Highlights C/C++ #if / #ifdef / #ifndef … #endif blocks with layered,
translucent backgrounds. Each nesting depth gets its own color, and because the
fills are semi-transparent, nested blocks visually stack and deepen — making it
easy to track where a block begins and ends even when they're deeply nested.
Features
Colors every preprocessor block by nesting depth (not just inactive branches).
Colors loop, so depth 6 reuses the depth-1 color, etc.
Status bar button to toggle highlighting on/off at any time.
Runs only for C / C++ files (c, cpp language IDs → .c, .cpp, .h, .hpp, …).
Fully configurable colors and per-layer alpha.
Settings
Setting
Default
Description
preprocessorRainbow.enabled
true
Master on/off (also toggled from the status bar).
preprocessorRainbow.colors
Paul Tol bright palette (5 colors)
Hex colors looped over per depth.
preprocessorRainbow.alphas
[0.12 × 5]
Per-layer alpha (0–1). Last value reused if shorter than colors.
preprocessorRainbow.maxDepth
24
Safety cap on nesting depth processed.
Default palette (color-blind friendly)
The defaults use the Paul Tol bright qualitative palette,
chosen specifically to remain distinguishable for the common forms of color
vision deficiency:
Depth
Color
1
#4477AA (blue)
2
#EE6677 (red)
3
#228833 (green)
4
#CCBB44 (yellow)
5
#AA3377 (purple)
Develop / run locally
npm install
npm run compile
Then press F5 in the editor (uses .vscode/launch.json) to launch an
Extension Development Host with the extension loaded. Open any .hpp/.cpp
file containing #if blocks to see it in action, and click the status bar
button (bottom right) to toggle.
Notes / limitations
Directives are matched even when indented.
Unbalanced #endif directives are skipped gracefully.
#if appearing inside comments or string literals is not currently excluded
(a simple line-based parser is used for speed).
