Indent Spectra

Indent Spectra is an indentation highlighter for Visual Studio Code. It colorizes indentation levels to make code structure instantly readable.

It has feature parity with Indent Rainbow, it's just faster, slimmer, modern.

Features

• High Performance: Built with a modernized O(1) rendering engine designed for speed.
• Color Presets: Includes palettes for 'Universal Contrast', Color Blindness (Protanopia/Deuteranopia/Tritanopia), and aesthetic themes.
• Error Highlighting: Highlights lines where indentation does not match the configured tab size.
• Mixed Indent Detection: Detects and highlights lines that mix tabs and spaces.
• Light Mode: Optional subtle line indicators instead of full background blocks.
• Live Configuration: Updates immediately when settings change—no window reload required.

Color Presets

Choose from color palettes designed from first principles using color theory frameworks Okabe-Ito, Temperature Alternation, and Analogous Harmony.

Configuration

Customize Indent Spectra in your settings.json or via the Settings UI:

// Choose a preset palette
"indentSpectra.colorPreset": "universal",

// OR use custom colors (requires preset set to 'custom')
"indentSpectra.colors": [
    "rgba(255, 215, 0, 0.15)",
    "rgba(65, 105, 225, 0.15)",
    "rgba(255, 105, 180, 0.15)",
    "rgba(0, 255, 255, 0.15)"
],

// Render style: 'classic' (block) or 'light' (thin line)
"indentSpectra.indicatorStyle": "classic",

// Color for indentation errors
"indentSpectra.errorColor": "rgba(200, 50, 50, 0.5)",

// Color for mixed tabs/spaces
"indentSpectra.mixColor": "rgba(150, 50, 150, 0.6)",

// Delay in ms before updating (debouncing)
"indentSpectra.updateDelay": 100

Requirements

VS Code 1.106.0+. Probably works on previous versions, but not tested.

Acknowledgements

Inspired by indent-rainbow.

Comparison with Indent Rainbow

For starters, it's lightweight: Indent Spectra install file = 18 KB, Indent Rainbow = 8.45 MB. Not a typo: 18 KB vs 8,450 KB.

1. Performance, Efficiency

The rendering engine was rewritten from scratch to handle large files without slowing down the editor.

• O(1) vs O(N) Lookups: The original extension uses Array.indexOf inside the main rendering loop to check for ignored lines, leading to quadratic complexity. Indent Spectra uses Set lookups (O(1)), making it instantaneously fast regardless of file size.
• Memory Management: Reduced Garbage Collection pressure by reusing RegExp objects and avoiding unnecessary string splitting/array allocations during the render loop.
• Smart Debouncing: Implemented input debouncing to prevent the extension from trying to render every single keystroke during rapid typing.

2. Accessibility, Color Theory

Rainbow uses a standard spectrum where adjacent colors (like Green and Cyan) blend together for many people.

• Interleaved Contrast: Instead of a gradient, Spectra alternates Warm (Gold, Pink) and Cool (Blue, Cyan) colors. This maximizes the "visual distance" between indentation levels.
• Accessibility Presets: Includes built-in palettes designed for Color Vision Deficiencies (Protanopia, Deuteranopia, and Tritanopia) based on the Okabe-Ito standard.

3. UX

• Live Configuration: Changing settings (colors, tab size, styles) updates the editor instantly. Rainbow requires a full window reload to apply settings.
• Web Native: Configured to run in VS Code for the Web (github.dev, vscode.dev) with virtualWorkspaces support enabled in the manifest.

4. Code Quality & Maintenance

• Strict Typing: TypeScript 5.9 / strict: true. Rainbow relies on loose var declarations and implicit any types.
• Modern Architecture: Clean class structure (IndentSpectra.ts) with proper lifecycle management (dispose patterns), so easier to maintain and less prone to memory leaks.

Summary Table

License

MIT