From 6a4a03ce9db68f3a4490ddf204b5eb607d7ebbf0 Mon Sep 17 00:00:00 2001
From: Emil Ernerfeldt <emilernerfeldt@gmail.com>
Date: Fri, 11 Dec 2020 23:39:32 +0100
Subject: [PATCH] Make struct Font a wrapper around FontImpl

---
 egui/src/paint/font.rs  | 97 +++++++++++++++++++++++++++++------------
 egui/src/paint/fonts.rs | 10 ++++-
 2 files changed, 78 insertions(+), 29 deletions(-)

diff --git a/egui/src/paint/font.rs b/egui/src/paint/font.rs
index 9c7bf5d0..dc0ec9b9 100644
--- a/egui/src/paint/font.rs
+++ b/egui/src/paint/font.rs
@@ -45,7 +45,7 @@ pub struct GlyphInfo {
 }
 
 /// The interface uses points as the unit for everything.
-pub struct Font {
+pub struct FontImpl {
     font: rusttype::Font<'static>,
     /// Maximum character height
     scale_in_pixels: f32,
@@ -55,13 +55,13 @@ pub struct Font {
     atlas: Arc<Mutex<TextureAtlas>>,
 }
 
-impl Font {
+impl FontImpl {
     pub fn new(
         atlas: Arc<Mutex<TextureAtlas>>,
         font_data: &'static [u8],
         scale_in_points: f32,
         pixels_per_point: f32,
-    ) -> Font {
+    ) -> FontImpl {
         assert!(scale_in_points > 0.0);
         assert!(pixels_per_point > 0.0);
 
@@ -82,7 +82,7 @@ impl Font {
             )
         });
 
-        let font = Font {
+        let font = Self {
             font,
             scale_in_pixels,
             pixels_per_point,
@@ -106,23 +106,6 @@ impl Font {
         font
     }
 
-    pub fn round_to_pixel(&self, point: f32) -> f32 {
-        (point * self.pixels_per_point).round() / self.pixels_per_point
-    }
-
-    /// Height of one row of text. In points
-    pub fn row_height(&self) -> f32 {
-        self.scale_in_pixels / self.pixels_per_point
-    }
-
-    pub fn uv_rect(&self, c: char) -> Option<UvRect> {
-        self.glyph_infos.read().get(&c).and_then(|gi| gi.uv_rect)
-    }
-
-    pub fn glyph_width(&self, c: char) -> f32 {
-        self.glyph_info(c).advance_width
-    }
-
     /// `\n` will (intentionally) show up as '?' (`REPLACEMENT_CHAR`)
     fn glyph_info(&self, c: char) -> GlyphInfo {
         {
@@ -145,6 +128,71 @@ impl Font {
         glyph_info
     }
 
+    pub fn pair_kerning(
+        &self,
+        last_glyph_id: rusttype::GlyphId,
+        glyph_id: rusttype::GlyphId,
+    ) -> f32 {
+        let scale_in_pixels = Scale::uniform(self.scale_in_pixels);
+        self.font
+            .pair_kerning(scale_in_pixels, last_glyph_id, glyph_id)
+            / self.pixels_per_point
+    }
+
+    pub fn round_to_pixel(&self, point: f32) -> f32 {
+        (point * self.pixels_per_point).round() / self.pixels_per_point
+    }
+
+    /// Height of one row of text. In points
+    pub fn row_height(&self) -> f32 {
+        self.scale_in_pixels / self.pixels_per_point
+    }
+
+    pub fn uv_rect(&self, c: char) -> Option<UvRect> {
+        self.glyph_infos.read().get(&c).and_then(|gi| gi.uv_rect)
+    }
+
+    pub fn glyph_width(&self, c: char) -> f32 {
+        self.glyph_info(c).advance_width
+    }
+
+    pub fn pixels_per_point(&self) -> f32 {
+        self.pixels_per_point
+    }
+}
+
+// TODO: rename Layouter ?
+/// Wrapper over multiple `FontImpl` (commonly two: primary + emoji fallback)
+pub struct Font {
+    font_impl: Arc<FontImpl>,
+}
+
+impl Font {
+    pub fn new(font_impl: Arc<FontImpl>) -> Self {
+        Self { font_impl }
+    }
+
+    pub fn round_to_pixel(&self, point: f32) -> f32 {
+        self.font_impl.round_to_pixel(point)
+    }
+
+    /// Height of one row of text. In points
+    pub fn row_height(&self) -> f32 {
+        self.font_impl.row_height()
+    }
+
+    pub fn uv_rect(&self, c: char) -> Option<UvRect> {
+        self.font_impl.uv_rect(c)
+    }
+
+    pub fn glyph_width(&self, c: char) -> f32 {
+        self.font_impl.glyph_width(c)
+    }
+
+    fn glyph_info(&self, c: char) -> GlyphInfo {
+        self.font_impl.glyph_info(c)
+    }
+
     /// Typeset the given text onto one row.
     /// Any `\n` will show up as `REPLACEMENT_CHAR` ('?').
     /// Always returns exactly one `Row` in the `Galley`.
@@ -244,8 +292,6 @@ impl Font {
     /// Assumes there are no `\n` in the text.
     /// Return `x_offsets`, one longer than the number of characters in the text.
     fn layout_single_row_fragment(&self, text: &str) -> Vec<f32> {
-        let scale_in_pixels = Scale::uniform(self.scale_in_pixels);
-
         let mut x_offsets = Vec::with_capacity(text.chars().count() + 1);
         x_offsets.push(0.0);
 
@@ -256,10 +302,7 @@ impl Font {
             let glyph = self.glyph_info(c);
 
             if let Some(last_glyph_id) = last_glyph_id {
-                cursor_x_in_points +=
-                    self.font
-                        .pair_kerning(scale_in_pixels, last_glyph_id, glyph.id)
-                        / self.pixels_per_point
+                cursor_x_in_points += self.font_impl.pair_kerning(last_glyph_id, glyph.id)
             }
             cursor_x_in_points += glyph.advance_width;
             cursor_x_in_points = self.round_to_pixel(cursor_x_in_points);
diff --git a/egui/src/paint/fonts.rs b/egui/src/paint/fonts.rs
index c148059b..dbe725d3 100644
--- a/egui/src/paint/fonts.rs
+++ b/egui/src/paint/fonts.rs
@@ -124,9 +124,15 @@ impl Fonts {
                 let typeface_data = ttf_data
                     .get(&family)
                     .unwrap_or_else(|| panic!("Missing TTF data for {:?}", family));
-                let font = Font::new(atlas.clone(), typeface_data, size, pixels_per_point);
+                let font_impl = super::font::FontImpl::new(
+                    atlas.clone(),
+                    typeface_data,
+                    size,
+                    pixels_per_point,
+                );
+                let font_impl = Arc::new(font_impl);
 
-                (text_style, font)
+                (text_style, Font::new(font_impl))
             })
             .collect();