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scripts/slideshow.js

/*

File: slideshow.js

Abstract: JavaScript file containing a class that manages the slide show.

Version: 1.1

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may be used to endorse or promote products derived from the Apple

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MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

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*/

/*

  assets paramter is JSON data like:

      'src' : 'foo/bar/baz.jpg',

      'thumb' : 'foo/bar/baz_thumb.jpg',

      'caption' : 'This is the caption',

      'uploaded' : 'John Doe',

      'date' : new Date(2005, 11, 28),

      'rating' : 4

},

...

*/

// This object does most of the heavy lifting for the photo gallery.

function Slideshow(photoContainer, slideshowContainer, assets)

  // Store references to the two elements that the slideshow cares about.

  this.photoContainer = photoContainer;

  this.slideshowContainer = slideshowContainer;

  // assets contains the list of images, with metadata.

  this.assetData = assets;

  this.thumbs = [];

  // This is the list of transitions that will run.

  this.transitions = [

      { name: "crossfade", transition: Transition },

      { name: "push", transition: Transition },

      { name: "pushdown", transition: Transition },

      { name: "zoomout", transition: Transition },

      { name: "scaleout", transition: Transition },

      { name: "drop", transition: Transition },

      { name: "pop", transition: Transition },

      { name: "spin", transition: Transition },

      { name: "batspin", transition: Transition },

      { name: "horizontalflip", transition: Transition },

      { name: "fall", transition: Transition },

      { name: "door", transition: Transition },

      { name: "swap", transition: Transition },

      { name: "cube", transition: Transition },

      { name: "swap", transition: Transition },

      { name: "cube", transition: Transition },

      { name: "door", transition: Transition },

      { name: "tile-drop", transition: DropTileTransition, duration: 4000 },

      { name: "tile-fall", transition: DropTileTransition, duration: 6000 },

      { name: "tile-unfold-right", transition: HorizontalUnfoldTileTransition, duration: 3000 },

      { name: "tile-unfold-down", transition: VerticalUnfoldTileTransition, duration: 3000 },

      { name: "tile-implode", transition: ImplodeTileTransition, duration: 2700 },

      { name: "push", transition: Transition },

      { name: "pushdown", transition: Transition },

      { name: "crossfade", transition: Transition },

      { name: "spin",  transition: Transition }

];

  this.iPad = navigator.userAgent.indexOf('iPad') != -1;

  this.currentIndex = 0;

  this.flipped = false;

  this.thumbContainer = document.getElementById('thumbs');

  this.thumbScroller = document.getElementById('thumb-scroller');

  this.setupThumbnails();

  this.showPhoto();

  this.highlightThumb();

};

Slideshow.prototype.setupThumbnails = function ()

  this.thumbGridView = new GridView(this.thumbScroller);

  // Size the grid view for the thumbnails appropriately.

  if (this.iPad) {

    this.thumbGridView.setVisibleColumns(8);

    this.thumbGridView.setRowWidth(800);

    this.thumbGridView.setRowElementWidth(101);

  } else {

    this.thumbGridView.setVisibleColumns(9);

    this.thumbGridView.setRowWidth(1024);

    this.thumbGridView.setRowElementWidth(115);

  this.thumbGridView.init(this, this);

// Flips the image over (via the Return key). Note how it just toggles a CSS classname.

Slideshow.prototype.toggleFlip = function ()

  if (this.isBusy())

    return;

  if (this.flipped) {

    this.slideshowContainer.removeClassName("flipped");

    this.flipped = false;

  } else {

    this.slideshowContainer.addClassName("flipped");

    this.flipped = true;

};

Slideshow.prototype.handleEvent = function(event)

  switch (event.type)

    // We wait for the next image or video to load before we start the transition to that asset.

    case 'load':  // called for images

    case 'canplaythrough':  // called for video

      if (this.currentTransition)

        this.currentTransition.contentsReady();

      break;

};

Slideshow.prototype.isBusy = function()

  return (this.currentTransition && this.currentTransition.playing());

};

// Return a Transition object for the asset at the given index.

Slideshow.prototype.transitionForImageIndex = function(index)

  this.transitionIndex = index % this.transitions.length;

  var currTransition = this.transitions[this.transitionIndex];

  var transitionType = currTransition.name;

  var transitionClass = currTransition.transition;

  var duration = currTransition.duration;

  return new transitionClass(transitionType, this.photoContainer, duration);

};

// Here's the function that actually kicks off the transition to the next image.

Slideshow.prototype.transitionToIndex = function(slowMode, newIndex)

  var oldContents = this.photoContainer.firstChild;

  if (!oldContents) {

    // Add a placeholder to simplify logic in transitionDone().

    oldContents = document.createElement('div');

    this.transitionContainer.appendChild(oldContents);

  // Get the transition to use for this image.

  this.currentTransition = this.transitionForImageIndex(this.currentIndex);

  // Remember the url of the current image. Some effects (like the tile effects) need this.

  this.currentTransition.outgoingImageURL = this.assetData[this.currentIndex].src;

  this.currentIndex = newIndex;

  // Create the content for the incoming asset. This might be a an <img>, <video> or a <div> containing children.

  var newContent = this.createElementForAssetAtIndex(this.currentIndex);

  // Start running the transition.

  this.startTransitionToPhoto(oldContents, newContent, this.currentTransition, slowMode);

  // Highlight the new thumbnail.

  this.highlightThumb();

Slideshow.prototype.nextImage = function(slowMode)

  if (this.isBusy())

    return;

  if (this.currentTransition && this.currentTransition.playing()) {

    // we're busy - do nothing

    return;

  var newIndex = (this.currentIndex + 1) % this.assetData.length;

  this.transitionToIndex(slowMode, newIndex)

};

Slideshow.prototype.previousImage = function(slowMode)

  if (this.isBusy())

    return;

  var newIndex = (this.currentIndex - 1) % this.assetData.length;

  if (newIndex < 0)

    newIndex = this.assetData.length - 1;

  this.transitionToIndex(slowMode, newIndex)

};

Slideshow.prototype.createElementForAssetAtIndex = function(assetIndex)

  if (assetIndex < 0 || assetIndex >= this.assetData.length)

    return undefined;

  var container = document.createElement('div');

  container.className = 'contents';

  var asset = this.assetData[assetIndex];

  var mediaElement;

  if (asset.src.match(/[.jpg|.png|.gif]$/)) {

    // If the asset has an image extension, make an image element.

    mediaElement  = new Image();

    // Register a load listener; when it fires, our handleEvent() method will get called.

    mediaElement.addEventListener('load', this, false);

    mediaElement.src = this.iPad ? asset.medium : asset.src;

  } else if (asset.src.match(/[.mov|.mp4|.m4v]$/)) {

    // For movies, create a video element.

    mediaElement = document.createElement('video');

    // Register a canplaythrough listener; when it fires, our handleEvent() method will get called.

    mediaElement.addEventListener('canplaythrough', this, false);

    mediaElement.src = asset.src;

    mediaElement.loop = true;

  // The dataElement contains the metadata for display on the back of the image (when flipped).

  var dataElement = this.createDataElementForAssetAtIndex(assetIndex);

  container.appendChild(mediaElement);

  container.appendChild(dataElement);

  return container;

// Create nodes for one line of metadata.

Slideshow.prototype.createDataLine = function(label, content)

  var caption = document.createElement('p');

  caption.innerText = content;

  return caption;

// Create the content for the metadata display on the back of the image.

Slideshow.prototype.createDataElementForAssetAtIndex = function(assetIndex)

  var asset = this.assetData[assetIndex];

  var dataContainer = document.createElement('div');

  dataContainer.className = 'data-container';

  dataContainer.appendChild(this.createDataLine('Title: ', asset.caption));

  dataContainer.appendChild(this.createDataLine('Author: ', asset.uploaded));

  dataContainer.appendChild(this.createDataLine('Date: ', asset.date.toLocaleDateString()));

  return dataContainer;

// Instantaneous switch. Only used when there is no transition.

Slideshow.prototype.showPhoto = function()

  this.photoContainer.removeAllChildren();

  var newContent = this.createElementForAssetAtIndex(this.currentIndex);

  this.photoContainer.appendChild(newContent);

};

Slideshow.prototype.startTransitionToPhoto = function(oldContents, newContents, transition, slowMode)

  if (transition)

    transition.initiateTransition(oldContents, newContents, slowMode);

  else

    this.showPhoto();

};

Slideshow.prototype.highlightThumb = function()

  var images = this.thumbContainer.querySelectorAll('img.selected');

  // Unhighlight the old one

  for (var i = 0; i < images.length; ++i) {

    var curThumb = images[i];

    curThumb.removeClassName('selected');

  // Highlight the new one.

  this.thumbs[this.currentIndex].addClassName('selected');

  this.thumbGridView.setActiveElementIndex(this.currentIndex);

};

Slideshow.prototype.thumbClicked = function(event)

  if (!"_thumbIndex" in event.target)

    return;

  var newIndex = event.target._thumbIndex;

  if (newIndex == this.currentIndex)

    return;

  this.transitionToIndex(false, newIndex)

};

// GridView data source methods.

Slideshow.prototype.gridViewNumberOfElements = function(grid)

  return this.assetData.length;

};

Slideshow.prototype.gridViewElementAtIndex = function(grid, index)

  if (index >= 0 && index < this.assetData.length) {

    if (!this.thumbs[index]) {

      var thumb = new Image();

      thumb.src = this.assetData[index].thumb;

      var _self = this;

      thumb.onclick = function(event) { _self.thumbClicked(event); };

      thumb._thumbIndex = index;

      this.thumbs[index] = thumb;

    return this.thumbs[index];

};

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