Preserve explicit miter limits in PPTX

crates/model/src/style.rs

@@ -324,6 +324,7 @@ pub struct Line {
     pub dash: Option<Dash>,
     pub cap: Option<LineCap>,
     pub join: Option<LineJoin>,
+    pub miter_limit: Option<u32>,
     pub compound: Option<Compound>,
     pub head: Option<LineEnd>,
     pub tail: Option<LineEnd>,
@@ -347,6 +348,7 @@ impl Line {
         }
         self.cap = self.cap.or(parent.cap);
         self.join = self.join.or(parent.join);
+        self.miter_limit = self.miter_limit.or(parent.miter_limit);
         self.compound = self.compound.or(parent.compound);
         if self.head.is_none() {
             self.head.clone_from(&parent.head);

crates/pptx/src/read/dml.rs

@@ -232,7 +232,10 @@ pub fn line(imp: &mut Imp, part: &Part, ln: &El) -> Line {
             }
             "round" => l.join = Some(LineJoin::Round),
             "bevel" => l.join = Some(LineJoin::Bevel),
-            "miter" => l.join = Some(LineJoin::Miter),
+            "miter" => {
+                l.join = Some(LineJoin::Miter);
+                l.miter_limit = e.attr("lim").and_then(|v| v.parse::<u32>().ok()).filter(|v| *v <= 1_000_000);
+            }
             "headEnd" => l.head = line_end(e),
             "tailEnd" => l.tail = line_end(e),
             _ => {}

crates/pptx/src/write/dml.rs

@@ -233,7 +233,7 @@ pub fn line(w: &mut W, x: &mut Exp, o: &mut Out, tag: &str, l: &Line) {
     match l.join {
         Some(LineJoin::Round) => w.empty0("a:round"),
         Some(LineJoin::Bevel) => w.empty0("a:bevel"),
-        Some(LineJoin::Miter) => w.empty0("a:miter"),
+        Some(LineJoin::Miter) => w.empty("a:miter", A::new().o("lim", l.miter_limit)),
         None => {}
     }
     for (t, e) in [("a:headEnd", &l.head), ("a:tailEnd", &l.tail)] {

crates/pptx/tests/it/roundtrip.rs

@@ -488,6 +488,20 @@ fn shapes_fills_lines_effects_round_trip() {
     assert_eq!(by_name(&q.slides[1], "Group").id, by_name(&p.slides[1], "Group").id);
 }
 
+#[test]
+fn line_miter_limit_survives_two_pptx_round_trips() {
+    let mut p = Presentation::default();
+    let mut limited = shape(&mut p, "Limited miter", 20.0, 20.0, 100.0, 100.0);
+    limited.line = Some(Line { join: Some(deckcraft_model::style::LineJoin::Miter), miter_limit: Some(200_000), ..Default::default() });
+    let mut defaulted = shape(&mut p, "Default miter", 140.0, 20.0, 100.0, 100.0);
+    defaulted.line = Some(Line { join: Some(deckcraft_model::style::LineJoin::Miter), ..Default::default() });
+    Arc::make_mut(&mut p.slides[0]).shapes.extend([limited, defaulted]);
+
+    let q = round(&round(&p));
+    assert_eq!(by_name(&q.slides[0], "Limited miter").line.as_ref().and_then(|line| line.miter_limit), Some(200_000));
+    assert_eq!(by_name(&q.slides[0], "Default miter").line.as_ref().and_then(|line| line.miter_limit), None);
+}
+
 #[test]
 fn pictures_media_and_ink_round_trip() {
     let p = rich_deck();