jQuery(document).ready(function($){
var dragging = false,
scrolling = false,
resizing = false;
//cache jQuery objects
var imageComparisonContainers = $(‘.cd-image-container’);
//check if the .cd-image-container is in the viewport
//if yes, animate it
checkPosition(imageComparisonContainers);
$(window).on(‘scroll’, function(){
if( !scrolling) {
scrolling = true;
( !window.requestAnimationFrame )
? setTimeout(function(){checkPosition(imageComparisonContainers);}, 100)
: requestAnimationFrame(function(){checkPosition(imageComparisonContainers);});
}
});

//make the .cd-handle element draggable and modify .cd-resize-img width according to its position
imageComparisonContainers.each(function(){
var actual = $(this);
drags(actual.find(‘.cd-handle’), actual.find(‘.cd-resize-img’), actual, actual.find(‘.cd-image-label[data-type=”original”]’), actual.find(‘.cd-image-label[data-type=”modified”]’));
});

//upadate images label visibility
$(window).on(‘resize’, function(){
if( !resizing) {
resizing = true;
( !window.requestAnimationFrame )
? setTimeout(function(){checkLabel(imageComparisonContainers);}, 100)
: requestAnimationFrame(function(){checkLabel(imageComparisonContainers);});
}
});

function checkPosition(container) {
container.each(function(){
var actualContainer = $(this);
if( $(window).scrollTop() + $(window).height()*0.5 > actualContainer.offset().top) {
actualContainer.addClass(‘is-visible’);
}
});

scrolling = false;
}

function checkLabel(container) {
container.each(function(){
var actual = $(this);
updateLabel(actual.find(‘.cd-image-label[data-type=”modified”]’), actual.find(‘.cd-resize-img’), ‘left’);
updateLabel(actual.find(‘.cd-image-label[data-type=”original”]’), actual.find(‘.cd-resize-img’), ‘right’);
});

resizing = false;
}

//draggable funtionality – credits to http://css-tricks.com/snippets/jquery/draggable-without-jquery-ui/
function drags(dragElement, resizeElement, container, labelContainer, labelResizeElement) {
dragElement.on(“mousedown vmousedown”, function(e) {
dragElement.addClass(‘draggable’);
resizeElement.addClass(‘resizable’);

var dragWidth = dragElement.outerWidth(),
xPosition = dragElement.offset().left + dragWidth – e.pageX,
containerOffset = container.offset().left,
containerWidth = container.outerWidth(),
minLeft = containerOffset + 10,
maxLeft = containerOffset + containerWidth – dragWidth – 10;

dragElement.parents().on(“mousemove vmousemove”, function(e) {
if( !dragging) {
dragging = true;
( !window.requestAnimationFrame )
? setTimeout(function(){animateDraggedHandle(e, xPosition, dragWidth, minLeft, maxLeft, containerOffset, containerWidth, resizeElement, labelContainer, labelResizeElement);}, 100)
: requestAnimationFrame(function(){animateDraggedHandle(e, xPosition, dragWidth, minLeft, maxLeft, containerOffset, containerWidth, resizeElement, labelContainer, labelResizeElement);});
}
}).on(“mouseup vmouseup”, function(e){
dragElement.removeClass(‘draggable’);
resizeElement.removeClass(‘resizable’);
});
e.preventDefault();
}).on(“mouseup vmouseup”, function(e) {
dragElement.removeClass(‘draggable’);
resizeElement.removeClass(‘resizable’);
});
}

function animateDraggedHandle(e, xPosition, dragWidth, minLeft, maxLeft, containerOffset, containerWidth, resizeElement, labelContainer, labelResizeElement) {
var leftValue = e.pageX + xPosition – dragWidth;
//constrain the draggable element to move inside his container
if(leftValue maxLeft) {
leftValue = maxLeft;
}

var widthValue = (leftValue + dragWidth/2 – containerOffset)*100/containerWidth+’%’;

$(‘.draggable’).css(‘left’, widthValue).on(“mouseup vmouseup”, function() {
$(this).removeClass(‘draggable’);
resizeElement.removeClass(‘resizable’);
});

$(‘.resizable’).css(‘width’, widthValue);

updateLabel(labelResizeElement, resizeElement, ‘left’);
updateLabel(labelContainer, resizeElement, ‘right’);
dragging = false;
}

function updateLabel(label, resizeElement, position) {
if(position == ‘left’) {
( label.offset().left + label.outerWidth() resizeElement.offset().left + resizeElement.outerWidth() ) ? label.removeClass(‘is-hidden’) : label.addClass(‘is-hidden’) ;
}
}
});