Resolve relative colors
Derive a concrete color from source channels and visible channel math, including an origin supplied by context.
oklch(from var(--brand)
calc(l + 0.1) c h / alpha)
- --brand
#806eae- l
l + 0.1- c / h / alpha
- unchanged
oklch(0.681141 0.0979163 296.154)
#9e8cce
Resolve the origin, then derive its channels
Without --brand, non-strict resolution retains a deferred RelativeColor.
Make the relative operation visible
The origin resolves first. The expression then adds 0.1 to lightness while passing chroma, hue, and alpha through unchanged.
<?php
use PhpColor\Color\Css\CssColor;
use PhpColor\Color\Css\CssContext;
$expression = CssColor::relative(
'oklch', CssColor::var('--brand'),
['l' => 'calc(l + 0.1)', 'c' => 'c', 'h' => 'h'],
'alpha',
);
$color = CssColor::resolve(
$expression,
CssContext::light(['--brand' => '#806eae']),
);
echo $color->toCss(); // oklch(0.681141 0.0979163 296.154)
echo $color->toHex(); // #9e8cceUse the implemented relative-color grammar
Use this workflow when the origin is deferred. Use Color::parse() for a self-contained relative expression, or instance methods for a concrete PHP color.
Channel order must match the target function. Numeric calc() supports arithmetic, parentheses, percentages, and available channel names.
CSS units, none, min(), max(), clamp(), and the complete browser grammar are not supported.
A deferred relative expression containing var() does not round-trip through CssColor::parse() in v1.