Resources in APK without compression?

I noticed that resources.arsc is not compressed in APK file. This means this file is just stored in archive with no compression.

Is this requirement of Android OS, or some bug in build tools? Big resource files in开发者_运维技巧 an APK use more bandwidth when downloaded (from Market) and take more space on device than if they were compressed.

I can't provide you with a link to an official answer but I can offer this link. It provides some details of compression of .apk files carried out by the packaging tool 'aapt'.

It seems that only selected file types are compressed and the only option is to switch compression off! I tried 'aapt -help' from my command line to see the switches available but apart from the compression off option I saw nothing to switch it on.