// JavaScript Document

// TOUCH-EVENTS SINGLE-FINGER SWIPE-SENSING JAVASCRIPT
		// Courtesy of PADILICIOUS.COM and MACOSXAUTOMATION.COM
	
		var photoCount = 8; // the number of images in the slideshow
		var fingerCount = 0;
		var startX = 0;
		var startY = 0;
		var curX = 0;
		var curY = 0;
		var deltaX = 0;
		var deltaY = 0;
		var horzDiff = 0;
		var vertDiff = 0;
		var minLength = 72; // the shortest distance the user may swipe
		var swipeLength = 0;
		var swipeAngle = null;
		var swipeDirection = null;
		var triggerElementID = null; // this variable is used throughout the script
	
		// The 4 Touch Event Handlers
		
		// the touchStart handler should also receive the ID of the triggering element
		// make sure it's ID is passed in the event call placed in the element declaration, like:
		// <div id="picture-frame" ontouchstart="touchStart(event,'picture-frame');"  ontouchend="touchEnd(event);" ontouchmove="touchMove(event);" ontouchcancel="touchCancel(event);"></div>
		function touchStart(event,passedID) {
			// disable the standard ability to select the touched object
			//event.preventDefault();
			// get the total number of fingers touching the screen
			fingerCount = event.touches.length;
			// since we're looking for a swipe (single finger) and not a gesture (multiple fingers),
			// check that only one finger was used
			if ( fingerCount == 1 ) {
				// get the coordinates of the touch
				startX = event.touches[0].pageX;
				startY = event.touches[0].pageY;
				// store the triggering element ID
				triggerElementID = passedID;
			} else {
				// more than one finger touched so cancel
				touchCancel(event);
			}
		}

		function touchMove(event) {
			event.preventDefault();
			if ( event.touches.length == 1 ) {
				curX = event.touches[0].pageX;
				curY = event.touches[0].pageY;
			} else {
				touchCancel(event);
			}
		}
		
		function touchEnd(event) {
			event.preventDefault();
			// check to see if more than one finger was used and that there is a and ending coordinate
			if ( fingerCount == 1 && curX != 0 ) {
				// use the Distance Formula to determine the length of the swipe
				swipeLength = Math.round(Math.sqrt(Math.pow(curX - startX,2) + Math.pow(curY - startY,2)));
				// if the user swiped more than the minimum length, perform the appropriate action
				if ( swipeLength >= minLength ) {
					caluculateAngle();
					determineSwipeDirection();
					processingRoutine();
					touchCancel(event);
				} else {
					touchCancel(event);
				}	
			} else {
				touchCancel(event);
			}
		}

		function touchCancel(event) {
			// reset the variables back to default values
			fingerCount = 0;
			startX = 0;
			startY = 0;
			curX = 0;
			curY = 0;
			deltaX = 0;
			deltaY = 0;
			horzDiff = 0;
			vertDiff = 0;
			swipeLength = 0;
			swipeAngle = null;
			swipeDirection = null;
			triggerElementID = null;
		}
		
		function caluculateAngle() {
			var X = startX-curX;
			var Y = curY-startY;
			var Z = Math.round(Math.sqrt(Math.pow(X,2)+Math.pow(Y,2))); //the distance - rounded - in pixels
			var r = Math.atan2(Y,X); //angle in radians (Cartesian system)
			swipeAngle = Math.round(r*180/Math.PI); //angle in degrees
			if ( swipeAngle < 0 ) { swipeAngle =  360 - Math.abs(swipeAngle); }
		}
		
		function determineSwipeDirection() {
			if ( (swipeAngle <= 45) && (swipeAngle >= 0) ) {
				swipeDirection = 'left';
			} else if ( (swipeAngle <= 360) && (swipeAngle >= 315) ) {
				swipeDirection = 'left';
			} else if ( (swipeAngle >= 135) && (swipeAngle <= 225) ) {
				swipeDirection = 'right';
			} else if ( (swipeAngle > 45) && (swipeAngle < 135) ) {
				swipeDirection = 'down';
			} else {
				swipeDirection = 'up';
			}
		}
		
		// the function for performing actions, possibly on the triggering element
		function processingRoutine() {
			// for this example, only respond to horizontal swipes
			if ( swipeDirection == 'left' ) {
				$('#next').click();
			} else if ( swipeDirection == 'right' ) {
				$('#prev').click();
			}
		}