From 6fc90360636d8543724afa1448c03ad995f98460 Mon Sep 17 00:00:00 2001
From: Michael Sloan <michael@zed.dev>
Date: Wed, 14 May 2025 00:10:35 +0200
Subject: [PATCH] Multi-glyph text runs on Linux  (#30660)

Release Notes:

- N/A
---
 crates/gpui/src/platform/linux/text_system.rs | 24 ++++++++++++-------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/crates/gpui/src/platform/linux/text_system.rs b/crates/gpui/src/platform/linux/text_system.rs
index 34bcc4759a9cac7090ab5517d97ca0dc1e57741f..08860978be18c9e68867f12db8b41b4f7c3a49ef 100644
--- a/crates/gpui/src/platform/linux/text_system.rs
+++ b/crates/gpui/src/platform/linux/text_system.rs
@@ -1,7 +1,7 @@
 use crate::{
     Bounds, DevicePixels, Font, FontFeatures, FontId, FontMetrics, FontRun, FontStyle, FontWeight,
     GlyphId, LineLayout, Pixels, PlatformTextSystem, Point, RenderGlyphParams, SUBPIXEL_VARIANTS,
-    ShapedGlyph, SharedString, Size, point, size,
+    ShapedGlyph, ShapedRun, SharedString, Size, point, size,
 };
 use anyhow::{Context as _, Ok, Result, anyhow};
 use collections::HashMap;
@@ -16,7 +16,7 @@ use pathfinder_geometry::{
     rect::{RectF, RectI},
     vector::{Vector2F, Vector2I},
 };
-use smallvec::SmallVec;
+use smallvec::{SmallVec, smallvec};
 use std::{borrow::Cow, sync::Arc};
 
 pub(crate) struct CosmicTextSystem(RwLock<CosmicTextSystemState>);
@@ -413,7 +413,7 @@ impl CosmicTextSystemState {
         );
         let layout = layout_lines.first().unwrap();
 
-        let mut runs = Vec::new();
+        let mut runs: Vec<ShapedRun> = Vec::new();
         for glyph in &layout.glyphs {
             let mut font_id = FontId(glyph.metadata);
             let mut loaded_font = self.loaded_font(font_id);
@@ -428,16 +428,24 @@ impl CosmicTextSystemState {
                 continue;
             }
 
-            // todo(linux) this is definitely wrong, each glyph in glyphs from cosmic-text is a cluster with one glyph, ShapedRun takes a run of glyphs with the same font and direction
-            let mut glyphs = SmallVec::new();
-            glyphs.push(ShapedGlyph {
+            let shaped_glyph = ShapedGlyph {
                 id: GlyphId(glyph.glyph_id as u32),
                 position: point(glyph.x.into(), glyph.y.into()),
                 index: glyph.start,
                 is_emoji,
-            });
+            };
 
-            runs.push(crate::ShapedRun { font_id, glyphs });
+            if let Some(last_run) = runs
+                .last_mut()
+                .filter(|last_run| last_run.font_id == font_id)
+            {
+                last_run.glyphs.push(shaped_glyph);
+            } else {
+                runs.push(ShapedRun {
+                    font_id,
+                    glyphs: smallvec![shaped_glyph],
+                });
+            }
         }
 
         LineLayout {