487a7ddc7d
Given that Node.js doesn't support Workers, general PDF.js performance will be worse when compared to browsers. In an attempt to improve at least memory usage a little bit, update the Node.js examples to release page resources once parsing is done for that page.
112 lines
3.5 KiB
JavaScript
112 lines
3.5 KiB
JavaScript
/* Copyright 2017 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 Canvas = require("canvas");
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const assert = require("assert").strict;
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const fs = require("fs");
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function NodeCanvasFactory() {}
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NodeCanvasFactory.prototype = {
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create: function NodeCanvasFactory_create(width, height) {
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assert(width > 0 && height > 0, "Invalid canvas size");
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const canvas = Canvas.createCanvas(width, height);
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const context = canvas.getContext("2d");
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return {
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canvas,
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context,
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};
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},
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reset: function NodeCanvasFactory_reset(canvasAndContext, width, height) {
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assert(canvasAndContext.canvas, "Canvas is not specified");
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assert(width > 0 && height > 0, "Invalid canvas size");
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canvasAndContext.canvas.width = width;
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canvasAndContext.canvas.height = height;
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},
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destroy: function NodeCanvasFactory_destroy(canvasAndContext) {
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assert(canvasAndContext.canvas, "Canvas is not specified");
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// Zeroing the width and height cause Firefox to release graphics
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// resources immediately, which can greatly reduce memory consumption.
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canvasAndContext.canvas.width = 0;
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canvasAndContext.canvas.height = 0;
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canvasAndContext.canvas = null;
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canvasAndContext.context = null;
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},
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};
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const pdfjsLib = require("pdfjs-dist/legacy/build/pdf.js");
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// Some PDFs need external cmaps.
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const CMAP_URL = "../../../node_modules/pdfjs-dist/cmaps/";
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const CMAP_PACKED = true;
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// Where the standard fonts are located.
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const STANDARD_FONT_DATA_URL =
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"../../../node_modules/pdfjs-dist/standard_fonts/";
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// Loading file from file system into typed array.
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const pdfPath =
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process.argv[2] || "../../../web/compressed.tracemonkey-pldi-09.pdf";
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const data = new Uint8Array(fs.readFileSync(pdfPath));
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// Load the PDF file.
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const loadingTask = pdfjsLib.getDocument({
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data,
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cMapUrl: CMAP_URL,
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cMapPacked: CMAP_PACKED,
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standardFontDataUrl: STANDARD_FONT_DATA_URL,
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});
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(async function () {
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try {
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const pdfDocument = await loadingTask.promise;
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console.log("# PDF document loaded.");
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// Get the first page.
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const page = await pdfDocument.getPage(1);
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// Render the page on a Node canvas with 100% scale.
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const viewport = page.getViewport({ scale: 1.0 });
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const canvasFactory = new NodeCanvasFactory();
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const canvasAndContext = canvasFactory.create(
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viewport.width,
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viewport.height
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);
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const renderContext = {
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canvasContext: canvasAndContext.context,
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viewport,
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canvasFactory,
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};
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const renderTask = page.render(renderContext);
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await renderTask.promise;
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// Convert the canvas to an image buffer.
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const image = canvasAndContext.canvas.toBuffer();
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fs.writeFile("output.png", image, function (error) {
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if (error) {
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console.error("Error: " + error);
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} else {
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console.log(
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"Finished converting first page of PDF file to a PNG image."
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);
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}
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});
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// Release page resources.
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page.cleanup();
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} catch (reason) {
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console.log(reason);
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}
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})();
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