Adds the ability to handle swipe events.
//Example Usage
$('#selector').each(function(){
swipedetect(this, function (swipedir){
// swipedir contains either "none", "left", "right", "top", or "down"
if (swipedir =='left') {
$("#selector").parent().find('.next').click();
}
if (swipedir =='right') {
$("#selector").parent().find('.prev').click();
}
});
});
// From http://www.javascriptkit.com/javatutors/touchevents2.shtml
function swipedetect(el, callback){
var touchsurface = el,
swipedir,
startX,
startY,
distX,
distY,
threshold = 150, //required min distance traveled to be considered swipe
restraint = 100, // maximum distance allowed at the same time in perpendicular direction
allowedTime = 300, // maximum time allowed to travel that distance
elapsedTime,
startTime,
handleswipe = callback || function (swipedir){}
touchsurface.addEventListener('touchstart', function(e){
var touchobj = e.changedTouches[0];
swipedir = 'none';
dist = 0;
startX = touchobj.pageX;
startY = touchobj.pageY;
startTime = new Date().getTime();
e.preventDefault();
}, false);
touchsurface.addEventListener('touchmove', function(e){
e.preventDefault(); // prevent scrolling when inside DIV
}, false);
touchsurface.addEventListener('touchend', function(e){
var touchobj = e.changedTouches[0];
distX = touchobj.pageX - startX; // get horizontal dist traveled by finger while in contact with surface
distY = touchobj.pageY - startY; // get vertical dist traveled by finger while in contact with surface
elapsedTime = new Date().getTime() - startTime;
if (elapsedTime <= allowedTime) {
if (Math.abs(distX) >= threshold && Math.abs(distY) <= restraint) {
swipedir = (distX < 0)? 'left' : 'right';
}
else if (Math.abs(distY) >= threshold && Math.abs(distX) <= restraint){
swipedir = (distY < 0)? 'up' : 'down'
}
}
handleswipe(swipedir);
e.preventDefault();
}, false)
}