<== Chapter 8 -- Chapter 10 ==>

Chapter 9 - NDK-build Files

So this is everyone's favorite part, building our project!

  • First thing we need to do is create two file type files in our cpp folder named Android.mk and Application.mk
    • NDK Build File Add

Android.mk

  • Here is what your Android.mk file should look like
LOCAL_PATH := $(call my-dir)
PROJECT_ROOT:= $(call my-dir)/../../../..

include $(CLEAR_VARS)
LOCAL_MODULE    := libtango_ndk_tutorial
LOCAL_SHARED_LIBRARIES := tango_client_api tango_support_api
LOCAL_CFLAGS    := -Werror -std=c++11
LOCAL_SRC_FILES := native-lib.cpp \
                   Tango_NDK_Tutorial.cpp
LOCAL_LDLIBS    := -llog -lGLESv3 -L$(SYSROOT)/usr/lib
include $(BUILD_SHARED_LIBRARY)

$(call import-add-path, $(PROJECT_ROOT))
$(call import-module,tango_client_api)
$(call import-module,tango_support_api)

  • IMPORTANT: Since our LOCAL_MODULE is libtango_ndk_tutorial our System.loadLibrary("tango_ndk_tutorial"); from Chapter 4 must be the same minus the prefix

    • Example:
      • if LOCAL_MODULE := libtango_tutorial
      • then System.loadLibrary("tango_tutorial");

  • Also note that if you are not including the Support API you can remove it from the LOCAL_SHARED_LIBRARIES section

  • If you want to add more C++ files you need to add them to the LOCAL_SRC_FILES
  • Having PROJECT_ROOT := $(call my-dir)/../../../.. is probably not the smoothest thing and open to better suggestions to get that route!
    • We need the path because it is pointing to our API folder
    • You can change $(call import-add-path, $(PROJECT_ROOT)) to point to a different location if your API folders are not in the same spot as this tutorial

Application.mk

  • This is super simple
APP_ABI := armeabi-v7a arm64-v8a
APP_STL := gnustl_static
APP_PLATFORM := android-23
  • Note we have option to compile for both ArmV7 and ArmV8 in the APP_ABI
    • Almost all mobile phones are built on Arm architecture and we are just setting which architecture we are going to build for
  • We are using gnustl_static and not the c++ std, why, I am not quite sure actually if we need it for Tango
    • You will find that gnustl_static doesn't have a std::to_string() method which gets annoying
    • APP_STL details
  • Also make sure to put the correct API version in this file as well

Gradle Settings

  • The main file we need to edit is the /app/build.gradle which is in charge of building our module.
    • Build Gradle File
  • First we are going to remove the externalNativeBuild {} object from the defaultConfig section
  • We are going to replace it with
ndk {
    abiFilters 'armeabi-v7a', 'arm64-v8a'
}
  • the externalNativeBuild {} object in the android section we are going to replace the CMake inside with
ndkBuild {
    path 'src/main/cpp/Android.mk'
}
  • Now we need to Sync our Gradle
    • Sync Gradle GUI

<== Chapter 8 -- Chapter 10 ==>