Spanning horizontal header in Qt - c++

Question

I want to merge(span) horizontal headers in QTableWidget. I tried googling for the same, but no luck and hence posting it. Please guide me.

Answer 1

You can subclass QHeaderView and create one section for each of the groups of columns/rows you would like to span and connect signals and slots to have them react to the different columns/rows.
The following example is for spanning the horizontal header:
#include <QtGui>
class MyHeaderModel : public QAbstractItemModel
{
public:
MyHeaderModel(QObject *parent = 0) : QAbstractItemModel(parent) {}
int columnCount(const QModelIndex &parent = QModelIndex()) const { return 2; }
QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const { return QVariant(); }
QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const { return QModelIndex(); }
QModelIndex parent(const QModelIndex &index) const { return QModelIndex(); }
int rowCount(const QModelIndex &parent = QModelIndex()) const { return 0; }
};
class MyHeader : public QHeaderView
{
Q_OBJECT
public:
MyHeader(QHeaderView *header, QWidget *parent = 0) : QHeaderView(Qt::Horizontal, header), mainHeader(header)
{
setModel(new MyHeaderModel(this));
// This example uses hardcoded groups, you can extend
// this yourself to save the groups
// Group 1 is 0-2 and Group 2 is 3-4
resizeSection(0, getSectionSizes(0, 2));
resizeSection(1, getSectionSizes(3, 4));
connect(this, SIGNAL(sectionResized(int,int,int)), this, SLOT(updateSizes()));
connect(((QTableWidget *)(mainHeader->parentWidget()))->horizontalScrollBar(), SIGNAL(valueChanged(int)), this, SLOT(updateOffset()));
setGeometry(0, 0, header->width(), header->height());
updateOffset();
mainHeader->installEventFilter(this);
}
public slots:
void updateSizes()
{
setOffset(mainHeader->offset());
mainHeader->resizeSection(2, mainHeader->sectionSize(2) + (sectionSize(0) - getSectionSizes(0, 2)));
mainHeader->resizeSection(4, mainHeader->sectionSize(4) + (sectionSize(1) - getSectionSizes(3, 4)));
}
void updateOffset()
{
setOffset(mainHeader->offset());
}
protected:
bool eventFilter(QObject *o, QEvent *e)
{
if (o == mainHeader) {
if (e->type() == QEvent::Resize) {
setOffset(mainHeader->offset());
setGeometry(0, 0, mainHeader->width(), mainHeader->height());
}
return false;
}
return QHeaderView::eventFilter(o, e);
}
private:
int getSectionSizes(int first, int second)
{
int size = 0;
for (int a=first;a<=second;++a)
size += mainHeader->sectionSize(a);
return size;
}
QHeaderView *mainHeader;
};
#include "main.moc"
int main(int argc, char **argv)
{
QApplication a(argc, argv);
QWidget w;
QVBoxLayout *vbox = new QVBoxLayout;
QTableWidget *tw = new QTableWidget(5, 5);
MyHeader *h = new MyHeader(tw->horizontalHeader());
vbox->addWidget(tw);
w.setLayout(vbox);
w.show();
return a.exec();
}