feat(widgets/list): repeat highlight symbol on multi-line items (#533)

When this option is true, the hightlight symbol is repeated for each
line of the selected item, instead of just the first line.

CHANGELOG.md

@@ -1,6 +1,8 @@
 # Changelog
 
 ## To be released
+### Features
+* Add option to `widgets::List` to repeat the hightlight symbol for each line of multi-line items.
 
 ## v0.16.0 - 2021-08-01
 

src/widgets/list.rs

@@ -87,6 +87,8 @@ pub struct List<'a> {
     highlight_style: Style,
     /// Symbol in front of the selected item (Shift all items to the right)
     highlight_symbol: Option<&'a str>,
+    /// Whether to repeat the highlight symbol for each line of the selected item
+    repeat_highlight_symbol: bool,
 }
 
 impl<'a> List<'a> {
@@ -101,6 +103,7 @@ impl<'a> List<'a> {
             start_corner: Corner::TopLeft,
             highlight_style: Style::default(),
             highlight_symbol: None,
+            repeat_highlight_symbol: false,
         }
     }
 
@@ -123,6 +126,11 @@ impl<'a> List<'a> {
         self.highlight_style = style;
         self
     }
+    
+    pub fn repeat_highlight_symbol(mut self, repeat: bool) -> List<'a> {
+        self.repeat_highlight_symbol = repeat;
+        self
+    }
 
     pub fn start_corner(mut self, corner: Corner) -> List<'a> {
         self.start_corner = corner;
@@ -227,19 +235,21 @@ impl<'a> StatefulWidget for List<'a> {
             buf.set_style(area, item_style);
 
             let is_selected = state.selected.map(|s| s == i).unwrap_or(false);
-            let elem_x = if has_selection {
-                let symbol = if is_selected {
+            for (j, line) in item.content.lines.iter().enumerate() {
+                // if the item is selected, we need to display the hightlight symbol:
+                // - either for the first line of the item only,
+                // - or for each line of the item if the appropriate option is set
+                let symbol = if is_selected && (j == 0 || self.repeat_highlight_symbol){
                     highlight_symbol
                 } else {
                     &blank_symbol
                 };
-                let (x, _) = buf.set_stringn(x, y, symbol, list_area.width as usize, item_style);
-                x
-            } else {
-                x
-            };
-            let max_element_width = (list_area.width - (elem_x - x)) as usize;
-            for (j, line) in item.content.lines.iter().enumerate() {
+                let (elem_x, max_element_width) = if has_selection {
+                    let (elem_x, _) = buf.set_stringn(x, y + j as u16, symbol, list_area.width as usize, item_style);
+                    (elem_x, (list_area.width - (elem_x - x)) as u16)
+                } else {
+                    (x, list_area.width)
+                };
                 buf.set_spans(elem_x, y + j as u16, line, max_element_width as u16);
             }
             if is_selected {

tests/widgets_list.rs

@@ -126,3 +126,72 @@ fn widgets_list_should_clamp_offset_if_items_are_removed() {
     let expected = Buffer::with_lines(vec!["   Item 3 ", "          ", "          ", "          "]);
     terminal.backend().assert_buffer(&expected);
 }
+
+#[test]
+fn widgets_list_should_display_multiline_items() {
+    let backend = TestBackend::new(10, 6);
+    let mut terminal = Terminal::new(backend).unwrap();
+    let mut state = ListState::default();
+    state.select(Some(1));
+    terminal
+        .draw(|f| {
+            let size = f.size();
+            let items = vec![
+                ListItem::new(vec![Spans::from("Item 1"), Spans::from("Item 1a")]),
+                ListItem::new(vec![Spans::from("Item 2"), Spans::from("Item 2b")]),
+                ListItem::new(vec![Spans::from("Item 3"), Spans::from("Item 3c")]),
+            ];
+            let list = List::new(items)
+                .highlight_style(Style::default().bg(Color::Yellow))
+                .highlight_symbol(">> ");
+            f.render_stateful_widget(list, size, &mut state);
+        })
+        .unwrap();
+    let mut expected = Buffer::with_lines(vec![
+        "   Item 1 ",
+        "   Item 1a",
+        ">> Item 2 ",
+        "   Item 2b",
+        "   Item 3 ",
+        "   Item 3c"]);
+    for x in 0..10 {
+        expected.get_mut(x, 2).set_bg(Color::Yellow);
+        expected.get_mut(x, 3).set_bg(Color::Yellow);
+    }
+    terminal.backend().assert_buffer(&expected);
+}
+
+#[test]
+fn widgets_list_should_repeat_highlight_symbol() {
+    let backend = TestBackend::new(10, 6);
+    let mut terminal = Terminal::new(backend).unwrap();
+    let mut state = ListState::default();
+    state.select(Some(1));
+    terminal
+        .draw(|f| {
+            let size = f.size();
+            let items = vec![
+                ListItem::new(vec![Spans::from("Item 1"), Spans::from("Item 1a")]),
+                ListItem::new(vec![Spans::from("Item 2"), Spans::from("Item 2b")]),
+                ListItem::new(vec![Spans::from("Item 3"), Spans::from("Item 3c")]),
+            ];
+            let list = List::new(items)
+                .highlight_style(Style::default().bg(Color::Yellow))
+                .highlight_symbol(">> ")
+                .repeat_highlight_symbol(true);
+            f.render_stateful_widget(list, size, &mut state);
+        })
+        .unwrap();
+    let mut expected = Buffer::with_lines(vec![
+        "   Item 1 ",
+        "   Item 1a",
+        ">> Item 2 ",
+        ">> Item 2b",
+        "   Item 3 ",
+        "   Item 3c"]);
+    for x in 0..10 {
+        expected.get_mut(x, 2).set_bg(Color::Yellow);
+        expected.get_mut(x, 3).set_bg(Color::Yellow);
+    }
+    terminal.backend().assert_buffer(&expected);
+}