Add bold italic font support

If the terminal escape sequences for bold and italic text are active,
the text should be rendered as bold and italic. However, due to missing
support in Alacritty, it would always render this text in bold.

This adds support for combining the bold and italic escapes to render
text in both styles and allows users to override the font for this
scenario using the `font.bold_italic` configuration option.

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Config option `window.gtk_theme_variant` to set GTK theme variant
 - Completions for `--class` and `-t` (short title)
 - Change the mouse cursor when hovering over the message bar and its close button
+- Support combined bold and italic text (with `font.bold_italic` to customize it)
 
 ### Changed
 

alacritty.yml

@@ -145,6 +145,17 @@ font:
     # The `style` can be specified to pick a specific face.
     #style: Italic
 
+  # Bold italic font face
+  #bold_italic:
+    # Font family
+    #
+    # If the bold italic family is not specified, it will fall back to the
+    # value specified for the normal font.
+    #family: monospace
+
+    # The `style` can be specified to pick a specific face.
+    #style: Bold Italic
+
   # Point size
   size: 11.0
 

alacritty_terminal/src/config/font.rs

@@ -23,11 +23,15 @@ pub struct Font {
 
     /// Bold font face
     #[serde(deserialize_with = "failure_default")]
-    italic: SecondaryFontDescription,
+    bold: SecondaryFontDescription,
 
     /// Italic font face
     #[serde(deserialize_with = "failure_default")]
-    bold: SecondaryFontDescription,
+    italic: SecondaryFontDescription,
+
+    /// Bold italic font face
+    #[serde(deserialize_with = "failure_default")]
+    bold_italic: SecondaryFontDescription,
 
     /// Font size in points
     #[serde(deserialize_with = "DeserializeSize::deserialize")]
@@ -53,6 +57,7 @@ impl Default for Font {
             normal: Default::default(),
             bold: Default::default(),
             italic: Default::default(),
+            bold_italic: Default::default(),
             glyph_offset: Default::default(),
             offset: Default::default(),
             #[cfg(target_os = "macos")]
@@ -72,14 +77,19 @@ impl Font {
         &self.normal
     }
 
+    // Get bold font description
+    pub fn bold(&self) -> FontDescription {
+        self.bold.desc(&self.normal)
+    }
+
     // Get italic font description
     pub fn italic(&self) -> FontDescription {
         self.italic.desc(&self.normal)
     }
 
-    // Get bold font description
-    pub fn bold(&self) -> FontDescription {
-        self.bold.desc(&self.normal)
+    // Get bold italic font description
+    pub fn bold_italic(&self) -> FontDescription {
+        self.bold_italic.desc(&self.normal)
     }
 
     #[cfg(target_os = "macos")]

alacritty_terminal/src/renderer/mod.rs

@@ -164,11 +164,14 @@ pub struct GlyphCache {
     /// regular font
     font_key: FontKey,
 
+    /// bold font
+    bold_key: FontKey,
+
     /// italic font
     italic_key: FontKey,
 
-    /// bold font
-    bold_key: FontKey,
+    /// bold italic font
+    bold_italic_key: FontKey,
 
     /// font size
     font_size: font::Size,
@@ -188,7 +191,7 @@ impl GlyphCache {
     where
         L: LoadGlyph,
     {
-        let (regular, bold, italic) = Self::compute_font_keys(font, &mut rasterizer)?;
+        let (regular, bold, italic, bold_italic) = Self::compute_font_keys(font, &mut rasterizer)?;
 
         // Need to load at least one glyph for the face before calling metrics.
         // The glyph requested here ('m' at the time of writing) has no special
@@ -205,6 +208,7 @@ impl GlyphCache {
             font_key: regular,
             bold_key: bold,
             italic_key: italic,
+            bold_italic_key: bold_italic,
             glyph_offset: font.glyph_offset,
             metrics,
         };
@@ -212,6 +216,7 @@ impl GlyphCache {
         cache.load_glyphs_for_font(regular, loader);
         cache.load_glyphs_for_font(bold, loader);
         cache.load_glyphs_for_font(italic, loader);
+        cache.load_glyphs_for_font(bold_italic, loader);
 
         Ok(cache)
     }
@@ -223,11 +228,11 @@ impl GlyphCache {
         }
     }
 
-    /// Computes font keys for (Regular, Bold, Italic)
+    /// Computes font keys for (Regular, Bold, Italic, Bold Italic)
     fn compute_font_keys(
         font: &config::Font,
         rasterizer: &mut Rasterizer,
-    ) -> Result<(FontKey, FontKey, FontKey), font::Error> {
+    ) -> Result<(FontKey, FontKey, FontKey, FontKey), font::Error> {
         let size = font.size;
 
         // Load regular font
@@ -256,7 +261,13 @@ impl GlyphCache {
 
         let italic = load_or_regular(italic_desc);
 
-        Ok((regular, bold, italic))
+        // Load bold italic font
+        let bold_italic_desc =
+            Self::make_desc(&font.bold_italic(), font::Slant::Italic, font::Weight::Bold);
+
+        let bold_italic = load_or_regular(bold_italic_desc);
+
+        Ok((regular, bold, italic, bold_italic))
     }
 
     fn make_desc(
@@ -314,7 +325,8 @@ impl GlyphCache {
 
         // Recompute font keys
         let font = font.to_owned().with_size(size);
-        let (regular, bold, italic) = Self::compute_font_keys(&font, &mut self.rasterizer)?;
+        let (regular, bold, italic, bold_italic) =
+            Self::compute_font_keys(&font, &mut self.rasterizer)?;
 
         self.rasterizer.get_glyph(GlyphKey { font_key: regular, c: 'm', size: font.size })?;
         let metrics = self.rasterizer.metrics(regular, size)?;
@@ -325,11 +337,13 @@ impl GlyphCache {
         self.font_key = regular;
         self.bold_key = bold;
         self.italic_key = italic;
+        self.bold_italic_key = bold_italic;
         self.metrics = metrics;
 
         self.load_glyphs_for_font(regular, loader);
         self.load_glyphs_for_font(bold, loader);
         self.load_glyphs_for_font(italic, loader);
+        self.load_glyphs_for_font(bold_italic, loader);
 
         Ok(())
     }
@@ -1013,12 +1027,14 @@ impl<'a> RenderApi<'a> {
 
         // Get font key for cell
         // FIXME this is super inefficient.
-        let font_key = if cell.flags.contains(cell::Flags::BOLD) {
-            glyph_cache.bold_key
-        } else if cell.flags.contains(cell::Flags::ITALIC) {
-            glyph_cache.italic_key
-        } else {
-            glyph_cache.font_key
+        let font_key = match (
+            cell.flags.contains(cell::Flags::BOLD),
+            cell.flags.contains(cell::Flags::ITALIC),
+        ) {
+            (false, false) => glyph_cache.font_key,
+            (true, false) => glyph_cache.bold_key,
+            (false, true) => glyph_cache.italic_key,
+            (true, true) => glyph_cache.bold_italic_key,
         };
 
         // Don't render text of HIDDEN cells