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Android Camera on QT5.12 Opencv4android4.3 c++



  • HI,
    I managed to put all together to build android apps on QTCreator with Opencv for Android, but now,
    I'm trying get camera image throw opencv using c++ but I have no idea how to do it.
    I look to a bunch of tutorials but all are in java and the ones in c++ are not complete.

    this is my code:

    cout << "Opening camera..." << endl;
           VideoCapture capture(0); // open the first camera
           if (!capture.isOpened())
           {
               ui->label->setText("Failed");
           }
           else
           {
               ui->label->setText("Working");
           }
    

    It returns always true (failed).
    why what i'm missing?
    Any help?



  • !!!...UPDATE...!!!

    Some times the better is restart, this is what i did!

    I restart from the bottom by configuring QT Creator
    configure qt for android

    Now it's building everything...really everything....all QT samples I piped in they work 80 or 90 percent in Android

    PS: I'm targeting the samples not designed for Android, I'm targeting all samples without "Android" in the green tags.

    For example the sample "Qt Quick Extras - Dashboard" with the kit QT 5.13.0 and it worked 100%

    Next stop Rebuilding Opencv4Android....


  • Lifetime Qt Champion

    @dedetuga On Android your app needs to request access to the camera. I'm not an Android expert, but I think you need to do that in the manifest file.



  • Hi @jsulm thanks for reply.

    I add thins to my manifest 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 the app didn't ask for permissions and I still can't get the camera image so I add this code in my mainwindow.cpp

    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)
                {
    
                }
            }
    

    still no camera image, when i check

    if (!capture.isOpened())
    

    It return "Not opened"

    This is my full Manifest.xml

    <?xml version="1.0"?>
    <manifest package="org.qtproject.example" xmlns:android="http://schemas.android.com/apk/res/android" android:versionName="-- %%INSERT_VERSION_NAME%% --" android:versionCode="-- %%INSERT_VERSION_CODE%% --" android:installLocation="auto">
        <uses-sdk android:minSdkVersion="24" android:targetSdkVersion="28"/>
    
        <!-- The following comment will be replaced upon deployment with default permissions based on the dependencies of the application.
             Remove the comment if you do not require these default permissions. -->
        <!-- %%INSERT_PERMISSIONS -->
        <uses-permission android:name="android.permission.CAMERA"/>
    
    
        <!-- The following comment will be replaced upon deployment with default features based on the dependencies of the application.
             Remove the comment if you do not require these default features. -->
        <!-- %%INSERT_FEATURES -->
    
        <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"/>
    
        <supports-screens android:largeScreens="true" android:normalScreens="true" android:anyDensity="true" android:smallScreens="true"/>
    
        <application android:hardwareAccelerated="true" android:name="org.qtproject.qt5.android.bindings.QtApplication" android:label="-- %%INSERT_APP_NAME%% --">
            <activity android:configChanges="orientation|uiMode|screenLayout|screenSize|smallestScreenSize|layoutDirection|locale|fontScale|keyboard|keyboardHidden|navigation|mcc|mnc|density" android:name="org.qtproject.qt5.android.bindings.QtActivity" android:label="-- %%INSERT_APP_NAME%% --" android:screenOrientation="unspecified" android:launchMode="singleTop">
                <intent-filter>
                    <action android:name="android.intent.action.MAIN"/>
                    <category android:name="android.intent.category.LAUNCHER"/>
                </intent-filter>
    
                <!-- Application arguments -->
                <!-- meta-data android:name="android.app.arguments" android:value="arg1 arg2 arg3"/ -->
                <!-- Application arguments -->
    
                <meta-data android:name="android.app.lib_name" android:value="MyFirstQT_Android_APP"/>
                <meta-data android:name="android.app.qt_sources_resource_id" android:resource="@array/qt_sources"/>
                <meta-data android:name="android.app.repository" android:value="default"/>
                <meta-data android:name="android.app.qt_libs_resource_id" android:resource="@array/qt_libs"/>
                <meta-data android:name="android.app.bundled_libs_resource_id" android:resource="@array/bundled_libs"/>
                <!-- Deploy Qt libs as part of package -->
                <meta-data android:name="android.app.bundle_local_qt_libs" android:value="-- %%BUNDLE_LOCAL_QT_LIBS%% --"/>
                <meta-data android:name="android.app.bundled_in_lib_resource_id" android:resource="@array/bundled_in_lib"/>
                <meta-data android:name="android.app.bundled_in_assets_resource_id" android:resource="@array/bundled_in_assets"/>
                <!-- Run with local libs -->
                <meta-data android:name="android.app.use_local_qt_libs" android:value="-- %%USE_LOCAL_QT_LIBS%% --"/>
                <meta-data android:name="android.app.libs_prefix" android:value="/data/local/tmp/qt/"/>
                <meta-data android:name="android.app.load_local_libs" android:value="-- %%INSERT_LOCAL_LIBS%% --"/>
                <meta-data android:name="android.app.load_local_jars" android:value="-- %%INSERT_LOCAL_JARS%% --"/>
                <meta-data android:name="android.app.static_init_classes" android:value="-- %%INSERT_INIT_CLASSES%% --"/>
                <!-- Used to specify custom system library path to run with local system libs -->
                <!-- <meta-data android:name="android.app.system_libs_prefix" android:value="/system/lib/"/> -->
                <!--  Messages maps -->
                <meta-data android:value="@string/ministro_not_found_msg" android:name="android.app.ministro_not_found_msg"/>
                <meta-data android:value="@string/ministro_needed_msg" android:name="android.app.ministro_needed_msg"/>
                <meta-data android:value="@string/fatal_error_msg" android:name="android.app.fatal_error_msg"/>
                <meta-data android:value="@string/unsupported_android_version" android:name="android.app.unsupported_android_version"/>
                <!--  Messages maps -->
    
                <!-- Splash screen -->
                <!-- Orientation-specific (portrait/landscape) data is checked first. If not available for current orientation,
                     then android.app.splash_screen_drawable. For best results, use together with splash_screen_sticky and
                     use hideSplashScreen() with a fade-out animation from Qt Android Extras to hide the splash screen when you
                     are done populating your window with content. -->
                <!-- meta-data android:name="android.app.splash_screen_drawable_portrait" android:resource="@drawable/logo_portrait" / -->
                <!-- meta-data android:name="android.app.splash_screen_drawable_landscape" android:resource="@drawable/logo_landscape" / -->
                <!-- meta-data android:name="android.app.splash_screen_drawable" android:resource="@drawable/logo"/ -->
                <!-- meta-data android:name="android.app.splash_screen_sticky" android:value="true"/ -->
                <!-- Splash screen -->
    
                <!-- Background running -->
                <!-- Warning: changing this value to true may cause unexpected crashes if the
                              application still try to draw after
                              "applicationStateChanged(Qt::ApplicationSuspended)"
                              signal is sent! -->
                <meta-data android:name="android.app.background_running" android:value="false"/>
                <!-- Background running -->
    
                <!-- auto screen scale factor -->
                <meta-data android:name="android.app.auto_screen_scale_factor" android:value="false"/>
                <!-- auto screen scale factor -->
    
                <!-- extract android style -->
                <!-- available android:values :
                    * default - In most cases this will be the same as "full", but it can also be something else if needed, e.g., for compatibility reasons
                    * full - useful QWidget & Quick Controls 1 apps
                    * minimal - useful for Quick Controls 2 apps, it is much faster than "full"
                    * none - useful for apps that don't use any of the above Qt modules
                    -->
                <meta-data android:name="android.app.extract_android_style" android:value="default"/>
                <!-- extract android style -->
        </activity>
    
        <!-- For adding service(s) please check: https://wiki.qt.io/AndroidServices -->
    
        </application>
    
        <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"/>
    
    </manifest>
    

    This is my full mainwindow.cpp

    #include "mainwindow.h"
    #include "ui_mainwindow.h"
    
    
    #include <camera/NdkCameraCaptureSession.h>
    #include <camera/NdkCameraDevice.h>
    #include <camera/NdkCameraError.h>
    #include <camera/NdkCameraManager.h>
    #include <camera/NdkCameraMetadata.h>
    #include <camera/NdkCameraMetadataTags.h>
    //#include <camera/NdkCameraWindowType.h>
    #include <camera/NdkCaptureRequest.h>
    
    //http://hxr99.blogspot.com/2011/12/opencv-examples-camera-capture.html
    #include <opencv2/highgui/highgui.hpp>
    #include <opencv2/imgproc/imgproc.hpp>
    #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>
    
    using namespace cv;
    using std::cout; using std::cerr; using std::endl;
    
    #include <jni.h>
    #include <string>
    #include <opencv2/core.hpp>
    #include <opencv2/opencv.hpp>
    
    using namespace std;
    using namespace cv;
    
    #include <QtAndroidExtras/QtAndroid>
    #include <QtAndroidExtras/QtAndroid>
    #include <QtMultimedia/qmultimedia.h>
    
    
    MainWindow::MainWindow(QWidget *parent)
        : QMainWindow(parent)
        , ui(new Ui::MainWindow)
    {
        ui->setupUi(this);
    
    
        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)
                {
    
                }
            }
    
        //Mat frame;
           cout << "Opening camera..." << endl;
           VideoCapture capture(1099); // open the first camera
           if (!capture.isOpened())
           {
               ui->label->setText("Failed");
           }
           else
           {
               ui->label->setText("Working");
           }
    
    
    
    }
    
    MainWindow::~MainWindow()
    {
        delete ui;
    }
    


  • !!!...UPDATE...!!!

    Some times the better is restart, this is what i did!

    I restart from the bottom by configuring QT Creator
    configure qt for android

    Now it's building everything...really everything....all QT samples I piped in they work 80 or 90 percent in Android

    PS: I'm targeting the samples not designed for Android, I'm targeting all samples without "Android" in the green tags.

    For example the sample "Qt Quick Extras - Dashboard" with the kit QT 5.13.0 and it worked 100%

    Next stop Rebuilding Opencv4Android....


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