iScroll with native scrolling on one axis

Question

I am using the most wonderful javascript tool iScroll4 http://cubiq.org/iscroll-4 on a mobile website for iOS and Android. Here is what my layout looks like:

The horizontally scroll-able area is making use of iScroll4 with the following settings:

   var myScroll = new iScroll('frame',  { hScrollbar: false, vScrollbar: false, vScroll: false })

The horizontal scrolling part works great. This issue is what happens when a user attempts to scroll up or down the page placing their finger on the horizontal scrolling area. So I need native vertical scrolling, and iScroll horizontal scrolling on the same area.

What I have tried so far: Removing e.preventDefault() in the iScroll code (allows for native scrolling, but in BOTH axes). Removing e.preventDefault() and then disabling horizontal scrolling page wide with this:

var touchMove;

document.ontouchstart = function(e){
    touchMove = e.touches[0];
}

document.ontouchmove = function(e){
    var theTouch = e.touches[0] || e.changedTouches[0];
    var Xer      = rs(touchMove.pageX - theTouch.pageX).toPos();
    var Yer      = rs(touchMove.pageY - theTouch.pageY).toPos();        
    touchMove    = theTouch;
    if(Yer > Xer){ e.preventDefault(); }
}

which seems to do nothing. How can I allow for native vertical scrolling in the horizontal scrolling area, without loosing the horizontal scrolling of iScroll? I am really stumped here. Thanks in advance.

(just for the record rs(foo).toPos() is a function that makes foo a positive number regardless of its value).

Answer 1

If you would like to achieve the effect described by Fresheyeball without hacking the core, and without changing from iScroll to swipeview, then iScroll 4 does offer you its event listeners to work with.

myScroll = new iScroll('scrollpanel', {
    // other options go here...
    vScroll: false,
    onBeforeScrollMove: function ( e ) {
        if ( this.absDistX > (this.absDistY + 5 ) ) {
            // user is scrolling the x axis, so prevent the browsers' native scrolling
            e.preventDefault();
        } else {
            // delegate the scrolling to window object
        window.scrollBy( 0, -this.distY );
    }
    },
});

By doing so, the onBeforeScrollMove-Handler checks whether the scroll direction seems to be horizontal, and then prevents the default handler, thus effectively locking the scroll action to the X-Axis (try commenting it out, you'll see the difference). Otherwise, if the scroll direction needs to be vertical, we make the browser scroll via the window.scrollBy() method. This is not exactly native, but does the job just fine.

Hope that helps

Lukx

[EDIT] My original solution, which didn't use window.scrollBy() ,did not work on slower Samsung phones, which is why I needed to adapt the answer.

Answer 2

Suggested edit to @Lukx's excellent solution. New versions of iScroll4 place the e.preventDefault() in onBeforeScrollMove which can be overridden. By placing the if block into this option, default is not prevented for vertical scrolling, and vertical can scroll natively.

myScroll = new iScroll('scrollpanel', {
    // other options go here...
    vScroll: false,
    onBeforeScrollStart: function ( e ) {
        if ( this.absDistX > (this.absDistY + 5 ) ) {
            // user is scrolling the x axis, so prevent the browsers' native scrolling
            e.preventDefault();
        }
    },
});

Answer 3

With iscroll 5, you can set eventPassthrough: true to achieve this. See http://iscrolljs.com/#configuring

Answer 4

OLD ANSWER

UPDATE a special pluggin has been written just to address this problem: http://cubiq.org/swipeview

I found a way!

add a variable to the top of the document: if android is 15 and is iOS is 3

 var scrollTolerance = ( rs().isDevice('android') )?15:3;

disable the original e.preventDefault(); for scrolling. This is under onBeforeScrollStart:

the in _move just under

 timestamp = e.timeStamp || Date.now();

add this line

if( Math.sqrt(deltaX*deltaX) > scrollTolerance){e.preventDefault();}

What this does is the following: the scrollTolerance sets, you guessed it, a tolerance for finger direction. We don't want to demand a perfect vertical angle to get the up down native scroll. Also iOS does not detect properly and will never be higher than 4 for some reason so I used 3. Then we disable iScroll's standard e.preventDefault(); which prevents native vertical scrolling on our bi-scrollable area. Then we insert e.preventDefault(); only upon move and based on finger direction from tolerance.

This does not work perfect. But is acceptable and works on iOS and Android. If anyone sees better ways please post here. This is something I (and assume others) need to use regularly, and we should have a perfect rock solid solution.

Thanks.

Answer 5

Please test this solution from Adam. https://gist.github.com/hotmeteor/2231984

I think the trick is to add the check in onBeforeScrollMove. First get the initial touch position in onBeforeScrollTouchStart and then in onBeforeScrollMove check the new position and then disable the required scroll based on the difference.

Answer 6

iScroll 5 supports native scrolling of any axis!

http://iscrolljs.com/

Answer 7

on iScroll5 just set eventPassthrougt to true. That fixes it.