Make size and alignment of emoji-icon-font match the rest of the fonts

This is done via a hack (for now).

CHANGELOG.md

@@ -13,6 +13,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 * Add `ui.allocate_at_least` and `ui.allocate_exact_size`.
 
+### Changed 🔧
+
+* Tweak size and alignment of some emojis to match other text.
+
 ### Fixed 🐛
 
 * Fixed a bug that would sometimes trigger a "Mismatching panels" panic in debug builds.

egui/src/math/vec2.rs

@@ -34,6 +34,9 @@ impl From<&[f32; 2]> for Vec2 {
 }
 
 impl Vec2 {
+    pub const X: Vec2 = Vec2 { x: 1.0, y: 0.0 };
+    pub const Y: Vec2 = Vec2 { x: 0.0, y: 1.0 };
+
     pub fn zero() -> Self {
         Self { x: 0.0, y: 0.0 }
     }

egui/src/paint/font.rs

@@ -57,6 +57,9 @@ pub struct FontImpl {
     rusttype_font: Arc<rusttype::Font<'static>>,
     /// Maximum character height
     scale_in_pixels: f32,
+    height_in_points: f32,
+    // move each character by this much (hack)
+    y_offset: f32,
     pixels_per_point: f32,
     glyph_info_cache: RwLock<AHashMap<char, GlyphInfo>>, // TODO: standard Mutex
     atlas: Arc<Mutex<TextureAtlas>>,
@@ -68,15 +71,24 @@ impl FontImpl {
         pixels_per_point: f32,
         rusttype_font: Arc<rusttype::Font<'static>>,
         scale_in_points: f32,
+        y_offset: f32,
     ) -> FontImpl {
         assert!(scale_in_points > 0.0);
         assert!(pixels_per_point > 0.0);
 
         let scale_in_pixels = pixels_per_point * scale_in_points;
 
+        let height_in_points = scale_in_points;
+        // TODO: use v_metrics for line spacing ?
+        // let v = rusttype_font.v_metrics(Scale::uniform(scale_in_pixels));
+        // let height_in_pixels = v.ascent - v.descent + v.line_gap;
+        // let height_in_points = height_in_pixels / pixels_per_point;
+
         Self {
             rusttype_font,
             scale_in_pixels,
+            height_in_points,
+            y_offset,
             pixels_per_point,
             glyph_info_cache: Default::default(),
             atlas,
@@ -100,6 +112,7 @@ impl FontImpl {
                 &mut self.atlas.lock(),
                 glyph,
                 self.scale_in_pixels,
+                self.y_offset,
                 self.pixels_per_point,
             );
             self.glyph_info_cache.write().insert(c, glyph_info);
@@ -120,7 +133,7 @@ impl FontImpl {
 
     /// Height of one row of text. In points
     pub fn row_height(&self) -> f32 {
-        self.scale_in_pixels / self.pixels_per_point
+        self.height_in_points
     }
 
     pub fn pixels_per_point(&self) -> f32 {
@@ -452,6 +465,7 @@ fn allocate_glyph(
     atlas: &mut TextureAtlas,
     glyph: rusttype::Glyph<'static>,
     scale_in_pixels: f32,
+    y_offset: f32,
     pixels_per_point: f32,
 ) -> GlyphInfo {
     assert!(glyph.id().0 != 0);
@@ -477,13 +491,10 @@ fn allocate_glyph(
                 }
             });
 
-            let offset_y_in_pixels =
+            let offset_in_pixels = vec2(bb.min.x as f32, scale_in_pixels as f32 + bb.min.y as f32);
-                scale_in_pixels as f32 + bb.min.y as f32 - 4.0 * pixels_per_point; // TODO: use font.v_metrics
+            let offset = offset_in_pixels / pixels_per_point + y_offset * Vec2::Y;
             Some(UvRect {
-                offset: vec2(
+                offset,
-                    bb.min.x as f32 / pixels_per_point,
-                    offset_y_in_pixels / pixels_per_point,
-                ),
                 size: vec2(glyph_width as f32, glyph_height as f32) / pixels_per_point,
                 min: (glyph_pos.0 as u16, glyph_pos.1 as u16),
                 max: (

egui/src/paint/fonts.rs

@@ -322,11 +322,24 @@ impl FontImplCache {
             }
         }
 
+        let y_offset = if font_name == "emoji-icon-font" {
+            1.0 // TODO: remove font alignment hack
+        } else {
+            -3.0 // TODO: remove font alignment hack
+        };
+
+        let scale_in_points = if font_name == "emoji-icon-font" {
+            scale_in_points - 2.0 // TODO: remove HACK!
+        } else {
+            scale_in_points
+        };
+
         let font_impl = Arc::new(FontImpl::new(
             self.atlas.clone(),
             self.pixels_per_point,
             self.rusttype_font(font_name),
             scale_in_points,
+            y_offset,
         ));
         self.cache
             .push((font_name.to_owned(), scale_in_points, font_impl.clone()));

egui/src/paint/tessellator.rs

@@ -845,14 +845,12 @@ impl Tessellator {
         let tex_w = fonts.texture().width as f32;
         let tex_h = fonts.texture().height as f32;
 
-        let text_offset = vec2(0.0, 1.0); // Eye-balled for buttons. TODO: why is this needed?
-
         let clip_rect = self.clip_rect.expand(2.0); // Some fudge to handle letters that are slightly larger than expected.
 
         let font = &fonts[text_style];
         let mut chars = galley.text.chars();
         for line in &galley.rows {
-            let line_min_y = pos.y + line.y_min + text_offset.x;
+            let line_min_y = pos.y + line.y_min;
             let line_max_y = line_min_y + font.row_height();
             let is_line_visible = line_max_y >= clip_rect.min.y && line_min_y <= clip_rect.max.y;
 
@@ -866,8 +864,7 @@ impl Tessellator {
                 }
 
                 if let Some(glyph) = font.uv_rect(c) {
-                    let mut left_top =
+                    let mut left_top = pos + glyph.offset + vec2(*x_offset, line.y_min);
-                        pos + glyph.offset + vec2(*x_offset, line.y_min) + text_offset;
                     left_top.x = font.round_to_pixel(left_top.x); // Pixel-perfection.
                     left_top.y = font.round_to_pixel(left_top.y); // Pixel-perfection.