A Mirror window for sketch entities, holding both picks until OK (#734)

Sketch Mirror now opens a tool window with Entities and Mirror line inputs, so both picks stay visible and editable until OK, replacing the old click-then-right-click flow.

crates/ui-egui/src/sketch_modify_ui.rs

@@ -4,9 +4,10 @@
 //! reached no tool and no dialog at all, so a press ran `sketch.scale` with no parameters and
 //! the engine answered "`factor` must be a positive number". Offset joins it here (upstream
 //! issue #162 item 1: "Offset does not create a constraint, the size of the offset seems
-//! random"). `sketch.fillet`, the three `sketch.chamfer.*` commands, the sketch patterns,
-//! `sketch.mirror` and `sketch.move` are the same gap and join this module later, each its own
-//! change.
+//! random"). Mirror joins them here, which ran as a bare click flow: entities until a
+//! right-click, then one more click for the line, with nothing on screen saying what was
+//! picked. `sketch.fillet`, the three `sketch.chamfer.*` commands, the sketch patterns and
+//! `sketch.move` are the same gap and join this module later, each its own change.
 
 use serde_json::{Map, Value, json};
 use solidcraft_engine::Sel;
@@ -14,7 +15,7 @@ use solidcraft_engine::doc::expr::Kind as ValueKind;
 
 use crate::SolveApp;
 use crate::dialogs::{Kind, check, field, row_label};
-use crate::selection::{CURVES, POINTS, SelInput};
+use crate::selection::{AXES, CURVES, POINTS, SelInput};
 
 /// A sketch modify tool window's values.
 #[derive(Clone, Debug, PartialEq)]
@@ -27,6 +28,10 @@ pub enum Mod {
     /// chain follows. A positive distance is left of the chain, as the command defines it;
     /// `flip` reverses whatever sign the field holds.
     Offset { distance: String, chain: bool, flip: bool },
+    /// `sketch.mirror`: the entities and the line they reflect in. The command has no number of
+    /// its own, so the window's whole job is to show what is picked and let a pick be changed
+    /// before anything is committed.
+    Mirror,
 }
 
 impl Mod {
@@ -34,15 +39,17 @@ impl Mod {
         match self {
             Mod::Scale { .. } => "SKETCH SCALE",
             Mod::Offset { .. } => "OFFSET",
+            Mod::Mirror => "MIRROR",
         }
     }
 
     /// The value on the canvas.
     pub fn primary(&mut self) -> Option<(&'static str, ValueKind, &mut String)> {
-        Some(match self {
-            Mod::Scale { factor } => ("Factor", ValueKind::Unitless, factor),
-            Mod::Offset { distance, .. } => ("Distance", ValueKind::Length, distance),
-        })
+        match self {
+            Mod::Scale { factor } => Some(("Factor", ValueKind::Unitless, factor)),
+            Mod::Offset { distance, .. } => Some(("Distance", ValueKind::Length, distance)),
+            Mod::Mirror => None,
+        }
     }
 }
 
@@ -50,6 +57,8 @@ fn inputs(k: &Mod) -> Vec<SelInput> {
     match k {
         Mod::Scale { .. } => vec![SelInput::new("Entities", CURVES | POINTS, true), SelInput::new("Base point", POINTS, false)],
         Mod::Offset { .. } => vec![SelInput::new("Curves", CURVES, true)],
+        // AXES is the mask that takes a straight sketch curve (`selection::SelInput::accepts`).
+        Mod::Mirror => vec![SelInput::new("Entities", CURVES | POINTS, true), SelInput::new("Mirror line", AXES, false)],
     }
 }
 
@@ -58,6 +67,7 @@ pub fn start(_app: &SolveApp, id: &str) -> Option<(Kind, Vec<SelInput>)> {
     let k = match id {
         "sketch.scale" => Mod::Scale { factor: "2".into() },
         "sketch.offset" => Mod::Offset { distance: "2 mm".into(), chain: true, flip: false },
+        "sketch.mirror" => Mod::Mirror,
         _ => return None,
     };
     let i = inputs(&k);
@@ -84,6 +94,8 @@ pub fn rows(ui: &mut egui::Ui, k: &mut Mod) -> bool {
             check(ui, chain);
             ui.end_row();
         }
+        // Mirror has no value of its own: its inputs are the whole window.
+        Mod::Mirror => {}
     }
     enter
 }
@@ -167,6 +179,23 @@ pub fn commands(app: &SolveApp, k: &Mod, inputs: &[SelInput], extra: &Map<String
             let d = signed_length(app, distance, *flip)?;
             ("sketch.offset", json!({"curves": curves, "distance": d, "chain": chain}))
         }
+        Mod::Mirror => {
+            let entities = entity_ids(inputs, 0);
+            if entities.is_empty() {
+                return Err("Select the sketch curves or points to mirror first".into());
+            }
+            // The AXES mask also takes an origin axis, which is not a curve of this sketch and
+            // cannot be a mirror line.
+            let line = match items(inputs, 1).first() {
+                Some(Sel::SketchCurve { id }) => id.clone(),
+                Some(_) => return Err("The mirror line must be a straight curve of this sketch, not an origin axis".into()),
+                None => return Err("Select the mirror line".into()),
+            };
+            if entities.contains(&line) {
+                return Err("The mirror line cannot also be mirrored".into());
+            }
+            ("sketch.mirror", json!({"entities": entities, "line": line}))
+        }
     };
     if let Value::Object(m) = &mut params {
         for (key, value) in extra {