How to accelerate the selection in the QTableView ?

cyberpunker

I use the MVC to show a bund of of filenames , and there are opertions of selecting all and dissecting all in the CTableView . The number of files may thousands , so , I write a thread to do these ,like:

for (int row = 0; row < m_ImgMgr->m_TableModel->rowCount(); row++)
	{


		//QtSleep(5);

		for (int column = 0; column < m_ImgMgr->m_TableModel->columnCount(); column++)
		{

			//LogLog( QString(" sel 1") ) ;
			m_ImgMgr->listImages2->selectionModel()->select(m_ImgMgr->listImages2->model()->index(row, column), QItemSelectionModel::Select);

		}

		//LogLog(QString(" sel 2"));

		m_ImgMgr->labelImageIndex->setText(QString::number(row+1) + QString("/") + QString::number(m_ImgMgr->m_TableModel->rowCount()));
		
		//LogLog(QString(" sel 3"));

	}

but consuming time is not acceptable . And if the number is very large , the operation seems become more and more slowly by the end of the loop , it can be seen by the count number displayed in the GUI .

I also tried like below:

	QItemSelection sel = m_ImgMgr->listImages2->selectionModel()->selection( ) ;

	QModelIndex topleft     = m_ImgMgr->listImages2->model()->index( 0 , 0 ) ;
	QModelIndex bottonright = m_ImgMgr->listImages2->model()->index(m_ImgMgr->m_TableModel->rowCount(), 3 ) ;

	sel.select( topleft  , bottonright ) ;

no funtional.

VRonin

I can't reproduce the problem. try this minimal example and see if it works for you:

#include <QTableView>
#include <QVBoxLayout>
#include <QStandardItemModel>
#include <QApplication>
#include <QPushButton>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QWidget mainWid;
    QAbstractItemModel* model = new QStandardItemModel(&mainWid);
    model->insertColumns(0,4);
    model->insertRows(0,5000);
    for(int rowIter = 0, maxRow = model->rowCount();rowIter<maxRow;++rowIter){
        for(int colIter = 0, maxCol = model->columnCount();colIter<maxCol;++colIter){
            model->setData(model->index(rowIter,colIter),QStringLiteral("%1,%2").arg(rowIter+1).arg(colIter+1));
        }
    }
    QTableView* table = new QTableView(&mainWid);
    table->setModel(model);
    QPushButton* selectAllButton = new QPushButton(QStringLiteral("Select All"),&mainWid);
    QObject::connect(selectAllButton,&QPushButton::clicked,table,[table]()->void{
        const QItemSelection selec(table->model()->index(0,0),table->model()->index(table->model()->rowCount()-1,table->model()->columnCount()-1));
        table->selectionModel()->select(selec,QItemSelectionModel::ClearAndSelect);
    });
    QVBoxLayout* mainLay = new QVBoxLayout(&mainWid);
    mainLay->addWidget(selectAllButton);
    mainLay->addWidget(table);
    mainWid.show();
    return a.exec();
}

P.S.

I write a thread to do these

Don't do GUI operations in secondary threads

Christian Ehrlicher

How should your second approach work when you don't pass it to the selection model?
And doing stuff for a model/view in a thread will not work out of the box since the models and views are not threadsafe

cyberpunker

@VRonin said in How to accelerate the selection in the QTableView ?:

QTableView* table = new QTableView(&mainWid);

So great , I am still totally ignorant to MVC .

Really apreciation.

cyberpunker

@Christian-Ehrlicher

thanks for your suggestion.