overrides, DIMSCALE (0 = the drawing's) and text font.
     let style = d.dim_style(&dm.style).cloned().unwrap_or_default().with_overrides(&dm.overrides);
     let g = cadcraft_render::dimension_in(d, dm);
@@ -1451,8 +1415,41 @@ pub(crate) fn explode_kind(d: &cadcraft_doc::Drawing, e: &Entity) -> Option<Vec<
             }),
         });
     }
-            Some(v)
+    v
 }
+
+pub(crate) fn explode_kind(d: &cadcraft_doc::Drawing, e: &Entity) -> Option<Vec<Entity>> {
+    // An annotative object explodes into plain objects as it draws at the current annotation scale.
+    if cadcraft_doc::is_annotative(e) {
+        let mut se = match d.anno_draw(e) {
+            cadcraft_doc::AnnoDraw::Scaled(f) => cadcraft_doc::anno_scaled(e, f),
+            _ => e.clone(),
+        };
+        se.common.anno_scales.clear();
+        return explode_kind(d, &se);
+    }
+    match &e.kind {
+        EntityKind::LwPolyline(p) => {
+            let pl = Polyline { vertices: p.vertices.clone(), closed: p.closed };
+            Some(segment_entities(e, pl.segments()))
+        }
+        EntityKind::Insert(ins) => explode_block_ref(d, e, ins),
+        // A helix explodes into its spline (seen from above).
+        EntityKind::Helix(h) => Some(vec![Entity { handle: Handle(0), common: e.common.clone(), kind: EntityKind::Spline(h.spline()) }]),
+        EntityKind::Polyline3d(p) => Some(
+            p.points
+                .windows(2)
+                .filter_map(|w| {
+                    let kind = EntityKind::Line(cadcraft_doc::Line { a: *w.first()?, b: *w.get(1)? });
+                    Some(Entity { handle: Handle(0), common: e.common.clone(), kind })
+                })
+                .collect(),
+        ),
+        EntityKind::MLine(m) => Some(super::draw2::mline::explode(e, m)),
+        EntityKind::MText(m) => Some(explode_mtext(e, m)),
+        // A region explodes into its boundary's lines and arcs.
+        EntityKind::Region(r) => Some(segment_entities(e, r.segments())),
+        EntityKind::Dimension(dm) => Some(explode_dimension(d, e, dm)),
         EntityKind::Tolerance(t) => Some(super::tolerance::explode(d, e, t)),
         _ => None,
     }

crates/render/src/hatch.rs

@@ -465,6 +465,26 @@ impl Family<'_> {
         self.origin + p.rotate(self.ang)
     }
 
+    /// The range of the lines swept, in this frame: the boundary's extent, cut to the view's
+    /// when there is one, and the view's x extent that spans are cut to. Spans are cut to the
+    /// view's extent only: they already lie within the boundary, and cutting them to its extent
+    /// too would move an end that sits on a boundary corner by a rounding error, so a view
+    /// covering the hatch would change its lines. `None` when the view misses the boundary.
+    fn lines_range(&self, bb: &Bounds2, view: Option<&Bounds2>) -> Option<(Vec2, Vec2, Option<(f64, f64)>)> {
+        let (mut lo, mut hi) = (bb.min, bb.max);
+        let mut span_cut = None;
+        if let Some(v) = view {
+            let vb = Bounds2::from_points(v.corners().iter().map(|p| self.to_local(*p)));
+            if vb.is_empty() || !vb.intersects(bb) {
+                return None;
+            }
+            lo = Vec2::new(lo.x.max(vb.min.x), lo.y.max(vb.min.y));
+            hi = Vec2::new(hi.x.min(vb.max.x), hi.y.min(vb.max.y));
+            span_cut = Some((vb.min.x, vb.max.x));
+        }
+        Some((lo, hi, span_cut))
+    }
+
     /// Intersect a pattern family with boundary loops, respecting view, output, cancellation, and shared dash-work limits.
     fn sweep(&self, loops: &[Vec<Vec2>], px: f64, view: Option<&Bounds2>, cancel: Option<&AtomicBool>, out: &mut Vec<Vec<Vec2>>, work: &mut u64) {
         let local: Vec<Vec<Vec2>> = loops.iter().map(|l| l.iter().map(|p| self.to_local(*p)).collect()).collect();
@@ -472,21 +492,7 @@ impl Family<'_> {
         if bb.is_empty() {
             return;
         }
-        // The lines swept: the boundary's extent, cut to the view's (its corners in this frame)
+        let Some((lo, hi, span_cut)) = self.lines_range(&bb, view) else { return };
-        // when there is one. Spans are cut to the view's extent only: they already lie within the
-        // boundary, and cutting them to its extent too would move an end that sits on a boundary
-        // corner by a rounding error, so a view covering the hatch would change its lines.
-        let (mut lo, mut hi) = (bb.min, bb.max);
-        let mut span_cut = None;
-        if let Some(v) = view {
-            let vb = Bounds2::from_points(v.corners().iter().map(|p| self.to_local(*p)));
-            if vb.is_empty() || !vb.intersects(&bb) {
-                return;
-            }
-            lo = Vec2::new(lo.x.max(vb.min.x), lo.y.max(vb.min.y));
-            hi = Vec2::new(hi.x.min(vb.max.x), hi.y.min(vb.max.y));
-            span_cut = Some((vb.min.x, vb.max.x));
-        }
         let shift_per_line = self.delta.rotate(-self.ang).x;
         let k0 = (lo.y / self.spacing).floor() as i64;
         let k1 = (hi.y / self.spacing).ceil() as i64;
@@ -504,17 +510,7 @@ impl Family<'_> {
                 return;
             }
             let y = k as f64 * self.spacing;
-            let mut xs: Vec<f64> = Vec::new();
+            let xs = crossings(&local, y);
-            for l in &local {
-                let n = l.len();
-                for i in 0..n {
-                    let (Some(a), Some(b)) = (l.get(i), l.get((i + 1) % n)) else { continue };
-                    if (a.y > y) != (b.y > y) {
-                        xs.push(a.x + (b.x - a.x) * (y - a.y) / (b.y - a.y));
-                    }
-                }
-            }
-            xs.sort_by(f64::total_cmp);
             let offset = shift_per_line * k as f64;
             for span in xs.chunks(2) {
                 let [x0, x1] = span else { continue };
@@ -565,6 +561,22 @@ impl Family<'_> {
     }
 }
 
+/// The x positions where the boundary loops cross the horizontal line at `y`, in order.
+fn crossings(local: &[Vec<Vec2>], y: f64) -> Vec<f64> {
+    let mut xs: Vec<f64> = Vec::new();
+    for l in local {
+        let n = l.len();
+        for i in 0..n {
+            let (Some(a), Some(b)) = (l.get(i), l.get((i + 1) % n)) else { continue };
+            if (a.y > y) != (b.y > y) {
+                xs.push(a.x + (b.x - a.x) * (y - a.y) / (b.y - a.y));
+            }
+        }
+    }
+    xs.sort_by(f64::total_cmp);
+    xs
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

crates/ui-egui/src/canvas/compare.rs

@@ -4,7 +4,8 @@
 
 use std::sync::Arc;
 
-use cadcraft_engine::doc::Handle;
+use cadcraft_engine::cmd::file::compare::Comparison;
+use cadcraft_engine::doc::{Drawing, Handle};
 use cadcraft_render::DisplayList;
 use egui::{Rect, RichText, Stroke, vec2};
 use serde_json::json;
@@ -29,6 +30,23 @@ fn id() -> egui::Id {
     egui::Id::unique("cadcraft-compare-overlay")
 }
 
+/// The display lists of the differences for this frame: the stored ones when they still match
+/// `key`, otherwise rebuilt at zoom `scale` and stored.
+fn cache_for(ctx: &egui::Context, key: (u64, u64, usize, usize, i64), doc: &Drawing, c: &Comparison, scale: f64) -> Cache {
+    let mut cache: Cache = ctx.data_mut(|d| d.get_temp(id())).unwrap_or_default();
+    if cache.key != key || cache.ours.is_none() {
+        let opts = cadcraft_render::Options { tolerance: 0.5 / scale.max(1e-12), ..Default::default() };
+        let ours: Vec<Handle> = c.added.iter().copied().chain(c.changed.iter().map(|(a, _)| *a)).take(MAX_DRAWN).collect();
+        let theirs: Vec<Handle> = c.removed.iter().copied().chain(c.changed.iter().map(|(_, b)| *b)).take(MAX_DRAWN).collect();
+        let list = |d: &Drawing, hs: &[Handle]| {
+            Arc::new(cadcraft_render::build_entities(d, hs.iter().filter_map(|h| d.entity(*h)).map(|e| e.as_ref()), &opts))
+        };
+        cache = Cache { key, ours: Some(list(doc, &ours)), theirs: Some(list(&c.other, &theirs)) };
+        ctx.data_mut(|d| d.insert_temp(id(), cache.clone()));
+    }
+    cache
+}
+
 /// Draw the comparison over the canvas when it was made for the drawing and tab shown.
 pub(super) fn paint(app: &mut CadApp, ctx: &egui::Context, p: &egui::Painter, xf: &Xf, rect: Rect) {
     let t = Tokens::get();
@@ -38,17 +56,7 @@ pub(super) fn paint(app: &mut CadApp, ctx: &egui::Context, p: &egui::Painter, xf
     p.rect_filled(rect, 0.0, t.canvas.gamma_multiply(0.75));
     let band = xf.scale.max(1e-300).log2().round() as i64;
     let key = (st.uid, st.revision, Arc::as_ptr(&c.other) as usize, c.differences(), band);
-    let mut cache: Cache = ctx.data_mut(|d| d.get_temp(id())).unwrap_or_default();
+    let cache = cache_for(ctx, key, &st.doc, c, xf.scale);
-    if cache.key != key || cache.ours.is_none() {
-        let opts = cadcraft_render::Options { tolerance: 0.5 / xf.scale.max(1e-12), ..Default::default() };
-        let ours: Vec<Handle> = c.added.iter().copied().chain(c.changed.iter().map(|(a, _)| *a)).take(MAX_DRAWN).collect();
-        let theirs: Vec<Handle> = c.removed.iter().copied().chain(c.changed.iter().map(|(_, b)| *b)).take(MAX_DRAWN).collect();
-        let list = |d: &cadcraft_engine::doc::Drawing, hs: &[Handle]| {
-            Arc::new(cadcraft_render::build_entities(d, hs.iter().filter_map(|h| d.entity(*h)).map(|e| e.as_ref()), &opts))
-        };
-        cache = Cache { key, ours: Some(list(&st.doc, &ours)), theirs: Some(list(&c.other, &theirs)) };
-        ctx.data_mut(|d| d.insert_temp(id(), cache.clone()));
-    }
     for (list, color) in [(&cache.theirs, t.compare_other), (&cache.ours, t.compare_this)] {
         if let Some(l) = list {
             let all: Vec<usize> = (0..l.prims.len()).collect();

crates/ui-egui/src/options/dialog.rs

@@ -217,6 +217,23 @@ fn display(app: &CadApp, ui: &mut egui::Ui, changes: &mut Map<String, Value>) {
 /// Files tab: save format and default version, new-drawing units, autosave interval and autosave file location; edits accumulate in `changes`.
 fn files(app: &CadApp, ui: &mut egui::Ui, changes: &mut Map<String, Value>) {
     grid(ui, "options_files", |ui| {
+        save_format_row(ui, app, changes);
+        ui.end_row();
+        save_version_row(ui, app, changes);
+        ui.end_row();
+        units_row(ui, app, changes);
+        ui.end_row();
+        autosave_row(ui, changes);
+        ui.end_row();
+        savefile_row(ui, changes);
+        ui.end_row();
+    });
+    hint(ui, crate::tl!("New and the first drawing at startup use these units unless a default template is set (QNEWTEMPLATE)."));
+    hint(ui, crate::tl!("A drawing opened from a file keeps that file's format."));
+    hint(ui, crate::tl!("Drawings with no file yet are saved in the default version. 0 minutes turns automatic save off."));
+}
+
+fn save_format_row(ui: &mut egui::Ui, app: &CadApp, changes: &mut Map<String, Value>) {
     ui.label(crate::tl!("Save new drawings as"));
     ui.horizontal(|ui| {
         for f in crate::SaveFormat::ALL {
@@ -229,8 +246,9 @@ fn files(app: &CadApp, ui: &mut egui::Ui, changes: &mut Map<String, Value>) {
             }
         }
     });
-        ui.end_row();
+}
 
+fn save_version_row(ui: &mut egui::Ui, app: &CadApp, changes: &mut Map<String, Value>) {
     let version_caption = ui.label(crate::tl!("Default save version"));
     let current = crate::SaveVersion::parse(&app.ui.save_version).unwrap_or_default();
     let mut version = current;
@@ -243,8 +261,9 @@ fn files(app: &CadApp, ui: &mut egui::Ui, changes: &mut Map<String, Value>) {
     if version != current {
         changes.insert("saveVersion".into(), json!(version.year()));
     }
-        ui.end_row();
+}
 
+fn units_row(ui: &mut egui::Ui, app: &CadApp, changes: &mut Map<String, Value>) {
     ui.label(crate::tl!("Units of new drawings"));
     ui.horizontal(|ui| {
         let metric = app.session.settings.measureinit;
@@ -255,20 +274,18 @@ fn files(app: &CadApp, ui: &mut egui::Ui, changes: &mut Map<String, Value>) {
             changes.insert("MEASUREINIT".into(), json!(1));
         }
     });
-        ui.end_row();
+}
 
+fn autosave_row(ui: &mut egui::Ui, changes: &mut Map<String, Value>) {
     let minutes_caption = ui.label(crate::tl!("Automatic save every"));
     let mut minutes = cadcraft_engine::autosave::savetime();
     let max = cadcraft_engine::autosave::MAX_SAVETIME;
-        if ui
+    if ui.add(egui::DragValue::new(&mut minutes).range(0..=max).suffix(format!(" {}", crate::tl!("min")))).labelled_by(minutes_caption.id).changed() {
-            .add(egui::DragValue::new(&mut minutes).range(0..=max).suffix(format!(" {}", crate::tl!("min"))))
-            .labelled_by(minutes_caption.id)
-            .changed()
-        {
         changes.insert("SAVETIME".into(), json!(minutes));
     }
-        ui.end_row();
+}
 
+fn savefile_row(ui: &mut egui::Ui, changes: &mut Map<String, Value>) {
     let savefile_label = ui.label(crate::tl!("Automatic save file location"));
     // Edited as text; the folder changes when the field loses focus.
     let id = egui::Id::unique("cc_options_savefilepath");
@@ -284,11 +301,6 @@ fn files(app: &CadApp, ui: &mut egui::Ui, changes: &mut Map<String, Value>) {
             changes.insert("SAVEFILEPATH".into(), json!(path.trim()));
         }
     }
-        ui.end_row();
-    });
-    hint(ui, crate::tl!("New and the first drawing at startup use these units unless a default template is set (QNEWTEMPLATE)."));
-    hint(ui, crate::tl!("A drawing opened from a file keeps that file's format."));
-    hint(ui, crate::tl!("Drawings with no file yet are saved in the default version. 0 minutes turns automatic save off."));
 }
 
 /// Drafting tab: object-snap marker size and aperture previews plus the Drafting Settings entry; edits accumulate in `changes` and the entry may request a command through `start`.