feat: pick sketch profiles by their bounding curve ids so features keep the same region when parameters move the geometry, matching curves cut into pieces, refusing ambiguous or missing picks instead of taking another region, and storing point picks by curves

crates/sketch/src/lib.rs

@@ -27,7 +27,7 @@ pub use dims::{DimFrame, DimLayout, chain_centres, default_text, dim_frame, dim_
 pub use link::{Link, LinkGeom, LinkKind, LinkSource, MAX_LINK_ENTITIES};
 pub use model::{Constraint, ConstraintKind, Curve, CurveKind, SPoint, Sketch, SketchError, SketchView};
 pub use offset::OffsetChain;
-pub use profiles::{Profile, find_drawn_profiles, find_profiles, merge_regions};
+pub use profiles::{CurvePick, Profile, distinct_curves, find_drawn_profiles, find_profiles, merge_regions, profile_at_point, profile_by_curves};
 pub use shape::{Shape, intersections};
 pub use solver::{Hold, SolveReport, SolveStatus, measure_dimension, solve, solve_holding};
 pub use text::{MAX_TEXT_CHARS, text_geometry};

crates/sketch/src/profiles.rs

@@ -829,6 +829,69 @@ pub fn find_profiles(sk: &Sketch) -> Vec<Profile> {
     out
 }
 
+/// Why no single profile is bounded by a list of curves.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum CurvePick {
+    /// No profile's outer loop is made of exactly those curves.
+    Missing,
+    /// This many profiles are (e.g. both halves of a circle cut by a line).
+    Ambiguous(usize),
+}
+
+/// The profile picked by the curves around it, by index into `profiles`. A profile matches when
+/// its outer loop is made of the listed curves and no others: every listed curve, or a piece of
+/// it where other curves cut it, lies on the loop, and every piece of the loop belongs to a
+/// listed curve. Order and repeats don't matter. Holes don't take part (islands inside a profile
+/// are its holes, as for a profile picked by a point). When several profiles match, one whose
+/// loop has exactly the listed pieces (a curve listed twice for two pieces) wins; otherwise the
+/// pick is ambiguous, never a guess.
+pub fn profile_by_curves(profiles: &[Profile], ids: &[String]) -> Result<usize, CurvePick> {
+    use std::collections::BTreeSet;
+    let want: BTreeSet<&str> = ids.iter().map(String::as_str).collect();
+    if want.is_empty() {
+        return Err(CurvePick::Missing);
+    }
+    let hits: Vec<usize> = profiles
+        .iter()
+        .enumerate()
+        .filter(|(_, p)| p.outer_curves.iter().map(String::as_str).collect::<BTreeSet<_>>() == want)
+        .map(|(i, _)| i)
+        .collect();
+    match hits.as_slice() {
+        [] => Err(CurvePick::Missing),
+        [i] => Ok(*i),
+        _ => {
+            fn sorted(v: &[String]) -> Vec<&str> {
+                let mut v: Vec<&str> = v.iter().map(String::as_str).collect();
+                v.sort_unstable();
+                v
+            }
+            let exact = sorted(ids);
+            let same: Vec<usize> = hits.iter().copied().filter(|i| profiles.get(*i).is_some_and(|p| sorted(&p.outer_curves) == exact)).collect();
+            match same.as_slice() {
+                [i] => Ok(*i),
+                _ => Err(CurvePick::Ambiguous(hits.len())),
+            }
+        }
+    }
+}
+
+/// The innermost profile containing a sketch point, by index into `profiles`.
+pub fn profile_at_point(profiles: &[Profile], p: Vec2) -> Option<usize> {
+    profiles.iter().enumerate().filter(|(_, q)| q.region.contains(p)).min_by(|a, b| a.1.area.total_cmp(&b.1.area)).map(|(i, _)| i)
+}
+
+/// The distinct curve ids of a loop, in loop order (a curve cut into pieces is listed once).
+pub fn distinct_curves(ids: &[String]) -> Vec<String> {
+    let mut out: Vec<String> = Vec::with_capacity(ids.len());
+    for id in ids {
+        if !out.contains(id) {
+            out.push(id.clone());
+        }
+    }
+    out
+}
+
 fn same_seg(a: &Seg2, b: &Seg2, tol: f64) -> bool {
     match (*a, *b) {
         (Seg2::Line { a: p, b: q }, Seg2::Line { a: r, b: s }) => p.dist(r) <= tol && q.dist(s) <= tol,