Ich bin neu in der Verwendung von JNI für Android und entschuldige mich im Voraus, wenn dies etwas Dummes ist. Ich habe das SDK installiert und es in Eclipse als Bibliothek für das Projekt hinzugefügt. Nachdem ich alles fertiggestellt habe, habe ich versucht, die ndk-build-Funktion auszuführen, erhalte aber diesen Fehler:

Compile++ thumb  : face_detect_rec <= jni_part.cpp
In file included from jni/face_detect_rec.h:11:0,
                 from jni/jni_part.cpp:3:
/Users/Justin/Documents/Android/opencv-2.4.3.2-android-sdk/sdk/native/jni/include/opencv2/core/core.hpp:56:21: fatal error: algorithm: No such file or directory
compilation terminated.
make: *** [obj/local/armeabi/objs/face_detect_rec/jni_part.o] Error 1

In dieser Datei befindet sich die Datei core.hpp. Ich bin nicht sicher, warum dies ein Problem ist. Ich werde meinen Code unten als Referenz posten, danke Jungs!

jni_part.cpp:

#include <jni.h>
#include "face_detect_rec.h"

using namespace std;
using namespace cv;

extern "C" {


JNIEXPORT void JNICALL Java_com_example_opencvandroidtest_MainActivity_detectFaces(
        JNIEnv* env, jclass mClass, jstring filePath)
{
    detectFaces(filePath);
}
}

face_detect_rec.h

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <math.h>
#include <float.h>
#include <limits.h>
#include <time.h>
#include <ctype.h>

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/contrib/contrib.hpp>
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>

using namespace cv;
using namespace std;

static void detectFaces(string filePath);

face_detect_rec.cpp:

#include "face_detect_rec.h"
// Create a string that contains the exact cascade name
string faceCascade_name =
        "/Users/Justin/Documents/OpenCV/data/haarcascades/haarcascade_frontalface_alt2.xml";
/*    "haarcascade_profileface.xml";*/
string eyeCascade_name =
        "/Users/Justin/Documents/OpenCV/data/haarcascades/haarcascade_mcs_lefteye.xml";
//string rightEyeCascade_name =
//    "/Users/Justin/Documents/OpenCV/data/haarcascades/haarcascade_mcs_righteye.xml";


// Function to detect and draw any faces that is present in an image
static void detectFaces(string filePath)
{
    // Create a new Haar classifier
    CascadeClassifier faceCascade;
    Mat img = imread(filePath);

    //int scale = 1;

    // Load the HaarClassifierCascade
    faceCascade.load(faceCascade_name);

    // Check whether the cascade has loaded successfully. Else report and error and quit
    if( faceCascade.empty() )
    {
        cout << "ERROR: Could not load classifier cascade\n";
        return;
    }

    // There can be more than one face in an image. So create a growable sequence of faces.
    // Detect the objects and store them in the sequence
    vector<Rect> faces;
    faceCascade.detectMultiScale(img, faces, 1.1, 2, CV_HAAR_SCALE_IMAGE, cvSize(70, 70));

    // Loop the number of faces found.
    for( int i=0; i<faces.size(); i++ )
    {
        //save image
        Mat faceROI = img(faces[i]);
        stringstream s;
        s << "/mnt/sdcard/Pictures/TagSense" << i << ".jpg";
        imwrite(s.str(), faceROI);
    }
}
}