Add Style::strong_font and Style::emphasis_font for real bold/italic rendering

crates/egui/src/style.rs

@@ -346,6 +346,78 @@ pub struct Style {
 
     /// Use a more compact style for menus.
     pub compact_menu_style: bool,
+
+    /// Optional [`FontFamily`] to use for bold/strong text.
+    ///
+    /// By default ([`None`]), [`RichText::strong()`] applies a color change
+    /// (using [`Visuals::strong_text_color`]) to convey emphasis.
+    /// When this is set to [`Some`], strong text will instead be rendered with the
+    /// specified font family, and the color change is skipped.
+    ///
+    /// To use this, first register a bold font via [`crate::Context::set_fonts`],
+    /// then point this field at it:
+    ///
+    /// ```
+    /// # let ctx = egui::Context::default();
+    /// // 1. Register the bold font data and family
+    /// let mut fonts = egui::FontDefinitions::default();
+    /// let bold_font_data: &[u8] = &[]; // bytes of a .ttf file
+    /// fonts.font_data.insert(
+    ///     "my_bold_font".to_owned(),
+    ///     egui::FontData::from_static(bold_font_data).into(),
+    /// );
+    /// fonts.families.insert(
+    ///     egui::FontFamily::Name("Bold".into()),
+    ///     vec!["my_bold_font".to_owned()],
+    /// );
+    /// ctx.set_fonts(fonts);
+    ///
+    /// // 2. Tell egui to use it for strong text
+    /// ctx.global_style_mut(|style| {
+    ///     style.strong_font = Some(egui::FontFamily::Name("Bold".into()));
+    /// });
+    /// ```
+    ///
+    /// **Note:** When text is both strong and italic, and both `strong_font` and
+    /// [`Self::emphasis_font`] are configured, `emphasis_font` takes precedence
+    /// because a single [`FontId`] can only reference one font family.
+    pub strong_font: Option<FontFamily>,
+
+    /// Optional [`FontFamily`] to use for italic/emphasis text.
+    ///
+    /// By default ([`None`]), [`RichText::italics()`] fakes italics by applying a
+    /// horizontal vertex skew during tessellation.
+    /// When this is set to [`Some`], italic text will instead be rendered with the
+    /// specified font family, and the vertex skew is skipped.
+    ///
+    /// To use this, first register an italic font via [`crate::Context::set_fonts`],
+    /// then point this field at it:
+    ///
+    /// ```
+    /// # let ctx = egui::Context::default();
+    /// // 1. Register the italic font data and family
+    /// let mut fonts = egui::FontDefinitions::default();
+    /// let italic_font_data: &[u8] = &[]; // bytes of a .ttf file
+    /// fonts.font_data.insert(
+    ///     "my_italic_font".to_owned(),
+    ///     egui::FontData::from_static(italic_font_data).into(),
+    /// );
+    /// fonts.families.insert(
+    ///     egui::FontFamily::Name("Italic".into()),
+    ///     vec!["my_italic_font".to_owned()],
+    /// );
+    /// ctx.set_fonts(fonts);
+    ///
+    /// // 2. Tell egui to use it for italic text
+    /// ctx.global_style_mut(|style| {
+    ///     style.emphasis_font = Some(egui::FontFamily::Name("Italic".into()));
+    /// });
+    /// ```
+    ///
+    /// **Note:** When text is both strong and italic, and both [`Self::strong_font`] and
+    /// `emphasis_font` are configured, `emphasis_font` takes precedence
+    /// because a single [`FontId`] can only reference one font family.
+    pub emphasis_font: Option<FontFamily>,
 }
 
 #[test]
@@ -1370,6 +1442,8 @@ impl Default for Style {
             always_scroll_the_only_direction: false,
             scroll_animation: ScrollAnimation::default(),
             compact_menu_style: true,
+            strong_font: None,
+            emphasis_font: None,
         }
     }
 }
@@ -1684,6 +1758,8 @@ impl Style {
             always_scroll_the_only_direction,
             scroll_animation,
             compact_menu_style,
+            strong_font: _,
+            emphasis_font: _,
         } = self;
 
         crate::Grid::new("_options").show(ui, |ui| {

crates/egui/src/widget_text.rs

@@ -4,7 +4,7 @@ use std::fmt::Formatter;
 use std::{borrow::Cow, sync::Arc};
 
 use crate::{
-    Align, Color32, FontFamily, FontSelection, Galley, Style, TextStyle, TextWrapMode, Ui, Visuals,
+    Align, Color32, FontFamily, FontSelection, Galley, Style, TextStyle, TextWrapMode, Ui,
     text::{LayoutJob, TextWrapping},
 };
 
@@ -379,7 +379,28 @@ impl RichText {
         fallback_font: FontSelection,
         default_valign: Align,
     ) -> (String, crate::text::TextFormat) {
-        let text_color = self.get_text_color(&style.visuals);
+        let text_color = self.get_text_color(style);
+
+        // Resolve font family overrides for bold/italic before destructuring `self`.
+        //
+        // When `Style::strong_font` or `Style::emphasis_font` is configured, we
+        // swap the font family to a real bold/italic typeface instead of relying on
+        // the default color-change (bold) or vertex-skew (italic) approximations.
+        //
+        // If both are configured and the text is both strong and italic,
+        // `emphasis_font` takes precedence (a single FontId can only reference one
+        // family). Users who need a combined bold-italic face can register a
+        // dedicated BoldItalic font family and apply it via `RichText::family()`.
+        let bold_family = if self.strong {
+            style.strong_font.clone()
+        } else {
+            None
+        };
+        let italic_family = if self.italics {
+            style.emphasis_font.clone()
+        } else {
+            None
+        };
 
         let Self {
             text,
@@ -415,15 +436,28 @@ impl RichText {
             if let Some(family) = family {
                 font_id.family = family;
             }
+
+            // Apply bold/italic font family overrides.
+            // Italic is applied second so it wins when both are set.
+            if let Some(bold_family) = bold_family {
+                font_id.family = bold_family;
+            }
+            if let Some(italic_family) = italic_family {
+                font_id.family = italic_family;
+            }
+
             font_id
         };
 
+        // When a real italic font is configured, skip the vertex skew —
+        // the typeface itself provides proper italic letterforms.
+        let italics = italics && style.emphasis_font.is_none();
+
         let background_color = if code {
             style.visuals.code_bg_color
         } else {
             background_color
         };
-
         let underline = if underline {
             crate::Stroke::new(1.0, line_color)
         } else {
@@ -458,15 +492,33 @@ impl RichText {
         )
     }
 
-    fn get_text_color(&self, visuals: &Visuals) -> Option<Color32> {
+    /// Resolve the text color, accounting for bold font overrides.
+    ///
+    /// Priority (highest first):
+    /// 1. Explicit color set via [`RichText::color()`]
+    /// 2. Strong color — but only when no [`Style::strong_font`] is configured,
+    ///    because a real bold typeface provides visual distinction on its own
+    /// 3. Weak color
+    /// 4. Global [`crate::Visuals::override_text_color`]
+    fn get_text_color(&self, style: &Style) -> Option<Color32> {
         if let Some(text_color) = self.text_color {
+            // Explicit color always wins.
             Some(text_color)
         } else if self.strong {
-            Some(visuals.strong_text_color())
+            if style.strong_font.is_some() {
+                // A real bold font provides visual weight through thicker strokes,
+                // so we don't need the fallback strong color. Use the default
+                // text color instead.
+                style.visuals.override_text_color
+            } else {
+                // No bold font configured — fall back to the strong color
+                // (brighter than normal text) to convey emphasis.
+                Some(style.visuals.strong_text_color())
+            }
         } else if self.weak {
-            Some(visuals.weak_text_color())
+            Some(style.visuals.weak_text_color())
         } else {
-            visuals.override_text_color
+            style.visuals.override_text_color
         }
     }
 }