CODEWITHSUNDEEP
c++qt
James Hirschorn
James Hirschorn

Reputation: 7994

How to programatically get the margin width of a QTableWidgetItem?

I think the title speaks for itself: Given a QTableWidget with items added by the setItem member function, I want to know what the margin is for each item. In particular, I want the width of the left margin in these cells.

Upvotes: 2

Views: 1633

Answers (1)

Tomas
Tomas

Reputation: 2210

I have prepared a little example computing text margins (a space between item rectangle and text content rectangle) of an item users clicks on:

int main(int argc, char *argv[])
{
  QApplication app(argc, argv); 
  QMainWindow mainWin;

  QTableWidget* table = new QTableWidget(3, 3, &mainWin);
  table->setItem(0, 0, new QTableWidgetItem("Item A"));
  table->setItem(1, 0, new QTableWidgetItem("Item B"));
  table->setItem(2, 0, new QTableWidgetItem("Item C"));
  table->setItem(0, 1, new QTableWidgetItem("Item D"));
  table->setItem(1, 1, new QTableWidgetItem("Item E"));
  table->setItem(2, 1, new QTableWidgetItem("Item F"));
  table->setItem(0, 2, new QTableWidgetItem("Item G"));
  table->setItem(1, 2, new QTableWidgetItem("Item H"));
  table->setItem(2, 2, new QTableWidgetItem("Item I"));

  mainWin.setCentralWidget(table);
  mainWin.show();

  auto slot = [&table](QTableWidgetItem* item){
    QStyleOptionViewItem option;
    option.font = item->font();
    option.fontMetrics = QFontMetrics(item->font());

    if (item->textAlignment())    
      option.displayAlignment = static_cast<Qt::Alignment>(item->textAlignment());
    else
      option.displayAlignment = Qt::AlignLeft | Qt::AlignVCenter; // default alignment

    option.features |= QStyleOptionViewItem::HasDisplay;
    option.text = item->text();
    option.rect = table->visualItemRect(item);

    // If your table cells contain also decorations or check-state indicators,
    // you have to set also:
    // option.features |= QStyleOptionViewItem::HasDecoration;
    // option.icon = ...       
    // option.decorationSize = ...

    QRect textRect = table->style()->subElementRect(QStyle::SE_ItemViewItemText, &option, nullptr);

    double leftMargin = textRect.left() - option.rect.left();
    double rightMargin = option.rect.right() - textRect.right();
    double topMargin = textRect.top() - option.rect.top();
    double bottomMargin = option.rect.bottom() - textRect.bottom();
    qDebug() << leftMargin;
    qDebug() << rightMargin;
    qDebug() << topMargin;
    qDebug() << bottomMargin;
  };

  QObject::connect(table, &QTableWidget::itemClicked, slot);
  return app.exec();
}

EDIT

To compute an exact space between table cell border and the text pixels, you have to use a QFontMetrics class.

See the QFontMetrics::leftBearing() and QFontMetrics::tightBoundingRect().

Upvotes: 1

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