From c5ebf4d1cdc6c14cea34fab34ef1f2253885e555 Mon Sep 17 00:00:00 2001
From: MarekSpodBiedry <73122968+MarekSpodBiedry@users.noreply.github.com>
Date: Mon, 12 Oct 2026 01:52:51 +0200
Subject: [PATCH] Keep inter-word spaces in stroke-font MTEXT (#628) (#644)

Squash of PR #644 by @MarekSpodBiedry.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 crates/fonts/src/lib.rs        | 11 +++++++++++
 crates/fonts/src/mtext.rs      |  8 +++++++-
 crates/fonts/src/mtext/para.rs |  2 +-
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/crates/fonts/src/lib.rs b/crates/fonts/src/lib.rs
index 0217fa9..73e7794 100644
--- a/crates/fonts/src/lib.rs
+++ b/crates/fonts/src/lib.rs
@@ -213,6 +213,17 @@ pub fn line_width(s: &str, height: f64, width_factor: f64) -> f64 {
     (n - stroke::GAP / stroke::CAP * height * width_factor).max(0.0)
 }
 
+/// Width of the gap MTEXT leaves between two words. Words are measured without their trailing
+/// letter gap, so the stroke font's gap is added on both sides of the space, as TEXT lays it out.
+pub fn space_width(font: &TextFont, height: f64, width_factor: f64) -> f64 {
+    if let TextFont::Outline(face) = font
+        && let Some(w) = ttf::width(face, " ", height, width_factor)
+    {
+        return w;
+    }
+    stroke_advance(' ', height, width_factor) + stroke::GAP / stroke::CAP * height * width_factor
+}
+
 /// The font a piece of text is set in: the built-in stroke font or an installed TrueType /
 /// OpenType face (outlines). Either way, characters the font lacks come from a fallback font.
 #[derive(Clone, Debug, Default)]
diff --git a/crates/fonts/src/mtext.rs b/crates/fonts/src/mtext.rs
index 8c08a61..7129591 100644
--- a/crates/fonts/src/mtext.rs
+++ b/crates/fonts/src/mtext.rs
@@ -571,7 +571,7 @@ pub fn layout_mtext_with(contents: &str, p: &MTextParams) -> MTextLayout {
             }
             Atom::Word(segs) => {
                 let ww: f64 = segs.iter().map(|(sg, f)| seg_width(sg, fmt(*f))).sum();
-                let sw = pending_space.map(|f| text_width(&fmt(f).font, " ", fmt(f).height, fmt(f).wf)).unwrap_or(0.0);
+                let sw = pending_space.map(|f| crate::space_width(&fmt(f).font, fmt(f).height, fmt(f).wf)).unwrap_or(0.0);
                 if width > 0.0 && !line.items.is_empty() && line.width + sw + ww > width + 1e-9 {
                     finish(&mut lines, &mut line, fmt(last_fmt), para);
                 } else if !line.items.is_empty() || pending_space.is_some() {
@@ -693,6 +693,12 @@ mod tests {
         assert!((c.x - 5.0).abs() < 1e-9 && (c.y - 5.0).abs() < 1e-9);
     }
 
+    #[test]
+    fn stroke_word_space_matches_text() {
+        let l = layout_mtext("A B", Vec2::ZERO, 1.0, 0.0, 1, 0.0, 1.0);
+        assert!((l.bounds.width() - crate::line_width("A B", 1.0, 1.0)).abs() < 1e-9);
+    }
+
     fn lay(s: &str, width: f64) -> MTextLayout {
         layout_mtext(s, Vec2::ZERO, 1.0, width, 1, 0.0, 1.0)
     }
diff --git a/crates/fonts/src/mtext/para.rs b/crates/fonts/src/mtext/para.rs
index 6680369..80d7618 100644
--- a/crates/fonts/src/mtext/para.rs
+++ b/crates/fonts/src/mtext/para.rs
@@ -426,7 +426,7 @@ pub(super) fn layout(contents: &str, p: &MTextParams, base: &Fmt) -> MTextLayout
     let paras = Paragraphs::scan(contents);
     let (atoms, fmts) = parse(contents, base.clone());
     let fmt = |i: usize| fmts.get(i).unwrap_or(base);
-    let space_w = |f: usize| crate::text_width(&fmt(f).font, " ", fmt(f).height, fmt(f).wf);
+    let space_w = |f: usize| crate::space_width(&fmt(f).font, fmt(f).height, fmt(f).wf);
 
     let mut lines: Vec<PLine> = Vec::new();
     let mut k = 0usize;