jquery.adn-gallery.js

/**
 * Copyright (c) 2010 Anders Ekdahl (http://coffeescripter.com/)
 * Dual licensed under the MIT (http://www.opensource.org/licenses/mit-license.php)
 * and GPL (http://www.opensource.org/licenses/gpl-license.php) licenses.
 *
 * Version: 1.2.4
 *
 * Demo and documentation: http://coffeescripter.com/code/ad-gallery/
 */
 
(function($) {
  $.fn.adGallery = function(options) {
    var defaults = { loader_image: 'css/images/ad-gallery/loader.gif',
                     start_at_index: 0,
                     description_wrapper: false,
                     thumb_opacity: 0.7,
                     animate_first_image: false,
                     animation_speed: 400,
                     width: false,
                     height: false,
                     display_next_and_prev: true,
                     display_back_and_forward: true,
                     scroll_jump: 0, // If 0, it jumps the width of the container
                     slideshow: {
                       enable: true,
                       //autostart: false,
                       autostart: true,
                       speed: 5000,
                       start_label: 'Start',
                       stop_label: 'Stop',
                       stop_on_scroll: true,
                       countdown_prefix: '(',
                       countdown_sufix: ')',
                       onStart: false,
                       onStop: false
                     },
                    // effect: 'slide-hori', // or 'slide-vert', 'fade', or 'resize', 'none'
                     effect: 'fade', // or 'slide-vert', 'fade', or 'resize', 'none'
                     enable_keyboard_move: true,
                     cycle: true,
                     callbacks: {
                       init: false,
                       afterImageVisible: false,
                       beforeImageVisible: false
                     }
    };
    var settings = $.extend(false, defaults, options);
    if(options && options.slideshow) {
      settings.slideshow = $.extend(false, defaults.slideshow, options.slideshow);
    };
    if(!settings.slideshow.enable) {
      settings.slideshow.autostart = false;
    };
    var galleries = [];
    $(this).each(function() {
      var gallery = new AdGallery(this, settings);
      galleries[galleries.length] = gallery;
    });
    // Sorry, breaking the jQuery chain because the gallery instances
    // are returned so you can fiddle with them
    return galleries;
  };

  function VerticalSlideAnimation(img_container, direction, desc) {
    var current_top = parseInt(img_container.css('top'), 10);
    if(direction == 'left') {
      var old_image_top = '-'+ this.image_wrapper_height +'px';
      img_container.css('top', this.image_wrapper_height +'px');
    } else {
      var old_image_top = this.image_wrapper_height +'px';
      img_container.css('top', '-'+ this.image_wrapper_height +'px');
    };
    if(desc) {
      desc.css('bottom', '-'+ desc[0].offsetHeight +'px');
      desc.animate({bottom: 0}, this.settings.animation_speed * 2);
    };
    if(this.current_description) {
      this.current_description.animate({bottom: '-'+ this.current_description[0].offsetHeight +'px'}, this.settings.animation_speed * 2);
    };
    return {old_image: {top: old_image_top},
            new_image: {top: current_top}};
  };

  function HorizontalSlideAnimation(img_container, direction, desc) {
    var current_left = parseInt(img_container.css('left'), 10);
    if(direction == 'left') {
      var old_image_left = '-'+ this.image_wrapper_width +'px';
      img_container.css('left',this.image_wrapper_width +'px');
    } else {
      var old_image_left = this.image_wrapper_width +'px';
      img_container.css('left','-'+ this.image_wrapper_width +'px');
    };
    if(desc) {
      desc.css('bottom', '-'+ desc[0].offsetHeight +'px');
      desc.animate({bottom: 0}, this.settings.animation_speed * 2);
    };
    if(this.current_description) {
      this.current_description.animate({bottom: '-'+ this.current_description[0].offsetHeight +'px'}, this.settings.animation_speed * 2);
    };
    return {old_image: {left: old_image_left},
            new_image: {left: current_left}};
  };

  function ResizeAnimation(img_container, direction, desc) {
    var image_width = img_container.width();
    var image_height = img_container.height();
    var current_left = parseInt(img_container.css('left'), 10);
    var current_top = parseInt(img_container.css('top'), 10);
    img_container.css({width: 0, height: 0, top: this.image_wrapper_height / 2, left: this.image_wrapper_width / 2});
    return {old_image: {width: 0,
                        height: 0,
                        top: this.image_wrapper_height / 2,
                        left: this.image_wrapper_width / 2},
            new_image: {width: image_width,
                        height: image_height,
                        top: current_top,
                        left: current_left}};
  };

  function FadeAnimation(img_container, direction, desc) {
    img_container.css('opacity', 0);
    return {old_image: {opacity: 0},
            new_image: {opacity: 1}};
  };

  // Sort of a hack, will clean this up... eventually
  function NoneAnimation(img_container, direction, desc) {
    img_container.css('opacity', 0);
    return {old_image: {opacity: 0},
            new_image: {opacity: 1},
            speed: 0};
  };

  function AdGallery(wrapper, settings) {
    this.init(wrapper, settings);
  };
  AdGallery.prototype = {
    // Elements
    wrapper: false,
    image_wrapper: false,
    gallery_info: false,
    nav: false,
    loader: false,
    preloads: false,
    thumbs_wrapper: false,
    scroll_back: false,
    scroll_forward: false,
    next_link: false,
    prev_link: false,

    slideshow: false,
    image_wrapper_width: 0,
    image_wrapper_height: 0,
    current_index: 0,
    current_image: false,
    current_description: false,
    nav_display_width: 0,
    settings: false,
    images: false,
    in_transition: false,
    animations: false,
    init: function(wrapper, settings) {
      var context = this;
      this.wrapper = $(wrapper);
      this.settings = settings;
      this.setupElements();
      this.setupAnimations();
      if(this.settings.width) {
        this.image_wrapper_width = this.settings.width;
        this.image_wrapper.width(this.settings.width);
        this.wrapper.width(this.settings.width);
      } else {
        this.image_wrapper_width = this.image_wrapper.width();
      };
      if(this.settings.height) {
        this.image_wrapper_height = this.settings.height;
        this.image_wrapper.height(this.settings.height);
      } else {
        this.image_wrapper_height = this.image_wrapper.height();
      };
      this.nav_display_width = this.nav.width();
      this.current_index = 0;
      this.current_image = false;
      this.current_description = false;
      this.in_transition = false;
      this.findImages();
      if(this.settings.display_next_and_prev) {
        this.initNextAndPrev();
      };
      // The slideshow needs a callback to trigger the next image to be shown
      // but we don't want to give it access to the whole gallery instance
      var nextimage_callback = function(callback) {
        return context.nextImage(callback);
      };
      this.slideshow = new AdGallerySlideshow(nextimage_callback, this.settings.slideshow);
      this.controls.append(this.slideshow.create());
      if(this.settings.slideshow.enable) {
        this.slideshow.enable();
      } else {
        this.slideshow.disable();
      };
      if(this.settings.display_back_and_forward) {
        this.initBackAndForward();
      };
      if(this.settings.enable_keyboard_move) {
        this.initKeyEvents();
      };
      var start_at = parseInt(this.settings.start_at_index, 10);
      if(window.location.hash && window.location.hash.indexOf('#ad-image') === 0) {
        start_at = window.location.hash.replace(/[^0-9]+/g, '');
        // Check if it's a number
        if((start_at * 1) != start_at) {
          start_at = this.settings.start_at_index;
        };
      };

      this.loading(true);
      this.showImage(start_at,
        function() {
          // We don't want to start the slideshow before the image has been
          // displayed
          if(context.settings.slideshow.autostart) {
            context.preloadImage(start_at + 1);
            context.slideshow.start();
          };
        }
      );
      this.fireCallback(this.settings.callbacks.init);
    },
    setupAnimations: function() {
      this.animations = {
        'slide-vert': VerticalSlideAnimation,
        'slide-hori': HorizontalSlideAnimation,
        'resize': ResizeAnimation,
        'fade': FadeAnimation,
        'none': NoneAnimation
      };
    },
    setupElements: function() {
      this.controls = this.wrapper.find('.ad-controls');
      this.gallery_info = $('<p class="ad-info"></p>');
      this.controls.append(this.gallery_info);
      this.image_wrapper = this.wrapper.find('.ad-image-wrapper');
      this.image_wrapper.empty();
      this.nav = this.wrapper.find('.ad-nav');
      this.thumbs_wrapper = this.nav.find('.ad-thumbs');
      this.preloads = $('<div class="ad-preloads"></div>');
      this.loader = $('<img class="ad-loader" src="'+ this.settings.loader_image +'">');
      this.image_wrapper.append(this.loader);
      this.loader.hide();
      $(document.body).append(this.preloads);
    },
    loading: function(bool) {
      if(bool) {
        this.loader.show();
      } else {
        this.loader.hide();
      };
    },
    addAnimation: function(name, fn) {
      if($.isFunction(fn)) {
        this.animations[name] = fn;
      };
    },
    findImages: function() {
      var context = this;
      this.images = [];
      var thumb_wrapper_width = 0;
      var thumbs_loaded = 0;
      var thumbs = this.thumbs_wrapper.find('a');
      var thumb_count = thumbs.length;
      if(this.settings.thumb_opacity < 1) {
        thumbs.find('img').css('opacity', this.settings.thumb_opacity);
      };
      thumbs.each(
        function(i) {
          var link = $(this);
          var image_src = link.attr('href');
          var thumb = link.find('img');
          // Check if the thumb has already loaded
          if(!context.isImageLoaded(thumb[0])) {
            thumb.load(
              function() {
                thumb_wrapper_width += this.parentNode.parentNode.offsetWidth;
                thumbs_loaded++;
              }
            );
          } else{
            thumb_wrapper_width += thumb[0].parentNode.parentNode.offsetWidth;
            thumbs_loaded++;
          };
          link.addClass('ad-thumb'+ i);
          link.click(
            function() {
              context.showImage(i);
              context.slideshow.stop();
              return false;
            }
          ).hover(
            function() {
              if(!$(this).is('.ad-active') && context.settings.thumb_opacity < 1) {
                $(this).find('img').fadeTo(300, 1);
              };
              context.preloadImage(i);
            },
            function() {
              if(!$(this).is('.ad-active') && context.settings.thumb_opacity < 1) {
                $(this).find('img').fadeTo(300, context.settings.thumb_opacity);
              };
            }
          );
          var link = false;
          if(thumb.data('ad-link')) {
            link = thumb.data('ad-link');
          } else if(thumb.attr('longdesc') && thumb.attr('longdesc').length) {
            link = thumb.attr('longdesc');
          };
          var desc = false;
          if(thumb.data('ad-desc')) {
            desc = thumb.data('ad-desc');
          } else if(thumb.attr('alt') && thumb.attr('alt').length) {
            desc = thumb.attr('alt');
          };
          var title = false;
          if(thumb.data('ad-title')) {
            title = thumb.data('ad-title');
          } else if(thumb.attr('title') && thumb.attr('title').length) {
            title = thumb.attr('title');
          };
          context.images[i] = { thumb: thumb.attr('src'), image: image_src, error: false,
                                preloaded: false, desc: desc, title: title, size: false,
                                link: link };
        }
      );
      // Wait until all thumbs are loaded, and then set the width of the ul
      var inter = setInterval(
        function() {
          if(thumb_count == thumbs_loaded) {
            thumb_wrapper_width -= 100;
            var list = context.nav.find('.ad-thumb-list');
            list.css('width', thumb_wrapper_width +'px');
            var i = 1;
            var last_height = list.height();
            while(i < 201) {
              list.css('width', (thumb_wrapper_width + i) +'px');
              if(last_height != list.height()) {
                break;
              }
              last_height = list.height();
              i++;
            }
            clearInterval(inter);
          };
        },
        100
      );
    },
    initKeyEvents: function() {
      var context = this;
      $(document).keydown(
        function(e) {
          if(e.keyCode == 39) {
            // right arrow
            context.nextImage();
            context.slideshow.stop();
          } else if(e.keyCode == 37) {
            // left arrow
            context.prevImage();
            context.slideshow.stop();
          };
        }
      );
    },
    initNextAndPrev: function() {
      this.next_link = $('<div class="ad-next"><div class="ad-next-image"></div></div>');
      this.prev_link = $('<div class="ad-prev"><div class="ad-prev-image"></div></div>');
      this.image_wrapper.append(this.next_link);
      this.image_wrapper.append(this.prev_link);
      var context = this;
      this.prev_link.add(this.next_link).mouseover(
        function(e) {
          // IE 6 hides the wrapper div, so we have to set it's width
          $(this).css('height', context.image_wrapper_height);
          $(this).find('div').show();
        }
      ).mouseout(
        function(e) {
          $(this).find('div').hide();
        }
      ).click(
        function() {
          if($(this).is('.ad-next')) {
            context.nextImage();
            context.slideshow.stop();
          } else {
            context.prevImage();
            context.slideshow.stop();
          };
        }
      ).find('div').css('opacity', 0.7);
    },
    initBackAndForward: function() {
      var context = this;
      this.scroll_forward = $('<div class="ad-forward"></div>');
      this.scroll_back = $('<div class="ad-back"></div>');
      this.nav.append(this.scroll_forward);
      this.nav.prepend(this.scroll_back);
      var has_scrolled = 0;
      var thumbs_scroll_interval = false;
      $(this.scroll_back).add(this.scroll_forward).click(
        function() {
          // We don't want to jump the whole width, since an image
          // might be cut at the edge
          var width = context.nav_display_width - 50;
          if(context.settings.scroll_jump > 0) {
            var width = context.settings.scroll_jump;
          };
          if($(this).is('.ad-forward')) {
            var left = context.thumbs_wrapper.scrollLeft() + width;
          } else {
            var left = context.thumbs_wrapper.scrollLeft() - width;
          };
          if(context.settings.slideshow.stop_on_scroll) {
            context.slideshow.stop();
          };
          context.thumbs_wrapper.animate({scrollLeft: left +'px'});
          return false;
        }
      ).css('opacity', 0.6).hover(
        function() {
          var direction = 'left';
          if($(this).is('.ad-forward')) {
            direction = 'right';
          };
          thumbs_scroll_interval = setInterval(
            function() {
              has_scrolled++;
              // Don't want to stop the slideshow just because we scrolled a pixel or two
              if(has_scrolled > 30 && context.settings.slideshow.stop_on_scroll) {
                context.slideshow.stop();
              };
              var left = context.thumbs_wrapper.scrollLeft() + 1;
              if(direction == 'left') {
                left = context.thumbs_wrapper.scrollLeft() - 1;
              };
              context.thumbs_wrapper.scrollLeft(left);
            },
            10
          );
          $(this).css('opacity', 1);
        },
        function() {
          has_scrolled = 0;
          clearInterval(thumbs_scroll_interval);
          $(this).css('opacity', 0.6);
        }
      );
    },
    _afterShow: function() {
      this.gallery_info.html((this.current_index + 1) +' / '+ this.images.length);
      if(!this.settings.cycle) {
        // Needed for IE
        this.prev_link.show().css('height', this.image_wrapper_height);
        this.next_link.show().css('height', this.image_wrapper_height);
        if(this.current_index == (this.images.length - 1)) {
          this.next_link.hide();
        };
        if(this.current_index == 0) {
          this.prev_link.hide();
        };
      };
      this.fireCallback(this.settings.callbacks.afterImageVisible);
    },
    /**
     * Checks if the image is small enough to fit inside the container
     * If it's not, shrink it proportionally
     */
    _getContainedImageSize: function(image_width, image_height) {
      if(image_height > this.image_wrapper_height) {
        var ratio = image_width / image_height;
        image_height = this.image_wrapper_height;
        image_width = this.image_wrapper_height * ratio;
      };
      if(image_width > this.image_wrapper_width) {
  	    var ratio = image_height / image_width;
  	    image_width = this.image_wrapper_width;
  	    image_height = this.image_wrapper_width * ratio;
  	  };
      return {width: image_width, height: image_height};
    },
    /**
     * If the image dimensions are smaller than the wrapper, we position
     * it in the middle anyway
     */
    _centerImage: function(img_container, image_width, image_height) {
      img_container.css('top', '0px');
      if(image_height < this.image_wrapper_height) {
        var dif = this.image_wrapper_height - image_height;
        img_container.css('top', (dif / 2) +'px');
      };
      img_container.css('left', '0px');
      if(image_width < this.image_wrapper_width) {
        var dif = this.image_wrapper_width - image_width;
        img_container.css('left', (dif / 2) +'px');
      };
    },
    _getDescription: function(image) {
      var desc = false;
      if(image.desc.length || image.title.length) {
        var title = '';
        if(image.title.length) {
          title = '<strong class="ad-description-title">'+ image.title +'</strong>';
        };
        var desc = '';
        if(image.desc.length) {
          desc = '<span>'+ image.desc +'</span>';
        };
        desc = $('<p class="ad-image-description">'+ title + desc +'</p>');
      };
      return desc;
    },
    /**
     * @param function callback Gets fired when the image has loaded, is displaying
     *                          and it's animation has finished
     */
    showImage: function(index, callback) {
      if(this.images[index] && !this.in_transition) {
        var context = this;
        var image = this.images[index];
        this.in_transition = true;
        if(!image.preloaded) {
          this.loading(true);
          this.preloadImage(index, function() {
            context.loading(false);
            context._showWhenLoaded(index, callback);
          });
        } else {
          this._showWhenLoaded(index, callback);
        };
      };
    },
    /**
     * @param function callback Gets fired when the image has loaded, is displaying
     *                          and it's animation has finished
     */
    _showWhenLoaded: function(index, callback) {
      if(this.images[index]) {
        var context = this;
        var image = this.images[index];
        var img_container = $(document.createElement('div')).addClass('ad-image');
        var img = $(new Image()).attr('src', image.image);
        if(image.link) {
          var link = $('<a href="'+ image.link +'" target="_blank"></a>');
          link.append(img);
          img_container.append(link);
        } else {
          img_container.append(img);
        }
        this.image_wrapper.prepend(img_container);
        var size = this._getContainedImageSize(image.size.width, image.size.height);
        img.attr('width', size.width);
        img.attr('height', size.height);
        img_container.css({width: size.width +'px', height: size.height +'px'});
        this._centerImage(img_container, size.width, size.height);
        var desc = this._getDescription(image, img_container);
        if(desc) {
          if(!this.settings.description_wrapper) {
            img_container.append(desc);
            var width = size.width - parseInt(desc.css('padding-left'), 10) - parseInt(desc.css('padding-right'), 10);
            desc.css('width', width +'px');
          } else {
            this.settings.description_wrapper.append(desc);
          }
        };
        this.highLightThumb(this.nav.find('.ad-thumb'+ index));

        var direction = 'right';
        if(this.current_index < index) {
          direction = 'left';
        };
        this.fireCallback(this.settings.callbacks.beforeImageVisible);
        if(this.current_image || this.settings.animate_first_image) {
          var animation_speed = this.settings.animation_speed;
          var easing = 'swing';
          var animation = this.animations[this.settings.effect].call(this, img_container, direction, desc);
          if(typeof animation.speed != 'undefined') {
            animation_speed = animation.speed;
          };
          if(typeof animation.easing != 'undefined') {
            easing = animation.easing;
          };
          if(this.current_image) {
            var old_image = this.current_image;
            var old_description = this.current_description;
            old_image.animate(animation.old_image, animation_speed, easing,
              function() {
                old_image.remove();
                if(old_description) old_description.remove();
              }
            );
          };
          img_container.animate(animation.new_image, animation_speed, easing,
            function() {
              context.current_index = index;
              context.current_image = img_container;
              context.current_description = desc;
              context.in_transition = false;
              context._afterShow();
              context.fireCallback(callback);
            }
          );
        } else {
          this.current_index = index;
          this.current_image = img_container;
          context.current_description = desc;
          this.in_transition = false;
          context._afterShow();
          this.fireCallback(callback);
        };
      };
    },
    nextIndex: function() {
      if(this.current_index == (this.images.length - 1)) {
        if(!this.settings.cycle) {
          return false;
        };
        var next = 0;
      } else {
        var next = this.current_index + 1;
      };
      return next;
    },
    nextImage: function(callback) {
      var next = this.nextIndex();
      if(next === false) return false;
      this.preloadImage(next + 1);
      this.showImage(next, callback);
      return true;
    },
    prevIndex: function() {
      if(this.current_index == 0) {
        if(!this.settings.cycle) {
          return false;
        };
        var prev = this.images.length - 1;
      } else {
        var prev = this.current_index - 1;
      };
      return prev;
    },
    prevImage: function(callback) {
      var prev = this.prevIndex();
      if(prev === false) return false;
      this.preloadImage(prev - 1);
      this.showImage(prev, callback);
      return true;
    },
    preloadAll: function() {
      var context = this;
      var i = 0;
      function preloadNext() {
        if(i < context.images.length) {
          i++;
          context.preloadImage(i, preloadNext);
        };
      };
      context.preloadImage(i, preloadNext);
    },
    preloadImage: function(index, callback) {
      if(this.images[index]) {
        var image = this.images[index];
        if(!this.images[index].preloaded) {
          var img = $(new Image());
          img.attr('src', image.image);
          if(!this.isImageLoaded(img[0])) {
            this.preloads.append(img);
            var context = this;
            img.load(
              function() {
                image.preloaded = true;
                image.size = { width: this.width, height: this.height };
                context.fireCallback(callback);
              }
            ).error(
              function() {
                image.error = true;
                image.preloaded = false;
                image.size = false;
              }
            );
          } else {
            image.preloaded = true;
            image.size = { width: img[0].width, height: img[0].height };
            this.fireCallback(callback);
          };
        } else {
          this.fireCallback(callback);
        };
      };
    },
    isImageLoaded: function(img) {
      if(typeof img.complete != 'undefined' && !img.complete) {
        return false;
      };
      if(typeof img.naturalWidth != 'undefined' && img.naturalWidth == 0) {
        return false;
      };
      return true;
    },
    highLightThumb: function(thumb) {
      this.thumbs_wrapper.find('.ad-active').removeClass('ad-active');
      thumb.addClass('ad-active');
      if(this.settings.thumb_opacity < 1) {
        this.thumbs_wrapper.find('a:not(.ad-active) img').fadeTo(300, this.settings.thumb_opacity);
        thumb.find('img').fadeTo(300, 1);
      };
      var left = thumb[0].parentNode.offsetLeft;
      left -= (this.nav_display_width / 2) - (thumb[0].offsetWidth / 2);
      this.thumbs_wrapper.animate({scrollLeft: left +'px'});
    },
    fireCallback: function(fn) {
      if($.isFunction(fn)) {
        fn.call(this);
      };
    }
  };

  function AdGallerySlideshow(nextimage_callback, settings) {
    this.init(nextimage_callback, settings);
  };
  AdGallerySlideshow.prototype = {
    start_link: false,
    stop_link: false,
    countdown: false,
    controls: false,

    settings: false,
    nextimage_callback: false,
    enabled: false,
    running: false,
    countdown_interval: false,
    init: function(nextimage_callback, settings) {
      var context = this;
      this.nextimage_callback = nextimage_callback;
      this.settings = settings;
    },
    create: function() {
      this.start_link = $('<span class="ad-slideshow-start">'+ this.settings.start_label +'</span>');
      this.stop_link = $('<span class="ad-slideshow-stop">'+ this.settings.stop_label +'</span>');
      this.countdown = $('<span class="ad-slideshow-countdown"></span>');
      this.controls = $('<div class="ad-slideshow-controls"></div>');
      this.controls.append(this.start_link).append(this.stop_link).append(this.countdown);
      this.countdown.hide();

      var context = this;
      this.start_link.click(
        function() {
          context.start();
        }
      );
      this.stop_link.click(
        function() {
          context.stop();
        }
      );
      $(document).keydown(
        function(e) {
          if(e.keyCode == 83) {
            // 's'
            if(context.running) {
              context.stop();
            } else {
              context.start();
            };
          };
        }
      );
      return this.controls;
    },
    disable: function() {
      this.enabled = false;
      this.stop();
      this.controls.hide();
    },
    enable: function() {
      this.enabled = true;
      this.controls.show();
    },
    toggle: function() {
      if(this.enabled) {
        this.disable();
      } else {
        this.enable();
      };
    },
    start: function() {
      if(this.running || !this.enabled) return false;
      var context = this;
      this.running = true;
      this.controls.addClass('ad-slideshow-running');
      this._next();
      this.fireCallback(this.settings.onStart);
      return true;
    },
    stop: function() {
      if(!this.running) return false;
      this.running = false;
      this.countdown.hide();
      this.controls.removeClass('ad-slideshow-running');
      clearInterval(this.countdown_interval);
      this.fireCallback(this.settings.onStop);
      return true;
    },
    _next: function() {
      var context = this;
      var pre = this.settings.countdown_prefix;
      var su = this.settings.countdown_sufix;
      clearInterval(context.countdown_interval);
      this.countdown.show().html(pre + (this.settings.speed / 1000) + su);
      var slide_timer = 0;
      this.countdown_interval = setInterval(
        function() {
          slide_timer += 1000;
          if(slide_timer >= context.settings.speed) {
            var whenNextIsShown = function() {
              // A check so the user hasn't stoped the slideshow during the
              // animation
              if(context.running) {
                context._next();
              };
              slide_timer = 0;
            };
            if(!context.nextimage_callback(whenNextIsShown)) {
              context.stop();
            };
            slide_timer = 0;
          };
          var sec = parseInt(context.countdown.text().replace(/[^0-9]/g, ''), 10);
          sec--;
          if(sec > 0) {
            context.countdown.html(pre + sec + su);
          };
        },
        1000
      );
    },
    fireCallback: function(fn) {
      if($.isFunction(fn)) {
        fn.call(this);
      };
    }
  };
})(jQuery);