// @flow
import mix from './mix'
import curry from '../internalHelpers/_curry'
/**
* Shades a color by mixing it with black. Compared to `darken` it can produce
* hue shifts, wheres `darken` manipulates the luminance channel and therefor
* doesn't produce hue shifts.
*
* @example
* // Styles as object usage
* const styles = {
* background: shade(0.25, '#00f')
* }
*
* // styled-components usage
* const div = styled.div`
* background: ${shade(0.25, '#00f')};
* `
*
* // CSS in JS Output
*
* element {
* background: "#00003f";
* }
*/
function shade(percentage: number, color: string) {
if (typeof percentage !== 'number' || percentage > 1 || percentage < -1) throw new Error('Passed an incorrect argument to shade, please pass a percentage less than or equal to 1 and larger than or equal to -1.')
return mix(percentage, color, 'rgb(0, 0, 0)')
}
export default curry(shade)
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