Add configuration for min width of line-numbers gutter

helix-view/src/editor.rs

@@ -130,6 +130,10 @@ pub struct Config {
     pub cursorcolumn: bool,
     /// Gutters. Default ["diagnostics", "line-numbers"]
     pub gutters: Vec<GutterType>,
+    /// Minimum number of characters to display as part of line number gutter. Defaults to 2.
+    pub line_numbers_width_min: usize,
+    /// Maximum number of characters to display as part of line number gutter, or 0 for no maximum. Defaults to 0 (no maximum).
+    pub line_numbers_width_max: usize,
     /// Middle click paste support. Defaults to true.
     pub middle_click_paste: bool,
     /// Automatic insertion of pairs to parentheses, brackets,
@@ -595,6 +599,8 @@ impl Default for Config {
                 GutterType::Spacer,
                 GutterType::LineNumbers,
             ],
+            line_numbers_width_min: 2,
+            line_numbers_width_max: 0, // unlimited
             middle_click_paste: true,
             auto_pairs: AutoPairConfig::default(),
             auto_completion: true,
@@ -1039,7 +1045,14 @@ impl Editor {
                     .try_get(self.tree.focus)
                     .filter(|v| id == v.doc) // Different Document
                     .cloned()
-                    .unwrap_or_else(|| View::new(id, self.config().gutters.clone()));
+                    .unwrap_or_else(|| {
+                        View::new(
+                            id,
+                            self.config().gutters.clone(),
+                            self.config().line_numbers_width_min,
+                            self.config().line_numbers_width_max,
+                        )
+                    });
                 let view_id = self.tree.split(
                     view,
                     match action {
@@ -1182,7 +1195,12 @@ impl Editor {
                 .map(|(&doc_id, _)| doc_id)
                 .next()
                 .unwrap_or_else(|| self.new_document(Document::default()));
-            let view = View::new(doc_id, self.config().gutters.clone());
+            let view = View::new(
+                doc_id,
+                self.config().gutters.clone(),
+                self.config().line_numbers_width_min,
+                self.config().line_numbers_width_max,
+            );
             let view_id = self.tree.insert(view);
             let doc = doc_mut!(self, &doc_id);
             doc.ensure_view_init(view_id);

helix-view/src/gutter.rs

@@ -1,3 +1,4 @@
+use std::cmp::{max, min};
 use std::fmt::Write;
 
 use crate::{
@@ -90,13 +91,22 @@ pub fn line_numbers<'doc>(
     theme: &Theme,
     is_focused: bool,
 ) -> GutterFn<'doc> {
+    const ELLIPSIS: &str = "\u{2026}";
+
     let text = doc.text().slice(..);
-    let last_line = view.last_line(doc);
-    let width = GutterType::LineNumbers.width(view, doc);
+
+    let last_line = text.len_lines().saturating_sub(1);
+    let last_line_in_view = view.last_line(doc);
 
     // Whether to draw the line number for the last line of the
     // 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 draw_last = text.line_to_byte(last_line_in_view) < text.len_bytes();
+    let last_drawn_line = if draw_last { last_line + 1 } else { last_line };
+
+    // characters used to display last line, and settings for min/max
+    let n_last_line = count_digits(last_drawn_line);
+    let n_min = editor.config().line_numbers_width_min;
+    let n_max = editor.config().line_numbers_width_max;
 
     let linenr = theme.get("ui.linenr");
     let linenr_select = theme.get("ui.linenr.selected");
@@ -109,7 +119,8 @@ pub fn line_numbers<'doc>(
     let mode = editor.mode;
 
     Box::new(move |line: usize, selected: bool, out: &mut String| {
-        if line == last_line && !draw_last {
+        if line == last_line_in_view && !draw_last {
+            let width = clamp_line_numbers_width(n_last_line, n_min, n_max);
             write!(out, "{:>1$}", '~', width).unwrap();
             Some(linenr)
         } else {
@@ -132,20 +143,52 @@ pub fn line_numbers<'doc>(
                 linenr
             };
 
-            write!(out, "{:>1$}", display_num, width).unwrap();
+            let n_display = count_digits(display_num);
+            if n_max > 0 && n_display > n_max {
+                let display_num_trunc = display_num % (10 as usize).pow(n_max as u32);
+                write!(out, "{}{1:0>2$}", ELLIPSIS, display_num_trunc, n_max - 1).unwrap();
+            } else {
+                let width = clamp_line_numbers_width(n_last_line, n_min, n_max);
+                write!(out, "{:>1$}", display_num, width).unwrap();
+            }
+
             Some(style)
         }
     })
 }
 
-pub fn line_numbers_width(_view: &View, doc: &Document) -> usize {
+/// Clamp a line number width between a lower and upper bound
+///
+/// However, an upper bound of `0` is treated as having no maximum
+#[inline(always)]
+fn clamp_line_numbers_width(x: usize, lb: usize, ub: usize) -> usize {
+    if ub == 0 {
+        min(max(x, lb), ub)
+    } else {
+        max(x, lb)
+    }
+}
+
+/// The width of a "line-numbers" gutter
+///
+/// The width of the gutter depends on the number of lines in the document,
+/// whether there is content on the last line (the `~` line), and the `line-
+/// numbers-width-min` & `line-numbers-width-max` settings.
+pub fn line_numbers_width(view: &View, doc: &Document) -> usize {
     let text = doc.text();
     let last_line = text.len_lines().saturating_sub(1);
     let draw_last = text.line_to_byte(last_line) < text.len_bytes();
     let last_drawn = if draw_last { last_line + 1 } else { last_line };
+    let digits = count_digits(last_drawn);
+
+    let n_min = view.gutter_line_numbers_width_min;
+    let n_max = view.gutter_line_numbers_width_max;
 
-    // set a lower bound to 2-chars to minimize ambiguous relative line numbers
-    std::cmp::max(count_digits(last_drawn), 2)
+    if n_max > 0 {
+        min(max(digits, n_min), n_max)
+    } else {
+        max(digits, n_min)
+    }
 }
 
 pub fn padding<'doc>(

helix-view/src/view.rs

@@ -96,6 +96,9 @@ pub struct View {
     pub object_selections: Vec<Selection>,
     /// GutterTypes used to fetch Gutter (constructor) and width for rendering
     gutters: Vec<GutterType>,
+    /// Relevant gutter config settings
+    pub gutter_line_numbers_width_min: usize,
+    pub gutter_line_numbers_width_max: usize,
 }
 
 impl fmt::Debug for View {
@@ -109,7 +112,12 @@ impl fmt::Debug for View {
 }
 
 impl View {
-    pub fn new(doc: DocumentId, gutter_types: Vec<crate::editor::GutterType>) -> Self {
+    pub fn new(
+        doc: DocumentId,
+        gutter_types: Vec<crate::editor::GutterType>,
+        gutter_line_numbers_width_min: usize,
+        gutter_line_numbers_width_max: usize,
+    ) -> Self {
         Self {
             id: ViewId::default(),
             doc,
@@ -120,6 +128,8 @@ impl View {
             last_modified_docs: [None, None],
             object_selections: Vec::new(),
             gutters: gutter_types,
+            gutter_line_numbers_width_min,
+            gutter_line_numbers_width_max,
         }
     }
 
@@ -364,6 +374,8 @@ mod tests {
         let mut view = View::new(
             DocumentId::default(),
             vec![GutterType::Diagnostics, GutterType::LineNumbers],
+            2,
+            5,
         );
         view.area = Rect::new(40, 40, 40, 40);
         let rope = Rope::from_str("abc\n\tdef");
@@ -473,7 +485,7 @@ mod tests {
     fn test_text_pos_at_screen_coords_graphemes() {
         let mut view = View::new(
             DocumentId::default(),
-            vec![GutterType::Diagnostics, GutterType::LineNumbers],
+            vec![GutterType::Diagnostics, GutterType::LineNumbers, 2, 4],
         );
         view.area = Rect::new(40, 40, 40, 40);
         let rope = Rope::from_str("Hèl̀l̀ò world!");