设备坐标与逻辑坐标之间的关系以及转换一直是一个很让人困惑的问题，非常容易搞混，如果能够弄懂本文档内容，那上述问题就不复存在了。-Device coordinates and logical coordinates, as well as the relationship between the conversion has been a very confusing problem, very easy to confuse, if we can understand the contents of this document, and that these problems no longer exist.