288 lines
6.6 KiB
JavaScript
288 lines
6.6 KiB
JavaScript
import * as fontkit from "fontkit";
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const weightings = {
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"latin": {
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"0": 53e-4,
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"1": 23e-4,
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"2": 26e-4,
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"3": 1e-3,
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"4": 8e-4,
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"5": 15e-4,
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"6": 7e-4,
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"7": 5e-4,
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"8": 7e-4,
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"9": 6e-4,
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",": 83e-4,
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" ": 0.154,
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"t": 0.0672,
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"h": 0.0351,
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"e": 0.0922,
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"o": 0.0571,
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"f": 0.017,
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"P": 23e-4,
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"p": 0.0163,
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"l": 0.0304,
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"'": 14e-4,
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"s": 0.0469,
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"R": 15e-4,
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"u": 0.0207,
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"b": 0.0114,
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"i": 0.0588,
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"c": 0.0232,
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"C": 31e-4,
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"n": 0.0578,
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"a": 0.0668,
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"d": 0.0298,
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"y": 0.0123,
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"w": 0.011,
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"B": 2e-3,
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"r": 0.0526,
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"z": 11e-4,
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"G": 11e-4,
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"j": 9e-4,
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"T": 41e-4,
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".": 79e-4,
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"L": 12e-4,
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"k": 46e-4,
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"m": 0.0181,
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"]": 7e-4,
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"J": 9e-4,
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"F": 15e-4,
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"v": 76e-4,
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"g": 0.0155,
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"A": 4e-3,
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"N": 14e-4,
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"-": 18e-4,
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"H": 13e-4,
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"D": 13e-4,
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"M": 25e-4,
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"I": 22e-4,
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"E": 11e-4,
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'"': 12e-4,
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"S": 41e-4,
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"(": 1e-3,
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")": 1e-3,
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"x": 25e-4,
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"W": 12e-4,
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"Q": 1e-4,
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"Y": 3e-4,
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"q": 8e-4,
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"V": 5e-4,
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"á": 1e-4,
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"K": 7e-4,
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"U": 16e-4,
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"=": 7e-4,
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"[": 21e-4,
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"O": 9e-4,
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"é": 1e-4,
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"$": 2e-4,
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":": 8e-4,
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"|": 38e-4,
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"/": 1e-4,
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"%": 1e-4,
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"Z": 2e-4,
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";": 1e-4,
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"X": 1e-4
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},
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"thai": {
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"ส": 0.0258,
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"ว": 0.0372,
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"น": 0.0711,
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"บ": 0.0258,
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"จ": 0.0169,
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"า": 0.1024,
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"ก": 0.0552,
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"เ": 0.0419,
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"ร": 0.0873,
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"ม": 0.0416,
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"ค": 0.0214,
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"ำ": 97e-4,
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"ข": 0.0127,
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"อ": 0.0459,
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"ป": 0.0204,
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"ด": 0.0271,
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"ใ": 0.0109,
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"ภ": 46e-4,
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"ท": 0.0311,
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"พ": 0.0175,
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"ฤ": 9e-4,
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"ษ": 42e-4,
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"ศ": 63e-4,
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"ะ": 0.0255,
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"ช": 0.0158,
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"แ": 0.0158,
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"ล": 0.0339,
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"ง": 0.0433,
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"ย": 0.0345,
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"ห": 0.0197,
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"ฝ": 6e-4,
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"ต": 0.0239,
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"โ": 77e-4,
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"ญ": 39e-4,
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"ณ": 71e-4,
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"ผ": 77e-4,
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"ไ": 0.0111,
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"ฯ": 7e-4,
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"ฟ": 44e-4,
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"ธ": 68e-4,
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"ถ": 61e-4,
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"ฐ": 33e-4,
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"ซ": 46e-4,
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"ฉ": 23e-4,
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"ฑ": 4e-4,
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"ฆ": 2e-4,
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"ฬ": 3e-4,
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"ฏ": 2e-4,
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"ฎ": 3e-4,
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"ฒ": 12e-4,
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"ๆ": 3e-4,
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"ฮ": 4e-4,
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"๒": 1e-4,
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"๕": 1e-4
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}
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};
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const supportedSubsets = Object.keys(weightings);
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const weightingForCharacter = (character, subset) => {
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if (!Object.keys(weightings[subset]).includes(character)) {
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throw new Error(`No weighting specified for character: “${character}”`);
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}
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return weightings[subset][character];
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};
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const avgWidthForSubset = (font, subset) => {
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const sampleString = Object.keys(weightings[subset]).join("");
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const glyphs = font.glyphsForString(sampleString);
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const weightedWidth = glyphs.reduce((sum, glyph, index) => {
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const character = sampleString.charAt(index);
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let charWidth = font["OS/2"].xAvgCharWidth;
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try {
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charWidth = glyph.advanceWidth;
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} catch (e) {
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console.warn(
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`Couldn’t read 'advanceWidth' for character “${character === " " ? "<space>" : character}” from “${font.familyName}”. Falling back to “xAvgCharWidth”.`
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);
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}
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if (glyph.isMark) {
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return sum;
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}
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return sum + charWidth * weightingForCharacter(character, subset);
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}, 0);
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return Math.round(weightedWidth);
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};
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const unpackMetricsFromFont = (font) => {
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const {
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capHeight,
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ascent,
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descent,
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lineGap,
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unitsPerEm,
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familyName,
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fullName,
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postscriptName,
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xHeight
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} = font;
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const subsets = supportedSubsets.reduce(
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(acc, subset) => ({
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...acc,
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[subset]: {
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xWidthAvg: avgWidthForSubset(font, subset)
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}
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}),
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{}
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);
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return {
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familyName,
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fullName,
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postscriptName,
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capHeight,
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ascent,
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descent,
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lineGap,
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unitsPerEm,
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xHeight,
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xWidthAvg: subsets.latin.xWidthAvg,
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subsets
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};
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};
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const handleCollectionErrors = ({
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font,
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postscriptName,
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apiName,
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apiParamName
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}) => {
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if (postscriptName && font === null) {
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throw new Error(
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[
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`The provided \`postscriptName\` of “${postscriptName}” cannot be found in the provided font collection.
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`,
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"Run the same command without specifying a `postscriptName` in the options to see the available names in the collection.",
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"For example:",
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"------------------------------------------",
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`const metrics = await ${apiName}('<${apiParamName}>');`,
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"------------------------------------------\n",
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""
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].join("\n")
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);
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}
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if (font !== null && "fonts" in font && Array.isArray(font.fonts)) {
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const availableNames = font.fonts.map((f) => f.postscriptName);
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throw new Error(
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[
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"Metrics cannot be unpacked from a font collection.\n",
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"Provide either a single font or specify a `postscriptName` to extract from the collection via the options.",
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"For example:",
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"------------------------------------------",
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`const metrics = await ${apiName}('<${apiParamName}>', {`,
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` postscriptName: '${availableNames[0]}'`,
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"});",
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"------------------------------------------\n",
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"Available `postscriptNames` in this font collection are:",
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...availableNames.map((fontName) => ` - ${fontName}`),
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""
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].join("\n")
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);
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}
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};
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const fromFile = (path, options) => {
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const { postscriptName } = options || {};
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return fontkit.open(path, postscriptName).then((font) => {
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handleCollectionErrors({
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font,
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postscriptName,
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apiName: "fromFile",
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apiParamName: "path"
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});
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return unpackMetricsFromFont(font);
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});
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};
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const _fromBuffer = async (buffer, apiName, apiParamName, options) => {
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const { postscriptName } = options || {};
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const fontkitFont = fontkit.create(buffer, postscriptName);
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handleCollectionErrors({
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font: fontkitFont,
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postscriptName,
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apiName,
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apiParamName
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});
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return unpackMetricsFromFont(fontkitFont);
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};
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const fromBuffer = async (buffer, options) => {
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return _fromBuffer(buffer, "fromBuffer", "buffer", options);
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};
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const fromBlob = async (blob, options) => {
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const arrayBuffer = await blob.arrayBuffer();
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const buffer = Buffer.from(arrayBuffer);
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return _fromBuffer(buffer, "fromBlob", "blob", options);
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};
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const fromUrl = async (url, options) => {
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const response = await fetch(url);
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const arrayBuffer = await response.arrayBuffer();
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const buffer = Buffer.from(arrayBuffer);
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return _fromBuffer(buffer, "fromUrl", "url", options);
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};
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export {
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fromBlob,
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fromBuffer,
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fromFile,
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fromUrl,
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supportedSubsets
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};
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