32 lines
1.3 KiB
Plaintext
32 lines
1.3 KiB
Plaintext
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// The `loca` table stores the offsets to the locations of the glyphs in the font.
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// https://www.microsoft.com/typography/OTSPEC/loca.htm
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import parse from '../parse';
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// Parse the `loca` table. This table stores the offsets to the locations of the glyphs in the font,
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// relative to the beginning of the glyphData table.
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// The number of glyphs stored in the `loca` table is specified in the `maxp` table (under numGlyphs)
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// The loca table has two versions: a short version where offsets are stored as uShorts, and a long
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// version where offsets are stored as uLongs. The `head` table specifies which version to use
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// (under indexToLocFormat).
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function parseLocaTable(data, start, numGlyphs, shortVersion) {
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const p = new parse.Parser(data, start);
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const parseFn = shortVersion ? p.parseUShort : p.parseULong;
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// There is an extra entry after the last index element to compute the length of the last glyph.
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// That's why we use numGlyphs + 1.
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const glyphOffsets = [];
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for (let i = 0; i < numGlyphs + 1; i += 1) {
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let glyphOffset = parseFn.call(p);
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if (shortVersion) {
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// The short table version stores the actual offset divided by 2.
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glyphOffset *= 2;
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}
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glyphOffsets.push(glyphOffset);
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}
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return glyphOffsets;
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}
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export default { parse: parseLocaTable };
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