swipe.js

/*!
 * Swipe 2.0.6
 *
 * Brad Birdsall & Felix Liu
 * Copyright 2015, MIT License
 *
*/

// if the module has no dependencies, the above pattern can be simplified to
;(function (root, factory) {
  if (typeof define === 'function' && define.amd) {
    // AMD. Register as an anonymous module.
    define([], function(){
      return (root.Swipe = factory());
    });
  } else if (typeof exports === 'object') {
    // Node. Does not work with strict CommonJS, but
    // only CommonJS-like environments that support module.exports,
    // like Node.
    module.exports = factory();
  } else {
    // Browser globals
    root.Swipe = factory();
  }
}(this, function () {

  var root = this;
  var _document = root.document;

  function Swipe(container, options) {

    "use strict";

    // utilities
    var noop = function() {}; // simple no operation function
    var offloadFn = function(fn) { setTimeout(fn || noop, 0); }; // offload a functions execution

    // check browser capabilities
    var browser = {
      addEventListener: !!root.addEventListener,
      touch: ('ontouchstart' in root) || root.DocumentTouch && _document instanceof DocumentTouch,
      transitions: (function(temp) {
        var props = ['transitionProperty', 'WebkitTransition', 'MozTransition', 'OTransition', 'msTransition'];
        for ( var i in props ) {
          if (temp.style[ props[i] ] !== undefined){
            return true;
          }
        }
        return false;
      })(_document.createElement('swipe'))
    };

    // quit if no root element
    if (!container) {
      return;
    }

    var element = container.children[0];
    var slides, slidePos, width, length;
    options = options || {};
    var index = parseInt(options.startSlide, 10) || 0;
    var speed = options.speed || 300;
    options.continuous = options.continuous !== undefined ? options.continuous : true;

    // AutoRestart option: auto restart slideshow after user's touch event
    options.autoRestart = options.autoRestart !== undefined ? options.autoRestart : false;

    function setup() {

      // cache slides
      slides = element.children;
      length = slides.length;

      // set continuous to false if only one slide
      if (slides.length < 2) {
        options.continuous = false;
      }

      //special case if two slides
      if (browser.transitions && options.continuous && slides.length < 3) {
        element.appendChild(slides[0].cloneNode(true));
        element.appendChild(element.children[1].cloneNode(true));
        slides = element.children;
      }

      // create an array to store current positions of each slide
      slidePos = new Array(slides.length);

      // determine width of each slide
      width = container.getBoundingClientRect().width || container.offsetWidth;

      element.style.width = (slides.length * width * 2) + 'px';

      // stack elements
      var pos = slides.length;
      while(pos--) {

        var slide = slides[pos];

        slide.style.width = width + 'px';
        slide.setAttribute('data-index', pos);

        if (browser.transitions) {
          slide.style.left = (pos * -width) + 'px';
          move(pos, index > pos ? -width : (index < pos ? width : 0), 0);
        }

      }

      // reposition elements before and after index
      if (options.continuous && browser.transitions) {
        move(circle(index-1), -width, 0);
        move(circle(index+1), width, 0);
      }

      if (!browser.transitions) {
        element.style.left = (index * -width) + 'px';
      }

      container.style.visibility = 'visible';

    }

    function prev() {

      if (options.continuous) {
        slide(index-1);
      }
      else if (index) {
        slide(index-1);
      }

    }

    function next() {

      if (options.continuous) {
        slide(index+1);
      }
      else if (index < slides.length - 1) {
        slide(index+1);
      }

    }

    function circle(index) {

      // a simple positive modulo using slides.length
      return (slides.length + (index % slides.length)) % slides.length;

    }

    function getPos() {
      // Fix for the clone issue in the event of 2 slides
      var currentIndex = index;

      if (currentIndex >= length) {
        currentIndex = currentIndex - length;
      }

      return currentIndex;
    }

    function slide(to, slideSpeed) {

      // do nothing if already on requested slide
      if (index === to) {
        return;
      }

      if (browser.transitions) {

        var direction = Math.abs(index-to) / (index-to); // 1: backward, -1: forward

        // get the actual position of the slide
        if (options.continuous) {
          var natural_direction = direction;
          direction = -slidePos[circle(to)] / width;

          // if going forward but to < index, use to = slides.length + to
          // if going backward but to > index, use to = -slides.length + to
          if (direction !== natural_direction) {
            to =  -direction * slides.length + to;
          }

        }

        var diff = Math.abs(index-to) - 1;

        // move all the slides between index and to in the right direction
        while (diff--) {
          move( circle((to > index ? to : index) - diff - 1), width * direction, 0);
        }

        to = circle(to);

        move(index, width * direction, slideSpeed || speed);
        move(to, 0, slideSpeed || speed);

        if (options.continuous) { // we need to get the next in place
          move(circle(to - direction), -(width * direction), 0);
        }

      } else {

        to = circle(to);
        animate(index * -width, to * -width, slideSpeed || speed);
        //no fallback for a circular continuous if the browser does not accept transitions
      }

      index = to;
      offloadFn(options.callback && options.callback(getPos(), slides[index]));
    }

    function move(index, dist, speed) {

      translate(index, dist, speed);
      slidePos[index] = dist;

    }

    function translate(index, dist, speed) {

      var slide = slides[index];
      var style = slide && slide.style;

      if (!style) {
        return;
      }

      style.webkitTransitionDuration =
      style.MozTransitionDuration =
      style.msTransitionDuration =
      style.OTransitionDuration =
      style.transitionDuration = speed + 'ms';

      style.webkitTransform = 'translate(' + dist + 'px,0)' + 'translateZ(0)';
      style.msTransform =
      style.MozTransform =
      style.OTransform = 'translateX(' + dist + 'px)';

    }

    function animate(from, to, speed) {

      // if not an animation, just reposition
      if (!speed) {

        element.style.left = to + 'px';
        return;

      }

      var start = +new Date();

      var timer = setInterval(function() {

        var timeElap = +new Date() - start;

        if (timeElap > speed) {

          element.style.left = to + 'px';

          if (delay) {
            begin();
          }

          if (options.transitionEnd) {
            options.transitionEnd.call(event, getPos(), slides[index]);
          }

          clearInterval(timer);
          return;

        }

        element.style.left = (( (to - from) * (Math.floor((timeElap / speed) * 100) / 100) ) + from) + 'px';

      }, 4);

    }

    // setup auto slideshow
    var delay = options.auto || 0;
    var interval;

    function begin() {

      interval = setTimeout(next, delay);

    }

    function stop() {

      delay = 0;
      clearTimeout(interval);

    }

    function restart() {
      stop();
      delay = options.auto || 0;
      begin();
    }

    function isMouseEvent(e) {
      return /^mouse/.test(e.type);
    }

    // setup initial vars
    var start = {};
    var delta = {};
    var isScrolling;

    // setup event capturing
    var events = {

      handleEvent: function(event) {
        switch (event.type) {
          case 'mousedown':
          case 'touchstart': this.start(event); break;
          case 'mousemove':
          case 'touchmove': this.move(event); break;
          case 'mouseup':
          case 'mouseleave':
          case 'touchend': offloadFn(this.end(event)); break;
          case 'webkitTransitionEnd':
          case 'msTransitionEnd':
          case 'oTransitionEnd':
          case 'otransitionend':
          case 'transitionend': offloadFn(this.transitionEnd(event)); break;
          case 'resize': offloadFn(setup); break;
        }

        if (options.stopPropagation) {
          event.stopPropagation();
        }

      },
      start: function(event) {
        var touches;

        if (isMouseEvent(event)) {
          touches = event;
          event.preventDefault(); // For desktop Safari drag
        } else {
          touches = event.touches[0];
        }

        // measure start values
        start = {

          // get initial touch coords
          x: touches.pageX,
          y: touches.pageY,

          // store time to determine touch duration
          time: +new Date()

        };

        // used for testing first move event
        isScrolling = undefined;

        // reset delta and end measurements
        delta = {};

        // attach touchmove and touchend listeners
        if (isMouseEvent(event)) {
          element.addEventListener('mousemove', this, false);
          element.addEventListener('mouseup', this, false);
          element.addEventListener('mouseleave', this, false);
        } else {
          element.addEventListener('touchmove', this, false);
          element.addEventListener('touchend', this, false);
        }

      },
      move: function(event) {
        var touches;

        if (isMouseEvent(event)) {
          touches = event;
        } else {
          // ensure swiping with one touch and not pinching
          if ( event.touches.length > 1 || event.scale && event.scale !== 1) {
            return;
          }

          if (options.disableScroll) {
            event.preventDefault();
          }

          touches = event.touches[0];
        }

        // measure change in x and y
        delta = {
          x: touches.pageX - start.x,
          y: touches.pageY - start.y
        };

        // determine if scrolling test has run - one time test
        if ( typeof isScrolling === 'undefined') {
          isScrolling = !!( isScrolling || Math.abs(delta.x) < Math.abs(delta.y) );
        }

        // if user is not trying to scroll vertically
        if (!isScrolling) {

          // prevent native scrolling
          event.preventDefault();

          // stop slideshow
          stop();

          // increase resistance if first or last slide
          if (options.continuous) { // we don't add resistance at the end

            translate(circle(index-1), delta.x + slidePos[circle(index-1)], 0);
            translate(index, delta.x + slidePos[index], 0);
            translate(circle(index+1), delta.x + slidePos[circle(index+1)], 0);

          } else {

            delta.x =
              delta.x /
                ( (!index && delta.x > 0 ||             // if first slide and sliding left
                  index === slides.length - 1 &&        // or if last slide and sliding right
                  delta.x < 0                           // and if sliding at all
                ) ?
                ( Math.abs(delta.x) / width + 1 )      // determine resistance level
                : 1 );                                 // no resistance if false

            // translate 1:1
            translate(index-1, delta.x + slidePos[index-1], 0);
            translate(index, delta.x + slidePos[index], 0);
            translate(index+1, delta.x + slidePos[index+1], 0);
          }

        }

      },
      end: function(event) {

        // measure duration
        var duration = +new Date() - start.time;

        // determine if slide attempt triggers next/prev slide
        var isValidSlide =
              Number(duration) < 250 &&         // if slide duration is less than 250ms
              Math.abs(delta.x) > 20 ||         // and if slide amt is greater than 20px
              Math.abs(delta.x) > width/2;      // or if slide amt is greater than half the width

        // determine if slide attempt is past start and end
        var isPastBounds =
              !index && delta.x > 0 ||                      // if first slide and slide amt is greater than 0
              index === slides.length - 1 && delta.x < 0;   // or if last slide and slide amt is less than 0

        if (options.continuous) {
          isPastBounds = false;
        }

        // determine direction of swipe (true:right, false:left)
        var direction = delta.x < 0;

        // if not scrolling vertically
        if (!isScrolling) {

          if (isValidSlide && !isPastBounds) {

            if (direction) {

              if (options.continuous) { // we need to get the next in this direction in place

                move(circle(index-1), -width, 0);
                move(circle(index+2), width, 0);

              } else {
                move(index-1, -width, 0);
              }

              move(index, slidePos[index]-width, speed);
              move(circle(index+1), slidePos[circle(index+1)]-width, speed);
              index = circle(index+1);

            } else {
              if (options.continuous) { // we need to get the next in this direction in place

                move(circle(index+1), width, 0);
                move(circle(index-2), -width, 0);

              } else {
                move(index+1, width, 0);
              }

              move(index, slidePos[index]+width, speed);
              move(circle(index-1), slidePos[circle(index-1)]+width, speed);
              index = circle(index-1);

            }

            if (options.callback) {
              options.callback(getPos(), slides[index]);
            }

          } else {

            if (options.continuous) {

              move(circle(index-1), -width, speed);
              move(index, 0, speed);
              move(circle(index+1), width, speed);

            } else {

              move(index-1, -width, speed);
              move(index, 0, speed);
              move(index+1, width, speed);
            }

          }

        }

        // kill touchmove and touchend event listeners until touchstart called again
        if (isMouseEvent(event)) {
          element.removeEventListener('mousemove', events, false);
          element.removeEventListener('mouseup', events, false);
          element.removeEventListener('mouseleave', events, false);
        } else {
          element.removeEventListener('touchmove', events, false);
          element.removeEventListener('touchend', events, false);
        }

      },
      transitionEnd: function(event) {
        if (parseInt(event.target.getAttribute('data-index'), 10) === index) {

          if (delay || options.autoRestart) {
            restart();
          }

          if (options.transitionEnd) {
            options.transitionEnd.call(event, getPos(), slides[index]);
          }

        }

      }

    };

    // trigger setup
    setup();

    // start auto slideshow if applicable
    if (delay) {
      begin();
    }


    // add event listeners
    if (browser.addEventListener) {

      // set touchstart event on element
      if (browser.touch) {
        element.addEventListener('touchstart', events, false);
      }

      if (options.draggable) {
        element.addEventListener('mousedown', events, false);
      }

      if (browser.transitions) {
        element.addEventListener('webkitTransitionEnd', events, false);
        element.addEventListener('msTransitionEnd', events, false);
        element.addEventListener('oTransitionEnd', events, false);
        element.addEventListener('otransitionend', events, false);
        element.addEventListener('transitionend', events, false);
      }

      // set resize event on window
      root.addEventListener('resize', events, false);

    } else {

      root.onresize = function () { setup(); }; // to play nice with old IE

    }

    // expose the Swipe API
    return {
      setup: function() {

        setup();

      },
      slide: function(to, speed) {

        // cancel slideshow
        stop();

        slide(to, speed);

      },
      prev: function() {

        // cancel slideshow
        stop();

        prev();

      },
      next: function() {

        // cancel slideshow
        stop();

        next();

      },
      restart: function() {

        // Restart slideshow
        restart();

      },

      stop: function() {

        // cancel slideshow
        stop();

      },
      getPos: function() {

        // return current index position
        return getPos();

      },
      getNumSlides: function() {

        // return total number of slides
        return length;
      },
      kill: function() {

        // cancel slideshow
        stop();

        // reset element
        element.style.width = '';
        element.style.left = '';

        // reset slides
        var pos = slides.length;
        while (pos--) {

          var slide = slides[pos];
          slide.style.width = '';
          slide.style.left = '';

          if (browser.transitions) {
            translate(pos, 0, 0);
          }

        }

        // removed event listeners
        if (browser.addEventListener) {

          // remove current event listeners
          element.removeEventListener('touchstart', events, false);
          element.removeEventListener('mousedown', events, false);
          element.removeEventListener('webkitTransitionEnd', events, false);
          element.removeEventListener('msTransitionEnd', events, false);
          element.removeEventListener('oTransitionEnd', events, false);
          element.removeEventListener('otransitionend', events, false);
          element.removeEventListener('transitionend', events, false);
          root.removeEventListener('resize', events, false);

        }
        else {

          root.onresize = null;

        }

      }
    };

  }

  if ( root.jQuery || root.Zepto ) {
    (function($) {
      $.fn.Swipe = function(params) {
        return this.each(function() {
          $(this).data('Swipe', new Swipe($(this)[0], params));
        });
      };
    })( root.jQuery || root.Zepto );
  }

  return Swipe;

}));