feat(widgets/chart): add option to set the position of legend

ratatui-org · Aug 6, 2023 · 7f7fbc0 · 7f7fbc0
1 parent c8ddc16
commit 7f7fbc0
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Showing 3 changed files with 807 additions and 11 deletions.
diff --git a/examples/chart.rs b/examples/chart.rs
@@ -254,6 +254,7 @@ fn ui<B: Backend>(f: &mut Frame<B>, app: &App) {
                 .style(Style::default().fg(Color::Gray))
                 .bounds([0.0, 5.0])
                 .labels(vec!["0".bold(), "2.5".into(), "5".bold()]),
-        );
+        )
+        .legend_position(Corner::BottomLeft);
     f.render_widget(chart, chunks[2]);
 }
diff --git a/src/widgets/chart.rs b/src/widgets/chart.rs
@@ -4,7 +4,7 @@ use unicode_width::UnicodeWidthStr;
 
 use crate::{
     buffer::Buffer,
-    layout::{Alignment, Constraint, Rect},
+    layout::{Alignment, Constraint, Corner, Rect},
     style::{Color, Style, Styled},
     symbols,
     text::{Line as TextLine, Span},
@@ -202,6 +202,8 @@ pub struct Chart<'a> {
     style: Style,
     /// Constraints used to determine whether the legend should be shown or not
     hidden_legend_constraints: (Constraint, Constraint),
+    /// The position of a legend
+    legend_position: Corner,
 }
 
 impl<'a> Chart<'a> {
@@ -213,6 +215,7 @@ impl<'a> Chart<'a> {
             style: Style::default(),
             datasets,
             hidden_legend_constraints: (Constraint::Ratio(1, 4), Constraint::Ratio(1, 4)),
+            legend_position: Corner::TopRight,
         }
     }
 
@@ -257,6 +260,21 @@ impl<'a> Chart<'a> {
         self
     }
 
+    /// Set the position of a legend.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use ratatui::widgets::Chart;
+    /// # use ratatui::layout::Corner;
+    /// let _chart: Chart = Chart::new(vec![])
+    ///     .legend_position(Corner::TopLeft);
+    /// ```
+    pub fn legend_position(mut self, position: Corner) -> Chart<'a> {
+        self.legend_position = position;
+        self
+    }
+
     /// Compute the internal layout of the chart given the area. If the area is too small some
     /// elements may be automatically hidden
     fn layout(&self, area: Rect) -> ChartLayout {
@@ -318,12 +336,27 @@ impl<'a> Chart<'a> {
                 && legend_width < max_legend_width
                 && legend_height < max_legend_height
             {
-                layout.legend_area = Some(Rect::new(
-                    layout.graph_area.right() - legend_width,
-                    layout.graph_area.top(),
-                    legend_width,
-                    legend_height,
-                ));
+                let (x, y) = match self.legend_position {
+                    Corner::TopRight => (
+                        layout.graph_area.right() - legend_width,
+                        layout.graph_area.top(),
+                    ),
+                    Corner::TopLeft => (
+                        layout.graph_area.left(),
+                        layout.graph_area.top() + if self.y_axis.title.is_some() { 1 } else { 0 },
+                    ),
+                    Corner::BottomRight => (
+                        layout.graph_area.right() - legend_width,
+                        layout.graph_area.bottom()
+                            - legend_height
+                            - if self.x_axis.title.is_some() { 1 } else { 0 },
+                    ),
+                    Corner::BottomLeft => (
+                        layout.graph_area.left(),
+                        layout.graph_area.bottom() - legend_height,
+                    ),
+                };
+                layout.legend_area = Some(Rect::new(x, y, legend_width, legend_height));
             }
         }
         layout
@@ -559,7 +592,7 @@ impl<'a> Widget for Chart<'a> {
 
         if let Some((x, y)) = layout.title_x {
             let title = self.x_axis.title.unwrap();
-            let width = graph_area.right().saturating_sub(x);
+            let width = title.width() as u16;
             buf.set_style(
                 Rect {
                     x,
@@ -574,7 +607,7 @@ impl<'a> Widget for Chart<'a> {
 
         if let Some((x, y)) = layout.title_y {
             let title = self.y_axis.title.unwrap();
-            let width = graph_area.right().saturating_sub(x);
+            let width = title.width() as u16;
             buf.set_style(
                 Rect {
                     x,