Method InvertColor

internal/config/color.go:145–188

InvertColor inverts the color's lightness in Oklch space while preserving chroma (saturation). For chromatic colors, L is adjusted toward 0.5 only as needed to preserve a fraction of the original chroma (set by chromaPreserveFactor), since the sRGB gamut has less room for chroma at extreme lightness

()

// extreme lightness values.
// Special colors (default, transparent) are returned unchanged.
func (c Color) InvertColor() Color {
	if c == DefaultColor || c == TransparentColor || c == "" {
		return c
	}

	tc := c.Color()
	if tc == tcell.ColorDefault {
		return c
	}

	hex := tc.TrueColor().Hex()
	if hex < 0 {
		return c
	}

	col, err := colorful.Hex(fmt.Sprintf("#%06x", hex))
	if err != nil {
		return c
	}

	L, C, h := col.OkLch()

	// For achromatic colors, simply invert L
	if C < 0.01 {
		return NewColor(colorful.OkLch(1.0-L, 0, h).Clamped().Hex())
	}

	// For chromatic colors, find L closest to inverted that preserves
	// at least chromaPreserveFactor of the original chroma
	targetL := 1.0 - L
	minC := C * chromaPreserveFactor
	actualL := closestLForChroma(targetL, minC, h)

	// Use as much of the original chroma as the gamut allows at actualL
	maxC := maxChromaForLH(actualL, h)
	actualC := C
	if maxC < C {
		actualC = maxC
	}

	inverted := colorful.OkLch(actualL, actualC, h).Clamped()

	return NewColor(inverted.Hex())
}