1909197 - Android: 3rd finger in a multi-touch interaction is primary

Status: UNCONFIRMED

(Fenix :: General, defect)

Description

[daxpedda]

Firefox for Android

Steps to reproduce:

According to the specification, PointerEvent.isPrimary is supposed to signify which finger is the first one in a multi-touch interaction.

To test the issue I used this code:

window.addEventListener('pointerdown', (e) => console.log('pointerdown', e.pointerId, e.isPrimary))
window.addEventListener('pointermove', (e) => e.isPrimary ? console.log('pointermove', e.pointerId, e.isPrimary) : {})
window.addEventListener('pointerup', (e) => console.log('pointerup', e.pointerId, e.isPrimary))

Then I went ahead and put down one finger after the other until I had three on the screen. Then I moved them around a bit and lifted them off one by one in reverse order.

User agent string: Mozilla/5.0 (Android 13; Mobile; rv:128.0) Gecko/128.0 Firefox/128.0
Note: I got all this information through remote debugging.

Actual results:

Simplified:

pointerdown 0 true
pointerdown 1 false
pointerdown 2 true
pointermove 2 true
pointermove 1 false
pointermove 0 true
pointerup 2 true
pointerup 1 false
pointerup 0 true

I also attempted to lift the 3rd finger and put it down again, it still recognized it with the ID 2 and marked it as primary.

Expected results:

Only the first finger should be marked as primary.

pointerdown 0 true
pointerdown 1 false
pointerdown 2 false
pointermove 2 false
pointermove 1 false
pointermove 0 true
pointerup 2 false
pointerup 1 false
pointerup 0 true

Comment 1

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

The Bugbug bot thinks this bug should belong to the 'Fenix::General' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

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

The severity field is not set for this bug.
:royang, could you have a look please?

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