android有ldpi, mdpi, hdpi, xhdpi这些drawable文件夹，系统是依据什么去选择的？

Question

问题1：比如同样1080p的屏幕在4寸和5寸上dpi不一样，android系统是不是根据dpi选择不同的资源的呢，如果有些只放xhdpi,遇到hdpi，mdpi，系统又是怎么操作的？

问题2：如下图的dimens是什么原理？我算了下大部分手机是360dp和320dp，那为什么以w320p为基准？

Answer 1

1. As long as you have a copy of xhdpi, when the resolution is smaller than the value of xhdpi, the corresponding image resources will be automatically compressed

Answer 2

It is recommended to read this article——
http://blog.csdn.net/guolin_b...
There is a very detailed analysis of Drawable

Answer 3

The ppi of the screen: the number of diagonal pixels of the screen divided by the diagonal size.