http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/display/BitmapData.html
http://help.adobe.com/en_US/as3/dev/WS5b3ccc516d4fbf351e63e3d118a9b90204-7d61.html#WS5b3ccc516d4fbf351e63e3d118a9b90204-7d53
http://gamedevelopment.tutsplus.com/articles/gamedev-glossary-what-is-blitting--gamedev-2247