Android App with OpenCV and C++, Part 1

1. Preparation

• Install Eclipse
• Install Android SDK
• Install Android NDK
• Download and save OpenCV4Android

2. Create a hello world project

a. Create a regular Android application project

File->New->Android Application Project:

Select Blank Activity, click "Next", and "Finish"

b. Add NDK support:

Right click on HelloWorld project->Android Tools->Add Native Support.

Now you have new folder jni with two files:

Create a file "Application.mk", with following content:

APP_ABI := armeabi-v7a
NDK_TOOLCHAIN_VERSION := 4.9
APP_CPPFLAGS += -std=c++11 -fexceptions  -frtti
APP_STL := gnustl_static

And put to folder "jni".

Edit "Android.mk" so it contains:

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
OPENCV_SDK_JNI = c:\\OpenCV-2.4.11-android-sdk\\sdk\\native\\jni
include $(OPENCV_SDK_JNI)/OpenCV.mk
LOCAL_MODULE    := HelloWorld
LOCAL_SRC_FILES := HelloWorld.cpp
LOCAL_C_INCLUDES += $(OPENCV_SDK_JNI)/include
include $(BUILD_SHARED_LIBRARY)

Where OPENCV_SDK_JNI should point to the correct location in your machine.

Edit HelloWorld.cpp. Save everything.

#include <jni.h>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
using namespace std;
using namespace cv;
extern "C" {
JNIEXPORT int JNICALL Java_org_ski_helloworld_MainActivity_test0(JNIEnv*, jobject, jlong addrData){
         Mat& mDat = *(Mat*)addrData;
        //  doing stuff ...
    }
}

Select "Build Project".  Now you should have correct syntax highlighting of c++ files.