From 0df77d90740a6c7bbc786988cd1f7282a4d410a6 Mon Sep 17 00:00:00 2001
From: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
Date: Sat, 22 Jan 2022 15:39:13 +0100
Subject: [PATCH] Round font sizes to whole pixels before deduplicating them

---
 epaint/src/text/font.rs  | 21 ++++++-----------
 epaint/src/text/fonts.rs | 50 ++++++++++++++++++++--------------------
 2 files changed, 32 insertions(+), 39 deletions(-)

diff --git a/epaint/src/text/font.rs b/epaint/src/text/font.rs
index 6e7fe987..68e101d6 100644
--- a/epaint/src/text/font.rs
+++ b/epaint/src/text/font.rs
@@ -59,7 +59,7 @@ impl Default for GlyphInfo {
 pub struct FontImpl {
     ab_glyph_font: ab_glyph::FontArc,
     /// Maximum character height
-    scale_in_pixels: f32,
+    scale_in_pixels: u32,
     height_in_points: f32,
     // move each character by this much (hack)
     y_offset: f32,
@@ -73,20 +73,13 @@ impl FontImpl {
         atlas: Arc<Mutex<TextureAtlas>>,
         pixels_per_point: f32,
         ab_glyph_font: ab_glyph::FontArc,
-        scale_in_points: f32,
+        scale_in_pixels: u32,
         y_offset: f32,
     ) -> FontImpl {
-        assert!(scale_in_points > 0.0);
+        assert!(scale_in_pixels > 0);
         assert!(pixels_per_point > 0.0);
 
-        let scale_in_pixels = pixels_per_point * scale_in_points;
-
-        // Round to an even number of physical pixels to get even kerning.
-        // See https://github.com/emilk/egui/issues/382
-        let scale_in_pixels = scale_in_pixels.round();
-        let scale_in_points = scale_in_pixels / pixels_per_point;
-
-        let height_in_points = scale_in_points;
+        let height_in_points = scale_in_pixels as f32 / pixels_per_point;
 
         // TODO: use v_metrics for line spacing ?
         // let v = rusttype_font.v_metrics(Scale::uniform(scale_in_pixels));
@@ -162,7 +155,7 @@ impl FontImpl {
                 &mut self.atlas.lock(),
                 &self.ab_glyph_font,
                 glyph_id,
-                self.scale_in_pixels,
+                self.scale_in_pixels as f32,
                 self.y_offset,
                 self.pixels_per_point,
             );
@@ -180,7 +173,7 @@ impl FontImpl {
     ) -> f32 {
         use ab_glyph::{Font as _, ScaleFont};
         self.ab_glyph_font
-            .as_scaled(self.scale_in_pixels)
+            .as_scaled(self.scale_in_pixels as f32)
             .kern(last_glyph_id, glyph_id)
             / self.pixels_per_point
     }
@@ -375,7 +368,7 @@ fn allocate_glyph(
                 }
             });
 
-            let offset_in_pixels = vec2(bb.min.x as f32, scale_in_pixels as f32 + bb.min.y as f32);
+            let offset_in_pixels = vec2(bb.min.x as f32, scale_in_pixels + bb.min.y as f32);
             let offset = offset_in_pixels / pixels_per_point + y_offset * Vec2::Y;
             UvRect {
                 offset,
diff --git a/epaint/src/text/fonts.rs b/epaint/src/text/fonts.rs
index fdcd4501..98500cdf 100644
--- a/epaint/src/text/fonts.rs
+++ b/epaint/src/text/fonts.rs
@@ -503,9 +503,8 @@ struct FontImplCache {
     pixels_per_point: f32,
     ab_glyph_fonts: BTreeMap<String, ab_glyph::FontArc>,
 
-    /// Map font names and size to the cached `FontImpl`.
-    /// Can't have f32 in a HashMap or BTreeMap, so let's do a linear search
-    cache: Vec<(String, f32, Arc<FontImpl>)>,
+    /// Map font pixel sizes and names to the cached `FontImpl`.
+    cache: ahash::AHashMap<(u32, String), Arc<FontImpl>>,
 }
 
 impl FontImplCache {
@@ -528,20 +527,7 @@ impl FontImplCache {
         }
     }
 
-    pub fn ab_glyph_font(&self, font_name: &str) -> ab_glyph::FontArc {
-        self.ab_glyph_fonts
-            .get(font_name)
-            .unwrap_or_else(|| panic!("No font data found for {:?}", font_name))
-            .clone()
-    }
-
     pub fn font_impl(&mut self, font_name: &str, scale_in_points: f32) -> Arc<FontImpl> {
-        for entry in &self.cache {
-            if (entry.0.as_str(), entry.1) == (font_name, scale_in_points) {
-                return entry.2.clone();
-            }
-        }
-
         let y_offset = if font_name == "emoji-icon-font" {
             scale_in_points * 0.235 // TODO: remove font alignment hack
         } else {
@@ -555,15 +541,29 @@ impl FontImplCache {
             scale_in_points
         };
 
-        let font_impl = Arc::new(FontImpl::new(
-            self.atlas.clone(),
-            self.pixels_per_point,
-            self.ab_glyph_font(font_name),
-            scale_in_points,
-            y_offset,
-        ));
+        let scale_in_pixels = self.pixels_per_point * scale_in_points;
+
+        // Round to an even number of physical pixels to get even kerning.
+        // See https://github.com/emilk/egui/issues/382
+        let scale_in_pixels = scale_in_pixels.round() as u32;
+
         self.cache
-            .push((font_name.to_owned(), scale_in_points, font_impl.clone()));
-        font_impl
+            .entry((scale_in_pixels, font_name.to_owned()))
+            .or_insert_with(|| {
+                let ab_glyph_font = self
+                    .ab_glyph_fonts
+                    .get(font_name)
+                    .unwrap_or_else(|| panic!("No font data found for {:?}", font_name))
+                    .clone();
+
+                Arc::new(FontImpl::new(
+                    self.atlas.clone(),
+                    self.pixels_per_point,
+                    ab_glyph_font,
+                    scale_in_pixels,
+                    y_offset,
+                ))
+            })
+            .clone()
     }
 }