feat(barchart): set custom text value in the bar (#309)

for now the value is converted to a string and then printed. in many
cases the values are too wide or double values. so it make sense
to set a custom value text instead of the default behavior.

this patch suggests to add a method
"fn text_value(mut self, text_value: String)"
to the Bar, which allows to override the value printed in the bar

Signed-off-by: Ben Fekih, Hichem <hichem.f@live.de>

examples/barchart.rs

@@ -57,17 +57,17 @@ impl<'a> App<'a> {
             companies: [
                 Company {
                     label: "Comp.A",
-                    revenue: [9, 12, 5, 8],
+                    revenue: [9500, 12500, 5300, 8500],
                     bar_style: Style::default().fg(Color::Green),
                 },
                 Company {
                     label: "Comp.B",
-                    revenue: [1, 2, 3, 4],
+                    revenue: [1500, 2500, 3000, 4100],
                     bar_style: Style::default().fg(Color::Yellow),
                 },
                 Company {
                     label: "Comp.C",
-                    revenue: [10, 10, 9, 4],
+                    revenue: [10500, 10600, 9000, 4200],
                     bar_style: Style::default().fg(Color::White),
                 },
             ],
@@ -182,7 +182,8 @@ where
                             Style::default()
                                 .bg(c.bar_style.fg.unwrap())
                                 .fg(Color::Black),
-                        );
+                        )
+                        .text_value(format!("{:.1}", (c.revenue[i] as f64) / 1000.));
                     if bar_labels {
                         bar = bar.label(c.label.into());
                     }

src/widgets/barchart/bar.rs

@@ -12,7 +12,8 @@ use crate::{buffer::Buffer, style::Style, text::Line};
 ///     .label("Bar 1".into())
 ///     .value(10)
 ///     .style(Style::default().fg(Color::Red))
-///     .value_style(Style::default().bg(Color::Red).fg(Color::White));
+///     .value_style(Style::default().bg(Color::Red).fg(Color::White))
+///     .text_value("10°C".to_string());
 /// ```
 #[derive(Debug, Clone, Default)]
 pub struct Bar<'a> {
@@ -24,6 +25,8 @@ pub struct Bar<'a> {
     pub(super) style: Style,
     /// style of the value printed at the bottom of the bar.
     pub(super) value_style: Style,
+    /// optional text_value to be shown on the bar instead of the actual value
+    pub(super) text_value: Option<String>,
 }
 
 impl<'a> Bar<'a> {
@@ -47,43 +50,46 @@ impl<'a> Bar<'a> {
         self
     }
 
-    /// render the bar's value
+    /// set the text value printed in the bar. (By default self.value is printed)
-    pub(super) fn render_value(
+    pub fn text_value(mut self, text_value: String) -> Bar<'a> {
-        &self,
+        self.text_value = Some(text_value);
+        self
+    }
+
+    pub(super) fn render_label_and_value(
+        self,
         buf: &mut Buffer,
         max_width: u16,
         x: u16,
         y: u16,
-        default_style: Style,
+        default_value_style: Style,
+        default_label_style: Style,
     ) {
+        // render the value
         if self.value != 0 {
-            let value_label = format!("{}", self.value);
+            let value_label = if let Some(text) = self.text_value {
+                text
+            } else {
+                self.value.to_string()
+            };
+
             let width = value_label.len() as u16;
             if width < max_width {
                 buf.set_string(
                     x + (max_width.saturating_sub(value_label.len() as u16) >> 1),
                     y,
                     value_label,
-                    self.value_style.patch(default_style),
+                    self.value_style.patch(default_value_style),
                 );
             }
         }
-    }
 
-    /// render the bar's label
+        // render the label
-    pub(super) fn render_label(
-        self,
-        buf: &mut Buffer,
-        max_width: u16,
-        x: u16,
-        y: u16,
-        default_style: Style,
-    ) {
         if let Some(mut label) = self.label {
-            label.patch_style(default_style);
+            label.patch_style(default_label_style);
             buf.set_line(
                 x + (max_width.saturating_sub(label.width() as u16) >> 1),
-                y,
+                y + 1,
                 &label,
                 max_width,
             );

src/widgets/barchart/mod.rs

@@ -264,7 +264,7 @@ impl<'a> BarChart<'a> {
     fn render_labels_and_values(self, area: Rect, buf: &mut Buffer, label_height: u16) {
         // print labels and values in one go
         let mut bar_x = area.left();
-        let y_value_offset = area.bottom() - label_height - 1;
+        let bar_y = area.bottom() - label_height - 1;
         for group in self.data.into_iter() {
             // print group labels under the bars or the previous labels
             if let Some(mut label) = group.label {
@@ -282,13 +282,12 @@ impl<'a> BarChart<'a> {
 
             // print the bar values and numbers
             for bar in group.bars.into_iter() {
-                bar.render_value(buf, self.bar_width, bar_x, y_value_offset, self.value_style);
+                bar.render_label_and_value(
-
-                bar.render_label(
                     buf,
                     self.bar_width,
                     bar_x,
-                    y_value_offset + 1,
+                    bar_y,
+                    self.value_style,
                     self.label_style,
                 );
 

tests/widgets_barchart.rs

@@ -63,7 +63,8 @@ fn widgets_barchart_group() {
                                 .value_style(Style::default().fg(Color::Blue)),
                             Bar::default()
                                 .value(20)
-                                .style(Style::default().fg(Color::Green)),
+                                .style(Style::default().fg(Color::Green))
+                                .text_value("20M".to_string()),
                         ]),
                     )
                     .data(&vec![("C1", 50u64), ("C2", 40u64)])
@@ -86,7 +87,7 @@ fn widgets_barchart_group() {
         "│            ▇▇▇▇        ████ ████│",
         "│            ████ ████   ████ ████│",
         "│     ▄▄▄▄   ████ ████   ████ ████│",
-        "│▆10▆ █20█   █50█ █40█   █60█ █90█│",
+        "│▆10▆ 20M█   █50█ █40█   █60█ █90█│",
         "│ C1          C1   C2     C1   C2 │",
         "│   Mar                           │",
         "└─────────────────────────────────┘",