QListWidget items swapping

[sbenoitlaf]

Hi,

I am trying to swap the content of a QListWidget. Perhaps I am not using the right methods ... or maybe I need to use the listview + model instead ?

The context here is that I have a plotter and I am loading multple files. Each files has its own tab with the plotted data. Each tab contains an object with the filename, channelList, etc ..

The "Channel list" is in a general QListWidget and I would like to switch the content of that widget when I switch tab.

Each dataLog object contains the list of channels with a QList that contains items property:

QList<QListWidgetItem*> itemList;

QList<QListWidgetItem*> itemList;

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And here's the handler when I change tabs :

void MainWindow::on_tabWidget_logs_currentChanged(int index)
{
    foreach(logData* l, this->openedLogs)
    {
        if(l->parentWidget == ui->tabWidget_logs->widget(index))
        {
 
            int count = ui->listWidget_channels->count();
 
            //currentLog->itemList.clear();  // This actually deletes the items in the dataLog object so it's not good
 
            // This doesnt seem to be working since all the items are still in the QListWidget
            for ( int i=0; i<count; i++)
            {
                ui->listWidget_channels->takeItem(i);
            }
 
            currentLog = l;
            // Take the items from the log object and populate the QListWidget with them
            foreach(QListWidgetItem *i, currentLog->itemList)
            {
                ui->listWidget_channels->addItem(i);
            }
            ui->listWidget_channels->sortItems();
            break;
        }
    }
}

void MainWindow::on_tabWidget_logs_currentChanged(int index)
{
    foreach(logData* l, this->openedLogs)
    {
        if(l->parentWidget == ui->tabWidget_logs->widget(index))
        {

            int count = ui->listWidget_channels->count();

            //currentLog->itemList.clear();  // This actually deletes the items in the dataLog object so it's not good

            // This doesnt seem to be working since all the items are still in the QListWidget
            for ( int i=0; i<count; i++)
            {
                ui->listWidget_channels->takeItem(i);
            }

            currentLog = l;
            // Take the items from the log object and populate the QListWidget with them
            foreach(QListWidgetItem *i, currentLog->itemList)
            {
                ui->listWidget_channels->addItem(i);
            }
            ui->listWidget_channels->sortItems();
            break;
        }
    }
}

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[d_stranz]

The problem with your code to remove the items from listWidget_channels is that as soon as you take one item out, "count" is no longer valid. Try this:

while ( ui->listWidget_channels->count() > 0 )
  ui->listWidget_channels->takeItem( 0 );

while ( ui->listWidget_channels->count() > 0 )
  ui->listWidget_channels->takeItem( 0 );

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[sbenoitlaf]

Geez ! I really missed that one .. thanks.

I was aware of one bad thing and it always catch me ... the decreasing for loop when the count was in the if statement :

for (int i=0; i< ui->listWidget_channels->count(); i++ ){ ...

for (int i=0; i< ui->listWidget_channels->count(); i++ ){ ...

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But indeed, having a variable with count before taking items is still wrong.

Thanks again !