Problem passing QVector containing QPointF through signal-slot

[Mindstormer]

Hello!

I would like to know if someone know's how to pass a Qvector<QPointF> through signals & slots. I've been able to pass a QVector<int> through signals and slots but I'm unable to pass a vector containing QPointF. Could anyone tell me what I'm doing wrong? I will post some sample code below:

main.cpp:

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    app.setPalette(Qt::darkGray);
 
    qRegisterMetaType< QVector<int> >("QVector<int>");
 
    MainWindow mainWindow;
 
    SamplingThread samplingThread;
    samplingThread.setInterval(1000);
 
    mainWindow.connect(&samplingThread, SIGNAL(sendSampleVector(QVector<int>)), &mainWindow, SLOT(plotSampleVector(QVector<int>)));
 
    mainWindow.show();
 
    samplingThread.start();
 
    bool ok = app.exec();
 
    samplingThread.stop();
    samplingThread.wait(1000);
 
    return ok;
}

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    app.setPalette(Qt::darkGray);

    qRegisterMetaType< QVector<int> >("QVector<int>");

    MainWindow mainWindow;

    SamplingThread samplingThread;
    samplingThread.setInterval(1000);

    mainWindow.connect(&samplingThread, SIGNAL(sendSampleVector(QVector<int>)), &mainWindow, SLOT(plotSampleVector(QVector<int>)));

    mainWindow.show();

    samplingThread.start();

    bool ok = app.exec();

    samplingThread.stop();
    samplingThread.wait(1000);

    return ok;
}

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samplingthread.cpp (in samplingthread.h the signal is defined as: void sendSampleVector(QVector<int>))

#include "samplingthread.h"
#include <QVector>
 
SamplingThread::SamplingThread( QObject *parent ):
    QwtSamplingThread( parent )
{
}
 
void SamplingThread::sample(double elapsed)
{
    QVector<int> sampleVector;
    sampleVector.append(1);
    sampleVector.append(2);
    sampleVector.append(3);
 
    emit sendSampleVector(sampleVector);
}

#include "samplingthread.h"
#include <QVector>

SamplingThread::SamplingThread( QObject *parent ):
    QwtSamplingThread( parent )
{
}

void SamplingThread::sample(double elapsed)
{
    QVector<int> sampleVector;
    sampleVector.append(1);
    sampleVector.append(2);
    sampleVector.append(3);

    emit sendSampleVector(sampleVector);
}

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mainwindow.cpp (in mainwindow.cpp the slot is defined as void plotSampleVector(QVector<int>))

void MainWindow::plotSampleVector(QVector<int> sampleVector)
{
    qDebug()<<sampleVector;
}

void MainWindow::plotSampleVector(QVector<int> sampleVector)
{
    qDebug()<<sampleVector;
}

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Now, the code above works but when I swap the int to QPointf I get tons of errors and it doesn't work. What am I not understanding in this case?

Also, when using QPointF my samplingthread.cpp is:

void SamplingThread::sample(double elapsed)
{
    QVector<QPointF> sampleVector;
    sampleVector.append(QPointF(1.0,1.0));
    sampleVector.append(QPointF(2.0,2.0));
    sampleVector.append(QPointF(3.0,3.0));
 
    emit sendSampleVector(sampleVector);
}

void SamplingThread::sample(double elapsed)
{
    QVector<QPointF> sampleVector;
    sampleVector.append(QPointF(1.0,1.0));
    sampleVector.append(QPointF(2.0,2.0));
    sampleVector.append(QPointF(3.0,3.0));

    emit sendSampleVector(sampleVector);
}

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All help apreciated, thanks!

[stampede]

I get tons of errors and it doesn't work

Posting them here could be a good idea.
btw

when I swap the int to QPointf

Did you swap them in signal / slot definition and connect statements too ?

[Mindstormer]

Posting them here could be a good idea.
btw

Here is my compile output:
compileoutput.txt

Did you swap them in signal / slot definition and connect statements too ?

Yes I did.

Signal definition: void sendSampleVector(QVector<QPointF>)
Slot definition: void plotSampleVector(QVector<QPointF>)
connect: mainWindow.connect(&samplingThread, SIGNAL(sendSampleVector(QVector<QPointF>)), &mainWindow, SLOT(plotSampleVector(QVector<QPointF>)))

[wysota]

The first error seems to be a missing #include <QPointF> statement.

[Mindstormer]

The first error seems to be a missing #include <QPointF> statement.

Right, I missed that but I still get a bunch of errors. Below is the new compile output. (had to zip it because textfile was to large)
compileoutput2.txt.zip

Or does anyone know a better way to pass a number of points from one thread to another?

[wysota]

Still seems to be a missing include in samplingthread.h.

I can tell you in aedvance that once you solve these problems you will have to use qRegisterMetaType.

[Mindstormer]

Still seems to be a missing include in samplingthread.h.

I can tell you in aedvance that once you solve these problems you will have to use qRegisterMetaType.

Do you have any idea on what's missing? Because before when I forgot the includes I got errors in my own files but now they are somewhere else. And aren't I already using qRegisterMetaType (in the first post in main.cpp)?

Also, a more general question so I dont waste time on this problem if it's a bad/inefficient solution; do I have the right approach to what I'm trying to achieve?

What I'm doing is that I want to have a worker thread reading sensor data and at some times I want to append some of the collected samples to a plot. Would it be better to use sared memory or something between the two threads? Seems harder though...

[wysota]

Do you have any idea on what's missing?

Based on the first error posted, seems a missing #include <QPointF>

And aren't I already using qRegisterMetaType (in the first post in main.cpp)?

You are using it for QVector<int> and not QVector<QPointF>.

Also, a more general question so I dont waste time on this problem if it's a bad/inefficient solution; do I have the right approach to what I'm trying to achieve?

Well... it depends what you want to achieve. Most probably you can replace the thread with a timer. Of course this won't cause your missing include problem to disappear

[Mindstormer]

Based on the first error posted, seems a missing #include <QPointF>

Finally was able to solve the problem! It turns out that I was looking in the wrong file, I had QpointF included in my samplingthread.cpp but I had forgot to include it in my samplingthread.h file!

You know why I had to include QpointF when Qvector in the header file? I'm just curious... :P

You are using it for QVector<int> and not QVector<QPointF>.

I was using QVector<QPointF> in the registermetatype but the error was in the header file as I just discovered.

Thanks for all the help guys, problem solved and I'm happy to move on!

[wysota]

You know why I had to include QpointF when Qvector in the header file? I'm just curious... :P

Because you had a declaration of a QVector<QPointF> object in the header file.