1625934 - Scrolling is not working properly with Touch Simulation activated in RDM mode

Status: VERIFIED FIXED

(DevTools :: Responsive Design Mode, defect, P1)

Description

[Clara Guerrero ( Need Info Brindusa Tot Please)]

Attachment: scrolling.MOV

[Affected versions]
Beta 75.0b11 (64-bit)
Firefox Nightly 76.0a1 (2020-03-31) (64-bit)

[Affected platforms]
All

[Steps to reproduce]

1- Open youtube
2- Open RDM with touch simulation deactivated
3- Click notification button
4 - Scroll down within the notification window, and within the website window
5- Activate touch simulation
6- Click notification button
7- repeat setp 4

[Expected result]
Srolling should work without issues both with touch simulation on and off

[Actual result]
Scrolling is not working

Comment 1

[Clara Guerrero ( Need Info Brindusa Tot Please)]

In our latest version the buttons don't work at all when activating touch simulation , i'm attaching a new video. (Release is working fine both touch simulation on and off, beta and nightly aren't, I adjusted the flags accordingly). Youtube may have changed the page on their end.

Comment 2

[Clara Guerrero ( Need Info Brindusa Tot Please)]

Attachment: buttons.MOV

Comment 3

[Micah [:mtigley] (she/her)]

Attachment: Bug 1625934 - Use windowUtils' sendTouchEvent to dispatch touch events.

Comment 4

[Micah [:mtigley] (she/her)]

Console errors I'm getting with the STR above:

TypeError: can't access property "identifier", d is undefined
desktop_polymer_inlined_html_polymer_flags_v2.js:7600:337
TypeError: can't access property "clientX", b is undefined

Comment 5

[Brad Werth [:bradwerth] | Out until Feb 2025]

The un-minified code that is failing is this function: https://github.com/Polymer/polymer/blob/master/lib/utils/gestures.js#L405. From mapping that back to the minified error, it looks like the event we are sending to polymer has no changedTouches property. It seems likely that the new path used in D69891 is assigning this changedTouches property, where the current code does not.

Comment 6

[Brad Werth [:bradwerth] | Out until Feb 2025]

It appears that the comment in our code about touchend events must not send any changedTouches is in opposition to Polymer's expectations that assumes changedTouches exists for all non-touchstart events.

Checking against the spec, our assertion in touch-simulator.js is wrong. The spec says:

The touch point or points that were removed must be included in the changedTouches attribute of the TouchEvent, and must not be included in the touches and targetTouches attributes.

It looks like we misinterpreted this section when we fixed Bug 1250691. I'll try out a narrower version of this patch that doesn't wipe out changedTouches.

Comment 7

[Brad Werth [:bradwerth] | Out until Feb 2025]

Attachment: Bug 1625934 Part 1: Make touch-simulator correctly comply with spec for changedTouches on touchend and touchcancel events.

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/cc0f32718732
Use windowUtils' sendTouchEvent to dispatch touch events. r=bradwerth

Comment 9

[Daniel Varga [:dvarga]]

https://hg.mozilla.org/mozilla-central/rev/cc0f32718732

Comment 10

[Clara Guerrero ( Need Info Brindusa Tot Please)]

Hi,
This issue is still occuring in latest Nightly 79.0a1 (2020-06-22)
I'm sharing a new video
Best,
Clara

Comment 11

[Clara Guerrero ( Need Info Brindusa Tot Please)]

Attachment: cannot scroll youtube notification.mov

Comment 12

[Clara Guerrero ( Need Info Brindusa Tot Please)]

Hi,
This issue is not reproducible in beta 79.0b8 (64-bit) nor nightly 80.0a1 (2020-07-16) (64-bit)
I'm updating flags accordingly.
Best,
Clara