Use DefaultStyle trait for Text widget

core/src/widget/text.rs

@@ -6,7 +6,8 @@ use crate::renderer;
 use crate::text::{self, Paragraph};
 use crate::widget::tree::{self, Tree};
 use crate::{
-    Color, Element, Layout, Length, Pixels, Point, Rectangle, Size, Widget,
+    Color, Element, Layout, Length, Pixels, Point, Rectangle, Size, Theme,
+    Widget,
 };
 
 use std::borrow::Cow;
@@ -36,7 +37,10 @@ where
     Renderer: text::Renderer,
 {
     /// Create a new fragment of [`Text`] with the given contents.
-    pub fn new(content: impl Into<Cow<'a, str>>) -> Self {
+    pub fn new(content: impl Into<Cow<'a, str>>) -> Self
+    where
+        Theme: DefaultStyle,
+    {
         Text {
             content: content.into(),
             size: None,
@@ -47,7 +51,7 @@ where
             horizontal_alignment: alignment::Horizontal::Left,
             vertical_alignment: alignment::Vertical::Top,
             shaping: Shaping::Basic,
-            style: Style::default(),
+            style: Theme::default_style(),
         }
     }
 
@@ -312,6 +316,7 @@ where
 
 impl<'a, Theme, Renderer> From<&'a str> for Text<'a, Theme, Renderer>
 where
+    Theme: DefaultStyle,
     Renderer: text::Renderer,
 {
     fn from(content: &'a str) -> Self {
@@ -322,7 +327,7 @@ where
 impl<'a, Message, Theme, Renderer> From<&'a str>
     for Element<'a, Message, Theme, Renderer>
 where
-    Theme: 'a,
+    Theme: DefaultStyle + 'a,
     Renderer: text::Renderer + 'a,
 {
     fn from(content: &'a str) -> Self {
@@ -339,9 +344,12 @@ pub struct Appearance {
     pub color: Option<Color>,
 }
 
+/// The style of some [`Text`].
 #[derive(Debug)]
-enum Style<Theme> {
+pub enum Style<Theme> {
+    /// The [`Text`] is styled using some theme.
     Themed(fn(&Theme) -> Appearance),
+    /// The [`Text`] is styled using some [`Color`].
     Colored(Option<Color>),
 }
 
@@ -353,14 +361,28 @@ impl<Theme> Clone for Style<Theme> {
 
 impl<Theme> Copy for Style<Theme> {}
 
-impl<Theme> Default for Style<Theme> {
-    fn default() -> Self {
+/// The default style of some [`Text`].
+pub trait DefaultStyle: Sized {
+    /// Returns the default style of some [`Text`].
+    fn default_style() -> Style<Self>;
+}
+
+impl DefaultStyle for Theme {
+    fn default_style() -> Style<Self> {
         Style::Colored(None)
     }
 }
 
-impl<Theme> From<fn(&Theme) -> Appearance> for Style<Theme> {
-    fn from(f: fn(&Theme) -> Appearance) -> Self {
-        Style::Themed(f)
+impl DefaultStyle for Appearance {
+    fn default_style() -> Style<Self> {
+        Style::Themed(|appearance| *appearance)
+    }
+}
+
+impl DefaultStyle for Color {
+    fn default_style() -> Style<Self> {
+        Style::Themed(|color| Appearance {
+            color: Some(*color),
+        })
     }
 }

widget/src/helpers.rs

@@ -147,6 +147,7 @@ pub fn text<'a, Theme, Renderer>(
     text: impl ToString,
 ) -> Text<'a, Theme, Renderer>
 where
+    Theme: core::widget::text::DefaultStyle,
     Renderer: core::text::Renderer,
 {
     Text::new(text.to_string())