var graphics = new createjs.Graphics();
graphics
.beginBitmapFill(bmd, "repeat")
.drawRect(0, 0, 640, 960);
var shape = new createjs.Shape(graphics);
stage.addChild(shape);
//JSのcreatePatternつかってるぽい
//http://www.w3schools.com/tags/canvas_createpattern.asp