From a64553bbaf9e058f02d278dfa7104ea96fc58dd8 Mon Sep 17 00:00:00 2001
From: Greg Depoire--Ferrer <56923875+greg904@users.noreply.github.com>
Date: Wed, 16 Feb 2022 20:57:46 +0000
Subject: [PATCH] Reuse Rasterizer in Display::new

Instead of creating a `Rasterizer` to guess the window dimensions,
dropping it and then creating a new one for the glyph cache, reuse the
same `Rasterizer`.

This prevents the font from being loaded twice during startup.
---
 alacritty/src/display/mod.rs  | 9 +++++----
 alacritty/src/renderer/mod.rs | 8 +++++---
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/alacritty/src/display/mod.rs b/alacritty/src/display/mod.rs
index ef4cfc10..c58ded5d 100644
--- a/alacritty/src/display/mod.rs
+++ b/alacritty/src/display/mod.rs
@@ -232,7 +232,8 @@ impl Display {
         };
 
         // Guess the target window dimensions.
-        let metrics = GlyphCache::static_metrics(config.font.clone(), estimated_dpr)?;
+        let mut rasterizer = Rasterizer::new(estimated_dpr as f32, config.font.use_thin_strokes)?;
+        let metrics = GlyphCache::static_metrics(&mut rasterizer, config.font.clone())?;
         let (cell_width, cell_height) = compute_cell_size(config, &metrics);
 
         // Guess the target window size if the user has specified the number of lines/columns.
@@ -256,12 +257,13 @@ impl Display {
         )?;
 
         info!("Device pixel ratio: {}", window.dpr);
+        rasterizer.update_dpr(window.dpr as f32);
 
         // Create renderer.
         let mut renderer = QuadRenderer::new()?;
 
         let (glyph_cache, cell_width, cell_height) =
-            Self::new_glyph_cache(window.dpr, &mut renderer, config)?;
+            Self::new_glyph_cache(rasterizer, &mut renderer, config)?;
 
         if let Some(dimensions) = dimensions {
             if (estimated_dpr - window.dpr).abs() < f64::EPSILON {
@@ -361,12 +363,11 @@ impl Display {
     }
 
     fn new_glyph_cache(
-        dpr: f64,
+        rasterizer: Rasterizer,
         renderer: &mut QuadRenderer,
         config: &UiConfig,
     ) -> Result<(GlyphCache, f32, f32), Error> {
         let font = config.font.clone();
-        let rasterizer = Rasterizer::new(dpr as f32, config.font.use_thin_strokes)?;
 
         // Initialize glyph cache.
         let glyph_cache = {
diff --git a/alacritty/src/renderer/mod.rs b/alacritty/src/renderer/mod.rs
index ad59a4e1..e7878b6d 100644
--- a/alacritty/src/renderer/mod.rs
+++ b/alacritty/src/renderer/mod.rs
@@ -404,10 +404,12 @@ impl GlyphCache {
     }
 
     /// Calculate font metrics without access to a glyph cache.
-    pub fn static_metrics(font: Font, dpr: f64) -> Result<crossfont::Metrics, crossfont::Error> {
-        let mut rasterizer = crossfont::Rasterizer::new(dpr as f32, font.use_thin_strokes)?;
+    pub fn static_metrics(
+        rasterizer: &mut crossfont::Rasterizer,
+        font: Font,
+    ) -> Result<crossfont::Metrics, crossfont::Error> {
         let regular_desc = GlyphCache::make_desc(font.normal(), Slant::Normal, Weight::Normal);
-        let regular = Self::load_regular_font(&mut rasterizer, &regular_desc, font.size())?;
+        let regular = Self::load_regular_font(rasterizer, &regular_desc, font.size())?;
         rasterizer.get_glyph(GlyphKey { font_key: regular, character: 'm', size: font.size() })?;
 
         rasterizer.metrics(regular, font.size())