From 42c3a6fa72be91c115e28e3866012b95b4d63cf4 Mon Sep 17 00:00:00 2001
From: sitandr <60141933+sitandr@users.noreply.github.com>
Date: Fri, 19 May 2023 16:33:15 +0300
Subject: Fixed symbol style reset in stretching (#1195)

---
 library/src/math/fragment.rs | 50 +++++++++++++++++++++++++++-----------------
 library/src/math/stretch.rs  |  8 ++++---
 2 files changed, 36 insertions(+), 22 deletions(-)

(limited to 'library/src')

diff --git a/library/src/math/fragment.rs b/library/src/math/fragment.rs
index 40dca347..027ab7da 100644
--- a/library/src/math/fragment.rs
+++ b/library/src/math/fragment.rs
@@ -164,21 +164,7 @@ impl GlyphFragment {
     }
 
     pub fn with_id(ctx: &MathContext, c: char, id: GlyphId, span: Span) -> Self {
-        let advance = ctx.ttf.glyph_hor_advance(id).unwrap_or_default();
-        let italics = italics_correction(ctx, id).unwrap_or_default();
-        let bbox = ctx.ttf.glyph_bounding_box(id).unwrap_or(Rect {
-            x_min: 0,
-            y_min: 0,
-            x_max: 0,
-            y_max: 0,
-        });
-
-        let mut width = advance.scaled(ctx);
-        if !is_extended_shape(ctx, id) {
-            width += italics;
-        }
-
-        Self {
+        let mut fragment = Self {
             id,
             c,
             font: ctx.font.clone(),
@@ -186,17 +172,43 @@ impl GlyphFragment {
             fill: TextElem::fill_in(ctx.styles()),
             style: ctx.style,
             font_size: ctx.size,
-            width,
-            ascent: bbox.y_max.scaled(ctx),
-            descent: -bbox.y_min.scaled(ctx),
-            italics_correction: italics,
+            width: Abs::zero(),
+            ascent: Abs::zero(),
+            descent: Abs::zero(),
+            italics_correction: Abs::zero(),
             class: match c {
                 ':' => Some(MathClass::Relation),
                 _ => unicode_math_class::class(c),
             },
             span,
             meta: MetaElem::data_in(ctx.styles()),
+        };
+        fragment.set_id(ctx, id);
+        fragment
+    }
+
+    /// Sets element id and boxes in appropriate way without changing other
+    /// styles. This is used to replace the glyph with a stretch variant.
+    pub fn set_id(&mut self, ctx: &MathContext, id: GlyphId) {
+        let advance = ctx.ttf.glyph_hor_advance(id).unwrap_or_default();
+        let italics = italics_correction(ctx, id).unwrap_or_default();
+        let bbox = ctx.ttf.glyph_bounding_box(id).unwrap_or(Rect {
+            x_min: 0,
+            y_min: 0,
+            x_max: 0,
+            y_max: 0,
+        });
+
+        let mut width = advance.scaled(ctx);
+        if !is_extended_shape(ctx, id) {
+            width += italics;
         }
+
+        self.id = id;
+        self.width = width;
+        self.ascent = bbox.y_max.scaled(ctx);
+        self.descent = -bbox.y_min.scaled(ctx);
+        self.italics_correction = italics;
     }
 
     pub fn height(&self) -> Abs {
diff --git a/library/src/math/stretch.rs b/library/src/math/stretch.rs
index bb454022..bbb0c9c4 100644
--- a/library/src/math/stretch.rs
+++ b/library/src/math/stretch.rs
@@ -33,7 +33,7 @@ impl GlyphFragment {
 /// The resulting frame may not have the exact desired width.
 fn stretch_glyph(
     ctx: &MathContext,
-    base: GlyphFragment,
+    mut base: GlyphFragment,
     target: Abs,
     short_fall: Abs,
     horizontal: bool,
@@ -73,7 +73,8 @@ fn stretch_glyph(
 
     // This is either good or the best we've got.
     if short_target <= best_advance || construction.assembly.is_none() {
-        return GlyphFragment::with_id(ctx, base.c, best_id, base.span).into_variant();
+        base.set_id(ctx, best_id);
+        return base.into_variant();
     }
 
     // Assemble from parts.
@@ -142,7 +143,8 @@ fn assemble(
             advance += ratio * (max_overlap - min_overlap);
         }
 
-        let fragment = GlyphFragment::with_id(ctx, base.c, part.glyph_id, base.span);
+        let mut fragment = base.clone();
+        fragment.set_id(ctx, part.glyph_id);
         selected.push((fragment, advance));
     }
 
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