Android Studio + OpenCV3 + NDK

Template for OpenCV 3 project

To Setup from Scratch

Step 1 : OpenCV 3

• Download OpenCV 3.1 for Android
• Extract the package, for example C:\OpenCV-android-sdk

Step 2 : Android Studio 2.2

• Download and Install Android Studio
• Make sure you have NDK and CMake installed
  • File > Settings > Appearance & Behavior > System Settings > Android SDK, Under SDK Tools tab to find CMake and NDK

Step 3 : Create New Project

• Create new project, be sure to check "Include C++ support"
  • The rest of options are up to you.

Step 4 : Import OpenCV moudle

• File > New > Import Module
  • Source directory set to C:\OpenCV-android-sdk\sdk\java
• File > Project Structure
  • Modules > app, Dependencies Tab,
  • Click the green add button, add 3. Module Dependencies
  • Select openCVLibrary310

Step 5 : Setup OpenCV Gradle Scripts

• Go to project explorer and find Gradle Scripts section
  • Find build.gradle (Moudle openCVLibrary310) and modify it like below

compileSdkVersion 25
buildToolsVersion "25.0.0"

defaultConfig {
  minSdkVersion 23
  targetSdkVersion 25
}

Step 6 : Copy OpenCV libs

• File > New > Folder > JNI Folder
  • check Change Folder Location
  • set new folder location to src/main/jniLibs
• Go to C:\OpenCV-android-sdk\sdk\native\libs
  • press Ctral + A to select all and press Ctrl + C to copy
  • back to Android Studio select app in the project explorer and press Ctrl + V
  • Choose ...\app\src\main\jniLibs as your destination directory

Step 7 : Copy OpenCV Include

• Go to C:\OpenCV-android-sdk\sdk\native\jni\
  • select include folder and press Ctral + C to Copy
  • back to Android Studio select cpp section under app and press Ctrl + V

Step 8 : Setup CMake

• Go to project explorer and find External Build Files section
  • Open CMakeLists.txt and modify it like below

cmake_minimum_required(VERSION 3.4.1)

set(CMAKE_VERBOSE_MAKEFILE on)
set(libs "${CMAKE_SOURCE_DIR}/src/main/jniLibs")
include_directories(${CMAKE_SOURCE_DIR}/src/main/cpp/include)

# OpenCV Libs
add_library(libopencv_java3 SHARED IMPORTED )
set_target_properties(libopencv_java3 PROPERTIES
    IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_java3.so")

add_library( # Sets the name of the library.
             native-lib

             # Sets the library as a shared library.
             SHARED

             # Provides a relative path to your source file(s).
             src/main/cpp/native-lib.cpp )

find_library( # Sets the name of the path variable.
              log-lib

              # Specifies the name of the NDK library that
              # you want CMake to locate.
              log )

target_link_libraries( # Specifies the target library.
                       native-lib
                       libopencv_java3
                       # Links the target library to the log library
                       # included in the NDK.
                       ${log-lib} )

FAQ

Q. If you deploy this template onto your phone and see nothing display on screen ?
A. Go to your phone's Settings > Apps > 'Name of your app' > Permissions and toggle Camera