1849229 - Wheel scroll action fails for "deltaX" and "deltaY" properties on HiRes displays

Status: RESOLVED FIXED

(Remote Protocol :: Agent, defect, P1)

Description

[Henrik Skupin [:whimboo][⌚️UTC+2]]

As noticed today our WebDriver implementation for dispatch a scroll action fails when the test is executed from a machine that uses a HiRes display like a MacBook Pro. Here the device pixel ratio is set to 2 and as such 1 CSS pixel correlates to 2 device pixels.

This can easily be reproduced by Marionette once the patch on bug 1849227 will be available. For now here the log output of the test failure that I can see:

1692277067552	Marionette	DEBUG	3 -> [0,5,"WebDriver:PerformActions",{"actions":[{"type":"wheel","id":"id","actions":[{"type":"scroll","x":0,"y":0,"deltaX":5,"deltaY":10,"duration":0,"origin":{"element-6066-11e4-a52e-4f735466cecf":"792a2ba9-896b-4a33-86ac-8b6eb678c6a9"}}]}]}]
1692277067560	Marionette	TRACE	Dispatching tick 1/1
1692277067560	Marionette	TRACE	Dispatch WheelScrollAction with id: id deltaX: 5 deltaY: 10
1692277067561	Marionette	TRACE	moveOverTime start: 0,0 target: 5,10 duration: 0
1692277067570	Marionette	DEBUG	3 <- [1,5,null,{"value":null}]
1692277067571	Marionette	DEBUG	3 -> [0,6,"WebDriver:ExecuteScript",{"script":"return allEvents.events;","args":[],"newSandbox":true,"sandbox":null,"line":138,"filename":"_a/test_minimized.py"}]
1692277067573	Marionette	DEBUG	3 <- [1,6,null,{"value":[{"type":"wheel","button":0,"buttons":0,"deltaX":2.5,"deltaY":5,"deltaZ":0,"deltaMode":0,"target":"outer"}]}]

The caught scroll event has only a delta of 2.5/5 instead of 5/10.

A test like that works fine with wpt because the harness sets layout.css.devPixelsPerPx to 1.

Emilio, as it looks like we will have to convert the CSS pixels that WebDriver expects to device pixels. I assume the best option here is to use the window.devicePixelRatio value? Or should we use something else? Thanks!

Comment 1

[Henrik Skupin [:whimboo][⌚️UTC+2]]

Attachment: Bug 1849229 - [remote] Convert delta values for wheel scroll actions from CSS to device pixels.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/4ade93d36333
[remote] Convert delta values for wheel scroll actions from CSS to device pixels. r=webdriver-reviewers,jdescottes

Comment 3

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Failed to create upstream wpt PR due to merge conflicts. This requires fixup from a wpt sync admin.

Comment 4

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/41563 for changes under testing/web-platform/tests

Comment 5

[Iulian Moraru]

https://hg.mozilla.org/mozilla-central/rev/4ade93d36333

Comment 6

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream PR was closed without merging

Comment 7

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream PR merged by sideshowbarker

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/7f21aa1284eb
[wpt PR 41563] - [Gecko Bug 1849229] [remote] Convert delta values for wheel scroll actions from CSS to device pixels., a=testonly

Comment 9

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/7f21aa1284eb