These are sets of header files extracted from main components of
AOSP (Android Open Source Project), for each main release of AOSP.

Android NDK provided by Google contains subset of AOSP platform
headers which are deemed "external interface" by Google. However,
writing advanced software for Android necessitates access to complete
platform. Many aspects of it change, sometimes drastically, between
releases, so compiling user source code against platform headers for
different releases is required. This project intends to streamline
this process, allowing to access headers for all important Android
releases at once.

In this respect, it is similar to "linux-kernel-headers" found in
many Linux distributions - it allows to compile software without
the need to have hundreds of megabytes (or gigabytes) of complete
kernel (or platform) source code around.

To prepare these headers, all *.h and *.hpp files were extracted
from following AOSP projects:

 * system/core
 * frameworks/base
 * frameworks/native
 * hardware/libhardware
 * hardware/libhardware_legacy


NOTE: Project git repository may undergo rebases. Please rely on
tags when using in your projects. Use git pull --rebase for updating
your workcopy.

FAQ
---
Q: Google doesn't recommend usage of non-NDK headers.
A: Short answer: who cares. Long answer: Android is a multi-layer system,
and there're different rules for different levels. If you want maximum
portability, you should not use native code at all, and yet many applications
use it to improve performance, etc. Similar logic applies to usage of
not officially exported interfaces - sometimes they just need to be used
to get most of the underlying system.

Q: As these headers don't represent external interface, they can be
changed by a vendor of some device.
A: True, so we can figure out what particular vendors work on -
bringing up innovative products, cutting time to market, increasing
power efficiency, or fragmenting platform and breaking compatibility.

Q: How do I know that headers provided are correct?
A: You are encouraged to verify. Each header project directory contains
.git-org/refs/heads/master with revision of tag from which it was extracted.
Actually, extraction was automatic and script is provided. To easily verify
a particular tag:

    rm -rf android-1.6_r1
    scripts/fetch-headers android-1.6_r1
    git diff


TODO
----
1. Add platform "import" libraries to link with (devoid of code, only with
exported symbols) - in progress.

2. Similar "implib" jars to link Java code against - in progress.