player/js/elements/canvasElements/CVMaskElement.js

function CVMaskElement(data, element) {
  this.data = data;
  this.element = element;
  this.masksProperties = this.data.masksProperties || [];
  this.viewData = createSizedArray(this.masksProperties.length);
  var i, len = this.masksProperties.length, hasMasks = false;
  for (i = 0; i < len; i++) {
    if(this.masksProperties[i].mode !== 'n') {
      hasMasks = true;
    }
    this.viewData[i] = ShapePropertyFactory.getShapeProp(this.element, this.masksProperties[i], 3);
  }
  this.hasMasks = hasMasks;
  if(hasMasks) {
    this.element.addRenderableComponent(this);
  }
}

CVMaskElement.prototype.renderFrame = function () {
  if(!this.hasMasks) {
    return;
  }
  var transform = this.element.finalTransform.mat;
  var ctx = this.element.canvasContext;
  var i, len = this.masksProperties.length;
  var pt, pts, data;
  ctx.beginPath();
  for (i = 0; i < len; i++) {
    if(this.masksProperties[i].mode !== 'n') {
      if (this.masksProperties[i].inv) {
        ctx.moveTo(0, 0);
        ctx.lineTo(this.element.globalData.compSize.w, 0);
        ctx.lineTo(this.element.globalData.compSize.w, this.element.globalData.compSize.h);
        ctx.lineTo(0, this.element.globalData.compSize.h);
        ctx.lineTo(0, 0);
      }
      data = this.viewData[i].v;
      pt = transform.applyToPointArray(data.v[0][0], data.v[0][1], 0);
      ctx.moveTo(pt[0], pt[1]);
      var j, jLen = data._length;
      for (j = 1; j < jLen; j++) {
        pts = transform.applyToTriplePoints(data.o[j - 1], data.i[j], data.v[j]);
        ctx.bezierCurveTo(pts[0], pts[1], pts[2], pts[3], pts[4], pts[5]);
      }
      pts = transform.applyToTriplePoints(data.o[j - 1], data.i[0], data.v[0]);
      ctx.bezierCurveTo(pts[0], pts[1], pts[2], pts[3], pts[4], pts[5]);
    }
  }
  this.element.globalData.renderer.save(true);
  ctx.clip();
};

CVMaskElement.prototype.getMaskProperty = MaskElement.prototype.getMaskProperty;

CVMaskElement.prototype.destroy = function () {
  this.element = null;
};