How to change the text background in QTableView

[JonB]

@Emon-Haque
You would need to write your own QStyledItemDelegate to do whatever highlighting and attach it to the QTableView via QAbstractItemView::setItemDelegate(QAbstractItemDelegate *delegate).

You will then need to persuade the view to redraw every time you type a new character causing the view to want to change its highlighting. Normally a QTableView only redraws in response to a model data change.

[deleted385]

@JonB, sounds complicated. Could you please provide an example to help me understand it better?

[deleted385]

found a solution in other forum that works with this delegate:

Delegate::Delegate(){ selection.setBackground(Qt::green); /*QTextCharFormat*/}
void Delegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const{
    if(index.column() == 0){
        QTextDocument doc(index.model()->data(index, Qt::DisplayRole).toString());
        int position = 0;
        QTextCursor cur;
        do {
            cur = doc.find(query, position); // query is private QString
            cur.setCharFormat(selection);
            cur.movePosition(QTextCursor::Right);
            position = cur.position();
        } while (!cur.isNull());
        painter->save();
        painter->translate(option.rect.x(), option.rect.y());
        doc.drawContents(painter);
        painter->restore();
        if(option.state == QStyle::State_Selected){
            qDebug() << "here";
            painter->fillRect(option.rect, Qt::red);
        }
    }
    else QStyledItemDelegate::paint(painter, option, index);
}

and these in mainwindow:

Window::Window(QWidget *parent) : QWidget(parent){
    auto lay = new QVBoxLayout(this);
    auto hlay = new QHBoxLayout;
    auto textBox = new QLineEdit(this);
    auto label = new QLabel(this);
    label->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
    hlay->addWidget(textBox);
    hlay->addWidget(label);
    auto table = new QTableView(this);
    lay->addLayout(hlay);
    lay->addWidget(table);
    auto model = new QStandardItemModel;
    for (int i = 0; i < 50000; i++) {
        auto col1 = new QStandardItem("Column 1 : " + QString::number(i));
        auto col2 = new QStandardItem("Column 2 : " + QString::number(i));
        model->appendRow(QList<QStandardItem*>() << col1 << col2);
    }
    proxy = new QSortFilterProxyModel(table);
    proxy->setSourceModel(model);
    proxy->setFilterKeyColumn(0);
    table->setModel(proxy);
    delegate = new Delegate();
    table->setItemDelegate(delegate);
    table->horizontalHeader()->hide();
    table->verticalHeader()->hide();
    label->setText(locale().toString(proxy->rowCount()));
    connect(textBox, &QLineEdit::textChanged, [=]{
        auto query = textBox->text();
        delegate->setQuery(query);
        proxy->setFilterFixedString(query);
        proxy->invalidate();
        label->setText(locale().toString(proxy->rowCount()));
    });
}

Now, when I click on an item in column 1, it doesn't highlight and doesn't print qDebug() << "here";.

[deleted385]

Another problem is when I've long text in the column I want to highlight. Here's what I wanted to achieve:

When I typed the word heard in search textbox it found 752 occurrences in this WPF app. Now here's the table without delegate:

No idea why does it get 750 matches instead of 752! If I use delegate, I don't see any content in 7th column:

the delegate is same as before except the first line in paint instead of if(index.column() == 0), I, now have, if(index.column() == 6) and here's the content of Window:

Window::Window(QWidget *parent) : QWidget(parent){
    auto lay = new QVBoxLayout(this);
    auto hlay = new QHBoxLayout;
    auto textBox = new QLineEdit(this);
    auto label = new QLabel(this);
    label->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
    hlay->addWidget(textBox);
    hlay->addWidget(label);
    auto table = new QTableView(this);
    lay->addLayout(hlay);
    lay->addWidget(table);
    auto db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName("bukhari.db");
    db.open();
    auto model = new QSqlTableModel;
    model->setTable("Hadith");
    model->select();
    while (model->canFetchMore()) model->fetchMore();
    db.close();
    proxy = new QSortFilterProxyModel(table);
    proxy->setSourceModel(model);
    proxy->setFilterKeyColumn(6);
    table->setModel(proxy);
    delegate = new Delegate();
    table->setItemDelegate(delegate);
    table->verticalHeader()->hide();
    label->setText(locale().toString(proxy->rowCount()));
    connect(textBox, &QLineEdit::textChanged, [=]{
        auto query = textBox->text();
        delegate->setQuery(query);
        proxy->setFilterFixedString(query);
        proxy->invalidate();
        label->setText(locale().toString(proxy->rowCount()));
    });
    table->setVerticalScrollMode(QTableView::ScrollPerPixel);
    //table->resizeRowsToContents();
}

wanted to see the whole content in the last column BUT couldn't make it work.

EDIT

Found the difference 2, In WPF I actually have converted string to lower before applying filter BUT in Qt I didn't and there is two Heard.

[mrjj]

hi

try with

if (option.state & QStyle::State_Selected)

and not

if(option.state == QStyle::State_Selected){

to see if you get the qDebug() << "here";

[deleted385]

@mrjj, yes that works, now I get the red background and debug output. The paint is called twice when I click an item.

[mrjj]

@Emon-Haque said in How to change the text background in QTableView:

@mrjj, yes that works, now I get the red background and debug output. The paint is called twice when I click an item.

The reason that it works is that option.state also have other states like item is editable and
enabled SET already (default values) so you should use the & to test for other states as its a bit flag thing.

Im not sure it means anything the paint is called twice. there can be many reasons for that.

[deleted385]

Had to set the document size to get some content:

Delegate::Delegate(){ selection.setBackground(Qt::green); /*QTextCharFormat*/}
void Delegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const{
    if(index.column() == 6){
        if(option.state & QStyle::State_Selected)
            painter->fillRect(option.rect, Qt::gray);

        QTextDocument doc(index.model()->data(index, Qt::DisplayRole).toString());
        doc.setPageSize(QSizeF(option.rect.width(), option.rect.height()));
        int position = 0;
        QTextCursor cur;
        do {
            cur = doc.find(query, position); // query is private QString
            cur.setCharFormat(selection);
            cur.movePosition(QTextCursor::Right);
            position = cur.position();
        } while (!cur.isNull());
        painter->save();
        painter->translate(option.rect.x(), option.rect.y());
        doc.drawContents(painter);
        painter->restore();
    }
    else QStyledItemDelegate::paint(painter, option, index);
}

and have hidden all columns except the last and also set stretch and resizemode at the end of Window constructor:

...
table->setVerticalScrollMode(QTableView::ScrollPerPixel);
table->hideColumn(0);
table->hideColumn(1);
table->hideColumn(2);
table->hideColumn(3);
table->hideColumn(4);
table->hideColumn(5);
table->horizontalHeader()->setStretchLastSection(true);
table->verticalHeader()->setSectionResizeMode(QHeaderView::ResizeToContents);

and now it's like this:

1. it takes a long time to respond when I resize,
2. content is jumbled,
3. when I select an item it takes a while to response,
4. it doesn't show whole content in the cell,
5. feels like it doesn't scroll per pixel, and
6. when I type in search box it shows up those text after a long time.

EDIT

Here's link of the project in GitHub for testing. The sample database, bukhari.db, has been included.

[deleted385]

It's performance is similar without the delegate and with plain single column QListView. Looks like Qt model view architecture still isn't able to handle medium size dataset.

[uart]

Hello, I'm designing a combobox that contains 2 column items, and can do filters and shorting based on what is typed in the combobox, the problem is that the combobox doesn't always appear when I write a search.

void Dialog_Sell::getCmbStock(){
QStandardItemModel *model= new QStandardItemModel(arrStock.size(), 2, this);
for(int i=0; i<arrStock.size(); i++){
QStandardItem *kol1 = new QStandardItem( QString("%0").arg(code[i]) );
QStandardItem *kol2 = new QStandardItem( QString("%0").arg(name[i]) );
model->setItem(i, 0, kol1);
model->setItem(i, 1, kol2);
}

delegate = new Delegate();
QTableView* tableView = new QTableView( this );
QSortFilterProxyModel *proxyModel = new QSortFilterProxyModel(this);

proxyModel->setSourceModel(model);
proxyModel->setFilterKeyColumn(-1);
tableView->setModel( proxyModel);
tableView->setItemDelegate(delegate);
tableView->verticalHeader()->setVisible(false);
tableView->horizontalHeader()->setVisible(false);
tableView->setColumnWidth ( 0, 60 );
tableView->setColumnWidth ( 1, 260 );
tableView->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
//tableView->setSelectionBehavior(QAbstractItemView::SelectRows);
tableView->setStyleSheet("background-color: rgb(255, 255, 255);");
tableView->setAutoScroll(false);
tableView->setShowGrid(false);
tableView->setAlternatingRowColors(true);
tableView->setSortingEnabled(false);
tableView->setVerticalScrollMode(QTableView::ScrollPerPixel);


connect(ui->cmbStock, &QComboBox::editTextChanged, [=]{
    QString query = ui->cmbStock->currentText();
    delegate->setQuery(query);
    //proxyModel->setFilterRegularExpression(query);
    proxyModel->setFilterCaseSensitivity(Qt::CaseInsensitive);
    proxyModel->invalidate();
    //return ;
});


ui->cmbStock->setModel(proxyModel);
ui->cmbStock->setView( tableView );
ui->cmbStock->setStyleSheet("QComboBox QAbstractItemView {min-width: 250px;}"
                            "QComboBox { background-color: white; }");

}