Scroll wheel zooms instead of scrolling drivers#
Scroll wheel zooms instead of scrolling free#

They did do this change before passive event listener capability was added to the w3c events spec, so I see how this was Microsoft's way of fixing the laggy scrolling issue, but now this just leaves users of the device kind of handicapped compared to everyone else's devices. I just can't see them not going back to firing wheel events, it just doesn't make sense. I can't imagine what 'heuristic' they use to differentiate the two-finger gestures, but the result is that even if we wanted to add a two-touch gesture, the Precision Touchpad device isn't going to provide the events! There's only enough events provided to interpret drags or pinches. pointermove, pointerup events for two contacts) Two touches moved in different direction results in two separate sets of touch pointer events in the browser (pointerdown.pointermove, pointerup events for one contact) Two touches swiped for pan/scroll result in single-contact touch events in the browser (pointerdown.'wheel' events are no longer fired by the device.'Reasonably', however, is subjective - and I think they failed here ( info at the link posted above):

Scroll wheel zooms instead of scrolling drivers#

The Precision Touchpad drivers interpret multiple touches internally, and in the case of browser DOM events, fire events that reasonably match what users expect from the device.

Scroll wheel zooms instead of scrolling free#

True browser multi-touch devices provide events for all contacts individually, so event listeners are free to interpret the events into gestures any way desired. The Precision Touchpad is not a multi-touch device like most touch screens are (at least not in the way the device's events are exposed in browsers). The devices that do have the gesture either already work (Mac) or have a specific event (Windows precision touchpads), and in both cases you wouldn't want to reinvent the wheel (no pun intended), because you would miss some of the specifics of their I've looked deep into this.

I don't think we should be trying to interpret regular touch events to support this gesture, though, since most touch devices (such as phones and tablets) shouldn't have that gesture.

If you want to support that event, that could be cool. Looks like maybe the Windows 'Precision Touchpads' don't do that directly for some reason, but they do have a specific event (not a regular touch event) you can look for. The two finger drag on the trackpad just automatically gets turned into a scroll wheel event (taking into account the user's configuration for which direction is which), so OpenSeadragon doesn't need to know anything about it. The thing is, on the Mac at least, this already works fine.