将Mat对象从jni返回到java

Question

有人能帮我把对象数组从原生c返回到java吗？我完成了它的大部分，只是我需要设置Mat字段。

getFaces()函数应该返回一个Face[]数组。Face对象包含opencv.core.Rect、opencv.core.Mat、int、int、int fields

JNIEXPORT jobjectArray JNICALL Java_com_faceprocessing_PersonDetector_nativeGetFaces (JNIEnv * jenv, jclass) {

if (faceContainer.size()==0) return NULL;

jclass faceClass = jenv->FindClass("com/faceprocessing/Face");

jmethodID faceCtorID = jenv->GetMethodID(faceClass, "<init>", "()V");
jfieldID facePosID = jenv->GetFieldID(faceClass, "Position", "Lorg/opencv/core/Rect;");
jfieldID faceIDID = jenv->GetFieldID(faceClass, "PredictedID", "I");
jfieldID faceGenderID = jenv->GetFieldID(faceClass, "PredictedGender", "I");
jfieldID faceAgeID = jenv->GetFieldID(faceClass, "PredictedAge", "I");

jclass rectClass = jenv->FindClass("org/opencv/core/Rect");
jmethodID rectCtorID = jenv->GetMethodID(rectClass, "<init>", "(IIII)V");

jclass matClass = jenv->FindClass("org/opencv/core/Mat");


int correctCount = 0;
for (int i=0; i<faceContainer.size(); i++) {
    Face* pFace = faceContainer.at(i);
    if (!pFace->isError) correctCount++;
}

jobjectArray jFaceArray = jenv->NewObjectArray(correctCount, faceClass, NULL);

int j=0;
for (int i=0; i<faceContainer.size(); i++) {

    Face* pFace = faceContainer.at(i);
    if (pFace->isError) continue;
    jobject jFace = jenv->NewObject(faceClass, faceCtorID);
    jobject jRect = jenv->NewObject(rectClass, rectCtorID, pFace->facePosition->x, pFace->facePosition->y, pFace->facePosition->width, pFace->facePosition->height);
    jenv->SetObjectField(jFace, facePosID, jRect);
    jenv->SetIntField(jFace, faceIDID, pFace->predictedID);
    jenv->SetIntField(jFace, faceGenderID ,pFace->predictedGender);
    jenv->SetIntField(jFace, faceAgeID, pFace->predictedAge);
    jenv->SetObjectArrayElement(jFaceArray,j,jFace);
    j++;
}

return jFaceArray;
}

Answer 1

如果我是你，我不会返回cv::Mat数组。我每次都会返回一个cv::Mat，并在Java端根据需要多次调用该函数来创建数组。

所以基本上，我会有一个函数来获取数组的大小。以及另一个从face容器中获取面部图像的函数。

如果您不知道如何返回cv::Mat，请让我知道。

希望这能有所帮助。