Implement rich_text widget and markdown example

core/src/renderer/null.rs

@@ -77,6 +77,11 @@ impl text::Paragraph for () {
 
     fn with_text(_text: Text<&str>) -> Self {}
 
+    fn with_spans(
+        _text: Text<&[text::Span<'_, Self::Font>], Self::Font>,
+    ) -> Self {
+    }
+
     fn resize(&mut self, _new_bounds: Size) {}
 
     fn compare(&self, _text: Text<()>) -> text::Difference {

core/src/text.rs

@@ -10,6 +10,7 @@ pub use paragraph::Paragraph;
 use crate::alignment;
 use crate::{Color, Pixels, Point, Rectangle, Size};
 
+use std::borrow::Cow;
 use std::hash::{Hash, Hasher};
 
 /// A paragraph.
@@ -220,3 +221,150 @@ pub trait Renderer: crate::Renderer {
         clip_bounds: Rectangle,
     );
 }
+
+/// A span of text.
+#[derive(Debug, Clone, PartialEq)]
+pub struct Span<'a, Font = crate::Font> {
+    /// The [`Fragment`] of text.
+    pub text: Fragment<'a>,
+    /// The size of the [`Span`] in [`Pixels`].
+    pub size: Option<Pixels>,
+    /// The [`LineHeight`] of the [`Span`].
+    pub line_height: Option<LineHeight>,
+    /// The font of the [`Span`].
+    pub font: Option<Font>,
+    /// The [`Color`] of the [`Span`].
+    pub color: Option<Color>,
+}
+
+impl<'a, Font> Span<'a, Font> {
+    /// Creates a new [`Span`] of text with the given text fragment.
+    pub fn new(fragment: impl IntoFragment<'a>) -> Self {
+        Self {
+            text: fragment.into_fragment(),
+            size: None,
+            line_height: None,
+            font: None,
+            color: None,
+        }
+    }
+
+    /// Sets the size of the [`Span`].
+    pub fn size(mut self, size: impl Into<Pixels>) -> Self {
+        self.size = Some(size.into());
+        self
+    }
+
+    /// Sets the [`LineHeight`] of the [`Span`].
+    pub fn line_height(mut self, line_height: impl Into<LineHeight>) -> Self {
+        self.line_height = Some(line_height.into());
+        self
+    }
+
+    /// Sets the font of the [`Span`].
+    pub fn font(mut self, font: impl Into<Font>) -> Self {
+        self.font = Some(font.into());
+        self
+    }
+
+    /// Sets the [`Color`] of the [`Span`].
+    pub fn color(mut self, color: impl Into<Color>) -> Self {
+        self.color = Some(color.into());
+        self
+    }
+
+    /// Turns the [`Span`] into a static one.
+    pub fn to_static(self) -> Span<'static, Font> {
+        Span {
+            text: Cow::Owned(self.text.into_owned()),
+            size: self.size,
+            line_height: self.line_height,
+            font: self.font,
+            color: self.color,
+        }
+    }
+}
+
+impl<'a, Font> From<&'a str> for Span<'a, Font> {
+    fn from(value: &'a str) -> Self {
+        Span::new(value)
+    }
+}
+
+/// A fragment of [`Text`].
+///
+/// This is just an alias to a string that may be either
+/// borrowed or owned.
+pub type Fragment<'a> = Cow<'a, str>;
+
+/// A trait for converting a value to some text [`Fragment`].
+pub trait IntoFragment<'a> {
+    /// Converts the value to some text [`Fragment`].
+    fn into_fragment(self) -> Fragment<'a>;
+}
+
+impl<'a> IntoFragment<'a> for Fragment<'a> {
+    fn into_fragment(self) -> Fragment<'a> {
+        self
+    }
+}
+
+impl<'a, 'b> IntoFragment<'a> for &'a Fragment<'b> {
+    fn into_fragment(self) -> Fragment<'a> {
+        Fragment::Borrowed(self)
+    }
+}
+
+impl<'a> IntoFragment<'a> for &'a str {
+    fn into_fragment(self) -> Fragment<'a> {
+        Fragment::Borrowed(self)
+    }
+}
+
+impl<'a> IntoFragment<'a> for &'a String {
+    fn into_fragment(self) -> Fragment<'a> {
+        Fragment::Borrowed(self.as_str())
+    }
+}
+
+impl<'a> IntoFragment<'a> for String {
+    fn into_fragment(self) -> Fragment<'a> {
+        Fragment::Owned(self)
+    }
+}
+
+macro_rules! into_fragment {
+    ($type:ty) => {
+        impl<'a> IntoFragment<'a> for $type {
+            fn into_fragment(self) -> Fragment<'a> {
+                Fragment::Owned(self.to_string())
+            }
+        }
+
+        impl<'a> IntoFragment<'a> for &$type {
+            fn into_fragment(self) -> Fragment<'a> {
+                Fragment::Owned(self.to_string())
+            }
+        }
+    };
+}
+
+into_fragment!(char);
+into_fragment!(bool);
+
+into_fragment!(u8);
+into_fragment!(u16);
+into_fragment!(u32);
+into_fragment!(u64);
+into_fragment!(u128);
+into_fragment!(usize);
+
+into_fragment!(i8);
+into_fragment!(i16);
+into_fragment!(i32);
+into_fragment!(i64);
+into_fragment!(i128);
+into_fragment!(isize);
+
+into_fragment!(f32);
+into_fragment!(f64);

core/src/text/paragraph.rs

@@ -1,6 +1,6 @@
 //! Draw paragraphs.
 use crate::alignment;
-use crate::text::{Difference, Hit, Text};
+use crate::text::{Difference, Hit, Span, Text};
 use crate::{Point, Size};
 
 /// A text paragraph.
@@ -11,6 +11,9 @@ pub trait Paragraph: Sized + Default {
     /// Creates a new [`Paragraph`] laid out with the given [`Text`].
     fn with_text(text: Text<&str, Self::Font>) -> Self;
 
+    /// Creates a new [`Paragraph`] laid out with the given [`Text`].
+    fn with_spans(text: Text<&[Span<'_, Self::Font>], Self::Font>) -> Self;
+
     /// Lays out the [`Paragraph`] with some new boundaries.
     fn resize(&mut self, new_bounds: Size);
 

core/src/widget/text.rs

@@ -11,8 +11,6 @@ use crate::{
     Widget,
 };
 
-use std::borrow::Cow;
-
 pub use text::{LineHeight, Shaping};
 
 /// A paragraph of text.
@@ -22,7 +20,7 @@ where
     Theme: Catalog,
     Renderer: text::Renderer,
 {
-    fragment: Fragment<'a>,
+    fragment: text::Fragment<'a>,
     size: Option<Pixels>,
     line_height: LineHeight,
     width: Length,
@@ -40,7 +38,7 @@ where
     Renderer: text::Renderer,
 {
     /// Create a new fragment of [`Text`] with the given contents.
-    pub fn new(fragment: impl IntoFragment<'a>) -> Self {
+    pub fn new(fragment: impl text::IntoFragment<'a>) -> Self {
         Text {
             fragment: fragment.into_fragment(),
             size: None,
@@ -216,7 +214,7 @@ where
         let state = tree.state.downcast_ref::<State<Renderer::Paragraph>>();
         let style = theme.style(&self.class);
 
-        draw(renderer, defaults, layout, state, style, viewport);
+        draw(renderer, defaults, layout, state.0.raw(), style, viewport);
     }
 }
 
@@ -275,13 +273,12 @@ pub fn draw<Renderer>(
     renderer: &mut Renderer,
     style: &renderer::Style,
     layout: Layout<'_>,
-    state: &State<Renderer::Paragraph>,
+    paragraph: &Renderer::Paragraph,
     appearance: Style,
     viewport: &Rectangle,
 ) where
     Renderer: text::Renderer,
 {
-    let State(ref paragraph) = state;
     let bounds = layout.bounds();
 
     let x = match paragraph.horizontal_alignment() {
@@ -297,7 +294,7 @@ pub fn draw<Renderer>(
     };
 
     renderer.fill_paragraph(
-        paragraph.raw(),
+        paragraph,
         Point::new(x, y),
         appearance.color.unwrap_or(style.text_color),
         *viewport,
@@ -415,81 +412,3 @@ pub fn danger(theme: &Theme) -> Style {
         color: Some(theme.palette().danger),
     }
 }
-
-/// A fragment of [`Text`].
-///
-/// This is just an alias to a string that may be either
-/// borrowed or owned.
-pub type Fragment<'a> = Cow<'a, str>;
-
-/// A trait for converting a value to some text [`Fragment`].
-pub trait IntoFragment<'a> {
-    /// Converts the value to some text [`Fragment`].
-    fn into_fragment(self) -> Fragment<'a>;
-}
-
-impl<'a> IntoFragment<'a> for Fragment<'a> {
-    fn into_fragment(self) -> Fragment<'a> {
-        self
-    }
-}
-
-impl<'a, 'b> IntoFragment<'a> for &'a Fragment<'b> {
-    fn into_fragment(self) -> Fragment<'a> {
-        Fragment::Borrowed(self)
-    }
-}
-
-impl<'a> IntoFragment<'a> for &'a str {
-    fn into_fragment(self) -> Fragment<'a> {
-        Fragment::Borrowed(self)
-    }
-}
-
-impl<'a> IntoFragment<'a> for &'a String {
-    fn into_fragment(self) -> Fragment<'a> {
-        Fragment::Borrowed(self.as_str())
-    }
-}
-
-impl<'a> IntoFragment<'a> for String {
-    fn into_fragment(self) -> Fragment<'a> {
-        Fragment::Owned(self)
-    }
-}
-
-macro_rules! into_fragment {
-    ($type:ty) => {
-        impl<'a> IntoFragment<'a> for $type {
-            fn into_fragment(self) -> Fragment<'a> {
-                Fragment::Owned(self.to_string())
-            }
-        }
-
-        impl<'a> IntoFragment<'a> for &$type {
-            fn into_fragment(self) -> Fragment<'a> {
-                Fragment::Owned(self.to_string())
-            }
-        }
-    };
-}
-
-into_fragment!(char);
-into_fragment!(bool);
-
-into_fragment!(u8);
-into_fragment!(u16);
-into_fragment!(u32);
-into_fragment!(u64);
-into_fragment!(u128);
-into_fragment!(usize);
-
-into_fragment!(i8);
-into_fragment!(i16);
-into_fragment!(i32);
-into_fragment!(i64);
-into_fragment!(i128);
-into_fragment!(isize);
-
-into_fragment!(f32);
-into_fragment!(f64);