feat(helix-view): dynamic line numbers

helix-view/src/editor.rs

@@ -117,6 +117,10 @@ pub enum LineNumber {
 
     /// Show relative line number to the primary cursor
     Relative,
+
+    /// Show relative line number if focused and in normal/select mode.
+    /// Show absolute line number if unfocused or in insert mode.
+    Dynamic,
 }
 
 impl std::str::FromStr for LineNumber {

helix-view/src/gutter.rs

@@ -58,22 +58,23 @@ pub fn line_number<'doc>(
         .char_to_line(doc.selection(view.id).primary().cursor(text));
 
     let config = config.line_number;
+    let mode = doc.mode;
 
     Box::new(move |line: usize, selected: bool, out: &mut String| {
         if line == last_line && !draw_last {
             write!(out, "{:>1$}", '~', width).unwrap();
             Some(linenr)
         } else {
-            use crate::editor::LineNumber;
-            let line = match config {
-                LineNumber::Absolute => line + 1,
-                LineNumber::Relative => {
-                    if current_line == line {
-                        line + 1
-                    } else {
-                        abs_diff(current_line, line)
-                    }
-                }
+            use crate::{document::Mode, editor::LineNumber};
+            let use_relative = match config {
+                LineNumber::Absolute => false,
+                LineNumber::Relative => current_line != line,
+                LineNumber::Dynamic => current_line != line && is_focused && mode != Mode::Insert,
+            };
+            let line = if use_relative {
+                abs_diff(current_line, line)
+            } else {
+                line + 1
             };
             let style = if selected && is_focused {
                 linenr_select