<== Chapter 2 -- Chapter 4 ==>

Chapter 3 - Loading Tango API Libraries

The Tango API's are just like any C library where you have your include folder with the header files, the lib folder with the compiled shared library file and now its just a matter of have it build along with your Android APK.

Where is the library

  • The download site currently is on the offical Google Tango Developer site
  • You will want to download at least the client API (also named Tango SDK for C on site)
    • Also download the support API or 3D Reconstruction as needed

How to add it to Android.mk

  • First note, the names of files/folders are mainly arbitrary, but for best interest I would advise you to stick with the below naming conventions.
  • We first will start by making a folder called tango_client_api to hold the library
  • Inside we will have two subfolders: include and lib
    • include will hold the tango_client_api.h header file
    • lib will have a subfolder for each architecture
      • Note: if you know for sure you only need one then have one
      • The two subfolders used here are arm64-v8a and armeabi-v7a
      • Each of these subfolders contain the libtango_client_api.so library
      • For this tutorial you will also need the libtango_client_stub.a file in your lib folder found here. This static file is JUST for the client API

  • To build this library itself we will include an Android.mk file inside the tango_client_api folder.

    • You can find the file here, but we are also going to break down what the Android.mk file is doing: ``` LOCAL_PATH := $(call my-dir)

    include $(CLEAR_VARS) LOCAL_MODULE := tango_client_api

    ifeq ($(TARGET_ARCH), arm64) LOCAL_EXPORT_LDLIBS := -L$(LOCAL_PATH)/lib/arm64-v8a -ltango_client_api endif

    ifeq ($(TARGET_ARCH), arm) LOCAL_EXPORT_LDLIBS := -L$(LOCAL_PATH)/lib/armeabi-v7a -ltango_client_api endif

    LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include LOCAL_SRC_FILES := lib/libtango_client_stub.a

    include $(PREBUILT_STATIC_LIBRARY) `` * First we always start our makefiles with defining theLOCAL_PATHto the directory ourAndroid.mklives. Then we also always callinclude $(CLEAR_VARS)to clear unwanted local enviroment variables. * We load the module by name which in this case we just left out the "lib" prefix * Next we decided which architecture its building for and link it to the path of the.sofile as well and telling the linker to include it with the-ltango_client_apiflag * Next we export include the header file location * For the client API **ONLY** we also include the static file we added * Last thing we do is tell it generate the library as a Prebuilt Static library * We repeat the steps above for the support and 3D Reconstruction API as needed and then we can now add it to the mainAndroid.mkproject file * Here is the link to the [main project Android.mk file](../../Section_04_Project/Sample_Code/Tango-NDK-Tutorial/app/src/main/cpp/Android.mk) which we now need to add a few lines *LOCAL_SHARED_LIBRARIES := tango_client_apiis where we declare the shared libraries we plan to include *$(call import-add-path, $(PROJECT_ROOT))is used to add the folder location of yourtango_client_apifolder locations * Note: If you want to move yourtango_client_apifolder just create a path to the directory and add another line such as$(call import-add-path, $(PATH_TO_MY_TANGO_CLIENT_API_FOLDER))for example * The last thing we need to do is actually import the module we built using$(call import-module,tango_client_api)` which calls it in.

<== Chapter 2 -- Chapter 4 ==>