How can I allow user to pick a photo from his harddrive and import it as a sprite?
Develop games in your browser. Powerful, performant & highly capable.
Is it possible?
Nope, unfortunately not. C2 doesn't have read/write permissions for files on the player's disk.
No permissions issue though if the player picks it himself
http://www.scirra.com/forum/plugin-dragndrop-zone_topic58578.html