How do I create a default size for the rows in a table view?

In order to change the default size for the rows in a table view, you need to reimplement sizeHintForRow() and make sure resizeRowToContents() is called. See the documentation:

http://doc.trolltech.com/4.3/qtableview.html#sizeHintForRow

The example below demonstrates how this can be achieved

#include <QtGui>

class Model : public QAbstractTableModel
{
public:
        Model(QObject *parent) 
        {
               QStringList firstRow;
               QStringList secondRow;
               
               for (int i = 0; i < 5; i++ ) {
                      firstRow.insert(i,"Row 1 " + QString::number(i+1));
                      secondRow.insert(i,"Row 2 " + QString::number(i+1));
               }
               
               stringList << firstRow << secondRow;
        }
        
        // Returns the number of rows
        int rowCount ( const QModelIndex & parent = QModelIndex() ) const
        {
               return stringList.count();
        }
        
        // Returns the number of columns
        int columnCount ( const QModelIndex & parent = QModelIndex() ) const
        {
               return stringList[0].count();
               
        }
        
        
        // Returns an appropriate value for the requested data.
        // If the view requests an invalid index or if the role is not
        // Qt::DisplayRole, an invalid variant is returned.
        // Any valid index that corresponds to a string for the index's column and row in
        // the stringlist is returned
        QVariant data ( const QModelIndex & index, int role = Qt::DisplayRole ) const 
        {
               if (!index.isValid())
                      return QVariant();
               if (role != Qt::DisplayRole)
                      return QVariant();
               QStringList list = (QStringList)stringList.at(index.row());
               return list.at(index.column());        
        }
private:
        QList<QStringList>stringList;
        
};

class TableView : public QTableView
{
public:
        TableView(QWidget *parent) {}

        //Returns the needed size for the rows
        int sizeHintForRow ( int row ) const
        {
               return 200;
        }
};


int main(int argc, char **argv)
{
        QApplication app(argc, argv);
        QWidget widget;
        
        QHBoxLayout *layout = new QHBoxLayout(&widget);
        
        TableView *tableView = new TableView(&widget);
        Model *model = new Model(tableView);
        tableView->setModel(model);
        
        for (int i = 0; i < model->rowCount(); i++) {
	        tableView->resizeRowToContents(i); 
        }
        
        layout->addWidget(tableView);
        
        widget.show();
        return app.exec(); 
}