[tbb-bugs] #30542 [Applications/Tor Browser]: pinch-to-zoom viewport vs other screen/window

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#30542: pinch-to-zoom viewport vs other screen/window
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 Reporter:  Thorin                               |          Owner:  tbb-
                                                 |  team
     Type:  defect                               |         Status:  new
 Priority:  Medium                               |      Milestone:
Component:  Applications/Tor Browser             |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  tbb-fingerprinting, tbb-mobile,      |  Actual Points:
  tbb-parity                                     |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
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Changes (by sysrqb):

 * keywords:  tbb-fingerprinting, tbb-mobile => tbb-fingerprinting, tbb-
     mobile, tbb-parity


Comment:

 Thanks Thorin. I see two problems here. The first is related to exact
 screen dimensions (#27083) and the other is inconsistency of reported
 values. On the webpage on Android, I see these are (approximately) the
 same (based on pinch-to-zoom level): `screen resolution`, `available
 resolution`, `outer window`, `inner window`, and `view port`. And these
 remain as the original values after pinch-to-zoom: `[css] screen
 resolution` and `[css] inner window`.

 It seems like there isn't a feedback channel from the pinch-to-zoom
 function into the CSS engine (whatever that is). I also wonder if rounding
 the zoom level into buckets will help with this (in addition to any screen
 rounding and/or letterboxing we add). By this I mean on desktop, you can
 only zoom-in and zoom-out by fixed values, but pinch-to-zoom is relatively
 arbitrary. We can think about only allowing specific zoom levels.

 And, as a side note, this seems partly broken with Firefox Nightly on
 Android, so we should test this after the 68esr rebase.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/30542#comment:5>
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