1707983 - Pinch-zooming doesn't work in tabs that have been dragged into a different window

Status: VERIFIED FIXED

(Core :: Panning and Zooming, defect, P2)

Description

[Markus Stange [:mstange]]

Steps to reproduce:

1. Pinch-zoom a page and verify that it works.
2. Drag the tab into a different window (could be an existing window, or a new window by detaching the tab).
3. Pinch-zoom the page again, in the different window.

Expected results:
Pinch-zooming should work normally.

Actual results:
Nothing happens in response to the pinch-zoom gesture.

If the tab is dragged back into the original window, pinch-zooming works again.

Comment 1

[Timothy Nikkel (:tnikkel)]

The zoom constraints do not allow zoom, which means they probably haven't gotten an update from content at all and are in their initial values. Not a recent regression, 2020-11-01 has this bug.

Comment 2

[Timothy Nikkel (:tnikkel)]

Fix is probably just hooking up the zoom constraints client to a notification to refresh zoom constraints when we do a swapDocShells call, but what notification that is, not sure.

Comment 3

[Timothy Nikkel (:tnikkel)]

Looks like nsFrameLoader::SwapWithOtherLoader/nsFrameLoader::SwapWithOtherRemoteLoader calls BackingScaleFactorChanged

https://searchfox.org/mozilla-central/rev/4648b6ee31c2519b1753023e4f4853b14fdd16e5/dom/base/nsFrameLoader.cpp#1358
https://searchfox.org/mozilla-central/rev/4648b6ee31c2519b1753023e4f4853b14fdd16e5/dom/base/nsFrameLoader.cpp#1793

which calls nsPresContext::UIResolutionChangedSync

https://searchfox.org/mozilla-central/rev/4648b6ee31c2519b1753023e4f4853b14fdd16e5/layout/base/PresShell.h#1250

and that gets propagated through process etc.

Comment 4

[Timothy Nikkel (:tnikkel)]

Attachment: Bug 1707983. Refresh zoom constraints from UIResolutionChanged notification because it gets called when we swap docshells and get a new APZC tree manager. r?botond

I guess we need to do this every time we get a new APZC tree manager (because that is where the zoom constraints map/cache is stored). I'm not sure how to detect that or if there are other cases we haven't covered.

Comment 5

[BugBot [:suhaib / :marco/ :calixte]]

There's a r+ patch which didn't land and no activity in this bug for 2 weeks.
:tnikkel, could you have a look please?
For more information, please visit auto_nag documentation.

Comment 6

[Timothy Nikkel (:tnikkel)]

A test needs to be written.

Comment 8

[Timothy Nikkel (:tnikkel)]

Attachment: Bug 1707983. Add test. r?botond,hiro

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/e7b011f92cf4
Refresh zoom constraints from UIResolutionChanged notification because it gets called when we swap docshells and get a new APZC tree manager. r=botond
https://hg.mozilla.org/integration/autoland/rev/fd1d5e8fb5d0
Add test. r=hiro

Comment 10

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/e7b011f92cf4
https://hg.mozilla.org/mozilla-central/rev/fd1d5e8fb5d0

Comment 11

[Ciprian Georgiu, Desktop QA]

Reproduced this bug using an affected Nightly build (2021-04-27), using Win 10 x64 with touchscreen.

The issue is verified as fixed on latest Beta 97.0b7.