OpenCV-4.5.2 and Android NDK20, Kit armeabi-v7a, C++

[DQUY05]

Hi everyone !

I'm new bie, and I don't speak English well , I need use opencv lib for Qt, but have error code :

clang++: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [libuntitled_armeabi-v7a.so] Error 1
22:00:06: The process "C:\Qt\android-ndk-r20b\prebuilt\windows-x86_64\bin\make.exe" exited with code 2.
Error while building/deploying project untitled (kit: Android for armeabi-v7a,arm64-v8a,x86,x86_64 (Clang Qt 5.14.2 for Android))
When executing step "Make"

With .pro file:

OPENCVSDKNATIVE = C:/OpenCV-android-sdk/sdk/native
INCLUDEPATH += $$OPENCVSDKNATIVE/jni/include

equals(ANDROID_TARGET_ARCH, armeabi-v7a) {
    message("setting armeabi-v7a OPENCV libs")

    # OPENCV LIBS
LIBS +=\
    -L"$$OPENCVSDKNATIVE/3rdparty/libs/armeabi-v7a"\
    -L"$$OPENCVSDKNATIVE/staticlibs/armeabi-v7a"\
    -llibtiff -llibpng -lIlmImf -llibprotobuf\
    -lopencv_core -lopencv_imgproc -lopencv_imgcodecs -lopencv_videoio\

    ANDROID_EXTRA_LIBS += $$OPENCVSDKNATIVE/libs/armeabi-v7a/libopencv_java4.so
}

Can you help me?
Many thanks !

[jsulm]

@DQUY05 said in OpenCV-4.5.2 and Android NDK20, Kit armeabi-v7a, C++:

clang++: error: linker command failed with exit code 1 (use -v to see invocation)

Please post the actual linker error (should be above that line).

[DQUY05]

@jsulm

I fixed the error, but the function is always false , and the camera cannot be opened

    capture.open(1);

    if(!capture.isOpened())
    {
        ui->inform->setText("NG camera");
        qDebug() << "Could not open camera" << 1;
    }
else
    {
        ui->inform->setText("OK camera");
        qDebug() << "Opened camera" << 1;
    }

.cpp file

#include <opencv2/core.hpp>
#include "opencv2/opencv.hpp"
#include <opencv2/core/mat.hpp>
#include <opencv2/core/mat.inl.hpp>

#include <opencv2/core.hpp>
#include <opencv2/videoio.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc.hpp>  // cv::Canny()
#include <iostream>

.pro file

android {
    contains(ANDROID_TARGET_ARCH,arm64-v8a) {
        isEmpty(OPENCV_ANDROID) {
            error("Let OPENCV_ANDROID point to the opencv-android-sdk, recommended: v4.0")
        }
        INCLUDEPATH += "$$OPENCV_ANDROID/sdk/native/jni/include"
        LIBS += \
            -L"$$OPENCV_ANDROID/sdk/native/libs/arm64-v8a" \
            -L"$$OPENCV_ANDROID/sdk/native/3rdparty/libs/arm64-v8a" \
            -llibtiff \
            -llibjpeg-turbo \
            -llibpng \
            -lIlmImf \
            -ltbb \
            -ltegra_hal \
            -lade \
            -lcpufeatures \
            -lopencv_java4 \

        ANDROID_EXTRA_LIBS = $$OPENCV_ANDROID/sdk/native/libs/arm64-v8a/libopencv_java4.so
    } else {
        error("Unsupported architecture: $$ANDROID_TARGET_ARCH")
    }
}

App output

D libuntitled_arm64-v8a.so: Could not open camera 1

I hope you will help me,
Thanks!

[jsulm]

@DQUY05 said in OpenCV-4.5.2 and Android NDK20, Kit armeabi-v7a, C++:

I hope you will help me

This is an issue with OpenCV, not Qt. You should ask in a OpenCV forum.
One possible reason for your problem: on Android an app has to request rights to access camera.

[DQUY05]

@jsulm said in OpenCV-4.5.2 and Android NDK20, Kit armeabi-v7a, C++:

@DQUY05 said in OpenCV-4.5.2 and Android NDK20, Kit armeabi-v7a, C++:

I hope you will help me

This is an issue with OpenCV, not Qt. You should ask in a OpenCV forum.
One possible reason for your problem: on Android an app has to request rights to access camera.

I have add a function that requires to use the camera already

#include <QtAndroidExtras/QtAndroid>
#include <QtAndroidExtras/QtAndroid>
#include <QtMultimedia/qmultimedia.h>

and

    auto  result = QtAndroid::checkPermission(QString("android.permission.CAMERA"));
        if(result == QtAndroid::PermissionResult::Denied){
            QtAndroid::PermissionResultMap resultHash = QtAndroid::requestPermissionsSync(QStringList({"android.permission.CAMERA"}));
            if(resultHash["android.permission.CAMERA"] == QtAndroid::PermissionResult::Denied)
            {

            }
        }

and .xml file

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

But not work!
Many thanks!