I have a phonegap application that uses iOS native scrolling through -webkit-overflow-scrolling in a div. I want to be able to manually halt an ongoing scroll when the user clicks a button (to scroll back to the top of the page). Is this doable?
This is actually very possible when using fastclick.js. The lib removes the 300ms click delay on mobile devices and enables event capturing during inertia/momentum scrolling.
After including fastclick and attaching it to the body element, my code to stop scrolling and go to the top looks like this:
scrollElement.style.overflow = 'hidden';
scrollElement.scrollTop = 0;
setTimeout(function() {
scrollElement.style.overflow = '';
}, 10);
The trick is to set overflow: hidden, which stops the inertia/momentum scrolling. Please see my fiddle for a full implementation of stop scrolling during inertia/momentum.
Unfortunately this is not possible at the moment. The scroll event is triggered only when the scrolling has come to an end. As long as the momentum keeps moving the content no events are fired at all. You can see this in Figure 6-1 The panning gesture in Apple's "Safari Web Content Guide".
I also created a fiddle to demonstrate this behavior. The scrollTop value is set after iOS is done animating.
You can capture a touch event using 'touchstart' instead of 'click', as the click event sometimes doesn't seem to get fired until the momentum scroll completes. Try this jQuery solution:
$('#yourTrigger').on('touchstart', function () {
var $div = $('.yourScrollableDiv');
if ($div.scrollTop() === 0) {
return false; //if no scroll needed, do nothing.
}
$div.addClass('scrolling'); //apply the overflow:hidden style with a class
$div.animate({
scrollTop: 0
}, 600, function () {
$div.removeClass('scrolling'); //scrolling has finished, remove overflow:hidden
});
}
where the 'scrolling' class simply has the CSS property, overflow:hidden, which as #Patrick-Rudolph said, will halt any momentum scrolling in progress.
.scrolling {
overflow: hidden;
}
Note: It's best to use a callback function to tell when your scroll animation finishes, rather than setting a timer function.
Related
I have animation with ScrollMagic library and I am also using GSAP. This is description of animation on scroll in steps. Every number is one scroll:
Add class overflow-hidden to body, to disable scrolling.
Move credit-cards
Move remove some images
Start doing transform: translate(x,y) rotateZ(zdeg)
Stop scrolling and make image that was translated sticky
So this works good with mouse on mousewheel event. The question is:
What is the best way to implement touch scroll with very same effect when user comes from iOS or Andorid. (When user comes to my website from android, iPhone, iPad etc.)
I know that there is touchmove event.
var image = document.getElementById('image-phone');
if(step == 1){
//do first step
}...
//mousewheel event
window.addEventListener('mousewheel', function (e) {
//this is implemented
});
//touchnmove event
window.addEventListener('touchmove', function (e) {
//should I use this event
});
Quick disclaimer–I know there are similar questions but they don't provide the answer I'm looking for.
I'm trying to disable scrolling entirely when the page loads but still be able to listen to when user attempts to scroll. The goal is to trigger an animation function when user attempts to scroll and once the animation completes, the scroll would be re-enabled back to it's normal state.
I've tried to disable scroll and play my animation after user tries to scroll like this:
function blogHeaderMagic() {
//disable scroll function
disableScroll()
//my animation and on a callback you'll see I call allowScroll function to allow scroll normally once animation completes
TweenMax.to("#post-hero-media-wrapper", 1, {height:54, onComplete: allowScroll });
scrolled = true
}
document.onscroll = function() {
if( scrolled == false){
blogHeaderMagic();
}
}
And while this works great, in Chrome or Safari, it isn't such a smooth effect because when user first attempts to scroll, scroll is enabled so they can scroll like 100px from the top and only then scroll locks. This is why I would first like to disable the scroll and when user attempts to scroll (although they won't be able to) I would like to detect their attempt to scroll and trigger my animation function on that detection. Is this possible?
Answer
You could set the body tag to overflow:hidden; which won't allow the user to scroll and use these event handler, then put back the overflow property to whatever it was (probably auto if you didn't changed it in the first place).
// IE9, Chrome, Safari, Opera
document.body.addEventListener("mousewheel", MouseWheelHandler, false);
// Firefox
document.body.addEventListener("DOMMouseScroll", MouseWheelHandler, false);
function MouseWheelHandler() {
alert('scrolling with the mouse');
document.body.style.overflow = 'auto'
document.body.removeEventListener("mousewheel", MouseWheelHandler, false);
document.body.removeEventListener("DOMMouseScroll", MouseWheelHandler, false);
}
Interesting links
I did a quick codepen example. See here
Also this article
Edit----------------
Also found this Stack Overflow question
I dont think that there is a pure JS way of disabling all scroll while still detecting scroll events from the user (just reread your question) that's why I think the overflow solution is the simplest/most elegant solution (that I could come up with).
You could always detect scroll the set the scroll position to the top with something like window.scroll(0,0) and/or window.scrollTo(0,0). From what I have tested it doesn't seem to work quite well.
...without limiting the scroll inside the iframe or the need to specifically name/tag all scrollable elements.
Imagine google maps widget embedded in parent page. When you zoom in the widget you don't want the parent page to scroll, obviously.
I thought an answer to my previous question solved the problem:
While scrolling inside an iframe, the body doesn't know anything about
what happens there. But when iframe scroller reach the bottom or the
top, it pass scrolling to body.
Cancel the event that propagates from the iframe.
But the solution does not work in Firefox because Firefox will not - by design - propagate events captured by iframe to the parent page, yet strangely it will scroll the parent page. See jsfiddle here.
$('body').bind('mousewheel DOMMouseScroll', onWheel);
function onWheel (e){
if (e.target === iframe)
e.preventDefault();
console.log(e);
}
So, how do I prevent page from scrolling when user zooms content in embedded iframe, in Firefox?
Since it is a bug in Firefox, the workaround is to work directly with the scroll event, instead of the mousewheel / DOMMouseScroll ones.
The way I did: When user enters the mouse over the iframe, I set a flag to true, and when he leaves the mouse out there, I set it back to false.
Then, when user tries to scroll, but the mouse arrow is inside the iframe, I prevent the parent window scrolling. But, unfortunately, you can't prevent the window scrolling with the usual e.preventDefault() method, so we still need another workaround here, forcing the window to scroll exactly to the X and Y positions it was already before.
The full code:
(function(w) {
var s = { insideIframe: false }
$(iframe).mouseenter(function() {
s.insideIframe = true;
s.scrollX = w.scrollX;
s.scrollY = w.scrollY;
}).mouseleave(function() {
s.insideIframe = false;
});
$(document).scroll(function() {
if (s.insideIframe)
w.scrollTo(s.scrollX, s.scrollY);
});
})(window);
I've created an immediately executed function to prevent defining the s variable in the global scope.
Fiddle working: http://jsfiddle.net/qznujqjs/16/
Edit
Since your question was not tagged with jQuery (although inside it, you've showed a code using the library), the solution with vanilla JS is as simple as the above one:
(function(w) {
var s = { insideIframe: false }
iframe.addEventListener('mouseenter', function() {
s.insideIframe = true;
s.scrollX = w.scrollX;
s.scrollY = w.scrollY;
});
iframe.addEventListener('mouseleave', function() {
s.insideIframe = false;
});
document.addEventListener('scroll', function() {
if (s.insideIframe)
w.scrollTo(s.scrollX, s.scrollY);
});
})(window);
Given all the prerequisites, I think the following is the sanest way to make this work in Firefox.
Wrap your iframe with a div which is a little bit shorter to enable vertical scrolling in it:
<div id="wrapper" style="height:190px; width:200px; overflow-y: auto; overflow-x: hidden;">
<iframe id="iframeid" height="200px" width="200px" src="about:blank">
</iframe>
</div>
Now you can center the iframe vertically and re-position it every time
the wrapper receives a scroll event (it will occur when a user tries to scroll away at frame edges):
var topOffset = 3;
wrapper.scrollTop(topOffset);
wrapper.on("scroll", function(e) {
wrapper.scrollTop(topOffset);
});
Combine this with your previous fix for Chrome, and it should cover all major browsers. Here is a working example - http://jsfiddle.net/o2tk05ab/5/
The only outstanding issue will be the visible vertical scrollbar on a wrapper div. There are several ways to go about it, for instance - Hide scroll bar, but still being able to scroll
I think that will solve your problem
it solved mine
var myElem=function(event){
return $(event.toElement).closest('.slimScrollDiv')
}
$(document).mouseover(function(e){
window.isOnSub=myElem(e).length>0
})
$(document).on('mousewheel',function(e){
if(window.isOnSub){
console.log(e.originalEvent.wheelDelta);
if( myElem(e).prop('scrollHeight')-myElem(e).scrollTop()<=myElem(e).height()&&(e.originalEvent.wheelDelta<0)){
e.preventDefault()
}
}
})
replace '.slimScrollDiv' with the element selector you want to
prevent parent scroll while your mouse is on it
http://jsbin.com/cutube/1/edit?html,js,output
In all versions prior to iOS8, I was able to prevent the iPhone keyboard from pushing up (and destroying) my html/css/js view when the keyboard appeared by the following method:
$('input, select').focus(function(event) {
$(window).scrollTop(0);
// or via the scrollTo function
});
Since iOS8, this no longer works. One workaround is to place this code within a setTimeOut
setTimeout(function() { $(window).scrollTop(0); }, 0);
But it only makes the view do a jerky motion as the view is initially pushed up by iOS, then dragged back down by my js code. preventDefault and stopPropagation does not help either.
I've tried everything available on the web of course including my own solution posted here: How to prevent keyboard push up webview at iOS app using phonegap but so far, nothing works for iOS8. Any clever ideas on how to prevent the keyboard in iOS8 to push/move the view?
Try position:fixed on body, and/or wrap content in a div and position:fixed on it as well.
There are some options :
Make listener on your ios code, to move the screen up along with the keyboard height, so everything move up along with the keyboard, then your design save.
Make your css design responsive. Then no problem with change height, it will be scrollable inside your webview.
When keyboard pushes up view in iOS, a scroll event is triggered ($(window).scrollTop() is changed). You can put $(window).scrollTop(0) inside the scroll event handler. To prevent the jerky motion, set opacity to 0 during scrolling. Related codes may look like this:
function forceScrollTop() {
var scrollTop = $(window).scrollTop();
if (scrollTop != 0) {
$(window).scrollTop(0);
$(selector).css('opacity', 1);
$(window).off('scroll', forceScrollTop);
}
}
// when an input is focused ...
$(selector).css('opacity', 0);
$(window).on('scroll', forceScrollTop);
I can't seem to capture the scroll event on an iPad.
None of these work, what I am doing wrong?
window.onscroll=myFunction;
document.onscroll=myFunction;
window.attachEvent("scroll",myFunction,false);
document.attachEvent("scroll",myFunction,false);
They all work even on Safari 3 on Windows.
Ironically, EVERY browser on the PC supports window.onload= if you don't mind clobbering existing events. But no go on iPad.
The iPhoneOS does capture onscroll events, except not the way you may expect.
One-finger panning doesn’t generate any events until the user stops panning—an onscroll event is generated when the page stops moving and redraws—as shown in Figure 6-1.
Similarly, scroll with 2 fingers fires onscroll only after you've stopped scrolling.
The usual way of installing the handler works e.g.
window.addEventListener('scroll', function() { alert("Scrolled"); });
// or
$(window).scroll(function() { alert("Scrolled"); });
// or
window.onscroll = function() { alert("Scrolled"); };
// etc
(See also https://developer.apple.com/library/content/documentation/AppleApplications/Reference/SafariWebContent/HandlingEvents/HandlingEvents.html)
For iOS you need to use the touchmove event as well as the scroll event like this:
document.addEventListener("touchmove", ScrollStart, false);
document.addEventListener("scroll", Scroll, false);
function ScrollStart() {
//start of scroll event for iOS
}
function Scroll() {
//end of scroll event for iOS
//and
//start/end of scroll event for other browsers
}
Sorry for adding another answer to an old post but I usually get a scroll event very well by using this code (it works at least on 6.1)
element.addEventListener('scroll', function() {
console.log(this.scrollTop);
});
// This is the magic, this gives me "live" scroll events
element.addEventListener('gesturechange', function() {});
And that works for me. Only thing it doesn't do is give a scroll event for the deceleration of the scroll (Once the deceleration is complete you get a final scroll event, do as you will with it.) but if you disable inertia with css by doing this
-webkit-overflow-scrolling: none;
You don't get inertia on your elements, for the body though you might have to do the classic
document.addEventListener('touchmove', function(e) {e.preventDefault();}, true);
I was able to get a great solution to this problem with iScroll, with the feel of momentum scrolling and everything https://github.com/cubiq/iscroll The github doc is great, and I mostly followed it. Here's the details of my implementation.
HTML:
I wrapped the scrollable area of my content in some divs that iScroll can use:
<div id="wrapper">
<div id="scroller">
... my scrollable content
</div>
</div>
CSS:
I used the Modernizr class for "touch" to target my style changes only to touch devices (because I only instantiated iScroll on touch).
.touch #wrapper {
position: absolute;
z-index: 1;
top: 0;
bottom: 0;
left: 0;
right: 0;
overflow: hidden;
}
.touch #scroller {
position: absolute;
z-index: 1;
width: 100%;
}
JS:
I included iscroll-probe.js from the iScroll download, and then initialized the scroller as below, where updatePosition is my function that reacts to the new scroll position.
# coffeescript
if Modernizr.touch
myScroller = new IScroll('#wrapper', probeType: 3)
myScroller.on 'scroll', updatePosition
myScroller.on 'scrollEnd', updatePosition
You have to use myScroller to get the current position now, instead of looking at the scroll offset. Here is a function taken from http://markdalgleish.com/presentations/embracingtouch/ (a super helpful article, but a little out of date now)
function getScroll(elem, iscroll) {
var x, y;
if (Modernizr.touch && iscroll) {
x = iscroll.x * -1;
y = iscroll.y * -1;
} else {
x = elem.scrollTop;
y = elem.scrollLeft;
}
return {x: x, y: y};
}
The only other gotcha was occasionally I would lose part of my page that I was trying to scroll to, and it would refuse to scroll. I had to add in some calls to myScroller.refresh() whenever I changed the contents of the #wrapper, and that solved the problem.
EDIT: Another gotcha was that iScroll eats all the "click" events. I turned on the option to have iScroll emit a "tap" event and handled those instead of "click" events. Thankfully I didn't need much clicking in the scroll area, so this wasn't a big deal.
Since iOS 8 came out, this problem does not exist any more. The scroll event is now fired smoothly in iOS Safari as well.
So, if you register the scroll event handler and check window.pageYOffset inside that event handler, everything works just fine.
After some testing on the ios, I found that this is the way to go for ios and desktop, if you are not worried of that delay of 120ms on desktop. Works like a charm.
let isScrolling;
document.addEventListener("scroll", () => {
// Clear our timeout throughout the scroll
window.clearTimeout( isScrolling );
// Set a timeout to run after scrolling ends
isScrolling = setTimeout(function() {
// Run the callback
console.log( 'Scrolling has stopped.' );
}, 120);
});