How to put 2 Widgets in a MainWindow ?

[gen_mass]

Hi,

I want to put 2 widgets (a QwtPlot and a QTableWidget) on the same mainwindow with a QVBoxLayout, but I see nothing when I try with this code:

mainwindow::mainwindow(QWidget*p)
{
 
    double *buffer=NULL;
 
    plot=new Plot(100,250,buffer,buffer+1,p);
    data = new Data(250,buffer,p);
 
    QVBoxLayout* layout = new QVBoxLayout(p);
 
     layout->addWidget(plot);
    layout->addWidget(data);
 
     //Start of on_watcher 
     data->on_watcher();
 
}

mainwindow::mainwindow(QWidget*p)
{

    double *buffer=NULL;

    plot=new Plot(100,250,buffer,buffer+1,p);
    data = new Data(250,buffer,p);

    QVBoxLayout* layout = new QVBoxLayout(p);

     layout->addWidget(plot);
    layout->addWidget(data);

     //Start of on_watcher 
     data->on_watcher();

}

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And here's my construcors:

data .h:

Data(int _periode,double* &_voies,QWidget*parent=0);

Data(int _periode,double* &_voies,QWidget*parent=0);

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data.cpp:

Data::Data(int _periode,double * &_voies,QWidget *parent):QTableWidget(parent),periode( _periode )

Data::Data(int _periode,double * &_voies,QWidget *parent):QTableWidget(parent),periode( _periode )

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plot.h:

Plot( int duree, int periode,double * _time, double * _voie, QWidget * p = NULL );

Plot( int duree, int periode,double * _time, double * _voie, QWidget * p = NULL );

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plot.cpp:

Plot::Plot(int duree,int periode,double* _time,double* _voie,QWidget*p): QwtPlot(p)

Plot::Plot(int duree,int periode,double* _time,double* _voie,QWidget*p): QwtPlot(p)

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Thanks for your help !

[Zlatomir]

Try this:

QVBoxLayout* layout = new QVBoxLayout(this); //so that the layout can re-parent your widgets with this (the window itself) not the parent of the window (witch is most likely 0)

QVBoxLayout* layout = new QVBoxLayout(this); //so that the layout can re-parent your widgets with this (the window itself) not the parent of the window (witch is most likely 0)

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[gen_mass]

Ok, if I change my mainwindow.cpp to this:

mainwindow::mainwindow(QWidget*p)
{
 
    double *buffer=NULL;
 
    plot=new Plot(100,250,buffer,buffer+1,this);
    data = new Data(250,buffer,this);
 
    QVBoxLayout* layout = new QVBoxLayout(this);
    data->on_watcher();
}

mainwindow::mainwindow(QWidget*p)
{

    double *buffer=NULL;

    plot=new Plot(100,250,buffer,buffer+1,this);
    data = new Data(250,buffer,this);

    QVBoxLayout* layout = new QVBoxLayout(this);
    data->on_watcher();
}

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I see my QTableWidget in the left corner, and no plot at all...

[Zlatomir]

In the code from last post you didn't add the widgets to layout.

Did you did that in your actual project? (You still need to do that)

mainwindow::mainwindow(QWidget*p)
{
 
    double *buffer=NULL;
 
    plot=new Plot(100,250,buffer,buffer+1,p);
    data = new Data(250,buffer,p);
 
    QVBoxLayout* layout = new QVBoxLayout(this);
 
     layout->addWidget(plot);
    layout->addWidget(data);
 
     //Start of on_watcher 
     data->on_watcher();
 
}

mainwindow::mainwindow(QWidget*p)
{

    double *buffer=NULL;

    plot=new Plot(100,250,buffer,buffer+1,p);
    data = new Data(250,buffer,p);

    QVBoxLayout* layout = new QVBoxLayout(this);

     layout->addWidget(plot);
    layout->addWidget(data);

     //Start of on_watcher 
     data->on_watcher();

}

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[gen_mass]

oopps , I meant:

mainwindow::mainwindow(QWidget*p)
{
 
    double *buffer=NULL;
 
    plot=new Plot(100,250,buffer,buffer+1,this);
    data = new Data(250,buffer,this);
 
    QVBoxLayout* layout = new QVBoxLayout(this);
 
    layout->addWidget(plot);
    layout->addWidget(data);
 
     data->on_watcher();
 
}

mainwindow::mainwindow(QWidget*p)
{

    double *buffer=NULL;

    plot=new Plot(100,250,buffer,buffer+1,this);
    data = new Data(250,buffer,this);

    QVBoxLayout* layout = new QVBoxLayout(this);

    layout->addWidget(plot);
    layout->addWidget(data);

     data->on_watcher();
   
}

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[Zlatomir]

Are you sure this is what you want

plot=new Plot(100,250,buffer,buffer+1,this); // the buffer pointer is NULL and you are adding 1 to that???

plot=new Plot(100,250,buffer,buffer+1,this); // the buffer pointer is NULL and you are adding 1 to that???

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[gen_mass]

That's not the problem....buffer acts as a chart...everything works fine in there....when I do a setCentralWidget(plot) I see my plot and my program does what it's supposed to..
Altought, now, I want to add a QTableWidget, which is created and filled in my data class, and I don't know how to put both on my MainWindow

[Zlatomir]

Do you get some warnings about mainWindow allready have a layout?

Try to add a QWidget *test = new QWidget(0); make it the parent of the layout QVBoxLayout* layout = new QVBoxLayout(test); and setCentralWidget(test);

[ChrisW67]

For a start you need to set the QMainWindow's central widget... there can be only one. To get more than one widget into the main window central area you need to encapsulate them.

#include <QtGui>
 
class mainwindow: public QMainWindow {
public:
    mainwindow(QWidget *p = 0): QMainWindow(p) {
        QWidget *central = new QWidget(this); // a central widget
        QLabel *widget1 = new QLabel("one widget", this);
        widget1->setFrameStyle(QFrame::Box | QFrame::Plain);
        QLabel *widget2 = new QLabel("two widget", this);
        widget2->setFrameStyle(QFrame::Box | QFrame::Plain);
 
        QVBoxLayout *layout = new QVBoxLayout(this);
        layout->addWidget(widget1);
        layout->addWidget(widget2);
 
        central->setLayout(layout); 
        setCentralWidget(central);   // you were missing this
    }
 
};
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
 
    mainwindow m;
    m.show();
 
    return app.exec();
}

#include <QtGui>

class mainwindow: public QMainWindow {
public:
    mainwindow(QWidget *p = 0): QMainWindow(p) {
        QWidget *central = new QWidget(this); // a central widget
        QLabel *widget1 = new QLabel("one widget", this);
        widget1->setFrameStyle(QFrame::Box | QFrame::Plain);
        QLabel *widget2 = new QLabel("two widget", this);
        widget2->setFrameStyle(QFrame::Box | QFrame::Plain);

        QVBoxLayout *layout = new QVBoxLayout(this);
        layout->addWidget(widget1);
        layout->addWidget(widget2);

        central->setLayout(layout); 
        setCentralWidget(central);   // you were missing this
    }

};

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    mainwindow m;
    m.show();

    return app.exec();
}

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[gen_mass]

ok, thanks !!
when I put this code:

mainwindow::mainwindow(QWidget*p)
{
 
    double *buffer=NULL;
 
    plot=new Plot(100,250,buffer,buffer+1,this);
    data = new Data(250,buffer,this);
 
      QWidget *central = new QWidget(0); // a central widget.
 
      QVBoxLayout *layout = new QVBoxLayout(this);
      layout->addWidget(plot);
      layout->addWidget(data);
      central->setLayout(layout);
      setCentralWidget(central);  
 
     data->on_watcher();
 
}

mainwindow::mainwindow(QWidget*p)
{

    double *buffer=NULL;

    plot=new Plot(100,250,buffer,buffer+1,this);
    data = new Data(250,buffer,this);

      QWidget *central = new QWidget(0); // a central widget.

      QVBoxLayout *layout = new QVBoxLayout(this);
      layout->addWidget(plot);
      layout->addWidget(data);
      central->setLayout(layout);
      setCentralWidget(central);  

     data->on_watcher();

}

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I have exaclty what I want, but suddently the program shuts down with a code -1073741819 and I still get the error about the QLayout that Zlatomir talked about:

Starting C:\Users\Genevieve\Desktop\DETECTION\debug\DETECTION.exe...
QLayout: Attempting to add QLayout "" to mainwindow "", which already has a layout
C:\Users\Genevieve\Desktop\DETECTION\debug\DETECTION.exe exited with code -1073741819

Starting C:\Users\Genevieve\Desktop\DETECTION\debug\DETECTION.exe...
QLayout: Attempting to add QLayout "" to mainwindow "", which already has a layout
C:\Users\Genevieve\Desktop\DETECTION\debug\DETECTION.exe exited with code -1073741819

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When I debbuged with Visual it says:
Unhandled exception at 0x004056bc in DETECTION.exe: 0xC0000005: Access violation reading location 0x00000004.

[ChrisW67]

Make line 11 read:

QVBoxLayout *layout = new QVBoxLayout(central);

QVBoxLayout *layout = new QVBoxLayout(central);

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and the warning should go away.

The access violation is probably related to the buffer pointer; using it while it is NULL, accessing the "buffer+1" memory location, or trying to use the storage for the buffer pointer itself after it goes out of scope.

[gen_mass]

Ok, eveything works now!!!

just a last thing.. I want my plot to take 2/3 of the window andmy QTableWidget 1/3, is it possible to that with a QVBoxLayout ?

Thanks for your help !!!

[Zlatomir]

You can use something like this:

QSizePolicy PlotPolicy = plot->sizePolicy();
PlotPolicy.setVerticalStretch(1);                                   //don't remember the exact "formula", try with 1
plot->setSizePolicy(PlotPolicy);

QSizePolicy PlotPolicy = plot->sizePolicy();
PlotPolicy.setVerticalStretch(1);                                   //don't remember the exact "formula", try with 1
plot->setSizePolicy(PlotPolicy);

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if that doesn't do the right proportions, try this:

QSizePolicy PlotPolicy = plot->sizePolicy();
PlotPolicy.setVerticalStretch(2);                                   //don't remember the exact "formula", so play with this values
plot->setSizePolicy(PlotPolicy);
 
QSizePolicy DataPolicy = data->sizePolicy();
DataPolicy.setVerticalStretch(1);
plot->setSizePolicy(DataPolicy);

QSizePolicy PlotPolicy = plot->sizePolicy();
PlotPolicy.setVerticalStretch(2);                                   //don't remember the exact "formula", so play with this values
plot->setSizePolicy(PlotPolicy);

QSizePolicy DataPolicy = data->sizePolicy();
DataPolicy.setVerticalStretch(1);
plot->setSizePolicy(DataPolicy);

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[gen_mass]

Thanks Zlatomir !
I used your second method and it works well !!!

A last last question...is it possible to center my QTableWidget with that QVBoxLayout?
I want to do that because when I resize my window manually with a mouse, the QTableWidget stays align at the left.
Is there a similar function to

QTableWidget::setAlignement(Qt::AlignCenter)

QTableWidget::setAlignement(Qt::AlignCenter)

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that exists ?
I search the documentation, but couldn't find any easy way to do this