QItemSelectionModel signals doesnt work

Pbaodoge

Hi, I'm trying to use QItemSelectionModel to display a list of info(just for some reference). My code works and the window is displayed.
Here's my code:

#include <QApplication>
#include <QMainWindow>
#include <QSplitter>
#include <QTreeView>
#include <QItemSelectionModel>
#include <QStandardItemModel>
#include <QObject>
#include "mainwindow.hpp"
#include <QListView>
#include <QHBoxLayout>
int main( int argc, char **argv )
{
  QApplication app( argc, argv );
  QTreeView *tree = new QTreeView();
  QWidget *w = new QWidget;
  QHBoxLayout *layout = new QHBoxLayout;
  layout->addWidget(tree);
  w->setLayout(layout);

  QItemSelectionModel mselect;
  QStandardItemModel model(5, 2);

  MainWindow *st = new MainWindow();
  
  for( int r=0; r<5; r++ )
    for( int c=0; c<2; c++)
    {
      QStandardItem *item = new QStandardItem( QString("Row:%0, Column:%1").arg(r).arg(c) );
      if( c == 0 )
        for( int i=0; i<3; i++ )
        {
          QStandardItem *child = new QStandardItem( QString("Item %0").arg(i) );
          child->setEditable(false);
          item->appendRow(child);
        }
      model.setItem(r, c, item);
    }

  model.setHorizontalHeaderItem(0, new QStandardItem("C1"));
  model.setHorizontalHeaderItem(1, new QStandardItem("C2"));
  mselect.setModel(&model);
  tree->setModel(&model);
 //Signals And Slots setup
  QObject::connect(&mselect, &QItemSelectionModel::selectionChanged, st, &MainWindow::notification); //1
  QObject::connect(&mselect, &QItemSelectionModel::currentColumnChanged, st, &MainWindow::notification); //2
  QObject::connect(&mselect, &QItemSelectionModel::currentRowChanged, st, &MainWindow::notification);  //3

  w->show();

  return app.exec();
}

The problem starts at the signals and slots connection. I tried every signal, but none of them are emitted when an action is executed.
Is there anything wrong with my code?
Thank you.

mchinand

I think you need to specify the SelectionModel for your QTreeView. Note, this must be done after you set the view's model (see the note here).

jsulm

@Pbaodoge said in QItemSelectionModel signals doesnt work:

w->show();

Why do you have this widget AND MainWindow. You never show your MainWindow.
How do you know that MainWindow::notification is never called? Do you have any debug output there?

Pbaodoge

I wasn't really wanted to use MainWindow class. If you want the MainWindow class code then here it is:
.hpp

#ifndef MAINWINDOW_HPP
#define MAINWINDOW_HPP

#include <QMainWindow>
#include <QDebug>
#include <QApplication>

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
public slots:
    void notification();

};
#endif // MAINWINDOW_HPP

.cpp

#include "mainwindow.hpp"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{

}

void MainWindow::notification() {
    qDebug() << "Current Item has changed!\n";
}

I tried to use qDebug() to output emitted signals. And after many attempts on the Window, it is still not working.

mchinand

I think you need to specify the SelectionModel for your QTreeView. Note, this must be done after you set the view's model (see the note here).

Pbaodoge

That works perfectly. Thanks a lot