用于更改系统桌面背景，虽然微软本身有一个动态库提供了这个功能，但是这个库本身系统不带。因此用Delphi编写了这个程序，用于设置自动更换桌面背景-Change the system for the desktop background, while Microsoft itself has a dynamic library provides this functionality, but the library system does not take itself. Delphi there