fix(Barchart): horizontal labels were not displayed

Fixed horizontal bars label not displayed.
Also adds ways to configure label truncation.

src/widgets/barchart.rs

@@ -81,6 +81,8 @@ pub struct BarChart<'a> {
     /// Value necessary for a bar to reach the maximum height (if no value is specified,
     /// the maximum value in the data is taken as reference)
     max: Option<u64>,
+    /// the maximum length of bars label
+    label_max_len: Option<u16>,
     /// direction of the bars
     direction: Direction,
 }
@@ -99,6 +101,7 @@ impl<'a> Default for BarChart<'a> {
             group_gap: 0,
             bar_set: symbols::bar::NINE_LEVELS,
             style: Style::default(),
+            label_max_len: None,
             direction: Direction::Vertical,
         }
     }
@@ -258,6 +261,15 @@ impl<'a> BarChart<'a> {
         self
     }
 
+    /// Sets the maximum label length.
+    ///
+    /// If not set, there is no maximum.
+    /// For horizontal bars, this effectively reserve the specified length.
+    pub fn label_max_len(mut self, len: u16) -> Self {
+        self.label_max_len = Some(len);
+        self
+    }
+
     /// Set the direction of the bars.
     ///
     /// [`Vertical`](crate::layout::Direction::Vertical) bars are the default.
@@ -335,6 +347,32 @@ impl<'a> BarChart<'a> {
     }
 
     fn render_horizontal_bars(self, buf: &mut Buffer, bars_area: Rect, max: u64) {
+        let label_size = if let Some(length) = self.label_max_len {
+            length
+        } else {
+            // get the longest label
+            self.data
+                .iter()
+                .map(|group| {
+                    group
+                        .bars
+                        .iter()
+                        .map(|bar| bar.label.clone().map_or(0, |label| label.width()))
+                        .max()
+                        .unwrap_or(0)
+                })
+                .max()
+                .unwrap_or(0) as u16
+        };
+
+        let margin = if label_size == 0 { 0 } else { 1 };
+
+        let bars_area = Rect {
+            x: bars_area.x + label_size + margin,
+            width: bars_area.width - label_size - margin,
+            ..bars_area
+        };
+
         // convert the bar values to ratatui::symbols::bar::Set
         let groups: Vec<Vec<u16>> = self
             .data
@@ -348,7 +386,7 @@ impl<'a> BarChart<'a> {
             })
             .collect();
 
-        // print all visible bars
+        // print all visible bars, label and values
         let mut bar_y = bars_area.top();
         for (group_data, mut group) in groups.into_iter().zip(self.data) {
             let bars = std::mem::take(&mut group.bars);
@@ -374,6 +412,15 @@ impl<'a> BarChart<'a> {
                     y: bar_y + (self.bar_width >> 1),
                     ..bars_area
                 };
+
+                // label
+                buf.set_line(
+                    bars_area.left() - label_size - margin,
+                    bar_value_area.top(),
+                    &bar.label.clone().unwrap_or_default(),
+                    label_size,
+                );
+
                 bar.render_value_with_different_styles(
                     buf,
                     bar_value_area,
@@ -487,7 +534,7 @@ impl<'a> BarChart<'a> {
             for bar in bars.into_iter() {
                 bar.render_label_and_value(
                     buf,
-                    self.bar_width,
+                    u16::min(self.bar_width, self.label_max_len.unwrap_or(u16::MAX)),
                     bar_x,
                     bar_y,
                     self.value_style,
@@ -1093,6 +1140,37 @@ mod tests {
         test_horizontal_bars_label_width_greater_than_bar(Some(Color::White))
     }
 
+    /// Tests horizontal bars label are presents
+    #[test]
+    fn test_horizontal_label() {
+        let chart = BarChart::default()
+            .direction(Direction::Horizontal)
+            .bar_gap(0)
+            .data(&[("Jan", 10), ("Feb", 20), ("Mar", 5)]);
+
+        let mut buffer = Buffer::empty(Rect::new(0, 0, 10, 3));
+        chart.render(buffer.area, &mut buffer);
+        let expected = Buffer::with_lines(vec!["Jan 10█   ", "Feb 20████", "Mar 5     "]);
+
+        assert_buffer_eq!(buffer, expected);
+    }
+
+    /// Tests horizontal bars label are truncated
+    #[test]
+    fn test_horizontal_label_max_len() {
+        let chart = BarChart::default()
+            .direction(Direction::Horizontal)
+            .bar_gap(0)
+            .data(&[("January", 10), ("February", 20), ("March", 5)])
+            .label_max_len(1);
+
+        let mut buffer = Buffer::empty(Rect::new(0, 0, 10, 3));
+        chart.render(buffer.area, &mut buffer);
+        let expected = Buffer::with_lines(vec!["J 10██    ", "F 20██████", "M 5█      "]);
+
+        assert_buffer_eq!(buffer, expected);
+    }
+
     #[test]
     fn test_group_label_style() {
         let chart: BarChart<'_> = BarChart::default()