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

   1 define([ 'util/ensureCallback', 'sprites/canvas' ], function (ensureCallback, canvas) {
   2     function RenderContext(sourceData, frameData) {
   3         this.sourceData = sourceData;
   4         this.frameData = frameData;
   5
   6         this.previousTransforms = null;
   7         this.previousFrameIndex = null;
   8
   9         this.canvas = canvas();
  10
  11         this.context = this.canvas.getContext('2d');
  12         this.context.globalCompositeOperation = 'source-over';
  13     }
  14
  15     RenderContext.prototype.load = function load(callback) {
  16         callback = ensureCallback(callback);
  17
  18         // Anything not simply translated is disallowed
  19         var isValid = this.frameData.every(function (frame) {
  20             return frame.every(function (transform) {
  21                 return transform.matrix[0] === 1
  22                     && transform.matrix[1] === 0
  23                     && transform.matrix[3] === 0
  24                     && transform.matrix[4] === 1;
  25             });
  26         });
  27
  28         if (!isValid) {
  29             callback(new Error("Not supported"));
  30             return;
  31         }
  32
  33         document.body.appendChild(this.canvas);
  34
  35         callback(null);
  36     };
  37
  38     RenderContext.prototype.unload = function unload() {
  39         if (this.canvas.parentNode) {
  40             this.canvas.parentNode.removeChild(this.canvas);
  41         }
  42     };
  43
  44     RenderContext.prototype.clear = function clear() {
  45         this.canvas.width = this.canvas.width;
  46         this.previousTransforms = null;
  47     };
  48
  49     RenderContext.prototype.renderFrame = function renderFrame(frameIndex) {
  50         var context = this.context;
  51         var sourceData = this.sourceData;
  52
  53         var transforms = this.frameData[frameIndex];
  54         var count = transforms.length;
  55         var i;
  56
  57         var previousTransforms = this.previousTransforms;
  58         if (previousTransforms) {
  59             var frameInfo = sourceData.getFrameInfo(this.previousFrameIndex);
  60             var width = frameInfo.width;
  61             var height = frameInfo.height;
  62             for (i = 0; i < count; ++i) {
  63                 var transform = previousTransforms[i];
  64                 context.setTransform(1, 0, 0, 1, Math.floor(transform.x), Math.floor(transform.y));
  65                 context.clearRect(0, 0, width, height);
  66             }
  67         }
  68
  69         for (i = 0; i < count; ++i) {
  70             var transform = transforms[i];
  71             context.setTransform(1, 0, 0, 1, Math.floor(transform.x), Math.floor(transform.y));
  72             sourceData.drawToCanvas(context, 0, 0, frameIndex);
  73         }
  74
  75         this.previousTransforms = transforms;
  76         this.previousFrameIndex = frameIndex;
  77     };
  78
  79     return function (element, frameData) {
  80         return new RenderContext(element, frameData);
  81     };
  82 });