From 64a4f0dc7e60e86a7c1da1dc903497fff71abe2c Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Sat, 20 Jul 2024 09:41:44 +0200
Subject: [PATCH] Avoid downloading the document twice in
 `PDFViewerApplication.download`

The old implementation in `PDFViewerApplication.download` means that if the `getDocument`-call hasn't yet downloaded the *entire* PDF document it will be re-downloaded. This seems generally undesirable since:
 - In some (probably rare) cases a URL may not be valid an arbitrary number of times, which means that the download may fail.
 - It will lead to wasted resources, since we'll end up fetching the same PDF document *twice* in that case (once via the `getDocument`-call and once to allow the user to save it).

Hence this patch suggests that we change this very old code to instead always call the `PDFDocumentProxy.getData` method, since that'll trigger immediate downloading of the remaining document via the existing `getDocument`-call.

Finally, the patch removes the `PDFViewerApplication.downloadComplete` property since it's now unused.
---
 web/app.js | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/web/app.js b/web/app.js
index 83393b9b2..7a06a9c5c 100644
--- a/web/app.js
+++ b/web/app.js
@@ -151,7 +151,6 @@ const PDFViewerApplication = {
   /** @type {AnnotationEditorParams} */
   annotationEditorParams: null,
   isInitialViewSet: false,
-  downloadComplete: false,
   isViewerEmbedded: window.parent !== window,
   url: "",
   baseUrl: "",
@@ -942,7 +941,6 @@ const PDFViewerApplication = {
     this.pdfLinkService.externalLinkEnabled = true;
     this.store = null;
     this.isInitialViewSet = false;
-    this.downloadComplete = false;
     this.url = "";
     this.baseUrl = "";
     this._downloadUrl = "";
@@ -1072,12 +1070,9 @@ const PDFViewerApplication = {
   async download(options = {}) {
     let data;
     try {
-      if (this.downloadComplete) {
-        data = await this.pdfDocument.getData();
-      }
+      data = await this.pdfDocument.getData();
     } catch {
-      // When the PDF document isn't ready, or the PDF file is still
-      // downloading, simply download using the URL.
+      // When the PDF document isn't ready, simply download using the URL.
     }
     this.downloadManager.download(
       data,
@@ -1216,7 +1211,6 @@ const PDFViewerApplication = {
 
     pdfDocument.getDownloadInfo().then(({ length }) => {
       this._contentLength = length; // Ensure that the correct length is used.
-      this.downloadComplete = true;
       this.loadingBar?.hide();
 
       firstPagePromise.then(() => {