ngx-extended-pdf-viewer: Cannot display file offline on iOS

Hi, I am not sure this is actually a bug caused by this library (which is very cool and well documented, thank you!), however I have been struggling to find a solution to this problem and I hope that somebody could give me some suggestions.

I’m encountering a weird error when trying to load a Blob saved locally (temporary stored in IndexedDB) while offline (no internet connection). The application I am working on uses heavily the Service Worker to load the app offline and serve some features, including a PDF viewer. I have followed all the setup and the library works:

• online in any browser and device;
• offline on desktop browsers (Chrome and Safari) and on mobile Android devices (Chrome).

The lib component is configured like this in the html template:

<ngx-extended-pdf-viewer
  [src]="file" useBrowserLocale="true" height="85vh"
  [textLayer]="true" [showPresentationModeButton]="true"
  [enablePinchOnMobile]="true" [enablePrint]="false"
  [showBookmarkButton]="false" [showDownloadButton]="false"
  [showOpenFileButton]="false" [showPrintButton]="false"
></ngx-extended-pdf-viewer>

where file is a Blob saved in IndexedDB and passed to the component.

The final error showed in the pdf viewer is: PDF.js v2.7.667 (build: 162577ae4) Message: The PDF file is empty, i.e. its size is zero bytes However, the problem is not that there is no file, but it looks like that there is a network related issue that blocks the operation. Looking in the Network tab of the developer tools, it looks like the library tries to get something from the same application domain and fails (504) since there is no internet connection. Nonetheless, on desktop and Android it manage to continue its operations, download from cache the PDF.js file and shows the PDF file correctly. The same operation on iOS get blocked and shows the error in the viewer.

Version info

• 8.0.0-beta.8

Smartphone:

• iPhone 11 - iOS 14.4 - Safari (14.0.3 Mobile)

Demo PDF file Any PDF as the same issue.

Additional context I have previously tried out the ng2-pdfjs-viewer library but there I encounter a slightly different issue, which you can find in the related issue tracker. I though that, since that library uses an iframe, it could be some CORS/Security issue.

Finally, I added an issue directly in PDF.js issue tracker but with no luck (the issue was the one from the ng2-pdfjs-viewer library): https://github.com/mozilla/pdf.js/issues/12967#issue-802927639

As a side note, on iOS the Presentation Mode Button does not show up…!

As I said at the beginning, any help would be much appreciated! Thanks again for your nice work!

Screenshots You can find some screenshot of Android and iOS tests:

Android

iOS