Show LSP diagnostics inline

book/src/configuration.md

@@ -123,6 +123,7 @@ The following statusline elements can be configured:
 | `auto-signature-help` | Enable automatic popup of signature help (parameter hints)  | `true`  |
 | `display-inlay-hints` | Display inlay hints[^2]                                     | `false` |
 | `display-signature-help-docs` | Display docs under signature help popup             | `true`  |
+| `display-inline-diagnostics`  | Display diagnostics under their starting line       | `true`  |
 
 [^1]: By default, a progress spinner is shown in the statusline beside the file path.
 [^2]: You may also have to activate them in the LSP config for them to appear, not just in Helix.

book/src/themes.md

@@ -295,6 +295,7 @@ These scopes are used for theming the editor interface:
 | `ui.text.inactive`                | Same as `ui.text` but when the text is inactive (e.g. suggestions)                             |
 | `ui.text.info`                    | The key: command text in `ui.popup.info` boxes                                                 |
 | `ui.virtual.ruler`                | Ruler columns (see the [`editor.rulers` config][editor-section])                               |
+| `ui.virtual.diagnostics`    | Default style for inline diagnostics lines (notably control the background)                    |
 | `ui.virtual.whitespace`           | Visible whitespace characters                                                                  |
 | `ui.virtual.indent-guide`         | Vertical indent width guides                                                                   |
 | `ui.virtual.inlay-hint`           | Default style for inlay hints of all kinds                                                     |

helix-core/src/diagnostic.rs

@@ -23,6 +23,12 @@ pub struct Range {
     pub end: usize,
 }
 
+impl Range {
+    pub fn contains(self, pos: usize) -> bool {
+        (self.start..self.end).contains(&pos)
+    }
+}
+
 #[derive(Debug, Eq, Hash, PartialEq, Clone, Deserialize, Serialize)]
 pub enum NumberOrString {
     Number(i32),
@@ -47,3 +53,9 @@ pub struct Diagnostic {
     pub source: Option<String>,
     pub data: Option<serde_json::Value>,
 }
+
+impl Diagnostic {
+    pub fn severity(&self) -> Severity {
+        self.severity.unwrap_or(Severity::Warning)
+    }
+}

helix-core/src/graphemes.rs

@@ -28,6 +28,11 @@ pub enum Grapheme<'a> {
 }
 
 impl<'a> Grapheme<'a> {
+    pub fn new_decoration(g: &'static str) -> Grapheme<'a> {
+        assert_ne!(g, "\t");
+        Grapheme::new(g.into(), 0, 0)
+    }
+
     pub fn new(g: GraphemeStr<'a>, visual_x: usize, tab_width: u16) -> Grapheme<'a> {
         match g {
             g if g == "\t" => Grapheme::Tab {

helix-core/src/lib.rs

@@ -97,8 +97,8 @@ pub use {regex, tree_sitter};
 
 pub use graphemes::RopeGraphemes;
 pub use position::{
-    char_idx_at_visual_offset, coords_at_pos, pos_at_coords, visual_offset_from_anchor,
-    visual_offset_from_block, Position, VisualOffsetError,
+    char_idx_at_visual_offset, coords_at_pos, pos_at_coords, softwrapped_dimensions,
+    visual_offset_from_anchor, visual_offset_from_block, Position, VisualOffsetError,
 };
 #[allow(deprecated)]
 pub use position::{pos_at_visual_coords, visual_coords_at_pos};

helix-core/src/position.rs

@@ -135,6 +135,17 @@ pub fn visual_offset_from_block(
     (last_pos, block_start)
 }
 
+/// Returns the height of the given text when softwrapping
+pub fn softwrapped_dimensions(text: RopeSlice, text_fmt: &TextFormat) -> (usize, u16) {
+    let last_pos =
+        visual_offset_from_block(text, 0, usize::MAX, text_fmt, &TextAnnotations::default()).0;
+    if last_pos.row == 0 {
+        (1, last_pos.col as u16)
+    } else {
+        (last_pos.row + 1, text_fmt.viewport_width)
+    }
+}
+
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
 pub enum VisualOffsetError {
     PosBeforeAnchorRow,

helix-term/src/ui/document.rs

@@ -290,6 +290,42 @@ impl<'a> TextRenderer<'a> {
             col_offset,
         }
     }
+    /// Draws a single `grapheme` at the current render position with a specified `style`.
+    pub fn draw_decoration_grapheme(
+        &mut self,
+        grapheme: Grapheme,
+        mut style: Style,
+        row: u16,
+        col: u16,
+    ) -> bool {
+        if row >= self.viewport.height || col >= self.viewport.width {
+            return false;
+        }
+        let is_whitespace = grapheme.is_whitespace();
+
+        // TODO is it correct to apply the whitspace style to all unicode white spaces?
+        if is_whitespace {
+            style = style.patch(self.whitespace_style);
+        }
+
+        let grapheme = match grapheme {
+            Grapheme::Tab { width } => {
+                let grapheme_tab_width = char_to_byte_idx(&self.virtual_tab, width);
+                &self.virtual_tab[..grapheme_tab_width]
+            }
+            Grapheme::Other { ref g } if g == "\u{00A0}" => " ",
+            Grapheme::Other { ref g } => g,
+            Grapheme::Newline => " ",
+        };
+
+        self.surface.set_string(
+            self.viewport.x + col,
+            self.viewport.y + row as u16,
+            grapheme,
+            style,
+        );
+        true
+    }
 
     /// Draws a single `grapheme` at the current render position with a specified `style`.
     pub fn draw_grapheme(

helix-term/src/ui/editor.rs

@@ -6,7 +6,7 @@ use crate::{
     keymap::{KeymapResult, Keymaps},
     ui::{
         document::{render_document, LinePos, TextRenderer},
-        text_decorations::{self, Decoration, DecorationManager},
+        text_decorations::{self, Decoration, DecorationManager, InlineDiagnostics},
         Completion, ProgressSpinners,
     },
 };
@@ -187,17 +187,24 @@ impl EditorView {
             is_focused,
             &mut decorations,
         );
-
+        let primary_cursor = doc
+            .selection(view.id)
+            .primary()
+            .cursor(doc.text().slice(..));
         if is_focused {
             decorations.add_decoration(text_decorations::Cursor {
                 cache: &editor.cursor_cache,
-                primary_cursor: doc
-                    .selection(view.id)
-                    .primary()
-                    .cursor(doc.text().slice(..)),
+                primary_cursor,
             });
         }
-
+        if config.lsp.inline_diagnostics.enable(inner.width) {
+            decorations.add_decoration(InlineDiagnostics::new(
+                doc.diagnostics(),
+                theme,
+                primary_cursor,
+                config.lsp.inline_diagnostics.clone(),
+            ));
+        }
         render_document(
             surface,
             inner,

helix-term/src/ui/text_decorations.rs

@@ -5,6 +5,10 @@ use helix_view::editor::CursorCache;
 
 use crate::ui::document::{LinePos, TextRenderer};
 
+pub use diagnostics::InlineDiagnostics;
+
+mod diagnostics;
+
 /// Decorations are the primary mechanisim for extending the text rendering.
 ///
 /// Any on-screen element which is anchored to the rendered text in some form should
@@ -53,8 +57,8 @@ pub trait Decoration {
         &mut self,
         _renderer: &mut TextRenderer,
         _pos: LinePos,
-        _virt_off: usize,
-    ) -> usize {
+        _virt_off: u16,
+    ) -> u16 {
         0
     }
 
@@ -125,8 +129,11 @@ impl<'a> DecorationManager<'a> {
     }
 
     pub fn render_virtual_lines(&mut self, renderer: &mut TextRenderer, pos: LinePos) {
-        let mut virt_off = 0;
+        let mut virt_off = 1; // start at 1 so the line is never overwritten
         for (decoration, _) in &mut self.decorations {
+            if pos.visual_line + virt_off >= renderer.viewport.height {
+                break;
+            }
             virt_off += decoration.render_virt_lines(renderer, pos, virt_off);
         }
     }