Draft `Viewer` trait for `markdown`

9 files changed, 588 insertions, 234 deletions

diff --git a/Cargo.lock b/Cargo.lock
index c9c7ddc5..4175a188 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3299,7 +3299,10 @@ name = "markdown"
 version = "0.1.0"
 dependencies = [
  "iced",
+ "image",
  "open",
+ "reqwest",
+ "tokio",
 ]
 
 [[package]]
diff --git a/core/src/padding.rs b/core/src/padding.rs
index e26cdd9b..9ec02e6d 100644
--- a/core/src/padding.rs
+++ b/core/src/padding.rs
@@ -202,3 +202,9 @@ impl From<Padding> for Size {
         Self::new(padding.horizontal(), padding.vertical())
     }
 }
+
+impl From<Pixels> for Padding {
+    fn from(pixels: Pixels) -> Self {
+        Self::from(pixels.0)
+    }
+}
diff --git a/examples/changelog/src/main.rs b/examples/changelog/src/main.rs
index f889e757..a6528ce9 100644
--- a/examples/changelog/src/main.rs
+++ b/examples/changelog/src/main.rs
@@ -267,25 +267,21 @@ impl Generator {
                     } => {
                         let details = {
                             let title = rich_text![
-                                span(&pull_request.title).size(24).link(
-                                    Message::OpenPullRequest(pull_request.id)
-                                ),
+                                span(&pull_request.title)
+                                    .size(24)
+                                    .link(pull_request.id),
                                 span(format!(" by {}", pull_request.author))
                                     .font(Font {
                                         style: font::Style::Italic,
                                         ..Font::default()
                                     }),
                             ]
+                            .on_link_clicked(Message::OpenPullRequest)
                             .font(Font::MONOSPACE);
 
-                            let description = markdown::view(
-                                description,
-                                markdown::Settings::default(),
-                                markdown::Style::from_palette(
-                                    self.theme().palette(),
-                                ),
-                            )
-                            .map(Message::UrlClicked);
+                            let description =
+                                markdown::view(&self.theme(), description)
+                                    .map(Message::UrlClicked);
 
                             let labels =
                                 row(pull_request.labels.iter().map(|label| {
@@ -349,11 +345,11 @@ impl Generator {
                     container(
                         scrollable(
                             markdown::view(
-                                preview,
-                                markdown::Settings::with_text_size(12),
-                                markdown::Style::from_palette(
-                                    self.theme().palette(),
+                                markdown::Settings::with_text_size(
+                                    12,
+                                    &self.theme(),
                                 ),
+                                preview,
                             )
                             .map(Message::UrlClicked),
                         )
diff --git a/examples/markdown/Cargo.toml b/examples/markdown/Cargo.toml
index fa6ced74..4711b1c4 100644
--- a/examples/markdown/Cargo.toml
+++ b/examples/markdown/Cargo.toml
@@ -7,6 +7,12 @@ publish = false
 
 [dependencies]
 iced.workspace = true
-iced.features = ["markdown", "highlighter", "tokio", "debug"]
+iced.features = ["markdown", "highlighter", "image", "tokio", "debug"]
+
+reqwest.version = "0.12"
+reqwest.features = ["json"]
+
+image.workspace = true
+tokio.workspace = true
 
 open = "5.3"
diff --git a/examples/markdown/src/main.rs b/examples/markdown/src/main.rs
index ba93ee18..29625d79 100644
--- a/examples/markdown/src/main.rs
+++ b/examples/markdown/src/main.rs
@@ -1,10 +1,17 @@
 use iced::highlighter;
 use iced::time::{self, milliseconds};
 use iced::widget::{
-    self, hover, markdown, right, row, scrollable, text_editor, toggler,
+    self, center_x, horizontal_space, hover, image, markdown, pop, right, row,
+    scrollable, text_editor, toggler,
 };
 use iced::{Element, Fill, Font, Subscription, Task, Theme};
 
+use tokio::task;
+
+use std::collections::HashMap;
+use std::io;
+use std::sync::Arc;
+
 pub fn main() -> iced::Result {
     iced::application("Markdown - Iced", Markdown::update, Markdown::view)
         .subscription(Markdown::subscription)
@@ -14,6 +21,7 @@ pub fn main() -> iced::Result {
 
 struct Markdown {
     content: text_editor::Content,
+    images: HashMap<markdown::Url, Image>,
     mode: Mode,
     theme: Theme,
 }
@@ -26,10 +34,19 @@ enum Mode {
     },
 }
 
+enum Image {
+    Loading,
+    Ready(image::Handle),
+    #[allow(dead_code)]
+    Errored(Error),
+}
+
 #[derive(Debug, Clone)]
 enum Message {
     Edit(text_editor::Action),
     LinkClicked(markdown::Url),
+    ImageShown(markdown::Url),
+    ImageDownloaded(markdown::Url, Result<image::Handle, Error>),
     ToggleStream(bool),
     NextToken,
 }
@@ -43,6 +60,7 @@ impl Markdown {
         (
             Self {
                 content: text_editor::Content::with_text(INITIAL_CONTENT),
+                images: HashMap::new(),
                 mode: Mode::Preview(markdown::parse(INITIAL_CONTENT).collect()),
                 theme,
             },
@@ -70,6 +88,25 @@ impl Markdown {
 
                 Task::none()
             }
+            Message::ImageShown(url) => {
+                if self.images.contains_key(&url) {
+                    return Task::none();
+                }
+
+                let _ = self.images.insert(url.clone(), Image::Loading);
+
+                Task::perform(download_image(url.clone()), move |result| {
+                    Message::ImageDownloaded(url.clone(), result)
+                })
+            }
+            Message::ImageDownloaded(url, result) => {
+                let _ = self.images.insert(
+                    url,
+                    result.map(Image::Ready).unwrap_or_else(Image::Errored),
+                );
+
+                Task::none()
+            }
             Message::ToggleStream(enable_stream) => {
                 if enable_stream {
                     self.mode = Mode::Stream {
@@ -126,12 +163,13 @@ impl Markdown {
             Mode::Stream { parsed, .. } => parsed.items(),
         };
 
-        let preview = markdown(
+        let preview = markdown::view_with(
+            &MarkdownViewer {
+                images: &self.images,
+            },
+            &self.theme,
             items,
-            markdown::Settings::default(),
-            markdown::Style::from_palette(self.theme.palette()),
-        )
-        .map(Message::LinkClicked);
+        );
 
         row![
             editor,
@@ -167,3 +205,92 @@ impl Markdown {
         }
     }
 }
+
+struct MarkdownViewer<'a> {
+    images: &'a HashMap<markdown::Url, Image>,
+}
+
+impl<'a> markdown::Viewer<'a, Message> for MarkdownViewer<'a> {
+    fn on_link_clicked(url: markdown::Url) -> Message {
+        Message::LinkClicked(url)
+    }
+
+    fn image(
+        &self,
+        _settings: markdown::Settings,
+        _title: &markdown::Text,
+        url: &'a markdown::Url,
+    ) -> Element<'a, Message> {
+        if let Some(Image::Ready(handle)) = self.images.get(url) {
+            center_x(image(handle)).into()
+        } else {
+            pop(horizontal_space().width(0))
+                .key(url.as_str())
+                .on_show(|_size| Message::ImageShown(url.clone()))
+                .into()
+        }
+    }
+}
+
+async fn download_image(url: markdown::Url) -> Result<image::Handle, Error> {
+    use std::io;
+    use tokio::task;
+
+    let client = reqwest::Client::new();
+
+    let bytes = client
+        .get(url)
+        .send()
+        .await?
+        .error_for_status()?
+        .bytes()
+        .await?;
+
+    let image = task::spawn_blocking(move || {
+        Ok::<_, Error>(
+            ::image::ImageReader::new(io::Cursor::new(bytes))
+                .with_guessed_format()?
+                .decode()?
+                .to_rgba8(),
+        )
+    })
+    .await??;
+
+    Ok(image::Handle::from_rgba(
+        image.width(),
+        image.height(),
+        image.into_raw(),
+    ))
+}
+
+#[derive(Debug, Clone)]
+pub enum Error {
+    RequestFailed(Arc<reqwest::Error>),
+    IOFailed(Arc<io::Error>),
+    JoinFailed(Arc<task::JoinError>),
+    ImageDecodingFailed(Arc<::image::ImageError>),
+}
+
+impl From<reqwest::Error> for Error {
+    fn from(error: reqwest::Error) -> Self {
+        Self::RequestFailed(Arc::new(error))
+    }
+}
+
+impl From<io::Error> for Error {
+    fn from(error: io::Error) -> Self {
+        Self::IOFailed(Arc::new(error))
+    }
+}
+
+impl From<task::JoinError> for Error {
+    fn from(error: task::JoinError) -> Self {
+        Self::JoinFailed(Arc::new(error))
+    }
+}
+
+impl From<::image::ImageError> for Error {
+    fn from(error: ::image::ImageError) -> Self {
+        Self::ImageDecodingFailed(Arc::new(error))
+    }
+}
diff --git a/widget/src/helpers.rs b/widget/src/helpers.rs
index 4cba197d..2716d4c6 100644
--- a/widget/src/helpers.rs
+++ b/widget/src/helpers.rs
@@ -187,7 +187,7 @@ macro_rules! text {
 #[macro_export]
 macro_rules! rich_text {
     () => (
-        $crate::Column::new()
+        $crate::text::Rich::new()
     );
     ($($x:expr),+ $(,)?) => (
         $crate::text::Rich::from_iter([$($crate::text::Span::from($x)),+])
@@ -1155,9 +1155,9 @@ where
 ///     .into()
 /// }
 /// ```
-pub fn rich_text<'a, Link, Theme, Renderer>(
+pub fn rich_text<'a, Link, Message, Theme, Renderer>(
     spans: impl AsRef<[text::Span<'a, Link, Renderer::Font>]> + 'a,
-) -> text::Rich<'a, Link, Theme, Renderer>
+) -> text::Rich<'a, Link, Message, Theme, Renderer>
 where
     Link: Clone + 'static,
     Theme: text::Catalog + 'a,
diff --git a/widget/src/markdown.rs b/widget/src/markdown.rs
index 628a10c6..d8d33763 100644
--- a/widget/src/markdown.rs
+++ b/widget/src/markdown.rs
@@ -47,6 +47,7 @@
 //!     }
 //! }
 //! ```
+#![allow(missing_docs)]
 use crate::core::border;
 use crate::core::font::{self, Font};
 use crate::core::padding;
@@ -144,6 +145,7 @@ impl Content {
                     let mut state = State {
                         leftover: String::new(),
                         references: self.state.references.clone(),
+                        images: HashSet::new(),
                         highlighter: None,
                     };
 
@@ -153,6 +155,7 @@ impl Content {
                         self.items[*index] = item;
                     }
 
+                    self.state.images.extend(state.images.drain());
                     drop(state);
                 }
 
@@ -167,6 +170,11 @@ impl Content {
     pub fn items(&self) -> &[Item] {
         &self.items
     }
+
+    /// Returns the URLs of the Markdown images present in the [`Content`].
+    pub fn images(&self) -> impl Iterator<Item = &Url> {
+        self.state.images.iter()
+    }
 }
 
 /// A Markdown item.
@@ -187,130 +195,13 @@ pub enum Item {
         /// The items of the list.
         items: Vec<Vec<Item>>,
     },
-}
-
-impl Item {
-    /// Displays a Markdown [`Item`] using the default, built-in look for its children.
-    pub fn view<'a, 'b, Theme, Renderer>(
-        &'b self,
-        settings: Settings,
-        style: Style,
-        index: usize,
-    ) -> Element<'a, Url, Theme, Renderer>
-    where
-        Theme: Catalog + 'a,
-        Renderer: core::text::Renderer<Font = Font> + 'a,
-    {
-        self.view_with(index, settings, style, &DefaultView)
-    }
-
-    /// Displays a Markdown [`Item`] using the given [`View`] for its children.
-    pub fn view_with<'a, 'b, Theme, Renderer>(
-        &'b self,
-        index: usize,
-        settings: Settings,
-        style: Style,
-        view: &dyn View<'a, 'b, Url, Theme, Renderer>,
-    ) -> Element<'a, Url, Theme, Renderer>
-    where
-        Theme: Catalog + 'a,
-        Renderer: core::text::Renderer<Font = Font> + 'a,
-    {
-        let Settings {
-            text_size,
-            h1_size,
-            h2_size,
-            h3_size,
-            h4_size,
-            h5_size,
-            h6_size,
-            code_size,
-            spacing,
-        } = settings;
-
-        match self {
-            Item::Heading(level, heading) => {
-                container(rich_text(heading.spans(style)).size(match level {
-                    pulldown_cmark::HeadingLevel::H1 => h1_size,
-                    pulldown_cmark::HeadingLevel::H2 => h2_size,
-                    pulldown_cmark::HeadingLevel::H3 => h3_size,
-                    pulldown_cmark::HeadingLevel::H4 => h4_size,
-                    pulldown_cmark::HeadingLevel::H5 => h5_size,
-                    pulldown_cmark::HeadingLevel::H6 => h6_size,
-                }))
-                .padding(padding::top(if index > 0 {
-                    text_size / 2.0
-                } else {
-                    Pixels::ZERO
-                }))
-                .into()
-            }
-            Item::Paragraph(paragraph) => {
-                rich_text(paragraph.spans(style)).size(text_size).into()
-            }
-            Item::List { start: None, items } => {
-                column(items.iter().map(|items| {
-                    row![
-                        text("•").size(text_size),
-                        view_with(
-                            items,
-                            Settings {
-                                spacing: settings.spacing * 0.6,
-                                ..settings
-                            },
-                            style,
-                            view
-                        )
-                    ]
-                    .spacing(spacing)
-                    .into()
-                }))
-                .spacing(spacing * 0.75)
-                .into()
-            }
-            Item::List {
-                start: Some(start),
-                items,
-            } => column(items.iter().enumerate().map(|(i, items)| {
-                row![
-                    text!("{}.", i as u64 + *start).size(text_size),
-                    view_with(
-                        items,
-                        Settings {
-                            spacing: settings.spacing * 0.6,
-                            ..settings
-                        },
-                        style,
-                        view
-                    )
-                ]
-                .spacing(spacing)
-                .into()
-            }))
-            .spacing(spacing * 0.75)
-            .into(),
-            Item::CodeBlock(lines) => container(
-                scrollable(
-                    container(column(lines.iter().map(|line| {
-                        rich_text(line.spans(style))
-                            .font(Font::MONOSPACE)
-                            .size(code_size)
-                            .into()
-                    })))
-                    .padding(spacing.0 / 2.0),
-                )
-                .direction(scrollable::Direction::Horizontal(
-                    scrollable::Scrollbar::default()
-                        .width(spacing.0 / 2.0)
-                        .scroller_width(spacing.0 / 2.0),
-                )),
-            )
-            .width(Length::Fill)
-            .padding(spacing.0 / 2.0)
-            .class(Theme::code_block())
-            .into(),
-        }
-    }
+    /// An image.
+    Image {
+        /// The destination URL of the image.
+        url: Url,
+        /// The title of the image.
+        title: Text,
+    },
 }
 
 /// A bunch of parsed Markdown text.
@@ -470,6 +361,7 @@ pub fn parse(markdown: &str) -> impl Iterator<Item = Item> + '_ {
 struct State {
     leftover: String,
     references: HashMap<String, String>,
+    images: HashSet<Url>,
     #[cfg(feature = "highlighter")]
     highlighter: Option<Highlighter>,
 }
@@ -560,6 +452,10 @@ fn parse_with<'a>(
     mut state: impl BorrowMut<State> + 'a,
     markdown: &'a str,
 ) -> impl Iterator<Item = (Item, &'a str, HashSet<String>)> + 'a {
+    enum Scope {
+        List(List),
+    }
+
     struct List {
         start: Option<u64>,
         items: Vec<Vec<Item>>,
@@ -575,7 +471,8 @@ fn parse_with<'a>(
     let mut metadata = false;
     let mut table = false;
     let mut link = None;
-    let mut lists = Vec::new();
+    let mut image = None;
+    let mut stack = Vec::new();
 
     #[cfg(feature = "highlighter")]
     let mut highlighter = None;
@@ -616,10 +513,18 @@ fn parse_with<'a>(
     }
 
     let produce = move |state: &mut State,
-                        lists: &mut Vec<List>,
+                        stack: &mut Vec<Scope>,
                         item,
                         source: Range<usize>| {
-        if lists.is_empty() {
+        if let Some(scope) = stack.last_mut() {
+            match scope {
+                Scope::List(list) => {
+                    list.items.last_mut().expect("item context").push(item);
+                }
+            }
+
+            None
+        } else {
             state.leftover = markdown[source.start..].to_owned();
 
             Some((
@@ -627,16 +532,6 @@ fn parse_with<'a>(
                 &markdown[source.start..source.end],
                 broken_links.take(),
             ))
-        } else {
-            lists
-                .last_mut()
-                .expect("list context")
-                .items
-                .last_mut()
-                .expect("item context")
-                .push(item);
-
-            None
         }
     };
 
@@ -673,31 +568,36 @@ fn parse_with<'a>(
 
                 None
             }
+            pulldown_cmark::Tag::Image { dest_url, .. }
+                if !metadata && !table =>
+            {
+                image = Url::parse(&dest_url).ok();
+                None
+            }
             pulldown_cmark::Tag::List(first_item) if !metadata && !table => {
                 let prev = if spans.is_empty() {
                     None
                 } else {
                     produce(
                         state.borrow_mut(),
-                        &mut lists,
+                        &mut stack,
                         Item::Paragraph(Text::new(spans.drain(..).collect())),
                         source,
                     )
                 };
 
-                lists.push(List {
+                stack.push(Scope::List(List {
                     start: first_item,
                     items: Vec::new(),
-                });
+                }));
 
                 prev
             }
             pulldown_cmark::Tag::Item => {
-                lists
-                    .last_mut()
-                    .expect("list context")
-                    .items
-                    .push(Vec::new());
+                if let Some(Scope::List(list)) = stack.last_mut() {
+                    list.items.push(Vec::new());
+                }
+
                 None
             }
             pulldown_cmark::Tag::CodeBlock(
@@ -726,7 +626,7 @@ fn parse_with<'a>(
                 } else {
                     produce(
                         state.borrow_mut(),
-                        &mut lists,
+                        &mut stack,
                         Item::Paragraph(Text::new(spans.drain(..).collect())),
                         source,
                     )
@@ -748,7 +648,7 @@ fn parse_with<'a>(
             pulldown_cmark::TagEnd::Heading(level) if !metadata && !table => {
                 produce(
                     state.borrow_mut(),
-                    &mut lists,
+                    &mut stack,
                     Item::Heading(level, Text::new(spans.drain(..).collect())),
                     source,
                 )
@@ -770,12 +670,16 @@ fn parse_with<'a>(
                 None
             }
             pulldown_cmark::TagEnd::Paragraph if !metadata && !table => {
-                produce(
-                    state.borrow_mut(),
-                    &mut lists,
-                    Item::Paragraph(Text::new(spans.drain(..).collect())),
-                    source,
-                )
+                if spans.is_empty() {
+                    None
+                } else {
+                    produce(
+                        state.borrow_mut(),
+                        &mut stack,
+                        Item::Paragraph(Text::new(spans.drain(..).collect())),
+                        source,
+                    )
+                }
             }
             pulldown_cmark::TagEnd::Item if !metadata && !table => {
                 if spans.is_empty() {
@@ -783,18 +687,20 @@ fn parse_with<'a>(
                 } else {
                     produce(
                         state.borrow_mut(),
-                        &mut lists,
+                        &mut stack,
                         Item::Paragraph(Text::new(spans.drain(..).collect())),
                         source,
                     )
                 }
             }
             pulldown_cmark::TagEnd::List(_) if !metadata && !table => {
-                let list = lists.pop().expect("list context");
+                let scope = stack.pop()?;
+
+                let Scope::List(list) = scope;
 
                 produce(
                     state.borrow_mut(),
-                    &mut lists,
+                    &mut stack,
                     Item::List {
                         start: list.start,
                         items: list.items,
@@ -802,6 +708,15 @@ fn parse_with<'a>(
                     source,
                 )
             }
+            pulldown_cmark::TagEnd::Image if !metadata && !table => {
+                let url = image.take()?;
+                let title = Text::new(spans.drain(..).collect());
+
+                let state = state.borrow_mut();
+                let _ = state.images.insert(url.clone());
+
+                produce(state, &mut stack, Item::Image { url, title }, source)
+            }
             pulldown_cmark::TagEnd::CodeBlock if !metadata && !table => {
                 #[cfg(feature = "highlighter")]
                 {
@@ -810,7 +725,7 @@ fn parse_with<'a>(
 
                 produce(
                     state.borrow_mut(),
-                    &mut lists,
+                    &mut stack,
                     Item::CodeBlock(code.drain(..).collect()),
                     source,
                 )
@@ -910,15 +825,25 @@ pub struct Settings {
     pub code_size: Pixels,
     /// The spacing to be used between elements.
     pub spacing: Pixels,
+    /// The styling of the Markdown.
+    pub style: Style,
 }
 
 impl Settings {
+    /// Creates new [`Settings`] with default text size and the given [`Style`].
+    pub fn with_style(style: impl Into<Style>) -> Self {
+        Self::with_text_size(16, style)
+    }
+
     /// Creates new [`Settings`] with the given base text size in [`Pixels`].
     ///
     /// Heading levels will be adjusted automatically. Specifically,
     /// the first level will be twice the base size, and then every level
     /// after that will be 25% smaller.
-    pub fn with_text_size(text_size: impl Into<Pixels>) -> Self {
+    pub fn with_text_size(
+        text_size: impl Into<Pixels>,
+        style: impl Into<Style>,
+    ) -> Self {
         let text_size = text_size.into();
 
         Self {
@@ -931,13 +856,14 @@ impl Settings {
             h6_size: text_size,
             code_size: text_size * 0.75,
             spacing: text_size * 0.875,
+            style: style.into(),
         }
     }
 }
 
-impl Default for Settings {
-    fn default() -> Self {
-        Self::with_text_size(16)
+impl From<&Theme> for Settings {
+    fn from(theme: &Theme) -> Self {
+        Self::with_style(Style::from(theme))
     }
 }
 
@@ -969,6 +895,18 @@ impl Style {
     }
 }
 
+impl From<theme::Palette> for Style {
+    fn from(palette: theme::Palette) -> Self {
+        Self::from_palette(palette)
+    }
+}
+
+impl From<&Theme> for Style {
+    fn from(theme: &Theme) -> Self {
+        Self::from_palette(theme.palette())
+    }
+}
+
 /// Display a bunch of Markdown items.
 ///
 /// You can obtain the items with [`parse`].
@@ -1015,16 +953,15 @@ impl Style {
 ///     }
 /// }
 /// ```
-pub fn view<'a, 'b, Theme, Renderer>(
-    items: impl IntoIterator<Item = &'b Item>,
-    settings: Settings,
-    style: Style,
+pub fn view<'a, Theme, Renderer>(
+    settings: impl Into<Settings>,
+    items: impl IntoIterator<Item = &'a Item>,
 ) -> Element<'a, Url, Theme, Renderer>
 where
     Theme: Catalog + 'a,
     Renderer: core::text::Renderer<Font = Font> + 'a,
 {
-    view_with(items, settings, style, &DefaultView)
+    view_with(&DefaultViewer, settings, items)
 }
 
 /// Runs [`view`] but with a custom [`View`] to turn an [`Item`] into
@@ -1035,56 +972,288 @@ where
 ///
 /// You can use [`Item::view`] and [`Item::view_with`] for the default
 /// look.
-pub fn view_with<'a, 'b, Message, Theme, Renderer>(
-    items: impl IntoIterator<Item = &'b Item>,
-    settings: Settings,
-    style: Style,
-    view: &dyn View<'a, 'b, Message, Theme, Renderer>,
+pub fn view_with<'a, Message, Theme, Renderer>(
+    viewer: &impl Viewer<'a, Message, Theme, Renderer>,
+    settings: impl Into<Settings>,
+    items: impl IntoIterator<Item = &'a Item>,
 ) -> Element<'a, Message, Theme, Renderer>
 where
     Message: 'a,
     Theme: Catalog + 'a,
     Renderer: core::text::Renderer<Font = Font> + 'a,
 {
+    let settings = settings.into();
+
     let blocks = items
         .into_iter()
         .enumerate()
-        .map(move |(i, item)| view.view(settings, style, item, i));
+        .map(|(i, item_)| item(viewer, settings, item_, i));
 
     Element::new(column(blocks).spacing(settings.spacing))
 }
 
-/// A view strategy to display a Markdown [`Item`].
-pub trait View<'a, 'b, Message, Theme, Renderer> {
-    /// Displays a Markdown [`Item`] by projecting it into an [`Element`].
-    ///
-    /// You can use [`Item::view`] and [`Item::view_with`] for the default
-    /// look.
-    fn view(
+pub fn item<'a, Message, Theme, Renderer>(
+    viewer: &impl Viewer<'a, Message, Theme, Renderer>,
+    settings: Settings,
+    item: &'a Item,
+    index: usize,
+) -> Element<'a, Message, Theme, Renderer>
+where
+    Message: 'a,
+    Theme: Catalog + 'a,
+    Renderer: core::text::Renderer<Font = Font> + 'a,
+{
+    match item {
+        Item::Image { title, url } => viewer.image(settings, title, url),
+        Item::Heading(level, text) => {
+            viewer.heading(settings, index, level, text)
+        }
+        Item::Paragraph(text) => viewer.paragraph(settings, text),
+        Item::CodeBlock(lines) => viewer.code_block(settings, lines),
+        Item::List { start: None, items } => {
+            viewer.unordered_list(settings, items)
+        }
+        Item::List {
+            start: Some(start),
+            items,
+        } => viewer.ordered_list(settings, *start, items),
+    }
+}
+
+pub fn heading<'a, Message, Theme, Renderer>(
+    settings: Settings,
+    index: usize,
+    level: &'a HeadingLevel,
+    text: &'a Text,
+    on_link_clicked: impl Fn(Url) -> Message + 'a,
+) -> Element<'a, Message, Theme, Renderer>
+where
+    Message: 'a,
+    Theme: Catalog + 'a,
+    Renderer: core::text::Renderer<Font = Font> + 'a,
+{
+    let Settings {
+        h1_size,
+        h2_size,
+        h3_size,
+        h4_size,
+        h5_size,
+        h6_size,
+        text_size,
+        ..
+    } = settings;
+
+    container(
+        rich_text(text.spans(settings.style))
+            .on_link_clicked(on_link_clicked)
+            .size(match level {
+                pulldown_cmark::HeadingLevel::H1 => h1_size,
+                pulldown_cmark::HeadingLevel::H2 => h2_size,
+                pulldown_cmark::HeadingLevel::H3 => h3_size,
+                pulldown_cmark::HeadingLevel::H4 => h4_size,
+                pulldown_cmark::HeadingLevel::H5 => h5_size,
+                pulldown_cmark::HeadingLevel::H6 => h6_size,
+            }),
+    )
+    .padding(padding::top(if index > 0 {
+        text_size / 2.0
+    } else {
+        Pixels::ZERO
+    }))
+    .into()
+}
+
+pub fn paragraph<'a, Message, Theme, Renderer>(
+    settings: Settings,
+    text: &'a Text,
+    on_link_clicked: impl Fn(Url) -> Message + 'a,
+) -> Element<'a, Message, Theme, Renderer>
+where
+    Message: 'a,
+    Theme: Catalog + 'a,
+    Renderer: core::text::Renderer<Font = Font> + 'a,
+{
+    rich_text(text.spans(settings.style))
+        .size(settings.text_size)
+        .on_link_clicked(on_link_clicked)
+        .into()
+}
+
+pub fn unordered_list<'a, Message, Theme, Renderer>(
+    viewer: &impl Viewer<'a, Message, Theme, Renderer>,
+    settings: Settings,
+    items: &'a [Vec<Item>],
+) -> Element<'a, Message, Theme, Renderer>
+where
+    Message: 'a,
+    Theme: Catalog + 'a,
+    Renderer: core::text::Renderer<Font = Font> + 'a,
+{
+    column(items.iter().map(|items| {
+        row![
+            text("•").size(settings.text_size),
+            view_with(
+                viewer,
+                Settings {
+                    spacing: settings.spacing * 0.6,
+                    ..settings
+                },
+                items,
+            )
+        ]
+        .spacing(settings.spacing)
+        .into()
+    }))
+    .spacing(settings.spacing * 0.75)
+    .padding([0.0, settings.spacing.0])
+    .into()
+}
+
+pub fn ordered_list<'a, Message, Theme, Renderer>(
+    viewer: &impl Viewer<'a, Message, Theme, Renderer>,
+    settings: Settings,
+    start: u64,
+    items: &'a [Vec<Item>],
+) -> Element<'a, Message, Theme, Renderer>
+where
+    Message: 'a,
+    Theme: Catalog + 'a,
+    Renderer: core::text::Renderer<Font = Font> + 'a,
+{
+    column(items.iter().enumerate().map(|(i, items)| {
+        row![
+            text!("{}.", i as u64 + start).size(settings.text_size),
+            view_with(
+                viewer,
+                Settings {
+                    spacing: settings.spacing * 0.6,
+                    ..settings
+                },
+                items,
+            )
+        ]
+        .spacing(settings.spacing)
+        .into()
+    }))
+    .spacing(settings.spacing * 0.75)
+    .padding([0.0, settings.spacing.0])
+    .into()
+}
+
+pub fn code_block<'a, Message, Theme, Renderer>(
+    settings: Settings,
+    lines: &'a [Text],
+    on_link_clicked: impl Fn(Url) -> Message + Clone + 'a,
+) -> Element<'a, Message, Theme, Renderer>
+where
+    Message: 'a,
+    Theme: Catalog + 'a,
+    Renderer: core::text::Renderer<Font = Font> + 'a,
+{
+    container(
+        scrollable(
+            container(column(lines.iter().map(|line| {
+                rich_text(line.spans(settings.style))
+                    .on_link_clicked(on_link_clicked.clone())
+                    .font(Font::MONOSPACE)
+                    .size(settings.code_size)
+                    .into()
+            })))
+            .padding(settings.spacing.0 / 2.0),
+        )
+        .direction(scrollable::Direction::Horizontal(
+            scrollable::Scrollbar::default()
+                .width(settings.spacing.0 / 2.0)
+                .scroller_width(settings.spacing.0 / 2.0),
+        )),
+    )
+    .width(Length::Fill)
+    .padding(settings.spacing.0 / 2.0)
+    .class(Theme::code_block())
+    .into()
+}
+
+/// A view strategy to display a Markdown [`Item`].j
+pub trait Viewer<'a, Message, Theme = crate::Theme, Renderer = crate::Renderer>
+where
+    Self: Sized + 'a,
+    Message: 'a,
+    Theme: Catalog + 'a,
+    Renderer: core::text::Renderer<Font = Font> + 'a,
+{
+    fn on_link_clicked(url: Url) -> Message;
+
+    fn image(
+        &self,
+        settings: Settings,
+        title: &Text,
+        url: &'a Url,
+    ) -> Element<'a, Message, Theme, Renderer> {
+        let _url = url;
+
+        container(
+            rich_text(title.spans(settings.style))
+                .on_link_clicked(Self::on_link_clicked),
+        )
+        .padding(settings.spacing.0)
+        .class(Theme::code_block())
+        .into()
+    }
+
+    fn heading(
         &self,
         settings: Settings,
-        style: Style,
-        item: &'b Item,
         index: usize,
-    ) -> Element<'a, Message, Theme, Renderer>;
+        level: &'a HeadingLevel,
+        text: &'a Text,
+    ) -> Element<'a, Message, Theme, Renderer> {
+        heading(settings, index, level, text, Self::on_link_clicked)
+    }
+
+    fn paragraph(
+        &self,
+        settings: Settings,
+        text: &'a Text,
+    ) -> Element<'a, Message, Theme, Renderer> {
+        paragraph(settings, text, Self::on_link_clicked)
+    }
+
+    fn code_block(
+        &self,
+        settings: Settings,
+        lines: &'a [Text],
+    ) -> Element<'a, Message, Theme, Renderer> {
+        code_block(settings, lines, Self::on_link_clicked)
+    }
+
+    fn unordered_list(
+        &self,
+        settings: Settings,
+        items: &'a [Vec<Item>],
+    ) -> Element<'a, Message, Theme, Renderer> {
+        unordered_list(self, settings, items)
+    }
+
+    fn ordered_list(
+        &self,
+        settings: Settings,
+        start: u64,
+        items: &'a [Vec<Item>],
+    ) -> Element<'a, Message, Theme, Renderer> {
+        ordered_list(self, settings, start, items)
+    }
 }
 
 #[derive(Debug, Clone, Copy)]
-struct DefaultView;
+struct DefaultViewer;
 
-impl<'a, 'b, Theme, Renderer> View<'a, 'b, Url, Theme, Renderer> for DefaultView
+impl<'a, Theme, Renderer> Viewer<'a, Url, Theme, Renderer> for DefaultViewer
 where
     Theme: Catalog + 'a,
     Renderer: core::text::Renderer<Font = Font> + 'a,
 {
-    fn view(
-        &self,
-        settings: Settings,
-        style: Style,
-        item: &'b Item,
-        index: usize,
-    ) -> Element<'a, Url, Theme, Renderer> {
-        item.view(settings, style, index)
+    fn on_link_clicked(url: Url) -> Url {
+        url
     }
 }
 
diff --git a/widget/src/pop.rs b/widget/src/pop.rs
index 6e9df4be..950371ea 100644
--- a/widget/src/pop.rs
+++ b/widget/src/pop.rs
@@ -3,6 +3,7 @@ use crate::core::layout;
 use crate::core::mouse;
 use crate::core::overlay;
 use crate::core::renderer;
+use crate::core::text;
 use crate::core::widget;
 use crate::core::widget::tree::{self, Tree};
 use crate::core::window;
@@ -17,6 +18,7 @@ use crate::core::{
 #[allow(missing_debug_implementations)]
 pub struct Pop<'a, Message, Theme = crate::Theme, Renderer = crate::Renderer> {
     content: Element<'a, Message, Theme, Renderer>,
+    key: Option<text::Fragment<'a>>,
     on_show: Option<Box<dyn Fn(Size) -> Message + 'a>>,
     on_resize: Option<Box<dyn Fn(Size) -> Message + 'a>>,
     on_hide: Option<Message>,
@@ -34,6 +36,7 @@ where
     ) -> Self {
         Self {
             content: content.into(),
+            key: None,
             on_show: None,
             on_resize: None,
             on_hide: None,
@@ -66,6 +69,14 @@ where
         self
     }
 
+    /// Sets the key of the [`Pop`] widget, for continuity.
+    ///
+    /// If the key changes, the [`Pop`] widget will trigger again.
+    pub fn key(mut self, key: impl text::IntoFragment<'a>) -> Self {
+        self.key = Some(key.into_fragment());
+        self
+    }
+
     /// Sets the distance in [`Pixels`] to use in anticipation of the
     /// content popping into view.
     ///
@@ -77,10 +88,11 @@ where
     }
 }
 
-#[derive(Debug, Clone, Copy, Default)]
+#[derive(Debug, Clone, Default)]
 struct State {
     has_popped_in: bool,
     last_size: Option<Size>,
+    last_key: Option<String>,
 }
 
 impl<Message, Theme, Renderer> Widget<Message, Theme, Renderer>
@@ -118,8 +130,16 @@ where
     ) {
         if let Event::Window(window::Event::RedrawRequested(_)) = &event {
             let state = tree.state.downcast_mut::<State>();
-            let bounds = layout.bounds();
 
+            if state.has_popped_in
+                && state.last_key.as_deref() != self.key.as_deref()
+            {
+                state.has_popped_in = false;
+                state.last_key =
+                    self.key.as_ref().cloned().map(text::Fragment::into_owned);
+            }
+
+            let bounds = layout.bounds();
             let top_left_distance = viewport.distance(bounds.position());
 
             let bottom_right_distance = viewport
diff --git a/widget/src/text/rich.rs b/widget/src/text/rich.rs
index a9e544d1..02348b54 100644
--- a/widget/src/text/rich.rs
+++ b/widget/src/text/rich.rs
@@ -14,8 +14,13 @@ use crate::core::{
 
 /// A bunch of [`Rich`] text.
 #[allow(missing_debug_implementations)]
-pub struct Rich<'a, Link, Theme = crate::Theme, Renderer = crate::Renderer>
-where
+pub struct Rich<
+    'a,
+    Link,
+    Message,
+    Theme = crate::Theme,
+    Renderer = crate::Renderer,
+> where
     Link: Clone + 'static,
     Theme: Catalog,
     Renderer: core::text::Renderer,
@@ -31,9 +36,11 @@ where
     wrapping: Wrapping,
     class: Theme::Class<'a>,
     hovered_link: Option<usize>,
+    on_link_clicked: Option<Box<dyn Fn(Link) -> Message + 'a>>,
 }
 
-impl<'a, Link, Theme, Renderer> Rich<'a, Link, Theme, Renderer>
+impl<'a, Link, Message, Theme, Renderer>
+    Rich<'a, Link, Message, Theme, Renderer>
 where
     Link: Clone + 'static,
     Theme: Catalog,
@@ -54,6 +61,7 @@ where
             wrapping: Wrapping::default(),
             class: Theme::default(),
             hovered_link: None,
+            on_link_clicked: None,
         }
     }
 
@@ -127,6 +135,16 @@ where
         self
     }
 
+    /// Sets the message that will be produced when a link of the [`Rich`] text
+    /// is clicked.
+    pub fn on_link_clicked(
+        mut self,
+        on_link_clicked: impl Fn(Link) -> Message + 'a,
+    ) -> Self {
+        self.on_link_clicked = Some(Box::new(on_link_clicked));
+        self
+    }
+
     /// Sets the default style of the [`Rich`] text.
     #[must_use]
     pub fn style(mut self, style: impl Fn(&Theme) -> Style + 'a) -> Self
@@ -164,7 +182,8 @@ where
     }
 }
 
-impl<'a, Link, Theme, Renderer> Default for Rich<'a, Link, Theme, Renderer>
+impl<'a, Link, Message, Theme, Renderer> Default
+    for Rich<'a, Link, Message, Theme, Renderer>
 where
     Link: Clone + 'a,
     Theme: Catalog,
@@ -182,8 +201,8 @@ struct State<Link, P: Paragraph> {
     paragraph: P,
 }
 
-impl<Link, Theme, Renderer> Widget<Link, Theme, Renderer>
-    for Rich<'_, Link, Theme, Renderer>
+impl<Link, Message, Theme, Renderer> Widget<Message, Theme, Renderer>
+    for Rich<'_, Link, Message, Theme, Renderer>
 where
     Link: Clone + 'static,
     Theme: Catalog,
@@ -252,7 +271,8 @@ where
         let style = theme.style(&self.class);
 
         for (index, span) in self.spans.as_ref().as_ref().iter().enumerate() {
-            let is_hovered_link = Some(index) == self.hovered_link;
+            let is_hovered_link = self.on_link_clicked.is_some()
+                && Some(index) == self.hovered_link;
 
             if span.highlight.is_some()
                 || span.underline
@@ -363,9 +383,13 @@ where
         cursor: mouse::Cursor,
         _renderer: &Renderer,
         _clipboard: &mut dyn Clipboard,
-        shell: &mut Shell<'_, Link>,
+        shell: &mut Shell<'_, Message>,
         _viewport: &Rectangle,
     ) {
+        let Some(on_link_clicked) = &self.on_link_clicked else {
+            return;
+        };
+
         let was_hovered = self.hovered_link.is_some();
 
         if let Some(position) = cursor.position_in(layout.bounds()) {
@@ -414,7 +438,7 @@ where
                             .get(span)
                             .and_then(|span| span.link.clone())
                         {
-                            shell.publish(link);
+                            shell.publish(on_link_clicked(link));
                         }
                     }
                     _ => {}
@@ -509,8 +533,9 @@ where
     })
 }
 
-impl<'a, Link, Theme, Renderer> FromIterator<Span<'a, Link, Renderer::Font>>
-    for Rich<'a, Link, Theme, Renderer>
+impl<'a, Link, Message, Theme, Renderer>
+    FromIterator<Span<'a, Link, Renderer::Font>>
+    for Rich<'a, Link, Message, Theme, Renderer>
 where
     Link: Clone + 'a,
     Theme: Catalog,
@@ -524,16 +549,18 @@ where
     }
 }
 
-impl<'a, Link, Theme, Renderer> From<Rich<'a, Link, Theme, Renderer>>
-    for Element<'a, Link, Theme, Renderer>
+impl<'a, Link, Message, Theme, Renderer>
+    From<Rich<'a, Link, Message, Theme, Renderer>>
+    for Element<'a, Message, Theme, Renderer>
 where
+    Message: 'a,
     Link: Clone + 'a,
     Theme: Catalog + 'a,
     Renderer: core::text::Renderer + 'a,
 {
     fn from(
-        text: Rich<'a, Link, Theme, Renderer>,
-    ) -> Element<'a, Link, Theme, Renderer> {
+        text: Rich<'a, Link, Message, Theme, Renderer>,
+    ) -> Element<'a, Message, Theme, Renderer> {
         Element::new(text)
     }
 }