@cantoo/pdf-lib
Version:
Create and modify PDF files with JavaScript
89 lines • 4.22 kB
JavaScript
"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
const tslib_1 = require("tslib");
const errors_1 = require("../errors");
const PDFArray_1 = tslib_1.__importDefault(require("../objects/PDFArray"));
const PDFName_1 = tslib_1.__importDefault(require("../objects/PDFName"));
const PDFNumber_1 = tslib_1.__importDefault(require("../objects/PDFNumber"));
const PDFRef_1 = tslib_1.__importDefault(require("../objects/PDFRef"));
const ByteStream_1 = tslib_1.__importDefault(require("./ByteStream"));
class PDFXRefStreamParser {
constructor(rawStream) {
this.alreadyParsed = false;
this.dict = rawStream.dict;
this.bytes = ByteStream_1.default.fromPDFRawStream(rawStream);
this.context = this.dict.context;
const Size = this.dict.lookup(PDFName_1.default.of('Size'), PDFNumber_1.default);
const Index = this.dict.lookup(PDFName_1.default.of('Index'));
if (Index instanceof PDFArray_1.default) {
this.subsections = [];
for (let idx = 0, len = Index.size(); idx < len; idx += 2) {
const firstObjectNumber = Index.lookup(idx + 0, PDFNumber_1.default).asNumber();
const length = Index.lookup(idx + 1, PDFNumber_1.default).asNumber();
this.subsections.push({ firstObjectNumber, length });
}
}
else {
this.subsections = [{ firstObjectNumber: 0, length: Size.asNumber() }];
}
const W = this.dict.lookup(PDFName_1.default.of('W'), PDFArray_1.default);
this.byteWidths = [-1, -1, -1];
for (let idx = 0, len = W.size(); idx < len; idx++) {
this.byteWidths[idx] = W.lookup(idx, PDFNumber_1.default).asNumber();
}
}
parseIntoContext() {
if (this.alreadyParsed) {
throw new errors_1.ReparseError('PDFXRefStreamParser', 'parseIntoContext');
}
this.alreadyParsed = true;
this.context.trailerInfo = {
Root: this.dict.get(PDFName_1.default.of('Root')),
Encrypt: this.dict.get(PDFName_1.default.of('Encrypt')),
Info: this.dict.get(PDFName_1.default.of('Info')),
ID: this.dict.get(PDFName_1.default.of('ID')),
};
const entries = this.parseEntries();
// for (let idx = 0, len = entries.length; idx < len; idx++) {
// const entry = entries[idx];
// if (entry.deleted) this.context.delete(entry.ref);
// }
return entries;
}
parseEntries() {
const entries = [];
const [typeFieldWidth, offsetFieldWidth, genFieldWidth] = this.byteWidths;
for (let subsectionIdx = 0, subsectionLen = this.subsections.length; subsectionIdx < subsectionLen; subsectionIdx++) {
const { firstObjectNumber, length } = this.subsections[subsectionIdx];
for (let objIdx = 0; objIdx < length; objIdx++) {
let type = 0;
for (let idx = 0, len = typeFieldWidth; idx < len; idx++) {
type = (type << 8) | this.bytes.next();
}
let offset = 0;
for (let idx = 0, len = offsetFieldWidth; idx < len; idx++) {
offset = (offset << 8) | this.bytes.next();
}
let generationNumber = 0;
for (let idx = 0, len = genFieldWidth; idx < len; idx++) {
generationNumber = (generationNumber << 8) | this.bytes.next();
}
// When the `type` field is absent, it defaults to 1
if (typeFieldWidth === 0)
type = 1;
const objectNumber = firstObjectNumber + objIdx;
const entry = {
ref: PDFRef_1.default.of(objectNumber, generationNumber),
offset,
deleted: type === 0,
inObjectStream: type === 2,
};
entries.push(entry);
}
}
return entries;
}
}
PDFXRefStreamParser.forStream = (rawStream) => new PDFXRefStreamParser(rawStream);
exports.default = PDFXRefStreamParser;
//# sourceMappingURL=PDFXRefStreamParser.js.map