Breadcrumbs scroll horribly with a touchpad :(

[lampholder]

Related to #9314

You try and scroll horizontally but it only reacts to the accidental vertical component of your scroll action.

[bwindels]

wonder if this is the tooltip preventing scroll events.

[jryans]

Possibly related to #9394.

[turt2live]

I can't actually test this because my laptop is sub par, however I believe this would be caused by the scroll event being additive.

[turt2live]

@lampholder can you try this again on the latest develop?

[jryans]

For me, it still seems quite difficult to scroll horizontally. I guess there aren't any wheel properties that say "from touchpad"...? Ideally we wouldn't attempt to consider the vertical component at all from a touchpad.

[lampholder]

Yeah, I'm afraid it still feels very glitchy to me :(

[turt2live]

Can I get a video of what "glitchy" is? Without a trackpad myself it's impossible to reproduce this, so I'm hoping that a video showing the behaviour can be reverse engineered enough to solve the problem.

[bwindels]

For me, on Fedora 29, FF 66:

First scrolling horizontally on the touchpad, which feels fast and fluid (but didn't expect to use it like this, I intuitively used vertical touchpad scrolling). then vertical touchpad scrolling, which is slower, and then scroll wheel on my mouse, which is a lot slower still.

Ideally they would all scroll at the same rate.

[bwindels]

As you don't have the hardware, I'm also happy to have a look @turt2live

[jryans]

I believe the main issue I have noticed is that with a touchpad, you could hover over the breadcrumbs and move from the center of the touchpad to the top-right corner, in an attempt to scroll right. However, since there is both motion right and up, the vertical handling counteracts the horizontal, and it just kind of shakes around:

[jryans]

It seems like it's hard to distinguish mouse wheel vs. touchpad scrolling generally...

Maybe it would be sufficient to say if the wheel event contains any horizontal delta, it's probably from a touchpad-like device, so ignore the vertical component and only use the horizontal. Would that be reasonable?

[bwindels]

While testing with my touchpad, I see both deltaX and deltaY with a non-zero value, depending of how I scroll.

deltaX/Y values from the touchpad do always seem to be fractional, whereas from the mouse wheel always seem to be integers.

[jryans]

For Firefox on macOS with my MBP touchpad, the delta values are integers only.

[turt2live]

Recent changes were supposed to consider anything over a delta of 10 as horizontal only movement, but it sounds like that's too high. Maybe zero is the right answer for a threshold.

I'll put together a quick script for people to run to see if it fixes the issue later today.

[turt2live]

turns out the script is simple:

@jryans @bwindels can you give this a try in the js console? Will need to reload after setting to pick up the changes.

mxSettingsStore.setValue("breadcrumb_scroll_tolerances", null, "device", {xyThreshold: 0, yReduction: 1.0});

[jryans]

turns out the script is simple:

@jryans @bwindels can you give this a try in the js console? Will need to reload after setting to pick up the changes.

mxSettingsStore.setValue("breadcrumb_scroll_tolerances", null, "device", {xyThreshold: 0, yReduction: 1.0});

For me, this is almost enough. One extra bug fix is also needed: the xyThreshold allows any negative value to go through, so moving from center to bottom-left isn't correct yet. If I also change the code to

if (Math.abs(e.deltaX) >= xyThreshold) return;

then yes, the scrolling is great for me.

[bwindels]

Can't test atm without /develop