A tool window for sketch Offset, with a typed Distance, Flip and Chain (#731)

Sketch Offset gets its own tool window with a typed Distance, Flip and Chain, as a variant of the sketch modify window.

crates/ui-egui/src/sketch_modify_ui.rs

@@ -1,18 +1,19 @@
 //! Tool windows for sketch-space modify commands, on the `dialogs_surface` pattern (#19): one
 //! `Mod` enum behind one `Kind::SketchModify` variant, grown by one variant and one arm per
-//! command rather than by a new module each time. The first variant here is Scale, whose
-//! toolbar button 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".
-//! `sketch.offset`, `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.
+//! command rather than by a new module each time. Scale came first, whose toolbar button
+//! 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.
 
 use serde_json::{Map, Value, json};
 use solidcraft_engine::Sel;
 use solidcraft_engine::doc::expr::Kind as ValueKind;
 
 use crate::SolveApp;
-use crate::dialogs::{Kind, field, row_label};
+use crate::dialogs::{Kind, check, field, row_label};
 use crate::selection::{CURVES, POINTS, SelInput};
 
 /// A sketch modify tool window's values.
@@ -22,12 +23,17 @@ pub enum Mod {
     /// input; with none picked the command scales about the sketch origin, as its own default
     /// already does.
     Scale { factor: String },
+    /// `sketch.offset`: the curves to offset, the distance typed and whether the connected
+    /// 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 },
 }
 
 impl Mod {
     pub fn title(&self) -> &'static str {
         match self {
             Mod::Scale { .. } => "SKETCH SCALE",
+            Mod::Offset { .. } => "OFFSET",
         }
     }
 
@@ -35,6 +41,7 @@ impl Mod {
     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),
         })
     }
 }
@@ -42,6 +49,7 @@ impl Mod {
 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)],
     }
 }
 
@@ -49,6 +57,7 @@ fn inputs(k: &Mod) -> Vec<SelInput> {
 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 },
         _ => return None,
     };
     let i = inputs(&k);
@@ -64,6 +73,17 @@ pub fn rows(ui: &mut egui::Ui, k: &mut Mod) -> bool {
             enter |= field(ui, factor);
             ui.end_row();
         }
+        Mod::Offset { distance, chain, flip } => {
+            row_label(ui, "Distance");
+            enter |= field(ui, distance);
+            ui.end_row();
+            row_label(ui, "Flip");
+            check(ui, flip);
+            ui.end_row();
+            row_label(ui, "Chain");
+            check(ui, chain);
+            ui.end_row();
+        }
     }
     enter
 }
@@ -94,6 +114,11 @@ fn entity_ids(inputs: &[SelInput], i: usize) -> Vec<String> {
         .collect()
 }
 
+/// Sketch curve ids picked in input `i`.
+fn curve_ids(inputs: &[SelInput], i: usize) -> Vec<String> {
+    items(inputs, i).iter().filter_map(|x| if let Sel::SketchCurve { id } = x { Some(id.clone()) } else { None }).collect()
+}
+
 /// A typed scale factor as the command wants it: the field evaluated against the document's
 /// parameters, in the range the command accepts. Checking the range here lets the window say
 /// so in its own error line instead of the status bar.
@@ -105,9 +130,21 @@ fn factor(app: &SolveApp, text: &str) -> Result<f64, String> {
     Ok(v)
 }
 
+/// A typed distance as the command wants it: the field evaluated against the document's
+/// parameters, with the sign reversed when Flip is set. A bare number means the design's units,
+/// as a typed sketch value does everywhere else.
+fn signed_length(app: &SolveApp, text: &str, flip: bool) -> Result<f64, String> {
+    let doc = &app.session.doc;
+    let v = doc.eval(&doc.with_design_unit(text.trim(), ValueKind::Length), ValueKind::Length).map_err(|e| format!("Distance: {e}"))?;
+    if !v.is_finite() || v.abs() <= 1e-9 {
+        return Err("Distance must be a non-zero number".into());
+    }
+    Ok(if flip { -v } else { v })
+}
+
 /// The command a sketch modify dialog makes. `sketch.scale` takes a plain evaluated number for
-/// its factor, not an expression string: it has no model parameter to carry one, unlike
-/// `sketch.fillet`'s radius.
+/// its factor and `sketch.offset` one for its distance, not an expression string: neither has a
+/// model parameter to carry one, unlike `sketch.fillet`'s radius.
 pub fn commands(app: &SolveApp, k: &Mod, inputs: &[SelInput], extra: &Map<String, Value>) -> Result<Vec<(String, Value)>, String> {
     let (cmd, mut params) = match k {
         Mod::Scale { factor: text } => {
@@ -122,6 +159,14 @@ pub fn commands(app: &SolveApp, k: &Mod, inputs: &[SelInput], extra: &Map<String
             }
             ("sketch.scale", p)
         }
+        Mod::Offset { distance, chain, flip } => {
+            let curves = curve_ids(inputs, 0);
+            if curves.is_empty() {
+                return Err("Select the curves to offset first".into());
+            }
+            let d = signed_length(app, distance, *flip)?;
+            ("sketch.offset", json!({"curves": curves, "distance": d, "chain": chain}))
+        }
     };
     if let Value::Object(m) = &mut params {
         for (key, value) in extra {