Building with CMake for Android {#occt_dev_guides__building_android}
===================

@tableofcontents

This article describes the steps to build OCCT libraries for Android from a complete source package
with GNU make (makefiles) on Windows 7 and Ubuntu 15.10.

The steps on Windows and Ubuntu are similar. There is the only one difference: makefiles are built with mingw32-make
on Windows and native GNU make on Ubuntu.

Required tools (download and install if it is required):
  - CMake v3.0+ http://www.cmake.org/cmake/resources/software.html
  - Cross-compilation toolchain for CMake https://github.com/taka-no-me/android-cmake
  - Android NDK rev.10+ https://developer.android.com/tools/sdk/ndk/index.html
  - GNU Make: MinGW v4.82+ for Windows (http://sourceforge.net/projects/mingw/files/), GNU Make 4.0 for Ubuntu. 
  
## Generation of makefiles
Run GUI tool provided by CMake: cmake-gui

### Tools configuration
  - Specify the root folder of OCCT (<i>$CASROOT</i>, which contains *CMakelists.txt* file) by clicking **Browse Source**.
  - Specify the location (build folder) for Cmake generated project files by clicking **Browse Build**.

@figure{/dev_guides/building/android/images/android_image001.png}

Click **Configure** button. It opens the window with a drop-down list of generators supported by CMake project.

Select "MinGW MakeFiles" item from the list
  - Choose "Specify toolchain file for cross-compiling"
  - Click "Next"
@figure{/dev_guides/building/android/images/android_image002.png}

  - Specify a toolchain file at the next dialog by android.toolchain.cmake . It is contained by cross-compilation toolchain for CMake
  - Click "Finish"
@figure{/dev_guides/building/android/images/android_image003.png}

If ANDROID_NDK environment variable is not defined in current OS, add cache entry ANDROID_NDK (entry type is PATH) -- path to the NDK folder ("Add Entry" button)
@figure{/dev_guides/building/android/images/android_image004.png}

If on Windows the message is appeared: "CMake Error: CMake was unable to find a build program corresponding to "MinGW Makefiles"
CMAKE_MAKE_PROGRAM is not set.  You probably need to select a different build tool.",
specify **CMAKE_MAKE_PROGRAM** to mingw32-make executable.
@figure{/dev_guides/building/android/images/android_image005.png}

### OCCT Configuration

How to configure OCCT, see "OCCT Configuration" section of @ref occt_dev_guides__building_cmake "Building with CMake"
taking into account the specific configuration variables for android:
  - ANDROID_ABI = armeabi-v7a
  - ANDROID_NATIVE_API_LEVEL = 15
  - ANDROID_NDK_LAYOUT is equal to CMAKE_BUILD_TYPE variable
  - **BUILD_MODULE_Draw = OFF**

@figure{/dev_guides/building/android/images/android_image006.png}

### Generation of makefiles

Click **Generate** button and wait until the generation process is finished. 
Then makefiles will appear in the build folder (e.g. <i> D:/tmp/occt-android </i>).

## Building makefiles of OCCT

Open console and go to the build folder. Type "mingw32-make" (Windows) or "make" (Ubuntu) to start build process.

> mingw32-make
or
> make


Parallel building can be started with using **"-jN"** argument of "mingw32-make/make", where N is the number of building threads.

> mingw32-make -j4
or
> make -j4

## Install built OCCT libraries

Type "mingw32-make/make" with argument "install" to place the libraries 
to the install folder (see "OCCT Configuration" section of @ref occt_dev_guides__building_cmake "Building with CMake")

> mingw32-make install
or
> make install