[FIXED-360] scroller.scrollTo doesn't fire scroll event

[jeroenvduffelen]

panel.scroller.scrollTo({x: 0, y: scrollToPosY}, 360, 'cubic-bezier(0.4, .75, 0.5, .95)');

When I scroll the panel manually (with touch), the scroller fires the scroll event constantly. But when I scroll the panel with the above instruction it doesn't.

(sencha touch 0.95)

[BrendanC]

Thanks for the bug report.

[TommyMaintz]

This is because css transitions don't fire events during the animation. We won't be able to easily provide these. Is there any particular use case that you need these scroll events for during a scrollTo animation?

[jeroenvduffelen]

Hmmm.. but the scroll event does fire when the scroll animation / transition is triggered by touchscreen input. So when I swipe my finger over the screen and I let go, the scroll event keeps firing with the exact position of the scrollEl until the transition has ended.

I'm using the position quite a lot because I am keeping track of the progress of the scroller to check if some other event should be fired.


So when i do

this.scroller.on('scroll', this.onScroll, this)

onScroll: function(){
  console.log(this.scroller.getOffset().y);
}

I get all the positions the scroller passes... except when i scroll with .scrollTo.

[TommyMaintz]

Thats because when you release your finger, we determine momentum and apply velocity. The resulting momentum is handled purely by us, using intervals, and thus we can fire events. When you use scrollTo we just use a css transition. We tried doing the scrollTo animation using our custom javascript animation, but that would require us to determine the velocity required to get exactly to that position you are trying to get to. This is not such a big deal, but it was rather inprecise since sometimes it would two pixels too far etc. You could try playing around with applyVelocity function of scroller. I will look if we can somehow change this on our end, but that is something maybe for 1.1

[jeroenvduffelen]

Ah, clear explanation. I've build a simple work around for my progress checker so I don't need it at the moment but would be cool to have it in a later version!

[yuki]

Hi Tommy,

This is because css transitions don't fire events during the animation. We won't be able to easily provide these. Is there any particular use case that you need these scroll events for during a scrollTo animation?

When I use scrollTo for Ext.List's scroller, if grouped is true, the indexBar remains unchanged until I scroll it with the finger (sample code here. Scroll down to the bottom, and then click "top" button. indexBar "M" stays). This is because List needs "scroll" event from scroller to check the closest indexBar.

[TommyMaintz]

This seems to have been fixed in 1.0. Please let us know if this issue still exists for you and we will reinvestigate. Marking this bug as fixed for now.