Add rainbow indentation guides

ref: helix-editor#4493

Author: omentic

book/src/configuration.md

@@ -261,11 +261,12 @@ tabpad = "·" # Tabs will look like "→···" (depending on tab width)
 
 Options for rendering vertical indent guides.
 
-| Key           | Description                                             | Default |
-| ---           | ---                                                     | ---     |
-| `render`      | Whether to render indent guides                         | `false` |
-| `character`   | Literal character to use for rendering the indent guide | `│`     |
-| `skip-levels` | Number of indent levels to skip                         | `0`     |
+| Key           | Description                                                             | Default |
+| ---           | ---                                                                     | ---     |
+| `render`      | Whether to render indent indent-guides                                  | `false` |
+| `character`   | Literal character to use for rendering the indent guide                 | `│`     |
+| `skip-levels` | Number of indent levels to skip                                         | `0`     |
+| `rainbow-option` | Enum to set rainbow indentations. Options: `normal`, `dim` and `none`| `none`  |
 
 Example:
 
@@ -274,6 +275,7 @@ Example:
 render = true
 character = "╎" # Some characters that work well: "▏", "┆", "┊", "⸽"
 skip-levels = 1
+rainbow-option = "normal"
 ```
 
 ### `[editor.gutters]` Section

helix-term/src/ui/document.rs

@@ -7,9 +7,9 @@ use helix_core::syntax::Highlight;
 use helix_core::syntax::HighlightEvent;
 use helix_core::text_annotations::TextAnnotations;
 use helix_core::{visual_offset_from_block, Position, RopeSlice};
-use helix_view::editor::{WhitespaceConfig, WhitespaceRenderValue};
+use helix_view::editor::{RainbowIndentOptions, WhitespaceConfig, WhitespaceRenderValue};
 use helix_view::graphics::Rect;
-use helix_view::theme::Style;
+use helix_view::theme::{Modifier, Style};
 use helix_view::view::ViewPosition;
 use helix_view::Document;
 use helix_view::Theme;
@@ -310,6 +310,8 @@ pub struct TextRenderer<'a> {
     pub whitespace_style: Style,
     pub indent_guide_char: String,
     pub indent_guide_style: Style,
+    pub indent_guide_rainbow: RainbowIndentOptions,
+    pub theme: &'a Theme,
     pub newline: String,
     pub nbsp: String,
     pub space: String,
@@ -326,7 +328,7 @@ impl<'a> TextRenderer<'a> {
     pub fn new(
         surface: &'a mut Surface,
         doc: &Document,
-        theme: &Theme,
+        theme: &'a Theme,
         col_offset: usize,
         viewport: Rect,
     ) -> TextRenderer<'a> {
@@ -363,12 +365,19 @@ impl<'a> TextRenderer<'a> {
         };
 
         let text_style = theme.get("ui.text");
+        let basic_style = text_style.patch(
+            theme
+                .try_get("ui.virtual.indent-guide")
+                .unwrap_or_else(|| theme.get("ui.virtual.whitespace")),
+        );
 
         let indent_width = doc.indent_style.indent_width(tab_width) as u16;
 
         TextRenderer {
             surface,
             indent_guide_char: editor_config.indent_guides.character.into(),
+            indent_guide_rainbow: editor_config.indent_guides.rainbow_option.clone(),
+            theme,
             newline,
             nbsp,
             space,
@@ -379,11 +388,7 @@ impl<'a> TextRenderer<'a> {
             starting_indent: col_offset / indent_width as usize
                 + (col_offset % indent_width as usize != 0) as usize
                 + editor_config.indent_guides.skip_levels as usize,
-            indent_guide_style: text_style.patch(
-                theme
-                    .try_get("ui.virtual.indent-guide")
-                    .unwrap_or_else(|| theme.get("ui.virtual.whitespace")),
-            ),
+            indent_guide_style: basic_style,
             text_style,
             draw_indent_guides: editor_config.indent_guides.render,
             viewport,
@@ -477,8 +482,25 @@ impl<'a> TextRenderer<'a> {
                 as u16;
             let y = self.viewport.y + row;
             debug_assert!(self.surface.in_bounds(x, y));
-            self.surface
-                .set_string(x, y, &self.indent_guide_char, self.indent_guide_style);
+            match self.indent_guide_rainbow {
+                RainbowIndentOptions::None => {
+                    self.surface
+                        .set_string(x, y, &self.indent_guide_char, self.indent_guide_style)
+                }
+                RainbowIndentOptions::Dim => {
+                    let new_style = self
+                        .indent_guide_style
+                        .patch(self.theme.get_rainbow(i))
+                        .add_modifier(Modifier::DIM);
+                    self.surface
+                        .set_string(x, y, &self.indent_guide_char, new_style);
+                }
+                RainbowIndentOptions::Normal => {
+                    let new_style = self.indent_guide_style.patch(self.theme.get_rainbow(i));
+                    self.surface
+                        .set_string(x, y, &self.indent_guide_char, new_style);
+                }
+            };
         }
     }
 }

helix-view/src/editor.rs

@@ -743,12 +743,21 @@ impl Default for WhitespaceCharacters {
     }
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub enum RainbowIndentOptions {
+    None,
+    Dim,
+    Normal,
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case")]
 pub struct IndentGuidesConfig {
     pub render: bool,
     pub character: char,
     pub skip_levels: u8,
+    pub rainbow_option: RainbowIndentOptions,
 }
 
 impl Default for IndentGuidesConfig {
@@ -757,6 +766,7 @@ impl Default for IndentGuidesConfig {
             skip_levels: 0,
             render: false,
             character: '│',
+            rainbow_option: RainbowIndentOptions::None,
         }
     }
 }

helix-view/src/theme.rs

@@ -378,6 +378,10 @@ impl Theme {
     pub fn rainbow_length(&self) -> usize {
         self.rainbow_length
     }
+
+    pub fn get_rainbow(&self, index: usize) -> Style {
+        self.highlights[index % self.rainbow_length]
+    }
 }
 
 fn default_rainbow() -> Vec<Style> {