Implements modern wide gamut color formats with CSS Color Module Level 4
gamut mapping, addressing PR feedback with Go implementation, performance
benchmarks, and reorganized documentation.
Features:
- OKLCH (perceptually uniform color space)
- CIE LAB (device-independent color space)
- CSS Color 4 compliant gamut mapping algorithm
- Inline comment support in color config parsing
Addressing PR Feedback:
1. Go Implementation (tools/utils/style/):
- Complete OKLCH and LAB parsing with gamut mapping
- Matches Python implementation structure
- Comprehensive test suite (all tests passing)
- Performance benchmarks showing acceptable overhead
2. Performance Benchmarks:
- OKLCH: ~4.6 µs/op
- LAB: ~1.5 µs/op
- 10 mixed colors: ~13 µs total
- Typical config (50 colors): <0.5ms startup impact
3. Documentation Reorganization:
- Moved detailed color docs to docs/wide-gamut-colors.rst
- Configuration docs now link to separate documentation
- Reduces size of main configuration documentation
Gamut Mapping:
- Binary search chroma reduction from CSS Color Module Level 4
- Preserves lightness and hue while reducing chroma for out-of-gamut colors
- Uses deltaE OK (JND threshold: 0.02) for perceptual difference
- Ensures graceful degradation on sRGB displays
Python Implementation:
- parse_oklch(): OKLCH color parsing with gamut mapping
- parse_lab(): CIE LAB parsing with gamut mapping via OKLCH conversion
- lab_to_oklch(): LAB to OKLCH conversion for consistent gamut mapping
- oklch_to_srgb_gamut_map(): CSS Color 4 gamut mapping algorithm
- srgb_to_oklab(): Reverse conversion for deltaE calculations
- deltaE_ok(): Perceptual color difference in OKLab space
Go Implementation:
- colorspaces.go: All color space conversions and gamut mapping
- wrapper.go: ParseColor() updated to support OKLCH and LAB
- Comprehensive test coverage with benchmarks
- Matches Python implementation behavior
Robustness:
- NaN and infinity validation in all color parsing functions
- Defense-in-depth with validation at parsing and gamut mapping levels
- Returns None/error for invalid input (consistent error handling)
- Validates before clamping operations to prevent NaN propagation
Files changed:
- Python: kitty/rgb.py, kitty_tests/datatypes.py (+250 lines)
- Go: tools/utils/style/colorspaces.go, wrapper.go (+350 lines, tests)
- Docs: docs/wide-gamut-colors.rst (moved from inline)
- Config: kitty/options/definition.py (simplified, links to docs)
References:
- CSS Color Module Level 4: https://www.w3.org/TR/css-color-4/
- OKLCH Color Space: https://bottosson.github.io/posts/oklab/🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
This was needed to fix various corner cases when doing blending of colors
in linear space. The new architecture has the same performance as the
old in the common case of opaque rendering with no UI layers or images.
In the case of only positive z-index images there is a performance
decrease as the OS Window is now rendered to a offscreen texture and
then blitted to screen. However, in the future when we move to Vulkan or
I can figure out how to get Wayland to accept buffers with colors in
linear space, this performance penalty can be removed. The performance
penalty was not significant on my system but this is highly GPU
dependent. Modern GPUs are supposedly optimised for rendering to
offscreen buffers, so we will see. The awrit project might be a good
test case.
Now either we have 1-shot rendering for the case of opaque with only ext
or all the various pieces are rendered in successive draw calls into an
offscreen buffer that is blitted to the output buffer after all drawing
is done.
Fixes#8869
Now we do the rewrap of history and line buffers together. This is
faster and deals with multiline chars split between the two buffers
correctly. Also, considerably simpler code.
Follow PEP 0394 and use /usr/bin/env python so that the python in the
users venv is respected. Not that the kitty python files are meant to be
executed standalone anyway, but, whatever.
Fixes#6810
This allows us to have newline not affect the wrap status of a line.
Now a lines wrapping status is changed only when the last cell
in the line is changed. This actually matches the behavior of many other
terminal emulators so is probably a good thing from a ecosystem
compatibility perspective.
The fish shell expects this weird behavior of newline not changing
wrapping status, for unknown reasons, which is the actual motivation for
doing all this work.
Fixes#5766
