1403418 - Issues viewing PDF documents

Status: RESOLVED DUPLICATE of bug 1385845

(Firefox for iOS :: Browser, enhancement)

Description

[Justin D'Arcangelo [:justindarc]]

After scrolling a PDF document for a few seconds, the screen begins exhibiting major graphical issues with flicker. In addition, it seems as though it is not possible to pinch-to-zoom a PDF document.

For reference, here’s one such PDF document that I’ve recently viewed that exhibits this behavior:

http://manuals.ryobitools.com/system/files/400/original/TS1342_942_eng.pdf

Comment 1

[Justin D'Arcangelo [:justindarc]]

I also noticed that the pinch-to-zoom issue seems to be intermittent. Nominating this for triage as this is really bad and almost makes PDF viewing unusable.

Comment 2

[Richard Newman [:rnewman]]

Testing on an iOS 10 device, with a personal build from a few days ago: I see grey flashes when I change direction and the navigation bar slides into view, or when I reach the end of the document and the bottom navigation bar appears.

Presumably this is because we're resizing the content window.

In neither case is it what I'd call major graphical issues, though it's not polished. Could you be more specific or record a video?

Comment 3

[Justin D'Arcangelo [:justindarc]]

It definitely seems related to the navigation bar animation upon a second look. However, I disagree that its not a major issue though as this seems to also be messing with the scroll position. Zooming in on a PDF document only worsens the effects of this and makes it almost impossible to navigate the document. I'll try and capture a video tomorrow.

Comment 4

[Farhan Patel [:farhan]]

The reason why PDFs are treated differently than a regular url is because we have custom constraints when the page is a PDF so we can show the "open in" bar. 

I think the best way to fix this is to simply remove the bar. When using the share sheet from the page options menu we should always just share the PDF. This is what safari does.

This would remove a lot of the hacks from viewing PDFs. (we might have to introduce a couple new ones to pass the PDF around)

Comment 5

[:garvan]

Bug 1387616 fix improves only the case where the toolbars show at the end of the doc.

My interpretation of this bug is that it is fundamental to toolbar show/hide, which changes the webview constraints; this triggers a re-layout/reflow of the web content renderer.

However, it may be that the bug is as mentioned in comment 4 and just related to the extra constraints imposed by the "Open in" bar, that would be the first thing to try.