Problem with getting icons for applications

Cobra91151

Hi! I want to get icons for all installed applications (using registry) on Windows. The problem is:

QObject::connect: Cannot queue arguments of type 'QList<QIcon>'
(Make sure 'QList<QIcon>' is registered using qRegisterMetaType().)

How to fix it? Thanks in advance.

jsulm

@Cobra91151 What are you trying to connect to what?

Cobra91151

@jsulm

I'm connecting data from Worker class

QThread *programsThread = new QThread();
Worker *programsWorker = new Worker();
programsWorker->moveToThread(programsThread);
connect(programsWorker, &Worker::appData, this, &Test::setAppData);

QList<QIcon> programIcons;
emit appData(programIcons, displayNames, displayVersions, publishers, installLocation, uninstallLocations);

and in Test class setting data in QTreeWidgetItem (QTreeWidget)

void setAppData(QList<QIcon> icons, QStringList names, QStringList versions, QStringList publishers, QString installLocation, QStringList uninstallLocations);

jsulm

@Cobra91151 The error message actually tells you how to fix: "Make sure 'QList<QIcon>' is registered using qRegisterMetaType()".
See here for details: http://doc.qt.io/qt-5/qmetatype.html#qRegisterMetaType.
It should be enough to do it for QUcon, QList should already be supported.

Cobra91151

@jsulm
So I should use this function like: qRegisterMetaType<QIcon>("QIcon");

But where to initialize (call) it (in Worker or in Test class)? Thanks.

jsulm

@Cobra91151 where you do the connection

Cobra91151

@jsulm

void Test::appProgramsThread()
{
    qRegisterMetaType<QIcon>("QIcon");

    try {
        QThread *programsThread = new QThread();
        Worker *programsWorker = new Worker();
        programsWorker->moveToThread(programsThread);
        connect(programsThread, &QThread::started, programsWorker, &Test::programsData);
        connect(programsWorker, &Worker::appData, this, &Test::setAppData);
        connect(programsWorker, &Worker::noAppsData, this, &Test::allApplicationsEmptyData);
        connect(programsWorker, &Worker::appDataReady, this, &Test::setAppLogData);
        connect(programsWorker, &Worker::finished, programsThread, &QThread::quit);
        connect(programsWorker, &Worker::finished, programsWorker, &Worker::deleteLater);
        connect(programsThread, &QThread::finished, programsThread, &QThread::deleteLater);
        programsThread->start();
    } catch (...) {
        QMessageBox::critical(this, QObject::tr("Error"), QObject::tr("An error has occurred with detecting programs!"));
    }
}

Also I have tried to call it in setAppData function but it doesn't work. The same issue: QObject::connect: Cannot queue arguments of type 'QList<QIcon>' (Make sure 'QList<QIcon>' is registered using qRegisterMetaType().).

jsulm

@Cobra91151 Sorry, actually you should use http://doc.qt.io/qt-5/qmetatype.html#Q_DECLARE_METATYPE

Q_DECLARE_METATYPE(QIcon)

But I'm wondering why it is not working out of the box for QIcon as it is Qts own class.

Cobra91151

@jsulm

I have declare it in a header file (Test.h) where I make a connection

class Test : public QWidget
{
    Q_OBJECT

 public:
    Test();  

 signals:

 public slots:
       void setAppData(QList<QIcon> icons, QStringList names, QStringList versions, QStringList publishers, QString installLocation, QStringList uninstallLocations);

 private:
};

Q_DECLARE_METATYPE(QIcon)

The same issue is still present.

Cobra91151

When I use in Test class

class Test : public QWidget
{
    Q_OBJECT
    Q_DECLARE_METATYPE(QIcon)
....

I get errors:

error: C3412: 'QMetaTypeId<QIcon>': cannot specialize template in current scope

I'm using Qt 5.7.1 (Win 10).
So, where to initialize it? Thanks.

Cobra91151

@Cobra91151

Problem solved:

I have changed code to: qRegisterMetaType<QList<QIcon>>("QList<QIcon>"); and it works now.