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import ApiManager, { Registration } from "./ApiManager";
import { Method } from "../RouteManager";
import RouteSubscriber from "../RouteSubscriber";
import { exists, createReadStream, createWriteStream } from "fs";
import * as Pdfjs from 'pdfjs-dist';
import { createCanvas } from "canvas";
const imageSize = require("probe-image-size");
import * as express from "express";
import * as path from "path";
import { Directory, serverPathToFile, clientPathToFile } from "./UploadManager";
import { ConsoleColors } from "../ActionUtilities";
export default class PDFManager extends ApiManager {
protected initialize(register: Registration): void {
register({
method: Method.GET,
subscription: new RouteSubscriber("thumbnail").add("filename"),
onValidation: ({ req, res }) => getOrCreateThumbnail(req.params.filename, res)
});
}
}
function getOrCreateThumbnail(thumbnailName: string, res: express.Response) {
const noExtension = thumbnailName.substring(0, thumbnailName.length - ".png".length);
const pageString = noExtension.split('-')[1];
const pageNumber = parseInt(pageString);
return new Promise<void>(resolve => {
const path = serverPathToFile(Directory.pdf_thumbnails, thumbnailName);
exists(path, (exists: boolean) => {
if (exists) {
let existingThumbnail = createReadStream(path);
imageSize(existingThumbnail, (err: any, { width, height }: any) => {
if (err) {
console.log(ConsoleColors.Red, `In PDF thumbnail response, unable to determine dimensions of ${thumbnailName}:`);
console.log(err);
return;
}
res.send({
path: clientPathToFile(Directory.pdf_thumbnails, thumbnailName),
width,
height
});
});
} else {
const offset = thumbnailName.length - pageString.length - 5;
const name = thumbnailName.substring(0, offset) + ".pdf";
const path = serverPathToFile(Directory.pdfs, name);
CreateThumbnail(path, pageNumber, res);
}
resolve();
});
});
}
async function CreateThumbnail(file: string, pageNumber: number, res: express.Response) {
const documentProxy = await Pdfjs.getDocument(file).promise;
const factory = new NodeCanvasFactory();
const page = await documentProxy.getPage(pageNumber);
const viewport = page.getViewport(1 as any);
const { canvas, context } = factory.create(viewport.width, viewport.height);
const renderContext = {
canvasContext: context,
canvasFactory: factory,
viewport
};
await page.render(renderContext).promise;
const pngStream = canvas.createPNGStream();
const filenames = path.basename(file).split(".");
const pngFile = serverPathToFile(Directory.pdf_thumbnails, `${filenames[0]}-${pageNumber}.png`);
const out = createWriteStream(pngFile);
pngStream.pipe(out);
out.on("finish", () => {
res.send({
path: pngFile,
width: viewport.width,
height: viewport.height
});
});
out.on("error", error => {
console.log(ConsoleColors.Red, `In PDF thumbnail creation, encountered the following error when piping ${pngFile}:`);
console.log(error);
});
}
class NodeCanvasFactory {
create = (width: number, height: number) => {
var canvas = createCanvas(width, height);
var context = canvas.getContext('2d');
return {
canvas,
context
};
}
reset = (canvasAndContext: any, width: number, height: number) => {
canvasAndContext.canvas.width = width;
canvasAndContext.canvas.height = height;
}
destroy = (canvasAndContext: any) => {
canvasAndContext.canvas.width = 0;
canvasAndContext.canvas.height = 0;
canvasAndContext.canvas = null;
canvasAndContext.context = null;
}
}
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