How to fix flicker when using Webkit transforms & transitions
- by gargantaun
I have a very simple demo working that uses Webkit transforms and transitions for smooth horizontal scrolling between 'panels' (divs).
The reason I want to go this route as opposed to a Javascript driven system is that it's for the iPad and Javascript performance is quite poor, but the css transforms and transitions are smooth as silk. Sadly though, I'm getting a lot of flicker on the iPad with my Demo.
You can see the demo here
You'll need safari or and iPad to see it in action. I've never seen this happening in any of the demos for transforms and transitions so I'm hopeful that this is fixable.
Anyway here's the code that powers the thing....
The HTML looks like this.
<html>
<head>
<title>Swipe Demo</title>
<link href="test.css" rel="stylesheet" />
<link href="styles.css" rel="stylesheet" />
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript" src="functions.js"></script>
<script type="text/javascript" src="swiping.js"></script>
</head>
<body>
<div id="wrapper">
<div class='panel one'>
<h1>This is panel 1</h1>
</div>
<div class='panel two'>
<h1>This is panel 2</h1>
</div>
<div class='panel three'>
<h1>This is panel 3</h1>
</div>
<div class='panel four'>
<h1>This is panel 4</h1>
</div>
</div>
</body>
</html>
The CSS looks like this
body,
html
{
padding: 0;
margin: 0;
background: #000;
}
#wrapper
{
width: 10000px;
-webkit-transform: translateX(0px);
}
.panel
{
width: 1024px;
height: 300px;
background: #fff;
display: block;
float: left;
position: relative;
}
and the javascript looks like this
// Mouse / iPad Touch
var touchSupport = (typeof Touch == "object"),
touchstart = touchSupport ? 'touchstart' : 'mousedown',
touchmove = touchSupport ? 'touchmove' : 'mousemove',
touchend = touchSupport ? 'touchend' : 'mouseup';
$(document).ready(function(){
// set top and left to zero
$("#wrapper").css("top", 0);
$("#wrapper").css("left", 0);
// get total number of panels
var panelTotal;
$(".panel").each(function(){ panelTotal += 1 });
// Touch Start
// ------------------------------------------------------------------------------------------
var touchStartX;
var touchStartY;
var currentX;
var currentY;
var shouldMove = false;
document.addEventListener(touchstart, swipeStart, false);
function swipeStart(event){
touch = realEventType(event);
touchStartX = touch.pageX;
touchStartY = touch.pageY;
var pos = $("#wrapper").position();
currentX = parseInt(pos.left);
currentY = parseInt(pos.top);
shouldMove = true;
}
// Touch Move
// ------------------------------------------------------------------------------------------
var touchMoveX;
var touchMoveY;
var distanceX;
var distanceY;
document.addEventListener(touchmove, swipeMove, false);
function swipeMove(event){
if(shouldMove){
touch = realEventType(event);
event.preventDefault();
touchMoveX = touch.pageX;
touchMoveY = touch.pageY;
distanceX = touchMoveX - touchStartX;
distanceY = touchMoveY - touchStartY;
movePanels(distanceX);
}
}
function movePanels(distance){
newX = currentX + (distance/4);
$("#wrapper").css("left", newX);
}
// Touch End
// ------------------------------------------------------------------------------------------
var cutOff = 100;
var panelIndex = 0;
document.addEventListener(touchend, swipeEnd, false);
function swipeEnd(event){
touch = (touchSupport) ? event.changedTouches[0] : event;
var touchEndX = touch.pageX;
var touchEndY = touch.pageY;
updatePanelIndex(distanceX);
gotToPanel();
shouldMove = false;
}
// -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
function updatePanelIndex(distance){
if(distanceX > cutOff)
panelIndex -= 1;
if(distanceX < (cutOff * -1)){
panelIndex += 1;
}
if(panelIndex < 0){
panelIndex = 0;
}
if(panelIndex >= panelTotal)
panelIndex = panelTotal -1;
console.log(panelIndex);
}
// -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
function gotToPanel(){
var panelPos = getTotalWidthOfElement($(".panel")) * panelIndex * -1;
$("#wrapper").css("-webkit-transition-property", "translateX");
$("#wrapper").css("-webkit-transition-duration", "1s");
$("#wrapper").css("-webkit-transform", "translateX("+panelPos+"px)");
}
});
function realEventType(event){
e = (touchSupport) ? event.targetTouches[0] : event;
return e;
}
