Add rulers option (#2060)

* Add color_column option

* Rename to ruler

Co-authored-by: DeviousStoat <devious@stoat.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/helix-term/src/ui/editor.rs b/helix-term/src/ui/editor.rs
index 459a8c87..fc8b6470 100644
--- a/helix-term/src/ui/editor.rs
+++ b/helix-term/src/ui/editor.rs
@@ -126,6 +126,7 @@ impl EditorView {
 
         Self::render_text_highlights(doc, view.offset, inner, surface, theme, highlights);
         Self::render_gutter(editor, doc, view, view.area, surface, theme, is_focused);
+        Self::render_rulers(editor, doc, view, inner, surface, theme);
 
         if is_focused {
             Self::render_focused_view_elements(view, doc, inner, theme, surface);
@@ -152,6 +153,32 @@ impl EditorView {
         self.render_statusline(doc, view, statusline_area, surface, theme, is_focused);
     }
 
+    pub fn render_rulers(
+        editor: &Editor,
+        doc: &Document,
+        view: &View,
+        viewport: Rect,
+        surface: &mut Surface,
+        theme: &Theme,
+    ) {
+        let editor_rulers = &editor.config().rulers;
+        let ruler_theme = theme.get("ui.virtual.ruler");
+
+        let rulers = doc
+            .language_config()
+            .and_then(|config| config.rulers.as_ref())
+            .unwrap_or(editor_rulers);
+
+        rulers
+            .iter()
+            // View might be horizontally scrolled, convert from absolute distance
+            // from the 1st column to relative distance from left of viewport
+            .filter_map(|ruler| ruler.checked_sub(1 + view.offset.col as u16))
+            .filter(|ruler| ruler < &viewport.width)
+            .map(|ruler| viewport.clip_left(ruler).with_width(1))
+            .for_each(|area| surface.set_style(area, ruler_theme))
+    }
+
     /// Get syntax highlights for a document in a view represented by the first line
     /// and column (`offset`) and the last line. This is done instead of using a view
     /// directly to enable rendering syntax highlighted docs anywhere (eg. picker preview)