Momentum scrolling feels unnatural

[kjb]

Momentum scrolling of a long list feels very different from native momentum scrolling (iOS, Android) (see http://jqmobi.com/testdrive and select "Selectors" tab.)

[imaffett]

It's virtually impossible to get the exact native performance. Since only iOS 5 allows fixed positioning (and scrolling divs which act funky), everyone is stuck writing their own scrolling library.

If you can provide more info, we'll be happy to look into this.

[kjb]

The iScroll-4 library has an implementation that feels pretty good.

It uses a momentum function as follows:

_momentum: function (dist, time, maxDistUpper, maxDistLower, size) {
    var deceleration = 0.0006,
        speed = m.abs(dist) / time,
        newDist = (speed * speed) / (2 * deceleration),
        newTime = 0, outsideDist = 0;

    // Proportinally reduce speed if we are outside of the boundaries 
    if (dist > 0 && newDist > maxDistUpper) {
        outsideDist = size / (6 / (newDist / speed * deceleration));
        maxDistUpper = maxDistUpper + outsideDist;
        speed = speed * maxDistUpper / newDist;
        newDist = maxDistUpper;
    } else if (dist < 0 && newDist > maxDistLower) {
        outsideDist = size / (6 / (newDist / speed * deceleration));
        maxDistLower = maxDistLower + outsideDist;
        speed = speed * maxDistLower / newDist;
        newDist = maxDistLower;
    }

    newDist = newDist * (dist < 0 ? -1 : 1);
    newTime = speed / deceleration;

    return { dist: newDist, time: mround(newTime) };
},

Under an MIT-type license: https://github.com/cubiq/iscroll/blob/master/license.txt

[ryanflorence]

Sencha Touch's implementation feels better on Android than native. It can be done.

[matthias]

The same occurs for the carousel. Lists and carousel seem to have a maximum speed that is well bellow the speed of my thumb / fingers.

[sindresorhus]

Scrollability is also pretty smooth.

[imaffett]

Sencha Touch's performance has been sub par on every device we have tested (Galaxy S, Droid, Droid Bionic, Droid X/X2).

I think the issue is the easing method. @kjb please commit a patch/pull request and we'll test it.

[imaffett]

I broke out an iPad and found the big culprit is the CSS on the list item elements. When I remove them, scrolling is much better. We're redoing the CSS on the kitchen sink demo for the list items. Also looking into the momentum from iscroll4

[cjvraay]

It would also help if the "stretch tension" increased as you scroll beyond the bounds of the content, so as you drag the amount of movement becomes less.

[imaffett]

A lot of people seem to have opinions on how things should work, but very few are submitting patches. We're limited in time and resources for what we want to get in the 1.0 release. For the most part, we are happy with how core pieces function, so when we see requests like this it's really low on the priority list.

[imaffett]

@cjvraay - Ok...turns out we had something like this in another project, so it's been merged in and will be apart of the next update.

[cjvraay]

Thanks @imaffett