Introduce markdown::Settings

core/src/pixels.rs

@@ -9,6 +9,11 @@
 #[derive(Debug, Clone, Copy, PartialEq, PartialOrd, Default)]
 pub struct Pixels(pub f32);
 
+impl Pixels {
+    /// Zero pixels.
+    pub const ZERO: Self = Self(0.0);
+}
+
 impl From<f32> for Pixels {
     fn from(amount: f32) -> Self {
         Self(amount)
@@ -58,3 +63,19 @@ impl std::ops::Mul<f32> for Pixels {
         Pixels(self.0 * rhs)
     }
 }
+
+impl std::ops::Div for Pixels {
+    type Output = Pixels;
+
+    fn div(self, rhs: Self) -> Self {
+        Pixels(self.0 / rhs.0)
+    }
+}
+
+impl std::ops::Div<f32> for Pixels {
+    type Output = Pixels;
+
+    fn div(self, rhs: f32) -> Self {
+        Pixels(self.0 / rhs)
+    }
+}

examples/markdown/src/main.rs

@@ -64,7 +64,11 @@ impl Markdown {
             .padding(10)
             .font(Font::MONOSPACE);
 
-        let preview = markdown(&self.items, Message::LinkClicked);
+        let preview = markdown(
+            &self.items,
+            markdown::Settings::default(),
+            Message::LinkClicked,
+        );
 
         row![editor, scrollable(preview).spacing(10).height(Fill)]
             .spacing(10)

widget/src/markdown.rs

@@ -7,16 +7,17 @@
 use crate::core::font::{self, Font};
 use crate::core::padding;
 use crate::core::theme::{self, Theme};
-use crate::core::{self, Element, Length};
+use crate::core::{self, Element, Length, Pixels};
 use crate::{column, container, rich_text, row, span, text};
 
+pub use pulldown_cmark::HeadingLevel;
 pub use url::Url;
 
 /// A Markdown item.
 #[derive(Debug, Clone)]
 pub enum Item {
     /// A heading.
-    Heading(Vec<text::Span<'static, Url>>),
+    Heading(pulldown_cmark::HeadingLevel, Vec<text::Span<'static, Url>>),
     /// A paragraph.
     Paragraph(Vec<text::Span<'static, Url>>),
     /// A code block.
@@ -43,7 +44,6 @@ pub fn parse(
     }
 
     let mut spans = Vec::new();
-    let mut heading = None;
     let mut strong = false;
     let mut emphasis = false;
     let mut metadata = false;
@@ -81,12 +81,6 @@ pub fn parse(
     #[allow(clippy::drain_collect)]
     parser.filter_map(move |event| match event {
         pulldown_cmark::Event::Start(tag) => match tag {
-            pulldown_cmark::Tag::Heading { level, .. }
-                if !metadata && !table =>
-            {
-                heading = Some(level);
-                None
-            }
             pulldown_cmark::Tag::Strong if !metadata && !table => {
                 strong = true;
                 None
@@ -119,7 +113,11 @@ pub fn parse(
                 None
             }
             pulldown_cmark::Tag::Item => {
-                lists.last_mut().expect("List").items.push(Vec::new());
+                lists
+                    .last_mut()
+                    .expect("list context")
+                    .items
+                    .push(Vec::new());
                 None
             }
             pulldown_cmark::Tag::CodeBlock(
@@ -150,9 +148,11 @@ pub fn parse(
             _ => None,
         },
         pulldown_cmark::Event::End(tag) => match tag {
-            pulldown_cmark::TagEnd::Heading(_) if !metadata && !table => {
-                heading = None;
-                produce(&mut lists, Item::Heading(spans.drain(..).collect()))
+            pulldown_cmark::TagEnd::Heading(level) if !metadata && !table => {
+                produce(
+                    &mut lists,
+                    Item::Heading(level, spans.drain(..).collect()),
+                )
             }
             pulldown_cmark::TagEnd::Emphasis if !metadata && !table => {
                 emphasis = false;
@@ -180,7 +180,7 @@ pub fn parse(
                 }
             }
             pulldown_cmark::TagEnd::List(_) if !metadata && !table => {
-                let list = lists.pop().expect("List");
+                let list = lists.pop().expect("list context");
 
                 produce(
                     &mut lists,
@@ -228,18 +228,6 @@ pub fn parse(
 
             let span = span(text.into_string());
 
-            let span = match heading {
-                None => span,
-                Some(heading) => span.size(match heading {
-                    pulldown_cmark::HeadingLevel::H1 => 32,
-                    pulldown_cmark::HeadingLevel::H2 => 28,
-                    pulldown_cmark::HeadingLevel::H3 => 24,
-                    pulldown_cmark::HeadingLevel::H4 => 20,
-                    pulldown_cmark::HeadingLevel::H5 => 16,
-                    pulldown_cmark::HeadingLevel::H6 => 16,
-                }),
-            };
-
             let span = if strong || emphasis {
                 span.font(Font {
                     weight: if strong {
@@ -269,7 +257,15 @@ pub fn parse(
             None
         }
         pulldown_cmark::Event::Code(code) if !metadata && !table => {
-            spans.push(span(code.into_string()).font(Font::MONOSPACE));
+            let span = span(code.into_string()).font(Font::MONOSPACE);
+
+            let span = if let Some(link) = link.as_ref() {
+                span.color(palette.primary).link(link.clone())
+            } else {
+                span
+            };
+
+            spans.push(span);
             None
         }
         pulldown_cmark::Event::SoftBreak if !metadata && !table => {
@@ -284,54 +280,133 @@ pub fn parse(
     })
 }
 
+/// Configuration controlling Markdown rendering in [`view`].
+#[derive(Debug, Clone, Copy)]
+pub struct Settings {
+    /// The base text size.
+    pub text_size: Pixels,
+    /// The text size of level 1 heading.
+    pub h1_size: Pixels,
+    /// The text size of level 2 heading.
+    pub h2_size: Pixels,
+    /// The text size of level 3 heading.
+    pub h3_size: Pixels,
+    /// The text size of level 4 heading.
+    pub h4_size: Pixels,
+    /// The text size of level 5 heading.
+    pub h5_size: Pixels,
+    /// The text size of level 6 heading.
+    pub h6_size: Pixels,
+    /// The text size used in code blocks.
+    pub code_size: Pixels,
+}
+
+impl Settings {
+    /// 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 {
+        let text_size = text_size.into();
+
+        Self {
+            text_size,
+            h1_size: text_size * 2.0,
+            h2_size: text_size * 1.75,
+            h3_size: text_size * 1.5,
+            h4_size: text_size * 1.25,
+            h5_size: text_size,
+            h6_size: text_size,
+            code_size: text_size * 0.75,
+        }
+    }
+}
+
+impl Default for Settings {
+    fn default() -> Self {
+        Self::with_text_size(16)
+    }
+}
+
 /// Display a bunch of Markdown items.
 ///
 /// You can obtain the items with [`parse`].
 pub fn view<'a, Message, Renderer>(
     items: impl IntoIterator<Item = &'a Item>,
+    settings: Settings,
     on_link: impl Fn(Url) -> Message + Copy + 'a,
 ) -> Element<'a, Message, Theme, Renderer>
 where
     Message: '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,
+    } = settings;
+
+    let spacing = text_size * 0.625;
+
     let blocks = items.into_iter().enumerate().map(|(i, item)| match item {
-        Item::Heading(heading) => {
-            container(rich_text(heading).on_link(on_link))
-                .padding(padding::top(if i > 0 { 8 } else { 0 }))
-                .into()
+        Item::Heading(level, heading) => {
+            container(rich_text(heading).on_link(on_link).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 i > 0 {
+                text_size / 2.0
+            } else {
+                Pixels::ZERO
+            }))
+            .into()
         }
         Item::Paragraph(paragraph) => {
-            rich_text(paragraph).on_link(on_link).into()
+            rich_text(paragraph).on_link(on_link).size(text_size).into()
         }
         Item::List { start: None, items } => {
             column(items.iter().map(|items| {
-                row!["•", view(items, on_link)].spacing(10).into()
+                row![text("•").size(text_size), view(items, settings, on_link)]
+                    .spacing(spacing)
+                    .into()
             }))
-            .spacing(10)
+            .spacing(spacing)
             .into()
         }
         Item::List {
             start: Some(start),
             items,
         } => column(items.iter().enumerate().map(|(i, items)| {
-            row![text!("{}.", i as u64 + *start), view(items, on_link)]
-                .spacing(10)
-                .into()
+            row![
+                text!("{}.", i as u64 + *start).size(text_size),
+                view(items, settings, on_link)
+            ]
+            .spacing(spacing)
+            .into()
         }))
-        .spacing(10)
+        .spacing(spacing)
         .into(),
         Item::CodeBlock(code) => container(
             rich_text(code)
                 .font(Font::MONOSPACE)
-                .size(12)
+                .size(code_size)
                 .on_link(on_link),
         )
         .width(Length::Fill)
-        .padding(10)
+        .padding(spacing.0)
         .style(container::rounded_box)
         .into(),
     });
 
-    Element::new(column(blocks).width(Length::Fill).spacing(16))
+    Element::new(column(blocks).width(Length::Fill).spacing(text_size))
 }

widget/src/text/rich.rs

@@ -161,6 +161,15 @@ where
         self
     }
 
+    /// Sets the message handler for link clicks on the [`Rich`] text.
+    pub fn on_link_maybe(
+        mut self,
+        on_link: Option<impl Fn(Link) -> Message + 'a>,
+    ) -> Self {
+        self.on_link = on_link.map(|on_link| Box::new(on_link) as _);
+        self
+    }
+
     /// Sets the default style class of the [`Rich`] text.
     #[cfg(feature = "advanced")]
     #[must_use]