error: undefined reference to `ANativeWindow_fromSurface`



  • hello.
    I am a beginner of Qt,
    I was trying to use Qt to make an Android application and used GStreamer(not QtGStreamer) to stream video through RTSP.
    But when I used

    QPlatformNativeInterface *nativeInterface = QApplication::platformNativeInterface();
        jobject activity = (jobject)nativeInterface->nativeResourceForIntegration("QtActivity");
        QAndroidJniEnvironment * qjniEnv;
        JNIEnv * jniEnv;
        JavaVM * jvm = qjniEnv->javaVM();
        jvm->GetEnv(reinterpret_cast<void**>(&qjniEnv), JNI_VERSION_1_6);
        jvm->AttachCurrentThread(&jniEnv,NULL);
    
        jint r_id_content = QAndroidJniObject::getStaticField<jint>("android/R$id", "content");
    
        QAndroidJniObject view = ((QAndroidJniObject) activity).callObjectMethod("findViewById", "(I)Landroid/view/View;", r_id_content);
        if (view.isValid()) {
            QAndroidJniObject child1 = view.callObjectMethod("getChildAt", "(I)Landroid/view/View;", 0);
            QAndroidJniObject child2 = child1.callObjectMethod("getChildAt", "(I)Landroid/view/View;", 0);
            if (child2.isValid()) {
                QAndroidJniObject sHolder = child2.callObjectMethod("getHolder","()Landroid/view/SurfaceHolder;");
                if (sHolder.isValid()) {
                    QAndroidJniObject theSurface = sHolder.callObjectMethod("getSurface","()Landroid/view/Surface;");
                    if (theSurface.isValid()) {
                        ANativeWindow* awindow = ANativeWindow_fromSurface(jniEnv, theSurface.object());
                        qDebug() << "This is a ANativeWindow " << awindow;
                    }
                }
            } else {
                qDebug() << "Views are not loaded yet or you are not in the Qt UI Thread";
            }
        }
    

    to get the ANativeWindow,
    It got an error: undefined reference to 'ANativeWindow_fromSurface'

    I have added QT += androidextras in .pro and
    #include<android/native_window.h>
    #include<android/native_window_jni.h>
    in .cpp file, I don't know what else should I do.

    Is there anyone can help me to solve this problem?
    Thanks.



  • I found a similar java code vulkan post and I had no problem. After added the right includes everything worked fine.



  • Thanks for your reply,
    but I thought that my problem occurred when linking the "android/native_window_jni.h" or something else.
    Should I check my Android NDK?



  • Hi @SamuelYeh , I didn't read your reply before. I think that you didn't add something like this in your .pro. I think that the error comes because you are not linking with libandroid.

    LIBS += -L/opt/android-ndk-r12b/platforms/android-19/arch-arm/usr/lib -landroid
    

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