feat(barchart)!: allow axes to accept Lines (#1273)

Fixes: #1272

BREAKING-CHANGES.md

@@ -13,6 +13,7 @@ This is a quick summary of the sections below:
 - [v0.28.0](#v0280) (unreleased)
   - `Layout::init_cache` no longer returns bool and takes a `NonZeroUsize` instead of `usize`
   - `ratatui::terminal` module is now private
+  - `Axis::labels` now accepts `Vec<T: Into<Line>>`
 - [v0.27.0](#v0270)
   - List no clamps the selected index to list
   - Prelude items added / removed
@@ -61,6 +62,17 @@ This is a quick summary of the sections below:
 
 ## v0.28.0 (unreleased)
 
+### `Axis::labels()` now accepts `Vec<T: Into<Line>>` ([#1273])
+
+[#1273]: https://github.com/ratatui-org/ratatui/pull/1173
+
+Previously Axis::labels accepted `Vec<Span>`. Any code that uses conversion methods that infer the
+type will need to be rewritten as the compiler cannot infer the correct type.
+
+```diff
+- Axis::default().labels("a".into(), "b".into())
++ Axis::default().labels("a", "b")
+
 ### `Layout::init_cache` no longer returns bool and takes a `NonZeroUsize` instead of `usize` ([#1145])
 
 [#1145]: https://github.com/ratatui-org/ratatui/pull/1145

examples/chart.rs

@@ -325,14 +325,14 @@ fn render_scatter(f: &mut Frame, area: Rect) {
                 .title("Year")
                 .bounds([1960., 2020.])
                 .style(Style::default().fg(Color::Gray))
-                .labels(vec!["1960".into(), "1990".into(), "2020".into()]),
+                .labels(vec!["1960", "1990", "2020"]),
         )
         .y_axis(
             Axis::default()
                 .title("Cost")
                 .bounds([0., 75000.])
                 .style(Style::default().fg(Color::Gray))
-                .labels(vec!["0".into(), "37 500".into(), "75 000".into()]),
+                .labels(vec!["0", "37 500", "75 000"]),
         )
         .hidden_legend_constraints((Constraint::Ratio(1, 2), Constraint::Ratio(1, 2)));
 

src/widgets/chart.rs

@@ -39,7 +39,7 @@ pub struct Axis<'a> {
     /// Bounds for the axis (all data points outside these limits will not be represented)
     bounds: [f64; 2],
     /// A list of labels to put to the left or below the axis
-    labels: Option<Vec<Span<'a>>>,
+    labels: Option<Vec<Line<'a>>>,
     /// The style used to draw the axis itself
     style: Style,
     /// The alignment of the labels of the Axis
@@ -84,6 +84,11 @@ impl<'a> Axis<'a> {
     ///
     /// [issue 334]: https://github.com/ratatui-org/ratatui/issues/334
     ///
+    /// `labels` is a vector of any type that can be converted into a [`Line`] (e.g. `&str`,
+    /// `String`, `&Line`, `Span`, ...). This allows you to style the labels using the methods
+    /// provided by [`Line`]. Any alignment set on the labels will be ignored as the alignment is
+    /// determined by the axis.
+    ///
     /// This is a fluent setter method which must be chained or used as it consumes self
     ///
     /// # Examples
@@ -96,8 +101,8 @@ impl<'a> Axis<'a> {
     ///         .labels(vec!["0".bold(), "25".into(), "50".bold()]);
     /// ```
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn labels(mut self, labels: Vec<Span<'a>>) -> Self {
-        self.labels = Some(labels);
+    pub fn labels<T: Into<Line<'a>>>(mut self, labels: Vec<T>) -> Self {
+        self.labels = Some(labels.into_iter().map(Into::into).collect());
         self
     }
 
@@ -469,14 +474,14 @@ struct ChartLayout {
 ///     .title("X Axis".red())
 ///     .style(Style::default().white())
 ///     .bounds([0.0, 10.0])
-///     .labels(vec!["0.0".into(), "5.0".into(), "10.0".into()]);
+///     .labels(vec!["0.0", "5.0", "10.0"]);
 ///
 /// // Create the Y axis and define its properties
 /// let y_axis = Axis::default()
 ///     .title("Y Axis".red())
 ///     .style(Style::default().white())
 ///     .bounds([0.0, 10.0])
-///     .labels(vec!["0.0".into(), "5.0".into(), "10.0".into()]);
+///     .labels(vec!["0.0", "5.0", "10.0"]);
 ///
 /// // Create the chart and link all the parts together
 /// let chart = Chart::new(datasets)
@@ -578,7 +583,7 @@ impl<'a> Chart<'a> {
     ///     Axis::default()
     ///         .title("X Axis")
     ///         .bounds([0.0, 20.0])
-    ///         .labels(vec!["0".into(), "20".into()]),
+    ///         .labels(vec!["0", "20"]),
     /// );
     /// ```
     #[must_use = "method moves the value of self and returns the modified value"]
@@ -601,7 +606,7 @@ impl<'a> Chart<'a> {
     ///     Axis::default()
     ///         .title("Y Axis")
     ///         .bounds([0.0, 20.0])
-    ///         .labels(vec!["0".into(), "20".into()]),
+    ///         .labels(vec!["0", "20"]),
     /// );
     /// ```
     #[must_use = "method moves the value of self and returns the modified value"]
@@ -807,7 +812,7 @@ impl<'a> Chart<'a> {
             .y_axis
             .labels
             .as_ref()
-            .map(|l| l.iter().map(Span::width).max().unwrap_or_default() as u16)
+            .map(|l| l.iter().map(Line::width).max().unwrap_or_default() as u16)
             .unwrap_or_default();
 
         if let Some(first_x_label) = self
@@ -903,17 +908,13 @@ impl<'a> Chart<'a> {
         Rect::new(min_x, y, max_x - min_x, 1)
     }
 
-    fn render_label(buf: &mut Buffer, label: &Span, label_area: Rect, alignment: Alignment) {
-        let label_width = label.width() as u16;
-        let bounded_label_width = label_area.width.min(label_width);
-
-        let x = match alignment {
-            Alignment::Left => label_area.left(),
-            Alignment::Center => label_area.left() + label_area.width / 2 - bounded_label_width / 2,
-            Alignment::Right => label_area.right() - bounded_label_width,
+    fn render_label(buf: &mut Buffer, label: &Line, label_area: Rect, alignment: Alignment) {
+        let label = match alignment {
+            Alignment::Left => label.clone().left_aligned(),
+            Alignment::Center => label.clone().centered(),
+            Alignment::Right => label.clone().right_aligned(),
         };
-
-        buf.set_span(x, label_area.top(), label, bounded_label_width);
+        label.render(label_area, buf);
     }
 
     fn render_y_labels(

tests/widgets_chart.rs

@@ -203,7 +203,7 @@ fn widgets_chart_handles_long_labels<'line, Lines>(
         "          ",
         "          ",
         "──────────",
-        "AAA  B   C",
+        "AAA B    C",
     ],
 )]
 fn widgets_chart_handles_x_axis_labels_alignments<'line, Lines>(
@@ -229,9 +229,9 @@ fn widgets_chart_handles_x_axis_labels_alignments<'line, Lines>(
     "AAAAA              B",
 ])]
 #[case::center(Alignment::Center, [
-    "  D │               ",
+    " D  │               ",
     "    │               ",
-    "  C │               ",
+    " C  │               ",
     "    └───────────────",
     "AAAAA              B",
 ])]