feat: relative numbers

helix-term/src/ui/editor.rs

@@ -17,6 +17,7 @@ use helix_core::{
 };
 use helix_view::{
     document::Mode,
+    editor::LineNumber,
     graphics::{CursorKind, Modifier, Rect, Style},
     info::Info,
     input::KeyEvent,
@@ -71,6 +72,7 @@ impl EditorView {
         theme: &Theme,
         is_focused: bool,
         loader: &syntax::Loader,
+        config: &helix_view::editor::Config,
     ) {
         let area = Rect::new(
             view.area.x + GUTTER_OFFSET,
@@ -79,7 +81,7 @@ impl EditorView {
             view.area.height.saturating_sub(1),
         ); // - 1 for statusline
 
-        self.render_buffer(doc, view, area, surface, theme, is_focused, loader);
+        self.render_buffer(doc, view, area, surface, theme, is_focused, loader, config);
 
         // if we're not at the edge of the screen, draw a right border
         if viewport.right() != view.area.right() {
@@ -115,6 +117,7 @@ impl EditorView {
         theme: &Theme,
         is_focused: bool,
         loader: &syntax::Loader,
+        config: &helix_view::editor::Config,
     ) {
         let text = doc.text().slice(..);
 
@@ -336,6 +339,7 @@ impl EditorView {
         // document or not.  We only draw it if it's not an empty line.
         let draw_last = text.line_to_byte(last_line) < text.len_bytes();
 
+        let current_line = doc.text().char_to_line(selections.primary().anchor);
         for (i, line) in (view.first_line..(last_line + 1)).enumerate() {
             use helix_core::diagnostic::Severity;
             if let Some(diagnostic) = doc.diagnostics().iter().find(|d| d.line == line) {
@@ -358,7 +362,13 @@ impl EditorView {
             let line_number_text = if line == last_line && !draw_last {
                 "    ~".into()
             } else {
-                format!("{:>5}", line + 1)
+                match config.line_number {
+                    LineNumber::Absolute => format!("{:>5}", line + 1),
+                    LineNumber::Relative => {
+                        let relative_line = abs_diff(current_line, line);
+                        format!("{:>5}", relative_line)
+                    }
+                }
             };
             surface.set_stringn(
                 viewport.x + 1 - GUTTER_OFFSET,
@@ -925,6 +935,7 @@ impl Component for EditorView {
                 &cx.editor.theme,
                 is_focused,
                 loader,
+                &cx.editor.config,
             );
         }
 
@@ -998,3 +1009,12 @@ fn canonicalize_key(key: &mut KeyEvent) {
         key.modifiers.remove(KeyModifiers::SHIFT)
     }
 }
+
+#[inline]
+fn abs_diff(a: usize, b: usize) -> usize {
+    if a > b {
+        a - b
+    } else {
+        b - a
+    }
+}

helix-view/src/editor.rs

@@ -29,6 +29,18 @@ pub struct Config {
     pub scroll_lines: isize,
     /// Mouse support. Defaults to true.
     pub mouse: bool,
+    /// Line number mode.
+    pub line_number: LineNumber,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub enum LineNumber {
+    /// Show absolute line number
+    Absolute,
+
+    /// Show relative line number to the primary cursor
+    Relative,
 }
 
 impl Default for Config {
@@ -37,6 +49,7 @@ impl Default for Config {
             scrolloff: 5,
             scroll_lines: 3,
             mouse: true,
+            line_number: LineNumber::Absolute,
         }
     }
 }