When using a custom font you can now specify a font index (#873)

When using a custom font you can now specify a font index Closes #853
emilk · Nov 7, 2021 · 878eddd · 878eddd
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -11,6 +11,7 @@ NOTE: [`epaint`](epaint/CHANGELOG.md), [`eframe`](eframe/CHANGELOG.md), [`egui_w
 * Add context menus: See `Ui::menu_button` and `Response::context_menu` ([#543](https://github.com/emilk/egui/pull/543)).
 * You can now read and write the cursor of a `TextEdit` ([#848](https://github.com/emilk/egui/pull/848)).
 * Most widgets containing text (`Label`, `Button` etc) now supports rich text ([#855](https://github.com/emilk/egui/pull/855)).
+* When using a custom font you can now specify a font index ([#873](https://github.com/emilk/egui/pull/873)).
 
 ### Changed 🔧
 * Unifiy the four `Memory` data buckets (`data`, `data_temp`, `id_data` and `id_data_temp`) into a single `Memory::data`, with a new interface ([#836](https://github.com/emilk/egui/pull/836)).

diff --git a/egui/src/lib.rs b/egui/src/lib.rs
@@ -385,12 +385,15 @@ pub use epaint::emath;
 pub use emath::{lerp, pos2, remap, remap_clamp, vec2, Align, Align2, NumExt, Pos2, Rect, Vec2};
 pub use epaint::{
     color, mutex,
-    text::{FontDefinitions, FontFamily, TextStyle},
+    text::{FontData, FontDefinitions, FontFamily, TextStyle},
     ClippedMesh, Color32, Rgba, Shape, Stroke, Texture, TextureId,
 };
 
 pub mod text {
-    pub use epaint::text::{Fonts, Galley, LayoutJob, LayoutSection, TextFormat, TAB_SIZE};
+    pub use epaint::text::{
+        FontData, FontDefinitions, FontFamily, Fonts, Galley, LayoutJob, LayoutSection, TextFormat,
+        TextStyle, TAB_SIZE,
+    };
 }
 
 pub use {

diff --git a/epaint/src/text/fonts.rs b/epaint/src/text/fonts.rs
@@ -52,13 +52,43 @@ pub enum FontFamily {
     Proportional,
 }
 
-/// The data of a `.ttf` or `.otf` file.
-pub type FontData = std::borrow::Cow<'static, [u8]>;
+/// A `.ttf` or `.otf` file and a font face index.
+#[derive(Clone, Debug, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+pub struct FontData {
+    /// The data of a `.ttf` or `.otf` file.
+    pub font: std::borrow::Cow<'static, [u8]>,
+    /// Which font face in the file to use.
+    /// When in doubt, use `0`.
+    pub index: u32,
+}
+
+impl FontData {
+    pub fn from_static(font: &'static [u8]) -> Self {
+        Self {
+            font: std::borrow::Cow::Borrowed(font),
+            index: 0,
+        }
+    }
+
+    pub fn from_owned(font: Vec<u8>) -> Self {
+        Self {
+            font: std::borrow::Cow::Owned(font),
+            index: 0,
+        }
+    }
+}
 
 fn ab_glyph_font_from_font_data(name: &str, data: &FontData) -> ab_glyph::FontArc {
-    match data {
-        std::borrow::Cow::Borrowed(bytes) => ab_glyph::FontArc::try_from_slice(bytes),
-        std::borrow::Cow::Owned(bytes) => ab_glyph::FontArc::try_from_vec(bytes.clone()),
+    match &data.font {
+        std::borrow::Cow::Borrowed(bytes) => {
+            ab_glyph::FontRef::try_from_slice_and_index(bytes, data.index)
+                .map(ab_glyph::FontArc::from)
+        }
+        std::borrow::Cow::Owned(bytes) => {
+            ab_glyph::FontVec::try_from_vec_and_index(bytes.clone(), data.index)
+                .map(ab_glyph::FontArc::from)
+        }
     }
     .unwrap_or_else(|err| panic!("Error parsing {:?} TTF/OTF font file: {}", name, err))
 }
@@ -85,15 +115,15 @@ fn ab_glyph_font_from_font_data(name: &str, data: &FontData) -> ab_glyph::FontAr
 ///
 /// You can also install your own custom fonts:
 /// ```
-/// # use {epaint::text::{FontDefinitions, TextStyle, FontFamily}};
+/// # use {epaint::text::{FontDefinitions, TextStyle, FontFamily, FontData}};
 /// # struct FakeEguiCtx {};
 /// # impl FakeEguiCtx { fn set_fonts(&self, _: FontDefinitions) {} }
 /// # let ctx = FakeEguiCtx {};
 /// let mut fonts = FontDefinitions::default();
 ///
 /// // Install my own font (maybe supporting non-latin characters):
 /// fonts.font_data.insert("my_font".to_owned(),
-///    std::borrow::Cow::Borrowed(include_bytes!("../../fonts/Ubuntu-Light.ttf"))); // .ttf and .otf supported
+///    FontData::from_static(include_bytes!("../../fonts/Ubuntu-Light.ttf"))); // .ttf and .otf supported
 ///
 /// // Put my font first (highest priority):
 /// fonts.fonts_for_family.get_mut(&FontFamily::Proportional).unwrap()
@@ -110,10 +140,8 @@ fn ab_glyph_font_from_font_data(name: &str, data: &FontData) -> ab_glyph::FontAr
 #[cfg_attr(feature = "serde", serde(default))]
 pub struct FontDefinitions {
     /// List of font names and their definitions.
-    /// The definition must be the contents of either a `.ttf` or `.otf` font file.
     ///
-    /// `epaint` has built-in-default for these,
-    /// but you can override them if you like.
+    /// `epaint` has built-in-default for these, but you can override them if you like.
     pub font_data: BTreeMap<String, FontData>,
 
     /// Which fonts (names) to use for each [`FontFamily`].
@@ -139,22 +167,22 @@ impl Default for FontDefinitions {
         {
             font_data.insert(
                 "Hack".to_owned(),
-                std::borrow::Cow::Borrowed(include_bytes!("../../fonts/Hack-Regular.ttf")),
+                FontData::from_static(include_bytes!("../../fonts/Hack-Regular.ttf")),
             );
             font_data.insert(
                 "Ubuntu-Light".to_owned(),
-                std::borrow::Cow::Borrowed(include_bytes!("../../fonts/Ubuntu-Light.ttf")),
+                FontData::from_static(include_bytes!("../../fonts/Ubuntu-Light.ttf")),
             );
 
             // Some good looking emojis. Use as first priority:
             font_data.insert(
                 "NotoEmoji-Regular".to_owned(),
-                std::borrow::Cow::Borrowed(include_bytes!("../../fonts/NotoEmoji-Regular.ttf")),
+                FontData::from_static(include_bytes!("../../fonts/NotoEmoji-Regular.ttf")),
             );
             // Bigger emojis, and more. <http://jslegers.github.io/emoji-icon-font/>:
             font_data.insert(
                 "emoji-icon-font".to_owned(),
-                std::borrow::Cow::Borrowed(include_bytes!("../../fonts/emoji-icon-font.ttf")),
+                FontData::from_static(include_bytes!("../../fonts/emoji-icon-font.ttf")),
             );
 
             fonts_for_family.insert(

diff --git a/epaint/src/text/mod.rs b/epaint/src/text/mod.rs
@@ -10,7 +10,7 @@ mod text_layout_types;
 pub const TAB_SIZE: usize = 4;
 
 pub use {
-    fonts::{FontDefinitions, FontFamily, Fonts, TextStyle},
+    fonts::{FontData, FontDefinitions, FontFamily, Fonts, TextStyle},
     text_layout::layout,
     text_layout_types::*,
 };