e91b480c09
This isn't directly part of the official API, and having this class in its own file could help avoid future changes (e.g. issue 18148) affecting the size of the `src/display/api.js` file unnecessarily.
126 lines
3.4 KiB
JavaScript
126 lines
3.4 KiB
JavaScript
/* Copyright 2012 Mozilla Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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const INITIAL_DATA = Symbol("INITIAL_DATA");
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/**
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* A PDF document and page is built of many objects. E.g. there are objects for
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* fonts, images, rendering code, etc. These objects may get processed inside of
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* a worker. This class implements some basic methods to manage these objects.
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*/
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class PDFObjects {
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#objs = Object.create(null);
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/**
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* Ensures there is an object defined for `objId`.
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*
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* @param {string} objId
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* @returns {Object}
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*/
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#ensureObj(objId) {
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return (this.#objs[objId] ||= {
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...Promise.withResolvers(),
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data: INITIAL_DATA,
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});
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}
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/**
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* If called *without* callback, this returns the data of `objId` but the
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* object needs to be resolved. If it isn't, this method throws.
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*
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* If called *with* a callback, the callback is called with the data of the
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* object once the object is resolved. That means, if you call this method
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* and the object is already resolved, the callback gets called right away.
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*
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* @param {string} objId
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* @param {function} [callback]
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* @returns {any}
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*/
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get(objId, callback = null) {
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// If there is a callback, then the get can be async and the object is
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// not required to be resolved right now.
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if (callback) {
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const obj = this.#ensureObj(objId);
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obj.promise.then(() => callback(obj.data));
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return null;
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}
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// If there isn't a callback, the user expects to get the resolved data
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// directly.
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const obj = this.#objs[objId];
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// If there isn't an object yet or the object isn't resolved, then the
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// data isn't ready yet!
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if (!obj || obj.data === INITIAL_DATA) {
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throw new Error(`Requesting object that isn't resolved yet ${objId}.`);
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}
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return obj.data;
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}
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/**
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* @param {string} objId
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* @returns {boolean}
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*/
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has(objId) {
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const obj = this.#objs[objId];
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return !!obj && obj.data !== INITIAL_DATA;
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}
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/**
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* @param {string} objId
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* @returns {boolean}
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*/
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delete(objId) {
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const obj = this.#objs[objId];
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if (!obj || obj.data === INITIAL_DATA) {
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// Only allow removing the object *after* it's been resolved.
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return false;
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}
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delete this.#objs[objId];
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return true;
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}
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/**
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* Resolves the object `objId` with optional `data`.
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*
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* @param {string} objId
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* @param {any} [data]
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*/
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resolve(objId, data = null) {
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const obj = this.#ensureObj(objId);
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obj.data = data;
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obj.resolve();
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}
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clear() {
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for (const objId in this.#objs) {
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const { data } = this.#objs[objId];
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data?.bitmap?.close(); // Release any `ImageBitmap` data.
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}
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this.#objs = Object.create(null);
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}
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*[Symbol.iterator]() {
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for (const objId in this.#objs) {
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const { data } = this.#objs[objId];
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if (data === INITIAL_DATA) {
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continue;
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}
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yield [objId, data];
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}
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}
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}
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export { PDFObjects };
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