Merge pull request #2508 from iced-rs/feature/rich-text

`rich_text` and `markdown` widgets

4 files changed, 255 insertions, 104 deletions

diff --git a/core/src/renderer/null.rs b/core/src/renderer/null.rs
index e8709dbc..f9d1a5b0 100644
--- a/core/src/renderer/null.rs
+++ b/core/src/renderer/null.rs
@@ -77,9 +77,14 @@ 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<&str>) -> text::Difference {
+    fn compare(&self, _text: Text<()>) -> text::Difference {
         text::Difference::None
     }
 
diff --git a/core/src/text.rs b/core/src/text.rs
index b30feae0..22cfce13 100644
--- a/core/src/text.rs
+++ b/core/src/text.rs
@@ -1,8 +1,7 @@
 //! Draw and interact with text.
-mod paragraph;
-
 pub mod editor;
 pub mod highlighter;
+pub mod paragraph;
 
 pub use editor::Editor;
 pub use highlighter::Highlighter;
@@ -11,6 +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.
@@ -221,3 +221,162 @@ 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 font of the [`Span`], if any.
+    pub fn font_maybe(mut self, font: Option<impl Into<Font>>) -> Self {
+        self.font = font.map(Into::into);
+        self
+    }
+
+    /// Sets the [`Color`] of the [`Span`].
+    pub fn color(mut self, color: impl Into<Color>) -> Self {
+        self.color = Some(color.into());
+        self
+    }
+
+    /// Sets the [`Color`] of the [`Span`], if any.
+    pub fn color_maybe(mut self, color: Option<impl Into<Color>>) -> Self {
+        self.color = color.map(Into::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);
diff --git a/core/src/text/paragraph.rs b/core/src/text/paragraph.rs
index 8ff04015..4ee83798 100644
--- a/core/src/text/paragraph.rs
+++ b/core/src/text/paragraph.rs
@@ -1,5 +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.
@@ -10,12 +11,15 @@ 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);
 
     /// Compares the [`Paragraph`] with some desired [`Text`] and returns the
     /// [`Difference`].
-    fn compare(&self, text: Text<&str, Self::Font>) -> Difference;
+    fn compare(&self, text: Text<(), Self::Font>) -> Difference;
 
     /// Returns the horizontal alignment of the [`Paragraph`].
     fn horizontal_alignment(&self) -> alignment::Horizontal;
@@ -34,26 +38,87 @@ pub trait Paragraph: Sized + Default {
     /// Returns the distance to the given grapheme index in the [`Paragraph`].
     fn grapheme_position(&self, line: usize, index: usize) -> Option<Point>;
 
-    /// Updates the [`Paragraph`] to match the given [`Text`], if needed.
-    fn update(&mut self, text: Text<&str, Self::Font>) {
-        match self.compare(text) {
+    /// Returns the minimum width that can fit the contents of the [`Paragraph`].
+    fn min_width(&self) -> f32 {
+        self.min_bounds().width
+    }
+
+    /// Returns the minimum height that can fit the contents of the [`Paragraph`].
+    fn min_height(&self) -> f32 {
+        self.min_bounds().height
+    }
+}
+
+/// A [`Paragraph`] of plain text.
+#[derive(Debug, Clone, Default)]
+pub struct Plain<P: Paragraph> {
+    raw: P,
+    content: String,
+}
+
+impl<P: Paragraph> Plain<P> {
+    /// Creates a new [`Plain`] paragraph.
+    pub fn new(text: Text<&str, P::Font>) -> Self {
+        let content = text.content.to_owned();
+
+        Self {
+            raw: P::with_text(text),
+            content,
+        }
+    }
+
+    /// Updates the plain [`Paragraph`] to match the given [`Text`], if needed.
+    pub fn update(&mut self, text: Text<&str, P::Font>) {
+        if self.content != text.content {
+            text.content.clone_into(&mut self.content);
+            self.raw = P::with_text(text);
+            return;
+        }
+
+        match self.raw.compare(Text {
+            content: (),
+            bounds: text.bounds,
+            size: text.size,
+            line_height: text.line_height,
+            font: text.font,
+            horizontal_alignment: text.horizontal_alignment,
+            vertical_alignment: text.vertical_alignment,
+            shaping: text.shaping,
+        }) {
             Difference::None => {}
             Difference::Bounds => {
-                self.resize(text.bounds);
+                self.raw.resize(text.bounds);
             }
             Difference::Shape => {
-                *self = Self::with_text(text);
+                self.raw = P::with_text(text);
             }
         }
     }
 
-    /// Returns the minimum width that can fit the contents of the [`Paragraph`].
-    fn min_width(&self) -> f32 {
-        self.min_bounds().width
+    /// Returns the horizontal alignment of the [`Paragraph`].
+    pub fn horizontal_alignment(&self) -> alignment::Horizontal {
+        self.raw.horizontal_alignment()
     }
 
-    /// Returns the minimum height that can fit the contents of the [`Paragraph`].
-    fn min_height(&self) -> f32 {
-        self.min_bounds().height
+    /// Returns the vertical alignment of the [`Paragraph`].
+    pub fn vertical_alignment(&self) -> alignment::Vertical {
+        self.raw.vertical_alignment()
+    }
+
+    /// Returns the minimum boundaries that can fit the contents of the
+    /// [`Paragraph`].
+    pub fn min_bounds(&self) -> Size {
+        self.raw.min_bounds()
+    }
+
+    /// Returns the minimum width that can fit the contents of the
+    /// [`Paragraph`].
+    pub fn min_width(&self) -> f32 {
+        self.raw.min_width()
+    }
+
+    /// Returns the cached [`Paragraph`].
+    pub fn raw(&self) -> &P {
+        &self.raw
     }
 }
diff --git a/core/src/widget/text.rs b/core/src/widget/text.rs
index 91c9893d..d0ecd27b 100644
--- a/core/src/widget/text.rs
+++ b/core/src/widget/text.rs
@@ -3,15 +3,14 @@ use crate::alignment;
 use crate::layout;
 use crate::mouse;
 use crate::renderer;
-use crate::text::{self, Paragraph};
+use crate::text;
+use crate::text::paragraph::{self, Paragraph};
 use crate::widget::tree::{self, Tree};
 use crate::{
     Color, Element, Layout, Length, Pixels, Point, Rectangle, Size, Theme,
     Widget,
 };
 
-use std::borrow::Cow;
-
 pub use text::{LineHeight, Shaping};
 
 /// A paragraph of text.
@@ -21,7 +20,7 @@ where
     Theme: Catalog,
     Renderer: text::Renderer,
 {
-    fragment: Fragment<'a>,
+    fragment: text::Fragment<'a>,
     size: Option<Pixels>,
     line_height: LineHeight,
     width: Length,
@@ -39,7 +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,
@@ -155,7 +154,7 @@ where
 
 /// The internal state of a [`Text`] widget.
 #[derive(Debug, Default)]
-pub struct State<P: Paragraph>(P);
+pub struct State<P: Paragraph>(paragraph::Plain<P>);
 
 impl<'a, Message, Theme, Renderer> Widget<Message, Theme, Renderer>
     for Text<'a, Theme, Renderer>
@@ -168,7 +167,9 @@ where
     }
 
     fn state(&self) -> tree::State {
-        tree::State::new(State(Renderer::Paragraph::default()))
+        tree::State::new(State::<Renderer::Paragraph>(
+            paragraph::Plain::default(),
+        ))
     }
 
     fn size(&self) -> Size<Length> {
@@ -213,7 +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);
     }
 }
 
@@ -272,13 +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() {
@@ -412,81 +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);