Fix `WidgetText::Text` ignoring fallback font and overrides (#7361)

* closes https://github.com/emilk/egui/issues/7356

crates/egui/src/atomics/atom.rs

@@ -1,4 +1,4 @@
-use crate::{AtomKind, Id, SizedAtom, Ui};
+use crate::{AtomKind, FontSelection, Id, SizedAtom, Ui};
 use emath::{NumExt as _, Vec2};
 use epaint::text::TextWrapMode;
 
@@ -69,6 +69,7 @@ impl<'a> Atom<'a> {
         ui: &Ui,
         mut available_size: Vec2,
         mut wrap_mode: Option<TextWrapMode>,
+        fallback_font: FontSelection,
     ) -> SizedAtom<'a> {
         if !self.shrink && self.max_size.x.is_infinite() {
             wrap_mode = Some(TextWrapMode::Extend);
@@ -81,7 +82,9 @@ impl<'a> Atom<'a> {
             wrap_mode = Some(TextWrapMode::Truncate);
         }
 
-        let (intrinsic, kind) = self.kind.into_sized(ui, available_size, wrap_mode);
+        let (intrinsic, kind) = self
+            .kind
+            .into_sized(ui, available_size, wrap_mode, fallback_font);
 
         let size = self
             .size

crates/egui/src/atomics/atom_kind.rs

@@ -1,4 +1,4 @@
-use crate::{Id, Image, ImageSource, SizedAtomKind, TextStyle, Ui, WidgetText};
+use crate::{FontSelection, Id, Image, ImageSource, SizedAtomKind, Ui, WidgetText};
 use emath::Vec2;
 use epaint::text::TextWrapMode;
 
@@ -78,12 +78,12 @@ impl<'a> AtomKind<'a> {
         ui: &Ui,
         available_size: Vec2,
         wrap_mode: Option<TextWrapMode>,
+        fallback_font: FontSelection,
     ) -> (Vec2, SizedAtomKind<'a>) {
         match self {
             AtomKind::Text(text) => {
                 let wrap_mode = wrap_mode.unwrap_or(ui.wrap_mode());
-                let galley =
-                    text.into_galley(ui, Some(wrap_mode), available_size.x, TextStyle::Button);
+                let galley = text.into_galley(ui, Some(wrap_mode), available_size.x, fallback_font);
                 (galley.intrinsic_size(), SizedAtomKind::Text(galley))
             }
             AtomKind::Image(image) => {

crates/egui/src/atomics/atom_layout.rs

@@ -1,7 +1,7 @@
 use crate::atomics::ATOMS_SMALL_VEC_SIZE;
 use crate::{
-    AtomKind, Atoms, Frame, Id, Image, IntoAtoms, Response, Sense, SizedAtom, SizedAtomKind, Ui,
-    Widget,
+    AtomKind, Atoms, FontSelection, Frame, Id, Image, IntoAtoms, Response, Sense, SizedAtom,
+    SizedAtomKind, Ui, Widget,
 };
 use emath::{Align2, GuiRounding as _, NumExt as _, Rect, Vec2};
 use epaint::text::TextWrapMode;
@@ -36,6 +36,7 @@ pub struct AtomLayout<'a> {
     pub(crate) frame: Frame,
     pub(crate) sense: Sense,
     fallback_text_color: Option<Color32>,
+    fallback_font: Option<FontSelection>,
     min_size: Vec2,
     wrap_mode: Option<TextWrapMode>,
     align2: Option<Align2>,
@@ -56,6 +57,7 @@ impl<'a> AtomLayout<'a> {
             frame: Frame::default(),
             sense: Sense::hover(),
             fallback_text_color: None,
+            fallback_font: None,
             min_size: Vec2::ZERO,
             wrap_mode: None,
             align2: None,
@@ -94,6 +96,13 @@ impl<'a> AtomLayout<'a> {
         self
     }
 
+    /// Set the fallback (default) font.
+    #[inline]
+    pub fn fallback_font(mut self, font: impl Into<FontSelection>) -> Self {
+        self.fallback_font = Some(font.into());
+        self
+    }
+
     /// Set the minimum size of the Widget.
     ///
     /// This will find and expand atoms with `grow: true`.
@@ -154,8 +163,11 @@ impl<'a> AtomLayout<'a> {
             min_size,
             wrap_mode,
             align2,
+            fallback_font,
         } = self;
 
+        let fallback_font = fallback_font.unwrap_or_default();
+
         let wrap_mode = wrap_mode.unwrap_or(ui.wrap_mode());
 
         // If the TextWrapMode is not Extend, ensure there is some item marked as `shrink`.
@@ -220,7 +232,12 @@ impl<'a> AtomLayout<'a> {
                     continue;
                 }
             }
-            let sized = item.into_sized(ui, available_inner_size, Some(wrap_mode));
+            let sized = item.into_sized(
+                ui,
+                available_inner_size,
+                Some(wrap_mode),
+                fallback_font.clone(),
+            );
             let size = sized.size;
 
             desired_width += size.x;
@@ -239,7 +256,12 @@ impl<'a> AtomLayout<'a> {
                 available_inner_size.y,
             );
 
-            let sized = item.into_sized(ui, available_size_for_shrink_item, Some(wrap_mode));
+            let sized = item.into_sized(
+                ui,
+                available_size_for_shrink_item,
+                Some(wrap_mode),
+                fallback_font,
+            );
             let size = sized.size;
 
             desired_width += size.x;

crates/egui/src/style.rs

@@ -121,6 +121,7 @@ impl TextStyle {
 // ----------------------------------------------------------------------------
 
 /// A way to select [`FontId`], either by picking one directly or by using a [`TextStyle`].
+#[derive(Debug, Clone)]
 pub enum FontSelection {
     /// Default text style - will use [`TextStyle::Body`], unless
     /// [`Style::override_font_id`] or [`Style::override_text_style`] is set.
@@ -141,7 +142,18 @@ impl Default for FontSelection {
 }
 
 impl FontSelection {
+    /// Resolve to a [`FontId`].
+    ///
+    /// On [`Self::Default`] and no override in the style, this will
+    /// resolve to [`TextStyle::Body`].
     pub fn resolve(self, style: &Style) -> FontId {
+        self.resolve_with_fallback(style, TextStyle::Body.into())
+    }
+
+    /// Resolve with a final fallback.
+    ///
+    /// Fallback is resolved on [`Self::Default`] and no override in the style.
+    pub fn resolve_with_fallback(self, style: &Style, fallback: Self) -> FontId {
         match self {
             Self::Default => {
                 if let Some(override_font_id) = &style.override_font_id {
@@ -149,7 +161,7 @@ impl FontSelection {
                 } else if let Some(text_style) = &style.override_text_style {
                     text_style.resolve(style)
                 } else {
-                    TextStyle::Body.resolve(style)
+                    fallback.resolve(style)
                 }
             }
             Self::FontId(font_id) => font_id,

crates/egui/src/widget_text.rs

@@ -749,7 +749,9 @@ impl WidgetText {
                 let mut layout_job = LayoutJob::simple_format(
                     text,
                     TextFormat {
-                        font_id: FontSelection::Default.resolve(style),
+                        // We want the style overrides to take precedence over the fallback font
+                        font_id: FontSelection::default()
+                            .resolve_with_fallback(style, fallback_font),
                         color: crate::Color32::PLACEHOLDER,
                         valign: default_valign,
                         ..Default::default()

crates/egui/src/widgets/button.rs

@@ -1,7 +1,7 @@
 use crate::{
     Atom, AtomExt as _, AtomKind, AtomLayout, AtomLayoutResponse, Color32, CornerRadius, Frame,
-    Image, IntoAtoms, NumExt as _, Response, Sense, Stroke, TextWrapMode, Ui, Vec2, Widget,
-    WidgetInfo, WidgetText, WidgetType,
+    Image, IntoAtoms, NumExt as _, Response, Sense, Stroke, TextStyle, TextWrapMode, Ui, Vec2,
+    Widget, WidgetInfo, WidgetText, WidgetType,
 };
 
 /// Clickable button with text.
@@ -40,7 +40,9 @@ pub struct Button<'a> {
 impl<'a> Button<'a> {
     pub fn new(atoms: impl IntoAtoms<'a>) -> Self {
         Self {
-            layout: AtomLayout::new(atoms.into_atoms()).sense(Sense::click()),
+            layout: AtomLayout::new(atoms.into_atoms())
+                .sense(Sense::click())
+                .fallback_font(TextStyle::Button),
             fill: None,
             stroke: None,
             small: false,