52 lines
1.8 KiB
Plaintext
52 lines
1.8 KiB
Plaintext
// The `hmtx` table contains the horizontal metrics for all glyphs.
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// https://www.microsoft.com/typography/OTSPEC/hmtx.htm
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import parse from '../parse';
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function parseHmtxTableAll(data, start, numMetrics, numGlyphs, glyphs) {
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let advanceWidth;
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let leftSideBearing;
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const p = new parse.Parser(data, start);
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for (let i = 0; i < numGlyphs; i += 1) {
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// If the font is monospaced, only one entry is needed. This last entry applies to all subsequent glyphs.
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if (i < numMetrics) {
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advanceWidth = p.parseUShort();
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leftSideBearing = p.parseShort();
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}
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const glyph = glyphs.get(i);
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glyph.advanceWidth = advanceWidth;
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glyph.leftSideBearing = leftSideBearing;
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}
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}
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function parseHmtxTableOnLowMemory(font, data, start, numMetrics, numGlyphs) {
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font._hmtxTableData = {};
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let advanceWidth;
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let leftSideBearing;
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const p = new parse.Parser(data, start);
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for (let i = 0; i < numGlyphs; i += 1) {
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// If the font is monospaced, only one entry is needed. This last entry applies to all subsequent glyphs.
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if (i < numMetrics) {
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advanceWidth = p.parseUShort();
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leftSideBearing = p.parseShort();
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}
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font._hmtxTableData[i] = {
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advanceWidth: advanceWidth,
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leftSideBearing: leftSideBearing,
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};
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}
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}
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// Parse the `hmtx` table, which contains the horizontal metrics for all glyphs.
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// This function augments the glyph array, adding the advanceWidth and leftSideBearing to each glyph.
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function parseHmtxTable(font, data, start, numMetrics, numGlyphs, glyphs, opt) {
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if (opt.lowMemory)
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parseHmtxTableOnLowMemory(font, data, start, numMetrics, numGlyphs);
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else parseHmtxTableAll(data, start, numMetrics, numGlyphs, glyphs);
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}
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export default { parse: parseHmtxTable };
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