chrome/test/data/third_party/spaceport/js/sprites/renderers/DomContext.js

   1 define([ 'util/ensureCallback' ], function (ensureCallback) {
   2     function DomContext(sourceData, frameData, onLoad) {
   3         var onLoadCalled = 0;
   4         var onLoadExpected = 0;
   5         var onLoadReady = false;
   6
   7         function checkOnLoad() {
   8             if (onLoadReady) {
   9                 if (onLoadCalled === onLoadExpected) {
  10                     onLoad();
  11                 }
  12             }
  13         }
  14
  15         var sourcePool = [ ];
  16         var elementPool = [ ];
  17         var elements = [ ];
  18         var i, j;
  19
  20         for (i = 0; i < frameData.length; ++i) {
  21             var objectTransforms = frameData[i];
  22             var frameElements = [ ];
  23             var sourceElements = [ ];
  24
  25             for (j = 0; j < objectTransforms.length; ++j) {
  26                 var element;
  27                 var img = sourceData.getImage(i);
  28                 var index = sourcePool.indexOf(img);
  29
  30                 if (index >= 0) {
  31                     // Image is available in the pool; take it
  32                     element = elementPool.splice(index, 1)[0];
  33                     sourcePool.splice(index, 1);
  34                 } else {
  35                     // Image not in the pool; add it
  36                     element = img.cloneNode(true);
  37                     element.style.position = 'absolute';
  38                     element.style.left = '0';
  39                     element.style.top = '0';
  40
  41                     if (element instanceof Image) {
  42                         onLoadExpected += 1;
  43                         element.onload = function () {
  44                             onLoadCalled += 1;
  45                             checkOnLoad();
  46                         };
  47                         element.src = element.src;
  48                     }
  49                 }
  50
  51                 sourceElements.push(img);
  52                 frameElements.push(element);
  53             }
  54
  55             sourcePool.push.apply(sourcePool, sourceElements);
  56             elementPool.push.apply(elementPool, frameElements);
  57             elements.push(frameElements);
  58         }
  59
  60         onLoadReady = true;
  61         checkOnLoad();
  62
  63         this.elements = elements;
  64         this.activeElements = null;
  65
  66         this.transformData = null;
  67     }
  68
  69     DomContext.prototype.unload = function unload() {
  70         this.activeElements.forEach(function (el) {
  71             if (el.parentNode) {
  72                 el.parentNode.removeChild(el);
  73             }
  74         });
  75
  76         this.activeElements = null;
  77     };
  78
  79     DomContext.prototype.renderFrame = function renderFrame(frameIndex) {
  80         var transforms = this.transformData[frameIndex];
  81         var elements = this.elements[frameIndex];
  82
  83         this.processElements(elements, transforms);
  84
  85         // Elements no longer displayed must be removed from the DOM
  86         var activeElements = this.activeElements;
  87         if (activeElements) {
  88             var count = activeElements.length;
  89             var i;
  90             for (i = 0; i < count; ++i) {
  91                 var element = activeElements[i];
  92                 if (element.parentNode && elements.indexOf(element) < 0) {
  93                     element.parentNode.removeChild(element);
  94                 }
  95             }
  96         }
  97
  98         this.activeElements = elements;
  99     };
 100
 101     return DomContext;
 102 });