feat: add Visual selection and clipboard editing

src/tui.rs

@@ -242,6 +242,31 @@ fn draw(frame: &mut Frame, editor: &Editor, top: &mut usize, left: &mut usize) {
             buffer[(area.x + (column - *left) as u16, y)].set_style(style);
         }
     }
+    if let Some(selection) = editor.selection() {
+        let first = selection.start.row.max(*top);
+        let last = selection.end.row.min(top.saturating_add(height - 1));
+        let style = Style::default().fg(Color::White).bg(Color::Blue);
+        for row in first..=last {
+            let line = &editor.lines()[row];
+            let start = if row == selection.start.row {
+                display_column(line, selection.start.column)
+            } else {
+                0
+            };
+            let end = if row == selection.end.row {
+                display_column(line, selection.end.column)
+            } else {
+                display_column(line, usize::MAX) + 1
+            };
+            let start = start.max(*left);
+            let end = end.min(left.saturating_add(width));
+            let y = area.y + (row - *top) as u16;
+            let buffer = frame.buffer_mut();
+            for column in start..end {
+                buffer[(area.x + (column - *left) as u16, y)].set_style(style);
+            }
+        }
+    }
     let path = editor
         .path()
         .map(|p| p.to_string_lossy().into_owned())
@@ -301,6 +326,71 @@ mod tests {
         assert_eq!(visible_line(text, 5, 2), " e\u{301}");
     }
 
+    #[test]
+    fn visual_selection_highlights_graphemes_newlines_and_clipped_ranges_over_search() {
+        let mut editor = Editor::open(None, vec![]).unwrap();
+        editor
+            .apply(vec![crate::editor::Effect::Replace(
+                "a\t界e\u{301}z\n\nxy".into(),
+            )])
+            .unwrap();
+        editor.handle(Input::Char('/'));
+        for ch in "界e\u{301}".chars() {
+            editor.handle(Input::Char(ch));
+        }
+        editor.handle(Input::Enter);
+        editor.handle(Input::Char('v'));
+        editor.handle(Input::Left);
+        let mut terminal = Terminal::new(ratatui::backend::TestBackend::new(10, 6)).unwrap();
+        let (mut top, mut left) = (0, 0);
+        terminal
+            .draw(|frame| draw(frame, &editor, &mut top, &mut left))
+            .unwrap();
+        let buffer = terminal.backend().buffer();
+        for x in [1, 2, 3, 4] {
+            assert_eq!(buffer[(x, 0)].bg, Color::Blue);
+        }
+        assert_eq!(buffer[(4, 0)].symbol(), "界");
+        assert_eq!(buffer[(6, 0)].bg, Color::Yellow);
+        editor.handle(Input::Down);
+        editor.handle(Input::Down);
+        terminal
+            .draw(|frame| draw(frame, &editor, &mut top, &mut left))
+            .unwrap();
+        let buffer = terminal.backend().buffer();
+        assert_eq!(buffer[(8, 0)].symbol(), " ");
+        assert_eq!(buffer[(8, 0)].bg, Color::Blue);
+        assert_eq!(buffer[(0, 1)].bg, Color::Blue);
+        assert_eq!(buffer[(0, 2)].bg, Color::Blue);
+        assert_ne!(buffer[(1, 2)].bg, Color::Blue);
+
+        editor.handle(Input::Up);
+        editor.handle(Input::Up);
+        editor.handle(Input::End);
+        let mut terminal = Terminal::new(ratatui::backend::TestBackend::new(5, 6)).unwrap();
+        terminal
+            .draw(|frame| draw(frame, &editor, &mut top, &mut left))
+            .unwrap();
+        let buffer = terminal.backend().buffer();
+        assert_eq!(left, 4);
+        assert_eq!(buffer[(0, 0)].symbol(), "界");
+        assert_eq!(buffer[(2, 0)].symbol(), "e\u{301}");
+        assert_eq!(buffer[(4, 0)].symbol(), " ");
+        for x in [0, 2, 3, 4] {
+            assert_eq!(buffer[(x, 0)].bg, Color::Blue);
+        }
+        assert_ne!(buffer[(0, 1)].bg, Color::Blue);
+        editor.handle(Input::Escape);
+        terminal
+            .draw(|frame| draw(frame, &editor, &mut top, &mut left))
+            .unwrap();
+        let buffer = terminal.backend().buffer();
+        assert_eq!(buffer[(0, 0)].bg, Color::Yellow);
+        assert_eq!(buffer[(2, 0)].bg, Color::Yellow);
+        assert_ne!(buffer[(3, 0)].bg, Color::Blue);
+        assert_ne!(buffer[(4, 0)].bg, Color::Blue);
+    }
+
     #[test]
     fn active_search_highlight_uses_display_cells_and_clips_with_horizontal_scroll() {
         let mut editor = Editor::open(None, vec![]).unwrap();