Issue 1414 - Document how to build libadblockplus for Android

README.md

 libadblockplus
 ==============
 
 A C++ library offering the core functionality of Adblock Plus.
 
 Getting/updating the dependencies
 ---------------------------------
 
 libadblockplus has dependencies that aren't part of this repository. They are
 retrieved and updated during the build process, but you can also manually update
 them by running the following:
 
     ./ensure_dependencies.py
 
 Building
 --------
 
+### Supported compilers
+
+You need a C++11 compatible compiler to build libadblockplus.
+
+The compilation was tested with the following compilers:
+* g++ 4.8
+* Microsoft Visual Studio 2010, 2012
+* clang 3.4 for Android (from android-ndk-r9, android-ndk-r10c)
+* clang 3.6 for OS X

[sergei, 2016/06/10 11:36:01]

Could you please also add yet one line here?

* To compile for Android on linux one need to install g++-multilib

It's quite essential and can be tricky for a new person to find the proper
packet.

[anton, 2016/06/14 07:16:47]

Acknowledged.

+
+You can download *android-ndk-r10c* for [Win 32](http://dl.google.com/android/ndk/android-ndk-r10c-windows-x86.exe), [Win 64](http://dl.google.com/android/ndk/android-ndk-r10c-windows-x86_64.exe), [OSX](http://dl.google.com/android/ndk/android-ndk-r10c-darwin-x86_64.bin), [Linux 32](http://dl.google.com/android/ndk/android-ndk-r10c-linux-x86.bin), [Linux 64](http://dl.google.com/android/ndk/android-ndk-r10c-linux-x86_64.bin).

[Wladimir Palant, 2016/06/10 21:54:55]

I think this is getting confusing as it sort of implies that you need the
Android SDK for Windows in order to build the Windows version of libadblockplus.
This belongs into the "clang for Android" line above somehow.

[anton, 2016/06/14 07:30:30]

can you please explain what makes you think about SDK is required? The links are
about NDK and the only reason for it is that we need pretty-old versions of NDK
and they can't be found by the users on "Download NDK" google page.

[sergei, 2016/06/14 08:05:29]

Yeah, the links for windows were also confusing me, I think this section should
be restructured, like
Target platform:
- addition information.

Something like the following:

Win32:
- Microsoft Visual Studio 2010, 2012
Linux:
- g++ 5.2
Mac:
clang 3.6 for OS X
Android:
- the host system should be linux or OS X (BTW, it seems there is some issue
with recent updates on OS X)
- version of Android NDK
- links to Android NDK for linx and OS X (without links for Windows because
nobody tried it yet).
- g++ multilib.

[anton, 2016/06/14 08:07:29]

Acknowledged.

+
+If you have a question about another compiler please [create an issue](https://issues.adblockplus.org/).

[Wladimir Palant, 2016/06/10 21:54:55]

While you didn't add this sentence: Are we seriously suggesting creating issues
for questions? Maybe only create an issue if people try another compile and hit
issues?

[anton, 2016/06/14 07:16:47]

i've just left this sentence as it was and i agree we should get issues if the
user have a problem instead of just a question. Sergei, are you agree to change
this to "If you have a compilation problem with another compiler .." ?

[sergei, 2016/06/14 08:05:29]

Yes, I agree.

Just in case, I would like to precise that the current form is fine for me but
generally speaking we cannot support all other compilers (e.g. for MIPS).
However I would like to have such sentence in the readme file, because we can
always try to help with an advice or may be there is indeed a bug in our
configuration, which is not visible on our machines, as well as it's useful to
see who and what the interest has in this project.

+
 ### Unix
 
 All you need is Python 2.7 and Make:
 
     make
 
 The default target architecture is x64. On a 32 bit system, run:
 
     make ARCH=ia32
 
@@ skipping 16 matching lines @@
 
 * Execute `createsolution.bat` to generate project files, this will create
 `build\ia32\libadblockplus.sln` (solution for the 32 bit build) and
 `build\x64\libadblockplus.sln` (solution for the 64 bit build). Unfortunately,
 V8 doesn't support creating both from the same project files.
 * Open `build\ia32\libadblockplus.sln` or `build\x64\libadblockplus.sln` in
 Visual Studio and build the solution there. Alternatively you can use the
 `msbuild` command line tool, e.g. run `msbuild /m build\ia32\libadblockplus.sln`
 from the Visual Studio Developer Command Prompt to create a 32 bit debug build.
 
-### Supported compilers
+### Building for Android
 
-You need a C++11 compatible compiler to build libadblockplus.
+First set ANDROID_NDK_ROOT environment variable to your Android NDK directory.
 
-The compilation was tested with the following compilers:
-* g++ 4.8
-* Microsoft Visual Studio 2010, 2012
-* clang 3.4 for Android (from android-ndk-r9)
-* clang 3.6 for OS X
+To build for *x86* arch run:
 
-If you have a question about another compiler please [create an issue](https://issues.adblockplus.org/).
+    make android_x86
+
+To build for *arm* arch run:
+
+    make android_arm
 
 Usage
 -----
 
 You can use libadblockplus to build an ad blocker. Or, strictly speaking, a web
 content filter. Just like Adblock Plus, it can detect resources that should be
 blocked based on their URL and context information, and generate CSS selectors
 to hide DOM elements.
 
 The basic usage is explained below, see the
@@ skipping 134 matching lines @@
 
 ### Unix
 
 The shell is automatically built by `make`, you can run it as follows:
 
     build/out/abpshell
 
 ### Windows
 
 Just run the project *abpshell*.