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Move the OpenTypeFileBuilder from src/core/fonts.js and into its own file

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This commit is contained in:
Jonas Jenwald 2021-05-02 11:47:56 +02:00
parent f0817015bd
commit a783c7ca79
2 changed files with 165 additions and 144 deletions
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145
src/core/fonts.js
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@ -66,6 +66,7 @@ import {
} from "./core_utils.js";
import { FontRendererFactory } from "./font_renderer.js";
import { IdentityCMap } from "./cmap.js";
import { OpenTypeFileBuilder } from "./opentype_file_builder.js";
import { Stream } from "./stream.js";
import { Type1Parser } from "./type1_parser.js";
@ -408,150 +409,6 @@ var IdentityToUnicodeMap = (function IdentityToUnicodeMapClosure() {
return IdentityToUnicodeMap;
})();
var OpenTypeFileBuilder = (function OpenTypeFileBuilderClosure() {
function writeInt16(dest, offset, num) {
dest[offset] = (num >> 8) & 0xff;
dest[offset + 1] = num & 0xff;
}
function writeInt32(dest, offset, num) {
dest[offset] = (num >> 24) & 0xff;
dest[offset + 1] = (num >> 16) & 0xff;
dest[offset + 2] = (num >> 8) & 0xff;
dest[offset + 3] = num & 0xff;
}
function writeData(dest, offset, data) {
var i, ii;
if (data instanceof Uint8Array) {
dest.set(data, offset);
} else if (typeof data === "string") {
for (i = 0, ii = data.length; i < ii; i++) {
dest[offset++] = data.charCodeAt(i) & 0xff;
}
} else {
// treating everything else as array
for (i = 0, ii = data.length; i < ii; i++) {
dest[offset++] = data[i] & 0xff;
}
}
}
// eslint-disable-next-line no-shadow
function OpenTypeFileBuilder(sfnt) {
this.sfnt = sfnt;
this.tables = Object.create(null);
}
OpenTypeFileBuilder.getSearchParams = function OpenTypeFileBuilder_getSearchParams(
entriesCount,
entrySize
) {
var maxPower2 = 1,
log2 = 0;
while ((maxPower2 ^ entriesCount) > maxPower2) {
maxPower2 <<= 1;
log2++;
}
var searchRange = maxPower2 * entrySize;
return {
range: searchRange,
entry: log2,
rangeShift: entrySize * entriesCount - searchRange,
};
};
var OTF_HEADER_SIZE = 12;
var OTF_TABLE_ENTRY_SIZE = 16;
OpenTypeFileBuilder.prototype = {
toArray: function OpenTypeFileBuilder_toArray() {
var sfnt = this.sfnt;
// Tables needs to be written by ascendant alphabetic order
var tables = this.tables;
var tablesNames = Object.keys(tables);
tablesNames.sort();
var numTables = tablesNames.length;
var i, j, jj, table, tableName;
// layout the tables data
var offset = OTF_HEADER_SIZE + numTables * OTF_TABLE_ENTRY_SIZE;
var tableOffsets = [offset];
for (i = 0; i < numTables; i++) {
table = tables[tablesNames[i]];
var paddedLength = ((table.length + 3) & ~3) >>> 0;
offset += paddedLength;
tableOffsets.push(offset);
}
var file = new Uint8Array(offset);
// write the table data first (mostly for checksum)
for (i = 0; i < numTables; i++) {
table = tables[tablesNames[i]];
writeData(file, tableOffsets[i], table);
}
// sfnt version (4 bytes)
if (sfnt === "true") {
// Windows hates the Mac TrueType sfnt version number
sfnt = string32(0x00010000);
}
file[0] = sfnt.charCodeAt(0) & 0xff;
file[1] = sfnt.charCodeAt(1) & 0xff;
file[2] = sfnt.charCodeAt(2) & 0xff;
file[3] = sfnt.charCodeAt(3) & 0xff;
// numTables (2 bytes)
writeInt16(file, 4, numTables);
var searchParams = OpenTypeFileBuilder.getSearchParams(numTables, 16);
// searchRange (2 bytes)
writeInt16(file, 6, searchParams.range);
// entrySelector (2 bytes)
writeInt16(file, 8, searchParams.entry);
// rangeShift (2 bytes)
writeInt16(file, 10, searchParams.rangeShift);
offset = OTF_HEADER_SIZE;
// writing table entries
for (i = 0; i < numTables; i++) {
tableName = tablesNames[i];
file[offset] = tableName.charCodeAt(0) & 0xff;
file[offset + 1] = tableName.charCodeAt(1) & 0xff;
file[offset + 2] = tableName.charCodeAt(2) & 0xff;
file[offset + 3] = tableName.charCodeAt(3) & 0xff;
// checksum
var checksum = 0;
for (j = tableOffsets[i], jj = tableOffsets[i + 1]; j < jj; j += 4) {
var quad = readUint32(file, j);
checksum = (checksum + quad) >>> 0;
}
writeInt32(file, offset + 4, checksum);
// offset
writeInt32(file, offset + 8, tableOffsets[i]);
// length
writeInt32(file, offset + 12, tables[tableName].length);
offset += OTF_TABLE_ENTRY_SIZE;
}
return file;
},
addTable: function OpenTypeFileBuilder_addTable(tag, data) {
if (tag in this.tables) {
throw new Error("Table " + tag + " already exists");
}
this.tables[tag] = data;
},
};
return OpenTypeFileBuilder;
})();
/**
* 'Font' is the class the outside world should use, it encapsulate all the font
* decoding logics whatever type it is (assuming the font type is supported).