BEGINNER'S GUIDE TO SMALI CODING OF SYSTEMUI
Presenting to you a beginners guide to smali coding. This thread would focus specifically on SystemUI modding. Please keep questions related to other apks out of this thread.
This guide is provided "as is" with no warranties with regard to the accuracy and completeness of the information provided herein. I am not responsible for any bad outcomes you or anyone may have because you followed this guide. When I say beginners, I expect you to have
- Knowledge of some programming language (C,java,etc)
- An inquisitive mind to try things out
- The patience to first google and try to find answers to simple questions
I was also a noob at smali coding till few weeks back. What I have learnt through hours of google searching, reading over the internet, figuring things out and experimenting, I will try to write it up in this guide so that it becomes easier for other beginners to get into systemUI smali coding. This guide won't be just a copy paste guide to get certain mods to work in your systemUI. Rather it should get you started to write your own smali codes and edit systemUI. Lastly, I have limited knowledge on smali currently but I'll try to clarigy doubts as much as possible and I sincerely wish that the great devs around who knows smali coding would join up and help make this thread better and I certainly hope that we all get to learn more smali through this thread.
Ok cut the crap. Lets get to the real thing.
If you already know what is smali - goto : post_2
If you already know smaling and baksmaling - goto : post_3
If you just wanna know how to implement the my mod (right finger pull for quick panel toggles) of Serajr's JB like SystemUI - goto : post_4
If you already do smali coding and would like some tips to make life easier - goto : post_6
What is smali?
Android programmers write android apps in java. The compilers like eclipse are then used to build apks from these codes by converting the java source code into dalvik executables (.dex files). The dalvik virtual machine (dalvikvm) in Android can then run these executables. So the perfect way to mod systemUI would be to edit the source code of the systemUI and build the modded systemUI. This is possible for AOSP ROMs like cyanogenmod. So anyone who knows java can download the source code of cyanogenmod, do any crazy modification they want and build CM with the new systemUI. This is all possible because the CM is open source. But unfortunately the OEM Roms like Xperia, Sense, etc are not open source as far as I know. So their source code is not available.
But their dex files are available which would be in a totally unreadable. So to edit it we need to convert this .dex files to a more understandable form. This is where smali comes in. To make it easier to understand I can represent it like this:
.dex <------------------> .smali <--------------------- java source code
Converting a .dex file to smali (called baksmaling) gives us readable code in smali language. Now if you wonder why can't smali be converted into java source, that's because java is a very developed language and smali is more of an assembly based language. And so while going from java source to smali information is lost and that's why smali can't be used to completely reconstruct java source code