Add initial text annotations support

Currently supports putting annotations at EOL and overlaying.

helix-term/src/ui/editor.rs

@@ -16,6 +16,7 @@ use helix_core::{
     LineEnding, Position, Range, Selection,
 };
 use helix_view::{
+    decorations::{TextAnnotation, TextAnnotationKind},
     document::Mode,
     editor::LineNumber,
     graphics::{CursorKind, Modifier, Rect, Style},
@@ -280,6 +281,11 @@ impl EditorView {
         highlights: H,
     ) {
         let text = doc.text().slice(..);
+        let last_line = std::cmp::min(
+            // Saturating subs to make it inclusive zero indexing.
+            (offset.row + viewport.height as usize).saturating_sub(1),
+            doc.text().len_lines().saturating_sub(1),
+        );
 
         let mut spans = Vec::new();
         let mut visual_x = 0u16;
@@ -289,6 +295,33 @@ impl EditorView {
 
         let text_style = theme.get("ui.text");
 
+        let out_of_bounds = |visual_x: u16| {
+            visual_x < offset.col as u16 || visual_x >= viewport.width + offset.col as u16
+        };
+
+        let render_annotation =
+            |annot: &TextAnnotation, line: u16, pos: u16, surface: &mut Surface| {
+                let mut visual_x = pos;
+                for grapheme in annot.text.graphemes(true) {
+                    if out_of_bounds(visual_x) {
+                        break;
+                    }
+                    surface.set_string(
+                        viewport.x + visual_x - offset.col as u16,
+                        viewport.y + line,
+                        grapheme,
+                        annot.style,
+                    );
+                    visual_x = visual_x.saturating_add(grapheme.width() as u16);
+                }
+            };
+
+        let text_annotations = doc
+            .text_annotations()
+            .iter()
+            .filter(|t| (offset.row..last_line).contains(&t.line))
+            .collect::<Vec<_>>();
+
         'outer: for event in highlights {
             match event {
                 HighlightEvent::HighlightStart(span) => {
@@ -311,18 +344,23 @@ impl EditorView {
                     });
 
                     for grapheme in RopeGraphemes::new(text) {
-                        let out_of_bounds = visual_x < offset.col as u16
-                            || visual_x >= viewport.width + offset.col as u16;
-
                         if LineEnding::from_rope_slice(&grapheme).is_some() {
-                            if !out_of_bounds {
+                            if !out_of_bounds(visual_x) {
                                 // we still want to render an empty cell with the style
                                 surface.set_string(
                                     viewport.x + visual_x - offset.col as u16,
                                     viewport.y + line,
                                     " ",
                                     style,
                                 );
+                                visual_x += 1;
+                            }
+
+                            if let Some(annot) = text_annotations
+                                .iter()
+                                .find(|t| t.kind.is_eol() && t.line == offset.row + line as usize)
+                            {
+                                render_annotation(annot, line, visual_x, surface);
                             }
 
                             visual_x = 0;
@@ -345,7 +383,7 @@ impl EditorView {
                                 (grapheme.as_ref(), width)
                             };
 
-                            if !out_of_bounds {
+                            if !out_of_bounds(visual_x) {
                                 // if we're offscreen just keep going until we hit a new line
                                 surface.set_string(
                                     viewport.x + visual_x - offset.col as u16,
@@ -361,6 +399,13 @@ impl EditorView {
                 }
             }
         }
+
+        for annot in &text_annotations {
+            if let TextAnnotationKind::Overlay(visual_x) = annot.kind {
+                let line = (annot.line - offset.row) as u16;
+                render_annotation(annot, line, visual_x as u16, surface);
+            }
+        }
     }
 
     /// Render brace match, etc (meant for the focused view only)
@@ -390,7 +435,6 @@ impl EditorView {
                             .add_modifier(Modifier::REVERSED)
                             .add_modifier(Modifier::DIM)
                     });
-
                     surface
                         .get_mut(viewport.x + pos.col as u16, viewport.y + pos.row as u16)
                         .set_style(style);

helix-view/src/decorations.rs

@@ -0,0 +1,29 @@
+use crate::graphics::Style;
+
+#[derive(Clone, Copy, PartialEq)]
+pub enum TextAnnotationKind {
+    /// Add to end of line
+    Eol,
+    /// Replace actual text or arbitary cells with annotations.
+    /// Specifies an offset from the 0th column.
+    Overlay(usize),
+}
+
+impl TextAnnotationKind {
+    pub fn is_eol(&self) -> bool {
+        *self == Self::Eol
+    }
+
+    pub fn is_overlay(&self) -> bool {
+        matches!(*self, Self::Overlay(_))
+    }
+}
+
+pub struct TextAnnotation {
+    /// String used to namespace and identify similar annotations
+    pub scope: String,
+    pub text: String,
+    pub style: Style,
+    pub line: usize,
+    pub kind: TextAnnotationKind,
+}

helix-view/src/document.rs

@@ -18,7 +18,7 @@ use helix_core::{
 };
 use helix_lsp::util::LspFormatting;
 
-use crate::{DocumentId, Theme, ViewId};
+use crate::{decorations::TextAnnotation, DocumentId, Theme, ViewId};
 
 /// 8kB of buffer space for encoding and decoding `Rope`s.
 const BUF_SIZE: usize = 8192;
@@ -104,6 +104,7 @@ pub struct Document {
     version: i32, // should be usize?
 
     diagnostics: Vec<Diagnostic>,
+    text_annotations: Vec<TextAnnotation>,
     language_server: Option<Arc<helix_lsp::Client>>,
 }
 
@@ -337,6 +338,7 @@ impl Document {
             language: None,
             changes,
             old_state,
+            text_annotations: vec![],
             diagnostics: Vec::new(),
             version: 0,
             history: Cell::new(History::default()),
@@ -896,6 +898,22 @@ impl Document {
             .map(helix_core::path::get_relative_path)
     }
 
+    pub fn text_annotations(&self) -> &[TextAnnotation] {
+        &self.text_annotations
+    }
+
+    pub fn extend_text_annotations(&mut self, annots: Vec<TextAnnotation>) {
+        self.text_annotations.extend(annots)
+    }
+
+    /// Remove annotations that return true for the given predicate
+    pub fn remove_text_annotations<F>(&mut self, predicate: F)
+    where
+        F: Fn(&TextAnnotation) -> bool,
+    {
+        self.text_annotations.retain(|t| !predicate(t))
+    }
+
     // pub fn slice<R>(&self, range: R) -> RopeSlice where R: RangeBounds {
     //     self.state.doc.slice
     // }

helix-view/src/lib.rs

@@ -2,6 +2,7 @@
 pub mod macros;
 
 pub mod clipboard;
+pub mod decorations;
 pub mod document;
 pub mod editor;
 pub mod graphics;