文档： http://docs.sencha.com/touch/2.3.0/#!/api/Ext.device.Camera-method-capture
source : String
The source of where the image should be taken. Available options are:
album - prompts the user to choose an image from an album
camera - prompts the user to take a new photo
library - prompts the user to choose an image from the library
如果我选择相册或库，设备上会发生同样的事情。
摄像头捕捉中的“库”和“专辑”之间的区别是什么？