35 lines
1020 B
Plaintext
35 lines
1020 B
Plaintext
import { length, percentage } from './dataTypes'
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import { splitAtTopLevelOnly } from './splitAtTopLevelOnly'
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/**
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*
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* https://developer.mozilla.org/en-US/docs/Web/CSS/background-size#formal_syntax
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*
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* background-size =
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* <bg-size>#
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*
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* <bg-size> =
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* [ <length-percentage [0,∞]> | auto ]{1,2} |
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* cover |
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* contain
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*
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* <length-percentage> =
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* <length> |
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* <percentage>
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*
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* @param {string} value
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*/
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export function backgroundSize(value) {
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let keywordValues = ['cover', 'contain']
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// the <length-percentage> type will probably be a css function
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// so we have to use `splitAtTopLevelOnly`
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return splitAtTopLevelOnly(value, ',').every((part) => {
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let sizes = splitAtTopLevelOnly(part, '_').filter(Boolean)
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if (sizes.length === 1 && keywordValues.includes(sizes[0])) return true
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if (sizes.length !== 1 && sizes.length !== 2) return false
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return sizes.every((size) => length(size) || percentage(size) || size === 'auto')
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})
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}
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