From 1de0101cedbe69e4e37f380c2737b84e7759ba38 Mon Sep 17 00:00:00 2001
From: Harrison Booth <73434116+Harrison-Booth@users.noreply.github.com>
Date: Fri, 30 Oct 2026 23:11:12 -0500
Subject: [PATCH] Honor miter percentage schema bounds

---
 crates/pptx/src/read/dml.rs       | 23 ++++++++++++++++++++++-
 crates/pptx/src/write/dml.rs      |  5 ++++-
 crates/pptx/tests/it/roundtrip.rs |  5 ++++-
 3 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/crates/pptx/src/read/dml.rs b/crates/pptx/src/read/dml.rs
index e1e5dcd4..9ac99912 100644
--- a/crates/pptx/src/read/dml.rs
+++ b/crates/pptx/src/read/dml.rs
@@ -234,7 +234,7 @@ pub fn line(imp: &mut Imp, part: &Part, ln: &El) -> Line {
             "bevel" => l.join = Some(LineJoin::Bevel),
             "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);
+                l.miter_limit = e.attr("lim").and_then(parse_miter_limit);
             }
             "headEnd" => l.head = line_end(e),
             "tailEnd" => l.tail = line_end(e),
@@ -244,6 +244,17 @@ pub fn line(imp: &mut Imp, part: &Part, ln: &El) -> Line {
     l
 }
 
+fn parse_miter_limit(value: &str) -> Option<u32> {
+    const MAX: u32 = i32::MAX as u32;
+    let value = value.trim();
+    if let Some(percent) = value.strip_suffix('%') {
+        let units = percent.trim().parse::<f64>().ok()? * 1000.0;
+        (units.is_finite() && (0.0..=MAX as f64).contains(&units)).then(|| units.round() as u32)
+    } else {
+        value.parse::<u32>().ok().filter(|limit| *limit <= MAX)
+    }
+}
+
 fn line_end(e: &El) -> Option<LineEnd> {
     let kind = e.attr("type").unwrap_or("none");
     Some(LineEnd { kind: kind.to_string(), w: e.attr("w").unwrap_or("med").to_string(), len: e.attr("len").unwrap_or("med").to_string() })
@@ -671,6 +682,16 @@ mod tests {
         assert_eq!(color(&d.root).unwrap().base, ColorBase::Rgb { rgb: Rgba::rgb(255, 0, 0) });
     }
 
+    #[test]
+    fn miter_limit_accepts_both_percentage_forms_with_schema_bounds() {
+        assert_eq!(parse_miter_limit("200000"), Some(200_000));
+        assert_eq!(parse_miter_limit("200%"), Some(200_000));
+        assert_eq!(parse_miter_limit("1000001"), Some(1_000_001));
+        assert_eq!(parse_miter_limit("malformed"), None);
+        assert_eq!(parse_miter_limit("2147483648"), None);
+        assert_eq!(parse_miter_limit("2147483.648%"), None);
+    }
+
     #[test]
     fn body_props() {
         let d = parse(br#"<a:bodyPr lIns="91440" anchor="ctr" wrap="none" vert="vert270" numCol="2"><a:normAutofit fontScale="62500" lnSpcReduction="20000"/></a:bodyPr>"#).unwrap();
diff --git a/crates/pptx/src/write/dml.rs b/crates/pptx/src/write/dml.rs
index a6d00ff4..d46a7aae 100644
--- a/crates/pptx/src/write/dml.rs
+++ b/crates/pptx/src/write/dml.rs
@@ -233,7 +233,10 @@ 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.empty("a:miter", A::new().o("lim", l.miter_limit)),
+        Some(LineJoin::Miter) => {
+            let limit = l.miter_limit.filter(|limit| *limit <= i32::MAX as u32);
+            w.empty("a:miter", A::new().o("lim", limit));
+        }
         None => {}
     }
     for (t, e) in [("a:headEnd", &l.head), ("a:tailEnd", &l.tail)] {
diff --git a/crates/pptx/tests/it/roundtrip.rs b/crates/pptx/tests/it/roundtrip.rs
index 59904071..d0525241 100644
--- a/crates/pptx/tests/it/roundtrip.rs
+++ b/crates/pptx/tests/it/roundtrip.rs
@@ -495,11 +495,14 @@ fn line_miter_limit_survives_two_pptx_round_trips() {
     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 mut large = shape(&mut p, "Large miter", 260.0, 20.0, 100.0, 100.0);
+    large.line = Some(Line { join: Some(deckcraft_model::style::LineJoin::Miter), miter_limit: Some(1_000_001), ..Default::default() });
+    Arc::make_mut(&mut p.slides[0]).shapes.extend([limited, defaulted, large]);
 
     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);
+    assert_eq!(by_name(&q.slides[0], "Large miter").line.as_ref().and_then(|line| line.miter_limit), Some(1_000_001));
 }
 
 #[test]