Built-in PDF viewer

Feature Proposal
1

It is common for transport companies to send PDF tickets to emails, but some Android phones don’t have a PDF viewer out of the box.

A solution could be to have a built-in PDF viewer in Delta Chat. It seems Slack has a built-in PDF viewer so users don’t need to have a separate PDF viewer to see the documents. Security of this feature is questionable though, one of the first search results is a vulnerability in Slack because of its PDF viewer: HackerOne

SimpleX users/developers also discussed adding built-in PDF viewer recently, but some security-conscious users object in the user group because they are afraid of similar vulnerabilities and PDF viewer having access to the application storage.

Maybe it is possible to use WebView and pdf.js to securely display PDF files outside of the application context.

5 Likes
2

I agree with the pdfjs idea. That is widely used can probably also be configured / adjusted to disable potential risky/dangerous features.

2 Likes
3

pdfjs is what Firefox uses? :thinking: (Because seems to work fine there.) :ok_hand:
Kind regards!

4

Android has a built-in PDF renderer:
https://developer.android.com/reference/android/graphics/pdf/PdfRenderer

This has the advantage that it should not increase .apk size and can be used for basic preview. Basic constructor is API Level 21, so Android 5:
https://developer.android.com/reference/android/graphics/pdf/PdfRenderer#PdfRenderer(android.os.ParcelFileDescriptor)
More advanced features are API Level 35 aka Android 15 aka Android V, but we only need the basic thing for preview.

Pdfjs is a bit too large, on PDF.js - Getting Started version for modern browsers is 5.9 MB and a version for older browsers is 6.2 MB. For Desktop this is maybe ok, but for Android it’s too much. This includes .map files however, without them it should be smaller.

2 Likes
5

i am sceptical to spend resources to maintain an Built-in PDF viewer atm. that will require also quite some support, bind devs to to answer questions etc.

however, there is a webxdc that can show PDF, after selecting it from “Files”. if a system really cannot display PDF and you cannot add another apk, this is a workaround.

unfortunately, this PDF is not in the store yet.

6

Someone built a JS library based on Chromium PDF viewer as well: