Question

I am trying to change the background color for certain header sections. Some will use the default coloring, others will get a different color.

The HeaderView doesn’t accept delegates like the QTreeView does; it does all the painting itself. It does this using two methods —

• paintEvent
• paintSection

My initial attempt was to try and override paintSection, letting it paint the default stuff, and then adding my own.

def paintSection(self, painter, rect, logicalindex):
    QHeaderView.paintSection(self, painter, rect, logicalindex)
    painter.save()
    painter.fillRect(rect, QBrush(Qt.red))
    painter.restore()

This doesn’t appear to do anything. It will not draw the filled rect. If I comment out the call to the base paintSection method, it will draw the filled rect, but not very consistently (i.e. clicking and resizing the header causes it to fill sometimes and not others).

Any help is appreciated.

Answer 1

There is no need to implement anythingQHeaderView can be changed through stylesheets like almost all widgets.

Edit:

You mentioned that you wanted to change the background color per column depending on data, the easiest way to do that is probably to derive a new model from QAbstractItemModel or another model class and reimplement the headerData() call

QVariant QAbstractItemModel::headerData ( int section, Qt::Orientation orientation, int role = Qt::DisplayRole ) const [virtual]

the role that you want to react to is Qt::BackgroundColorRole so the function could look like this

QVariant VariableHeaderModel::headerData(int section Qt::Orientation orientation, int role)
{
  QVariant result;
  if (role == Qt::BackgroundColorRole)
  {
    result = <QColor from custom processing>
  }
  else
  {
    result = Superclass::headerData(section, orientation, role);
  }
  return result;
}

Generally in Qt, the model decides what to show, almost all of the times change the model, not the view. Also the ‘data()’ calls get called a lot, I don’t know about the ‘headerData()’ but you probably want to cache any results if there is a lot of calculation going on.

If you are using the QStandardItemModel you can probably just call

setHeaderData(section, orientation, <aColor>, Qt::BackgroundColorRole);