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'use strict' | ||
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/** | ||
* Font RegExp helpers. | ||
*/ | ||
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const weights = 'bold|bolder|lighter|[1-9]00' | ||
, styles = 'italic|oblique' | ||
, variants = 'small-caps' | ||
, stretches = 'ultra-condensed|extra-condensed|condensed|semi-condensed|semi-expanded|expanded|extra-expanded|ultra-expanded' | ||
, units = 'px|pt|pc|in|cm|mm|%|em|ex|ch|rem|q' | ||
, string = '\'([^\']+)\'|"([^"]+)"|[\\w-]+' | ||
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// [ [ <‘font-style’> || <font-variant-css21> || <‘font-weight’> || <‘font-stretch’> ]? | ||
// <‘font-size’> [ / <‘line-height’> ]? <‘font-family’> ] | ||
// https://drafts.csswg.org/css-fonts-3/#font-prop | ||
const weightRe = new RegExp(`(${weights}) +`, 'i') | ||
const styleRe = new RegExp(`(${styles}) +`, 'i') | ||
const variantRe = new RegExp(`(${variants}) +`, 'i') | ||
const stretchRe = new RegExp(`(${stretches}) +`, 'i') | ||
const sizeFamilyRe = new RegExp( | ||
'([\\d\\.]+)(' + units + ') *' | ||
+ '((?:' + string + ')( *, *(?:' + string + '))*)') | ||
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/** | ||
* Cache font parsing. | ||
*/ | ||
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const cache = {} | ||
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const defaultHeight = 16 // pt, common browser default | ||
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/** | ||
* Parse font `str`. | ||
* | ||
* @param {String} str | ||
* @return {Object} Parsed font. `size` is in device units. `unit` is the unit | ||
* appearing in the input string. | ||
* @api private | ||
*/ | ||
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module.exports = function (str) { | ||
// Cached | ||
if (cache[str]) return cache[str] | ||
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// Try for required properties first. | ||
const sizeFamily = sizeFamilyRe.exec(str) | ||
if (!sizeFamily) return // invalid | ||
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// Default values and required properties | ||
const font = { | ||
weight: 'normal', | ||
style: 'normal', | ||
stretch: 'normal', | ||
variant: 'normal', | ||
size: parseFloat(sizeFamily[1]), | ||
unit: sizeFamily[2], | ||
family: sizeFamily[3].replace(/["']/g, '').replace(/ *, */g, ',') | ||
} | ||
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// Optional, unordered properties. | ||
let weight, style, variant, stretch | ||
// Stop search at `sizeFamily.index` | ||
let substr = str.substring(0, sizeFamily.index) | ||
if ((weight = weightRe.exec(substr))) font.weight = weight[1] | ||
if ((style = styleRe.exec(substr))) font.style = style[1] | ||
if ((variant = variantRe.exec(substr))) font.variant = variant[1] | ||
if ((stretch = stretchRe.exec(substr))) font.stretch = stretch[1] | ||
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// Convert to device units. (`font.unit` is the original unit) | ||
// TODO: ch, ex | ||
switch (font.unit) { | ||
case 'pt': | ||
font.size /= 0.75 | ||
break | ||
case 'pc': | ||
font.size *= 16 | ||
break | ||
case 'in': | ||
font.size *= 96 | ||
break | ||
case 'cm': | ||
font.size *= 96.0 / 2.54 | ||
break | ||
case 'mm': | ||
font.size *= 96.0 / 25.4 | ||
break | ||
case '%': | ||
// TODO disabled because existing unit tests assume 100 | ||
// font.size *= defaultHeight / 100 / 0.75 | ||
break | ||
case 'em': | ||
case 'rem': | ||
font.size *= defaultHeight / 0.75 | ||
break | ||
case 'q': | ||
font.size *= 96 / 25.4 / 4 | ||
break | ||
} | ||
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return (cache[str] = font) | ||
} |
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