Qt QTreeWidget一一添加项

Question

this is my code

QList<QString> IPs;  //IP address
...
connect(this, SIGNAL(addItems(QTreeWidgetItem*)), this, 
              SLOT(addNewItemToTree(QTreeWidgetItem*)));

void MainWindow::startPing()
{        
    for (int i = ipStart; i <= ipEnd; i++)
    {           
        QTreeWidgetItem *item = new QTreeWidgetItem();
        item->setText(0, IPs.at(i));
        if (PingHost(IPs.at(i)))
        {
            item->setText(1, "online");

        }
        else
        {
            item->setText(1, "offline");
        }
        emit addItems(item);
    }
}

void MainWindow::addNewItemToTree(QTreeWidgetItem *item)
{
    items.append(item);
    ui->treeWidget->addTopLevelItem(item);
}

PingHost is a function, It's run time maybe over 2 second.

I compiled and run this program whitout any error or warning.

I think item will be added to treeWidget one by one (one item is been added, after 2 second, another one will be added.)

but, when I run it, I found all Item had been added one time after a long wait. why?

how to make those items added as my think?

Answer 1

You are blocking the GUI thread for too long.. Ideally, you should do PingHost in another thread and inside PingHost, you send a Signal when the result is available. Then you have a SLOT in mainwindow to add the item when the signal is received.

if you insist doing what you are doing now, you could try to update the treeWidget at the end of each loop. See QWidget::update()