Dynamically resize line number gutter width (helix-editor#3469)

* dynamically resize line number gutter width

* removing digits lower-bound, permitting spacer

* removing max line num char limit; adding notes; qualified successors; notes

* updating tests to use new line number width when testing views

* linenr width based on document line count

* using min width of 2 so line numbers relative is useful

* lint rolling; removing unnecessary type parameter lifetime

* merge change resolution

* reformat code

* rename row_styler to style; add int_log resource

* adding spacer to gutters default; updating book config entry

* adding view.inner_height(), swap for loop for iterator

* reverting change of current! to view! now that doc is not needed

book/src/configuration.md

@@ -46,7 +46,7 @@ on unix operating systems.
 | `line-number` | Line number display: `absolute` simply shows each line's number, while `relative` shows the distance from the current line. When unfocused or in insert mode, `relative` will still show absolute line numbers. | `absolute` |
 | `cursorline` | Highlight all lines with a cursor. | `false` |
 | `cursorcolumn` | Highlight all columns with a cursor. | `false` |
-| `gutters` | Gutters to display: Available are `diagnostics` and `line-numbers` and `spacer`, note that `diagnostics` also includes other features like breakpoints, 1-width padding will be inserted if gutters is non-empty | `["diagnostics", "line-numbers"]` |
+| `gutters` | Gutters to display: Available are `diagnostics` and `line-numbers` and `spacer`, note that `diagnostics` also includes other features like breakpoints, 1-width padding will be inserted if gutters is non-empty | `["diagnostics", "spacer", "line-numbers"]` |
 | `auto-completion` | Enable automatic pop up of auto-completion. | `true` |
 | `auto-format` | Enable automatic formatting on save. | `true` |
 | `auto-save` | Enable automatic saving on focus moving away from Helix. Requires [focus event support](https://github.com/helix-editor/helix/wiki/Terminal-Support) from your terminal. | `false` |

helix-term/src/commands.rs

@@ -870,7 +870,7 @@ fn goto_window(cx: &mut Context, align: Align) {
     let config = cx.editor.config();
     let (view, doc) = current!(cx.editor);
 
-    let height = view.inner_area().height as usize;
+    let height = view.inner_height();
 
     // respect user given count if any
     // - 1 so we have at least one gap in the middle.
@@ -1372,9 +1372,9 @@ pub fn scroll(cx: &mut Context, offset: usize, direction: Direction) {
         return;
     }
 
-    let height = view.inner_area().height;
+    let height = view.inner_height();
 
-    let scrolloff = config.scrolloff.min(height as usize / 2);
+    let scrolloff = config.scrolloff.min(height / 2);
 
     view.offset.row = match direction {
         Forward => view.offset.row + offset,
@@ -1412,25 +1412,25 @@ pub fn scroll(cx: &mut Context, offset: usize, direction: Direction) {
 
 fn page_up(cx: &mut Context) {
     let view = view!(cx.editor);
-    let offset = view.inner_area().height as usize;
+    let offset = view.inner_height();
     scroll(cx, offset, Direction::Backward);
 }
 
 fn page_down(cx: &mut Context) {
     let view = view!(cx.editor);
-    let offset = view.inner_area().height as usize;
+    let offset = view.inner_height();
     scroll(cx, offset, Direction::Forward);
 }
 
 fn half_page_up(cx: &mut Context) {
     let view = view!(cx.editor);
-    let offset = view.inner_area().height as usize / 2;
+    let offset = view.inner_height() / 2;
     scroll(cx, offset, Direction::Backward);
 }
 
 fn half_page_down(cx: &mut Context) {
     let view = view!(cx.editor);
-    let offset = view.inner_area().height as usize / 2;
+    let offset = view.inner_height() / 2;
     scroll(cx, offset, Direction::Forward);
 }
 
@@ -4342,7 +4342,7 @@ fn align_view_middle(cx: &mut Context) {
 
     view.offset.col = pos
         .col
-        .saturating_sub((view.inner_area().width as usize) / 2);
+        .saturating_sub((view.inner_area(doc).width as usize) / 2);
 }
 
 fn scroll_up(cx: &mut Context) {

helix-term/src/ui/editor.rs

@@ -79,7 +79,7 @@ impl EditorView {
         surface: &mut Surface,
         is_focused: bool,
     ) {
-        let inner = view.inner_area();
+        let inner = view.inner_area(doc);
         let area = view.area;
         let theme = &editor.theme;
 
@@ -736,9 +736,10 @@ impl EditorView {
         // avoid lots of small allocations by reusing a text buffer for each line
         let mut text = String::with_capacity(8);
 
-        for (constructor, width) in view.gutters() {
-            let gutter = constructor(editor, doc, view, theme, is_focused, *width);
-            text.reserve(*width); // ensure there's enough space for the gutter
+        for gutter_type in view.gutters() {
+            let gutter = gutter_type.style(editor, doc, view, theme, is_focused);
+            let width = gutter_type.width(view, doc);
+            text.reserve(width); // ensure there's enough space for the gutter
             for (i, line) in (view.offset.row..(last_line + 1)).enumerate() {
                 let selected = cursors.contains(&line);
                 let x = viewport.x + offset;
@@ -751,13 +752,13 @@ impl EditorView {
                 };
 
                 if let Some(style) = gutter(line, selected, &mut text) {
-                    surface.set_stringn(x, y, &text, *width, gutter_style.patch(style));
+                    surface.set_stringn(x, y, &text, width, gutter_style.patch(style));
                 } else {
                     surface.set_style(
                         Rect {
                             x,
                             y,
-                            width: *width as u16,
+                            width: width as u16,
                             height: 1,
                         },
                         gutter_style,
@@ -766,7 +767,7 @@ impl EditorView {
                 text.clear();
             }
 
-            offset += *width as u16;
+            offset += width as u16;
         }
     }
 
@@ -882,7 +883,7 @@ impl EditorView {
             .or_else(|| theme.try_get_exact("ui.cursorcolumn"))
             .unwrap_or_else(|| theme.get("ui.cursorline.secondary"));
 
-        let inner_area = view.inner_area();
+        let inner_area = view.inner_area(doc);
         let offset = view.offset.col;
 
         let selection = doc.selection(view.id);

helix-view/src/editor.rs

@@ -456,6 +456,7 @@ impl std::str::FromStr for GutterType {
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         match s.to_lowercase().as_str() {
             "diagnostics" => Ok(Self::Diagnostics),
+            "spacer" => Ok(Self::Spacer),
             "line-numbers" => Ok(Self::LineNumbers),
             _ => anyhow::bail!("Gutter type can only be `diagnostics` or `line-numbers`."),
         }
@@ -589,7 +590,11 @@ impl Default for Config {
             line_number: LineNumber::Absolute,
             cursorline: false,
             cursorcolumn: false,
-            gutters: vec![GutterType::Diagnostics, GutterType::LineNumbers],
+            gutters: vec![
+                GutterType::Diagnostics,
+                GutterType::Spacer,
+                GutterType::LineNumbers,
+            ],
             middle_click_paste: true,
             auto_pairs: AutoPairConfig::default(),
             auto_completion: true,
@@ -1308,7 +1313,7 @@ impl Editor {
             .primary()
             .cursor(doc.text().slice(..));
         if let Some(mut pos) = view.screen_coords_at_pos(doc, doc.text().slice(..), cursor) {
-            let inner = view.inner_area();
+            let inner = view.inner_area(doc);
             pos.col += inner.x as usize;
             pos.row += inner.y as usize;
             let cursorkind = config.cursor_shape.from_mode(self.mode);

helix-view/src/gutter.rs

@@ -1,21 +1,54 @@
 use std::fmt::Write;
 
 use crate::{
+    editor::GutterType,
     graphics::{Color, Style, UnderlineStyle},
     Document, Editor, Theme, View,
 };
 
+fn count_digits(n: usize) -> usize {
+    // NOTE: if int_log gets standardized in stdlib, can use checked_log10
+    // (https://github.com/rust-lang/rust/issues/70887#issue)
+    std::iter::successors(Some(n), |&n| (n >= 10).then(|| n / 10)).count()
+}
+
 pub type GutterFn<'doc> = Box<dyn Fn(usize, bool, &mut String) -> Option<Style> + 'doc>;
 pub type Gutter =
     for<'doc> fn(&'doc Editor, &'doc Document, &View, &Theme, bool, usize) -> GutterFn<'doc>;
 
+impl GutterType {
+    pub fn style<'doc>(
+        self,
+        editor: &'doc Editor,
+        doc: &'doc Document,
+        view: &View,
+        theme: &Theme,
+        is_focused: bool,
+    ) -> GutterFn<'doc> {
+        match self {
+            GutterType::Diagnostics => {
+                diagnostics_or_breakpoints(editor, doc, view, theme, is_focused)
+            }
+            GutterType::LineNumbers => line_numbers(editor, doc, view, theme, is_focused),
+            GutterType::Spacer => padding(editor, doc, view, theme, is_focused),
+        }
+    }
+
+    pub fn width(self, _view: &View, doc: &Document) -> usize {
+        match self {
+            GutterType::Diagnostics => 1,
+            GutterType::LineNumbers => line_numbers_width(_view, doc),
+            GutterType::Spacer => 1,
+        }
+    }
+}
+
 pub fn diagnostic<'doc>(
     _editor: &'doc Editor,
     doc: &'doc Document,
     _view: &View,
     theme: &Theme,
     _is_focused: bool,
-    _width: usize,
 ) -> GutterFn<'doc> {
     let warning = theme.get("warning");
     let error = theme.get("error");
@@ -56,10 +89,11 @@ pub fn line_numbers<'doc>(
     view: &View,
     theme: &Theme,
     is_focused: bool,
-    width: usize,
 ) -> GutterFn<'doc> {
     let text = doc.text().slice(..);
     let last_line = view.last_line(doc);
+    let width = GutterType::LineNumbers.width(view, 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();
@@ -91,24 +125,35 @@ pub fn line_numbers<'doc>(
             } else {
                 line + 1
             };
+
             let style = if selected && is_focused {
                 linenr_select
             } else {
                 linenr
             };
+
             write!(out, "{:>1$}", display_num, width).unwrap();
             Some(style)
         }
     })
 }
 
+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 };
+
+    // set a lower bound to 2-chars to minimize ambiguous relative line numbers
+    std::cmp::max(count_digits(last_drawn), 2)
+}
+
 pub fn padding<'doc>(
     _editor: &'doc Editor,
     _doc: &'doc Document,
     _view: &View,
     _theme: &Theme,
     _is_focused: bool,
-    _width: usize,
 ) -> GutterFn<'doc> {
     Box::new(|_line: usize, _selected: bool, _out: &mut String| None)
 }
@@ -128,7 +173,6 @@ pub fn breakpoints<'doc>(
     _view: &View,
     theme: &Theme,
     _is_focused: bool,
-    _width: usize,
 ) -> GutterFn<'doc> {
     let warning = theme.get("warning");
     let error = theme.get("error");
@@ -181,10 +225,9 @@ pub fn diagnostics_or_breakpoints<'doc>(
     view: &View,
     theme: &Theme,
     is_focused: bool,
-    width: usize,
 ) -> GutterFn<'doc> {
-    let diagnostics = diagnostic(editor, doc, view, theme, is_focused, width);
-    let breakpoints = breakpoints(editor, doc, view, theme, is_focused, width);
+    let diagnostics = diagnostic(editor, doc, view, theme, is_focused);
+    let breakpoints = breakpoints(editor, doc, view, theme, is_focused);
 
     Box::new(move |line, selected, out| {
         breakpoints(line, selected, out).or_else(|| diagnostics(line, selected, out))

helix-view/src/lib.rs

@@ -55,7 +55,7 @@ pub fn align_view(doc: &Document, view: &mut View, align: Align) {
         .cursor(doc.text().slice(..));
     let line = doc.text().char_to_line(pos);
 
-    let last_line_height = view.inner_area().height.saturating_sub(1) as usize;
+    let last_line_height = view.inner_height().saturating_sub(1);
 
     let relative = match align {
         Align::Center => last_line_height / 2,

helix-view/src/tree.rs

@@ -499,7 +499,7 @@ impl Tree {
                     // in a vertical container (and already correct based on previous search)
                     child_id = *container.children.iter().min_by_key(|id| {
                         let x = match &self.nodes[**id].content {
-                            Content::View(view) => view.inner_area().left(),
+                            Content::View(view) => view.area.left(),
                             Content::Container(container) => container.area.left(),
                         };
                         (current_x as i16 - x as i16).abs()
@@ -510,7 +510,7 @@ impl Tree {
                     // in a horizontal container (and already correct based on previous search)
                     child_id = *container.children.iter().min_by_key(|id| {
                         let y = match &self.nodes[**id].content {
-                            Content::View(view) => view.inner_area().top(),
+                            Content::View(view) => view.area.top(),
                             Content::Container(container) => container.area.top(),
                         };
                         (current_y as i16 - y as i16).abs()