Move line height calculation to LayoutLine

src/buffer.rs

@@ -126,17 +126,9 @@ impl<'b> Iterator for LayoutRunIter<'b> {
                     continue;
                 }
 
-                let mut line_height_opt: Option<f32> = None;
+                let line_height = layout_line
-                for glyph in layout_line.glyphs.iter() {
+                    .line_height_opt
-                    if let Some(glyph_line_height) = glyph.line_height_opt {
+                    .unwrap_or(self.buffer.metrics.line_height);
-                        line_height_opt = match line_height_opt {
-                            Some(line_height) => Some(line_height.max(glyph_line_height)),
-                            None => Some(glyph_line_height),
-                        };
-                    }
-                }
-
-                let line_height = line_height_opt.unwrap_or(self.buffer.metrics.line_height);
                 let line_top = self.line_top;
                 let glyph_height = layout_line.max_ascent + layout_line.max_descent;
                 let centering_offset = (line_height - glyph_height) / 2.0;

src/layout.rs

@@ -95,6 +95,8 @@ pub struct LayoutLine {
     pub max_ascent: f32,
     /// Maximum descent of the glyphs in line
     pub max_descent: f32,
+    /// Maximum line height of any spans in line
+    pub line_height_opt: Option<f32>,
     /// Glyphs in line
     pub glyphs: Vec<LayoutGlyph>,
 }

src/shape.rs

@@ -1453,6 +1453,16 @@ impl ShapeLine {
                 }
             }
 
+            let mut line_height_opt: Option<f32> = None;
+            for glyph in glyphs.iter() {
+                if let Some(glyph_line_height) = glyph.line_height_opt {
+                    line_height_opt = match line_height_opt {
+                        Some(line_height) => Some(line_height.max(glyph_line_height)),
+                        None => Some(glyph_line_height),
+                    };
+                }
+            }
+
             layout_lines.push(LayoutLine {
                 w: if align != Align::Justified {
                     visual_line.w
@@ -1463,6 +1473,7 @@ impl ShapeLine {
                 },
                 max_ascent,
                 max_descent,
+                line_height_opt,
                 glyphs,
             });
         }
@@ -1473,6 +1484,7 @@ impl ShapeLine {
                 w: 0.0,
                 max_ascent: 0.0,
                 max_descent: 0.0,
+                line_height_opt: None,
                 glyphs: Default::default(),
             });
         }