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Add wide gamut color support with OKLCH and LAB formats

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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 commit is contained in:
Jökull Sólberg
2025-12-25 15:36:23 +00:00
parent 0fb54d32b1
commit 64abd87a9e
8 changed files with 1269 additions and 1 deletions
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185
kitty_tests/datatypes.py
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@@ -77,6 +77,14 @@ class TestDataTypes(BaseTest):
c('rgb:23/45/67', 0x23, 0x45, 0x67)
c('rgb:abc/abc/def', 0xab, 0xab, 0xde)
c('red', 0xff)
# Wide gamut color formats
c('oklch(0.7 0.15 140)', 0x67, 0xb4, 0x56) # OKLCH green
c('oklch(0.9 0.05 265)', 0xcd, 0xde, 0xfe) # OKLCH light blue
c('p3(1.0 0.0 0.0)', 0xfe, 0x00, 0x00) # Display P3 red
c('color(display-p3 0.0 1.0 0.0)', 0x00, 0xfe, 0x00) # CSS P3 green
c('lab(70 50 -30)', 0xea, 0x88, 0xe2) # CIE LAB purple-ish
self.ae(int(Color(1, 2, 3)), 0x10203)
base = Color(12, 12, 12)
a = Color(23, 23, 23)
@@ -87,6 +95,183 @@ class TestDataTypes(BaseTest):
self.ae(Color(1, 2, 3, 4).as_sharp, '#04010203')
self.ae(Color(1, 2, 3, 4).rgb, 0x10203)
def test_oklch_gamut_mapping(self):
"""Test OKLCH color format with CSS Color 4 gamut mapping"""
def c(spec, r=0, g=0, b=0):
color = to_color(spec)
self.assertIsNotNone(color, f'Failed to parse: {spec}')
self.ae(color.red, r)
self.ae(color.green, g)
self.ae(color.blue, b)
def in_range(spec):
"""Verify color values are in valid 0-255 range"""
color = to_color(spec)
self.assertIsNotNone(color, f'Failed to parse: {spec}')
self.assertTrue(0 <= color.red <= 255, f'Red out of range: {color.red}')
self.assertTrue(0 <= color.green <= 255, f'Green out of range: {color.green}')
self.assertTrue(0 <= color.blue <= 255, f'Blue out of range: {color.blue}')
return color
# In-gamut colors should parse unchanged
c('oklch(0.5 0.1 180)', 0x00, 0x75, 0x65) # Mid-tone cyan with moderate chroma
# Out-of-gamut colors should be mapped to sRGB gamut
# High chroma red - should be mapped but remain reddish
color = in_range('oklch(0.7 0.35 25)')
self.assertGreater(color.red, 200, 'High chroma red should have high red component')
self.assertLess(color.green, 100, 'High chroma red should have low green component')
# Edge cases
c('oklch(0 0 0)', 0x00, 0x00, 0x00) # Pure black
c('oklch(1 0 0)', 0xff, 0xff, 0xff) # Pure white
# Achromatic colors (zero chroma)
c('oklch(0.5 0 180)', 0xbb, 0xbb, 0xbb) # Mid gray, hue irrelevant
c('oklch(0.25 0 90)', 0x88, 0x88, 0x88) # Dark gray
# Test various hues with moderate chroma
in_range('oklch(0.6 0.15 0)') # Red hue
in_range('oklch(0.6 0.15 60)') # Yellow hue
in_range('oklch(0.6 0.15 120)') # Green hue
in_range('oklch(0.6 0.15 180)') # Cyan hue
in_range('oklch(0.6 0.15 240)') # Blue hue
in_range('oklch(0.6 0.15 300)') # Magenta hue
# Test with different comma/space separators
c('oklch(0.5, 0.1, 180)', 0x00, 0x75, 0x65)
c('oklch(0.5,0.1,180)', 0x00, 0x75, 0x65)
# Test percentage lightness
color = to_color('oklch(50% 0.1 180)')
self.assertIsNotNone(color)
# Very high chroma should trigger gamut mapping
# These should all succeed and return valid RGB values
in_range('oklch(0.5 0.5 0)')
in_range('oklch(0.5 0.5 180)')
in_range('oklch(0.9 0.3 120)')
def test_inline_comments(self):
"""Test inline comments in color values"""
def c(spec, r=0, g=0, b=0):
color = to_color(spec)
self.assertIsNotNone(color, f'Failed to parse: {spec}')
self.ae(color.red, r)
self.ae(color.green, g)
self.ae(color.blue, b)
# OKLCH with inline comment
c('oklch(0.5 0.1 180) # Cyan color', 0x00, 0x75, 0x65)
c('oklch(0.7 0.15 140) # Green', 0x67, 0xb4, 0x56)
# Hex colors with inline comments
c('#ff0000 # Red', 0xff, 0x00, 0x00)
c('#00ff00 # Green', 0x00, 0xff, 0x00)
c('#0000ff # Blue', 0x00, 0x00, 0xff)
# P3 colors with inline comments
c('p3(1 0 0) # P3 Red', 0xfe, 0x00, 0x00)
c('color(display-p3 0 1 0) # P3 Green', 0x00, 0xfe, 0x00)
# LAB colors with inline comments
c('lab(70 50 -30) # Purple-ish', 0xea, 0x88, 0xe2)
# RGB with inline comments
c('rgb:ff/00/00 # RGB Red', 0xff, 0x00, 0x00)
# Named color should not be affected by text after it
# (not a comment, just ignored)
c('red', 0xff, 0x00, 0x00)
def test_p3_and_lab_parsing(self):
"""Test Display P3 and CIE LAB color format parsing"""
def c(spec, r=0, g=0, b=0):
color = to_color(spec)
self.assertIsNotNone(color, f'Failed to parse: {spec}')
self.ae(color.red, r)
self.ae(color.green, g)
self.ae(color.blue, b)
# P3 basic colors
c('p3(1 0 0)', 0xfe, 0x00, 0x00) # P3 red (wider than sRGB)
c('p3(0 1 0)', 0x00, 0xfe, 0x00) # P3 green (wider than sRGB)
c('p3(0 0 1)', 0x00, 0x00, 0xfe) # P3 blue (wider than sRGB)
c('p3(1 1 1)', 0xfe, 0xfe, 0xfe) # P3 white (slightly clipped in conversion)
c('p3(0 0 0)', 0x00, 0x00, 0x00) # P3 black
c('p3(0.5 0.5 0.5)', 0x7f, 0x7f, 0x7f) # P3 mid-gray
# P3 with different separators
c('p3(1, 0, 0)', 0xfe, 0x00, 0x00)
c('p3(1,0,0)', 0xfe, 0x00, 0x00)
# CSS color() function with display-p3
c('color(display-p3 1 0 0)', 0xfe, 0x00, 0x00)
c('color(display-p3 0 1 0)', 0x00, 0xfe, 0x00)
c('color(display-p3 0 0 1)', 0x00, 0x00, 0xfe)
# LAB basic colors
c('lab(0 0 0)', 0x00, 0x00, 0x00) # LAB black
c('lab(100 0 0)', 0xfe, 0xfe, 0xfe) # LAB white (slightly clipped in conversion)
c('lab(50 0 0)', 0xc6, 0xc6, 0xc6) # LAB mid-gray
# LAB with color components
c('lab(70 50 -30)', 0xea, 0x88, 0xe2) # Purple-ish
color = to_color('lab(50 50 50)') # Orange/red-ish (positive a and b)
self.assertIsNotNone(color)
self.assertGreater(color.red, 0xc0) # Should have high red
self.assertLess(color.blue, 0x50) # Should have low blue
# LAB with different separators
color = to_color('lab(70, 50, -30)')
self.assertIsNotNone(color)
color = to_color('lab(70,50,-30)')
self.assertIsNotNone(color)
# LAB with negative values (valid for a and b channels)
color = to_color('lab(50 -50 -50)')
self.assertIsNotNone(color)
color = to_color('lab(50 -50 50)')
self.assertIsNotNone(color)
def test_color_format_errors(self):
"""Test error handling for invalid color formats"""
# Invalid OKLCH
self.assertIsNone(to_color('oklch()'))
self.assertIsNone(to_color('oklch(0.5)'))
self.assertIsNone(to_color('oklch(0.5 0.1)'))
self.assertIsNone(to_color('oklch(a b c)'))
# Invalid P3
self.assertIsNone(to_color('p3()'))
self.assertIsNone(to_color('p3(1)'))
self.assertIsNone(to_color('p3(1 0)'))
self.assertIsNone(to_color('p3(a b c)'))
# Invalid LAB
self.assertIsNone(to_color('lab()'))
self.assertIsNone(to_color('lab(50)'))
self.assertIsNone(to_color('lab(50 0)'))
self.assertIsNone(to_color('lab(a b c)'))
# Invalid color() function
self.assertIsNone(to_color('color()'))
self.assertIsNone(to_color('color(display-p3)'))
self.assertIsNone(to_color('color(unknown 1 0 0)'))
# Empty and whitespace
self.assertIsNone(to_color(''))
self.assertIsNone(to_color(' '))
# Malformed hex
self.assertIsNone(to_color('#'))
self.assertIsNone(to_color('#12'))
self.assertIsNone(to_color('#1234'))
# Malformed rgb
self.assertIsNone(to_color('rgb:'))
self.assertIsNone(to_color('rgb:a/b'))
def test_linebuf(self):
old = filled_line_buf(2, 3, filled_cursor())
new = LineBuf(1, 3)