bug: fix scrollbar not drawing if the height was 2 or less (#2261)

.github/ci/release_notes.md

@@ -2,12 +2,12 @@
 
 ---
 
-## Bug Fixes
-
 ## Features
 
 ## Changes
 
+## Bug Fixes
+
 ## Other
 
 ## Internal Changes

CHANGELOG.md

@@ -18,14 +18,12 @@ Versioning for this project is based on [Semantic Versioning](https://semver.org
 
 That said, these are more guidelines rather than hard rules, though the project will generally try to follow them.
 
+<!--TODO: Make the changelog order standardized with features, changes, bugs, other -->
+
 ---
 
 ## 0.15.0 - Unreleased
 
-### Bug Fixes
-
-- [#2225](https://github.com/ClementTsang/bottom/pull/2225): Fix waking up NVIDIA GPUs when getting stats on Linux.
-
 ### Features
 
 - [#2239](https://github.com/ClementTsang/bottom/pull/2239): Initial Intel GPU support for Linux to get process GPU usage.
@@ -34,6 +32,15 @@ That said, these are more guidelines rather than hard rules, though the project
 - [#2251](https://github.com/ClementTsang/bottom/pull/2251): Add configurable binary disk capacity units for disk widget I/O.
 - [#2224](https://github.com/ClementTsang/bottom/pull/2224): Add swap column for processes for Linux.
 
+### Changes
+
+- [#2260](https://github.com/ClementTsang/bottom/pull/2260): Enable scrollbars by default.
+
+### Bug Fixes
+
+- [#2225](https://github.com/ClementTsang/bottom/pull/2225): Fix waking up NVIDIA GPUs when getting stats on Linux.
+- [#2261](https://github.com/ClementTsang/bottom/pull/2261): Fix scrollbars not drawing when height of bar was 2 or less.
+
 ### Other
 
 - [#2227](https://github.com/ClementTsang/bottom/pull/2227): Add missing documentation around disk I/O graph.

src/canvas/components/data_table.rs

@@ -192,7 +192,7 @@ mod test {
             left_to_right: false,
             is_basic: false,
             show_table_scroll_position: true,
-            show_table_scroll_bar: false,
+            show_table_scroll_bar: true,
             show_current_entry_when_unfocused: false,
         };
         let styling = DataTableStyling::default();

src/canvas/components/pipe_gauge.rs

@@ -315,7 +315,7 @@ mod tests {
     }
 
     /// Create a [`PipeGauge`] and return what it would have rendered.
-    fn render_gauge(
+    fn render_test_gauge(
         ratio: f64, bar_type: BarType, start_label: Option<&str>, inner_label: Option<&str>,
     ) -> String {
         const WIDTH: u16 = 12;
@@ -339,35 +339,44 @@ mod tests {
 
     #[test]
     fn test_pipe_bars() {
-        assert_eq!(render_gauge(0.0, BarType::Pipe, None, None), "[          ]");
-        assert_eq!(render_gauge(0.5, BarType::Pipe, None, None), "[|||||     ]");
         assert_eq!(
-            render_gauge(0.95, BarType::Pipe, None, None),
+            render_test_gauge(0.0, BarType::Pipe, None, None),
+            "[          ]"
+        );
+        assert_eq!(
+            render_test_gauge(0.5, BarType::Pipe, None, None),
+            "[|||||     ]"
+        );
+        assert_eq!(
+            render_test_gauge(0.95, BarType::Pipe, None, None),
             "[||||||||| ]"
         );
-        assert_eq!(render_gauge(1.0, BarType::Pipe, None, None), "[||||||||||]");
+        assert_eq!(
+            render_test_gauge(1.0, BarType::Pipe, None, None),
+            "[||||||||||]"
+        );
     }
 
     #[test]
     fn test_solid_bars() {
         assert_eq!(
-            render_gauge(0.0, BarType::Block, None, None),
+            render_test_gauge(0.0, BarType::Block, None, None),
             "[          ]"
         );
         assert_eq!(
-            render_gauge(0.5, BarType::Block, None, None),
+            render_test_gauge(0.5, BarType::Block, None, None),
             "[█████     ]"
         );
         assert_eq!(
-            render_gauge(0.55, BarType::Block, None, None),
+            render_test_gauge(0.55, BarType::Block, None, None),
             "[█████▌    ]"
         );
         assert_eq!(
-            render_gauge(0.9, BarType::Block, None, None),
+            render_test_gauge(0.9, BarType::Block, None, None),
             "[█████████ ]"
         );
         assert_eq!(
-            render_gauge(1.0, BarType::Block, None, None),
+            render_test_gauge(1.0, BarType::Block, None, None),
             "[██████████]"
         );
     }
@@ -375,15 +384,15 @@ mod tests {
     #[test]
     fn test_labelled_bars() {
         assert_eq!(
-            render_gauge(0.5, BarType::Pipe, Some("CPU"), Some(" 50%")),
+            render_test_gauge(0.5, BarType::Pipe, Some("CPU"), Some(" 50%")),
             "CPU[||| 50%]"
         );
         assert_eq!(
-            render_gauge(0.5, BarType::Block, Some("CPU"), Some(" 50%")),
+            render_test_gauge(0.5, BarType::Block, Some("CPU"), Some(" 50%")),
             "CPU[███ 50%]"
         );
         assert_eq!(
-            render_gauge(1.0, BarType::Block, Some("CPU"), Some("100%")),
+            render_test_gauge(1.0, BarType::Block, Some("CPU"), Some("100%")),
             "CPU[███100%]"
         );
     }

src/canvas/components/scroll_bar.rs

@@ -44,9 +44,20 @@ pub fn draw_scroll_bar(f: &mut Frame<'_>, area: Rect, args: ScrollBarArgs) {
         end: "▼",
     };
 
-    let scrollbar = Scrollbar::new(ScrollbarOrientation::VerticalRight)
-        .style(args.style)
-        .symbols(SYMBOLS);
+    // If the height is only 2, then there's no room for the thumb,
+    // so instead we just draw a track with no arrows.
+    let scrollbar = {
+        let tmp = Scrollbar::new(ScrollbarOrientation::VerticalRight).style(args.style);
+
+        if area.height > 2 {
+            tmp.symbols(SYMBOLS)
+        } else {
+            tmp.track_symbol(Some(SYMBOLS.track))
+                .thumb_symbol(SYMBOLS.thumb)
+                .begin_symbol(None)
+                .end_symbol(None)
+        }
+    };
 
     let mut state = ScrollbarState::new(args.content_length)
         .position(args.position)
@@ -54,3 +65,53 @@ pub fn draw_scroll_bar(f: &mut Frame<'_>, area: Rect, args: ScrollBarArgs) {
 
     f.render_stateful_widget(scrollbar, area, &mut state);
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use ratatui::{Terminal, backend::TestBackend};
+
+    fn render_test_bar(height: u16, content_length: usize, position: usize) -> Vec<String> {
+        let mut terminal = Terminal::new(TestBackend::new(1, height)).unwrap();
+        terminal
+            .draw(|f| {
+                draw_scroll_bar(
+                    f,
+                    Rect::new(0, 0, 1, height),
+                    ScrollBarArgs {
+                        content_length,
+                        viewport_length: 2,
+                        position,
+                        style: Style::default(),
+                    },
+                );
+            })
+            .unwrap();
+
+        let buf = terminal.backend().buffer().clone();
+        (0..height)
+            .map(|y| buf[(0, y)].symbol().to_string())
+            .collect()
+    }
+
+    /// Make sure that a short scrollbar (height <= 2) is still drawn, just without the head/tail arrows.
+    #[test]
+    fn test_small_height_scroll_still_drawn() {
+        assert_eq!(render_test_bar(1, 3, 0), ["█"]);
+        assert_eq!(render_test_bar(2, 3, 0), ["█", " "]);
+        assert_eq!(render_test_bar(2, 3, 2), [" ", "█"]);
+    }
+
+    #[test]
+    fn test_normal_height_scroll_all_drawn() {
+        assert_eq!(render_test_bar(3, 3, 0), ["▲", "█", "▼"]);
+        assert_eq!(render_test_bar(4, 3, 0), ["▲", "█", " ", "▼"]);
+        assert_eq!(render_test_bar(4, 3, 2), ["▲", " ", "█", "▼"]);
+    }
+
+    #[test]
+    fn test_no_scroll_bar_when_list_fits() {
+        assert_eq!(render_test_bar(4, 2, 0), [" ", " ", " ", " "]);
+        assert_eq!(render_test_bar(2, 1, 0), [" ", " "]);
+    }
+}