opencv4as

use opencv 2.4.13.5 without opencv manager to demo opencv sample tutorial2.

0. pre-condition

• install AS 3.1 (my env is Mac OS, Linux should be OK. Not checked with Windows)
• download opencv4android 2.4.13.5 and unzip it.

1. use the project code

• clone the code
• create 2 symlinks in code directories, assuming the code root directory is OPENCV4AS_ROOT and the opencv4android unzip directory is OPENCV_SDK:
  • ${OPENCV4AS_ROOT}/app/src/main/jniLibs --> ${OPENCV_SDK}/sdk/native/libs
  • ${OPENCV4AS_ROOT}/app/src/main/cpp/include --> ${OPENCV_SDK}/sdk/native/jni/include

2. or build by yourself from scratch

• start AS and create an android project, saying opencv4as here
• create the android application with 'basic activity' with C++ support. Just in case, choose 'c++11' in compiler compatibility options. All others just keep the defaults.
• create an android library in the project with the menu of 'New -> Module'. NOTE: u'd better set the library package name to be 'org.opencv', or else u have to make a lot of modifications in following steps. Assuming the name of the library created to be 'opencv'
• execute 'cp -Ra ${opencv4android SDK unzipped directory}/sdk/java/src/org/opencv/* ${Your project root directory}/opencv/src/main/java/org/opencv/'
• execute 'cp ${opencv4android SDK unzipped directory}/sdk/java/res/values/attrs.xml ${Your project root directory}/opencv/src/main/res/values'
• remove ${Your project root directory}/opencv/src/main/java/org/opencv/android/AsyncServiceHelper.java. and comment out its calling in ${Your project root directory}/opencv/src/main/java/org/opencv/android/OpenCVLoader.java
• click 'Sync Now' button in the library created
• choose App in menu of 'Project structure' and add dependencies for the app. select the type of dependency to be 'Module'. then choose the 'opencv' and click OK.
• try to build the whole project and see if anything wrong.
• if everything is OK so far, continue. or else, go back to fix it.
• execute 'ln -s ${opencv4android SDK unzipped directory}/sdk/native/libs ${Your project root directory}/app/src/main/jniLibs'
• execute 'ln -s ${opencv4android SDK unzipped directory}/sdk/native/jni/include ${Your project root directory}/app/src/main/cpp/'
• open ${opencv4android SDK unzipped directory}/samples/tutorial-2-mixedprocessing/jni/jni_part.cpp, and copy&past the JNI function body to lib-native.cpp in ${Your project root directory}/app/src/main/cpp/. NOTE: pls modify the JNI function name according to the sample JNI_String().
• open and change the app layout file (refer the project's 'app/src/main/res/layout/content_main.xml'). It puts the cameraView component in and deleted the original string component.
• make necessary changes to '${Your project root directory}/app/src/main/java/${your_pkgname}/MainActivity.java'. The main work is to add opencv_java library initialiation logic in, and the video capture and transform(gray, edge and feature detection) logic.
• add CAMERA related permission grant in project 'app/src/main/AndroidManifest.xml' as following:

       <uses-permission android:name="android.permission.CAMERA"/>
       <uses-feature android:name="android.hardware.camera"/>
       <uses-feature android:name="android.hardware.camera.autofocus"/>
       <uses-feature android:name="android.hardware.camera.front"/>
       <uses-feature android:name="android.hardware.camera.front.autofocus"/>

• modify the CMakeLists.txt to add opencv related stuff(include directory and libs) in:

include_directories(${CMAKE_CURRENT_SOURCE_DIR}/app/src/main/cpp/include)
   add_library( lib_opencv SHARED IMPORTED )
   set_target_properties(lib_opencv PROPERTIES IMPORTED_LOCATION ${CMAKE_CURRENT_SOURCE_DIR}/src/main/jniLibs/${ANDROID_ABI}/libopencv_java.so)
   target_link_libraries( # Specifies the target library.
                       native-lib
                       # Links the target library to the log library
                       # included in the NDK.
                       ${log-lib}
                       lib_opencv
                       )

• make and run!