Support scrolling forward and backward half a page

YS-L · Nov 26, 2023 · 0f23b38 · 0f23b38
1 parent fbed13d
commit 0f23b38
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Showing 3 changed files with 72 additions and 0 deletions.
diff --git a/src/app.rs b/src/app.rs
@@ -1065,4 +1065,62 @@ mod tests {
         let lines = to_lines(&actual_buffer);
         assert_eq!(lines, expected);
     }
+
+    #[test]
+    fn test_scroll_half_page() {
+        let mut app = App::new(
+            "tests/data/cities.csv",
+            Delimiter::Default,
+            None,
+            false,
+            None,
+            false,
+        )
+        .unwrap();
+        thread::sleep(time::Duration::from_millis(100));
+
+        let backend = TestBackend::new(40, 10);
+        let mut terminal = Terminal::new(backend).unwrap();
+
+        // TODO: since some states are updated late only during rendering, sometimes some extra
+        // no-ops are required to warm up the states. I don't like it, but this is how it has to be
+        // in tests for now.
+        step_and_draw(&mut app, &mut terminal, Control::Nothing);
+        step_and_draw(&mut app, &mut terminal, Control::Nothing);
+        step_and_draw(&mut app, &mut terminal, Control::ScrollHalfPageDown);
+        step_and_draw(&mut app, &mut terminal, Control::ScrollHalfPageDown);
+        let expected = vec![
+            "────────────────────────────────────────",
+            "      LatD    LatM    LatS    NS    …   ",
+            "───┬────────────────────────────────────",
+            "5  │  43      37      48      N     …   ",
+            "6  │  36      5       59      N     …   ",
+            "7  │  49      52      48      N     …   ",
+            "8  │  39      11      23      N     …   ",
+            "9  │  34      14      24      N     …   ",
+            "───┴────────────────────────────────────",
+            "stdin [Row 5/128, Col 1/10]             ",
+        ];
+        let actual_buffer = terminal.backend().buffer().clone();
+        let lines = to_lines(&actual_buffer);
+        assert_eq!(lines, expected);
+
+        step_and_draw(&mut app, &mut terminal, Control::Nothing);
+        step_and_draw(&mut app, &mut terminal, Control::ScrollHalfPageUp);
+        let expected = vec![
+            "────────────────────────────────────────",
+            "      LatD    LatM    LatS    NS    …   ",
+            "───┬────────────────────────────────────",
+            "3  │  46      35      59      N     …   ",
+            "4  │  42      16      12      N     …   ",
+            "5  │  43      37      48      N     …   ",
+            "6  │  36      5       59      N     …   ",
+            "7  │  49      52      48      N     …   ",
+            "───┴────────────────────────────────────",
+            "stdin [Row 3/128, Col 1/10]             ",
+        ];
+        let actual_buffer = terminal.backend().buffer().clone();
+        let lines = to_lines(&actual_buffer);
+        assert_eq!(lines, expected);
+    }
 }
diff --git a/src/input.rs b/src/input.rs
@@ -11,6 +11,8 @@ pub enum Control {
     ScrollBottom,
     ScrollPageUp,
     ScrollPageDown,
+    ScrollHalfPageUp,
+    ScrollHalfPageDown,
     ScrollPageLeft,
     ScrollPageRight,
     ScrollLeftMost,
@@ -118,6 +120,8 @@ impl InputHandler {
                 KeyCode::Char('H') => Control::Help,
                 KeyCode::PageDown => Control::ScrollPageDown,
                 KeyCode::PageUp => Control::ScrollPageUp,
+                KeyCode::Char('d') => Control::ScrollHalfPageDown,
+                KeyCode::Char('u') => Control::ScrollHalfPageUp,
                 KeyCode::Char(x) if "0123456789".contains(x.to_string().as_str()) => {
                     self.buffer_state = BufferState::Active(x.to_string());
                     self.mode = InputMode::GotoLine;
@@ -146,6 +150,8 @@ impl InputHandler {
             KeyModifiers::CONTROL => match key_event.code {
                 KeyCode::Char('f') => Control::ScrollPageDown,
                 KeyCode::Char('b') => Control::ScrollPageUp,
+                KeyCode::Char('d') => Control::ScrollHalfPageDown,
+                KeyCode::Char('u') => Control::ScrollHalfPageUp,
                 KeyCode::Char('h') => Control::ScrollPageLeft,
                 KeyCode::Char('l') => Control::ScrollPageRight,
                 KeyCode::Left => Control::ScrollLeftMost,

diff --git a/src/view.rs b/src/view.rs
@@ -444,6 +444,10 @@ impl RowsView {
                     self.increase_rows_from(1)?;
                 }
             }
+            Control::ScrollHalfPageDown => {
+                self.increase_rows_from(self.num_rows_rendered / 2)?;
+                self.selection.row.select_first()
+            }
             Control::ScrollPageDown => {
                 self.increase_rows_from(self.num_rows_rendered)?;
                 self.selection.row.select_first()
@@ -459,6 +463,10 @@ impl RowsView {
                     self.decrease_rows_from(1)?;
                 }
             }
+            Control::ScrollHalfPageUp => {
+                self.decrease_rows_from(self.num_rows_rendered / 2)?;
+                self.selection.row.select_first()
+            }
             Control::ScrollPageUp => {
                 self.decrease_rows_from(self.num_rows_rendered)?;
                 self.selection.row.select_first()