Phase 7: Plot settings and PDF export

- Add printpdf 0.9.1 dependency for native PDF generation.
- New src/io/pdf_export.rs: converts paper-space WireModels to a PDF
  page (per-wire stroke color, line weight in Pt, NaN-split segments).
  White/near-white colors are inverted to black for print output.
- Add PlotExport / PlotExportPath messages: opens a save-file dialog
  and writes a .pdf next to the drawing file.
- Add PageSetupOpen/Close/WidthEdit/HeightEdit/Commit messages: a
  centered modal panel lets the user enter paper width and height (mm);
  on commit the Layout object's min/max_limits are updated in-place.
- Register PRINT / PLOT / EXPORT and PAGESETUP (PS) commands in
  dispatch_command; fix MVIEW error message to English.
- Layout ribbon gains a "Plot" group with Page Setup and Export PDF
  ribbon buttons.

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

src/io/mod.rs

@@ -1,8 +1,10 @@
-// I/O module — open and save CAD documents.
+// I/O module — open, save, and export CAD documents.
 //
 // All file reading/writing goes through acadrust.
 // Default save format: DWG (AC1032 / R2018+).
 
+pub mod pdf_export;
+
 use acadrust::io::dwg::DwgReader;
 use acadrust::{CadDocument, DwgWriter, DxfReader, DxfWriter};
 use std::path::{Path, PathBuf};

src/io/pdf_export.rs

@@ -0,0 +1,127 @@
+// PDF export — converts the paper-space wire model to a PDF file using printpdf.
+//
+// Each WireModel becomes a sequence of DrawLine operations.  NaN values in the
+// points array act as segment separators (pen-up).
+//
+// Coordinate system: CAD uses mm units with origin at bottom-left and Y up.
+// printpdf's Point::new(Mm, Mm) also has origin at bottom-left, so no Y-flip
+// is needed — we just pass the coordinates through directly.
+
+use crate::scene::WireModel;
+use printpdf::{Color, Line, LineCapStyle, LineJoinStyle, LinePoint, Mm, Op, PdfDocument,
+               PdfPage, PdfSaveOptions, Point, Pt, Rgb};
+use std::io::Write;
+use std::path::Path;
+
+// ── Public entry point ────────────────────────────────────────────────────
+
+/// Export `wires` to a PDF file.
+///
+/// `paper_w` / `paper_h` are in millimetres (drawing units assumed = mm).
+pub fn export_pdf(
+    wires: &[WireModel],
+    paper_w: f64,
+    paper_h: f64,
+    path: &Path,
+) -> Result<(), String> {
+    let bytes = build_pdf(wires, paper_w as f32, paper_h as f32);
+    let mut file = std::fs::File::create(path).map_err(|e| e.to_string())?;
+    file.write_all(&bytes).map_err(|e| e.to_string())
+}
+
+/// Show a PDF save-file dialog and return the chosen path (or None if cancelled).
+pub async fn pick_pdf_path_owned(stem: String) -> Option<std::path::PathBuf> {
+    rfd::AsyncFileDialog::new()
+        .set_title("Export as PDF")
+        .set_file_name(&format!("{stem}.pdf"))
+        .add_filter("PDF Files", &["pdf"])
+        .add_filter("All Files", &["*"])
+        .save_file()
+        .await
+        .map(|h| h.path().to_path_buf())
+}
+
+// ── PDF builder ───────────────────────────────────────────────────────────
+
+fn build_pdf(wires: &[WireModel], paper_w: f32, paper_h: f32) -> Vec<u8> {
+    let mut doc = PdfDocument::new("H7CAD Export");
+    let mut ops: Vec<Op> = Vec::new();
+
+    // White page background rectangle.
+    ops.push(Op::SetFillColor {
+        col: Color::Rgb(Rgb { r: 1.0, g: 1.0, b: 1.0, icc_profile: None }),
+    });
+    ops.push(Op::DrawRectangle {
+        rectangle: printpdf::Rect::from_wh(Mm(paper_w).into(), Mm(paper_h).into()),
+    });
+
+    // Round line caps for CAD aesthetics.
+    ops.push(Op::SetLineCapStyle { cap: LineCapStyle::Round });
+    ops.push(Op::SetLineJoinStyle { join: LineJoinStyle::Round });
+
+    let mut last_color: Option<[f32; 4]> = None;
+    let mut last_lw: Option<f32> = None;
+
+    for wire in wires {
+        // Set stroke color (white → black for print; skip fully transparent).
+        let [mut r, mut g, mut b, a] = wire.color;
+        if a < 0.01 {
+            continue;
+        }
+        // Invert near-white to black so it prints on white paper.
+        if r > 0.85 && g > 0.85 && b > 0.85 {
+            r = 0.0;
+            g = 0.0;
+            b = 0.0;
+        }
+        let color_changed = last_color.map(|c| {
+            (c[0] - r).abs() > 0.01 || (c[1] - g).abs() > 0.01 || (c[2] - b).abs() > 0.01
+        }).unwrap_or(true);
+        if color_changed {
+            ops.push(Op::SetOutlineColor {
+                col: Color::Rgb(Rgb { r, g, b, icc_profile: None }),
+            });
+            last_color = Some([r, g, b, a]);
+        }
+
+        // Set line width (in points; 1 mm = 2.8346 pt).
+        let lw_pt = (wire.line_weight_px as f32 * 0.35278).max(0.1);
+        if last_lw.map(|l| (l - lw_pt).abs() > 0.01).unwrap_or(true) {
+            ops.push(Op::SetOutlineThickness { pt: Pt(lw_pt) });
+            last_lw = Some(lw_pt);
+        }
+
+        // Collect segments (split at NaN).
+        let mut segment: Vec<LinePoint> = Vec::new();
+        for &[x, y, _z] in &wire.points {
+            if x.is_nan() || y.is_nan() {
+                flush_line(&mut ops, &segment);
+                segment.clear();
+            } else {
+                segment.push(LinePoint {
+                    p: Point::new(Mm(x), Mm(y)),
+                    bezier: false,
+                });
+            }
+        }
+        flush_line(&mut ops, &segment);
+    }
+
+    let page = PdfPage::new(Mm(paper_w), Mm(paper_h), ops);
+    doc.pages.push(page);
+
+    let mut warnings = Vec::new();
+    doc.save(&PdfSaveOptions::default(), &mut warnings)
+}
+
+fn flush_line(ops: &mut Vec<Op>, pts: &[LinePoint]) {
+    if pts.len() < 2 {
+        return;
+    }
+    ops.push(Op::DrawLine {
+        line: Line {
+            points: pts.to_vec(),
+            is_closed: false,
+        },
+    });
+}