linux: Update cosmic_text (#13095)

Bumps cosmic_text, removes some stale `todo`s and stores a ShapeBuffer
to prevent reallocations

Improvements:

- Performance should be a lot better (haven't actually tested it)
- Fixed display of `\t` in the terminal

![image](https://github.com/zed-industries/zed/assets/71973804/ca994912-851d-48ef-8dc7-b244c9eb484d)

![image](https://github.com/zed-industries/zed/assets/71973804/42fa9acf-ec10-4247-a5e3-2d4fe664ded6)


Release Notes:

- N/A

crates/gpui/Cargo.toml

@@ -103,7 +103,7 @@ blade-graphics.workspace = true
 blade-macros.workspace = true
 blade-util.workspace = true
 bytemuck = "1"
-cosmic-text = "0.11.2"
+cosmic-text = { git = "https://github.com/pop-os/cosmic-text", rev = "542b20c" }
 copypasta = "0.10.1"
 
 [target.'cfg(target_os = "linux")'.dependencies]

crates/gpui/src/platform/cosmic_text/text_system.rs

@@ -6,7 +6,8 @@ use crate::{
 use anyhow::{anyhow, Context, Ok, Result};
 use collections::HashMap;
 use cosmic_text::{
-    Attrs, AttrsList, BufferLine, CacheKey, Family, Font as CosmicTextFont, FontSystem, SwashCache,
+    Attrs, AttrsList, CacheKey, Family, Font as CosmicTextFont, FontSystem, ShapeBuffer, ShapeLine,
+    SwashCache,
 };
 
 use itertools::Itertools;
@@ -23,6 +24,7 @@ pub(crate) struct CosmicTextSystem(RwLock<CosmicTextSystemState>);
 struct CosmicTextSystemState {
     swash_cache: SwashCache,
     font_system: FontSystem,
+    scratch: ShapeBuffer,
     /// Contains all already loaded fonts, including all faces. Indexed by `FontId`.
     loaded_fonts_store: Vec<Arc<CosmicTextFont>>,
     /// Caches the `FontId`s associated with a specific family to avoid iterating the font database
@@ -42,6 +44,7 @@ impl CosmicTextSystem {
         Self(RwLock::new(CosmicTextSystemState {
             font_system,
             swash_cache: SwashCache::new(),
+            scratch: ShapeBuffer::default(),
             loaded_fonts_store: Vec::new(),
             font_ids_by_family_cache: HashMap::default(),
             postscript_names: HashMap::default(),
@@ -60,8 +63,6 @@ impl PlatformTextSystem for CosmicTextSystem {
         self.0.write().add_fonts(fonts)
     }
 
-    // todo(linux) ensure that this integrates with platform font loading
-    // do we need to do more than call load_system_fonts()?
     fn all_font_names(&self) -> Vec<String> {
         self.0
             .read()
@@ -367,13 +368,11 @@ impl CosmicTextSystemState {
         }
     }
 
-    // todo(linux) This is all a quick first pass, maybe we should be using cosmic_text::Buffer
     #[profiling::function]
     fn layout_line(&mut self, text: &str, font_size: Pixels, font_runs: &[FontRun]) -> LineLayout {
         let mut attrs_list = AttrsList::new(Attrs::new());
         let mut offs = 0;
         for run in font_runs {
-            // todo(linux) We need to check we are doing utf properly
             let font = &self.loaded_fonts_store[run.font_id.0];
             let font = self.font_system.db().face(font.id()).unwrap();
             attrs_list.add_span(
@@ -386,17 +385,27 @@ impl CosmicTextSystemState {
             );
             offs += run.len;
         }
-        let mut line = BufferLine::new(text, attrs_list, cosmic_text::Shaping::Advanced);
-
-        let layout = line.layout(
+        let mut line = ShapeLine::new_in_buffer(
+            &mut self.scratch,
             &mut self.font_system,
+            text,
+            &attrs_list,
+            cosmic_text::Shaping::Advanced,
+            4,
+        );
+
+        let mut layout = Vec::with_capacity(1);
+        line.layout_to_buffer(
+            &mut self.scratch,
             font_size.0,
-            f32::MAX, // We do our own wrapping
+            None, // We do our own wrapping
             cosmic_text::Wrap::None,
             None,
+            &mut layout,
+            None,
         );
-        let mut runs = Vec::new();
 
+        let mut runs = Vec::new();
         let layout = layout.first().unwrap();
         for glyph in &layout.glyphs {
             let font_id = glyph.font_id;
@@ -412,7 +421,7 @@ impl CosmicTextSystemState {
             // 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
             glyphs.push(ShapedGlyph {
                 id: GlyphId(glyph.glyph_id as u32),
-                position: point((glyph.x).into(), glyph.y.into()),
+                position: point(glyph.x.into(), glyph.y.into()),
                 index: glyph.start,
                 is_emoji,
             });