Qt -- How to set a QBrush for a QGraphicsItemGroup? - c++

Question

I'm trying to create an interface for myself on Qt and I need a few rectangles over a DICOM image (a magnetic ressonance image), so they need to be some color other than black but I can't find a way to set a brush for the QGraphicsItemGroup I'm using to keep the rectangles organized.
QGraphicsScene lets me add a QRect associated to a QBrush individually with
QgraphicsScene *scene = new QGraphicsScene();
QRectF rect = QRectF(QPoint(1,2),QPoint(3,4));
scene->addRect(rect, QBrush(Qt::red)); // using red as example
but adding each rectangle individually would make it all too messy and probably way slower. I need a way to set a QBrush for the rectangles but using QGraphicsItemGroup to be added to the QGraphicsScene.

Answer 1

Why can you not reimplement QGraphicsItemGroup and inside have a function called:
void ReimplementedQGraphicsItemGroup::SetRectangleBrush(const QBrush& brush)
and inside that function iterate over every rectangle you have added to the group setting the brush
QgraphicsScene *scene = new QGraphicsScene();
ReimplementedQGraphicsItemGroup ReimplGraphicsGroup = new ReimplementedQGraphicsItemGroup()
// First rect
QGraphicsRectItem rect(1,2,3,4);
rect.setBrush(QColor(Qt::red);
ReimplGraphicsGroup->AddRectangle(rect);
// Second rect
QGraphicsRectItem rect2(5,6,7,8);
rect2.setBrush(QColor(Qt::blue);
ReimplGraphicsGroup->AddRectangle(rect2);
// add reimplemented graphics item group to scene
scene->addItem(ReimplGraphicsGroup);
void ReimplementedQGraphicsItemGroup::SetRectangleBrush(const QBrush& brush)
{
foreach (QGraphicsRectItem rect, m_ListRects)
{
rect.setBrush(brush);
}
}
class ReimplementedQGraphicsItemGroup : public QGraphicsItemGroup {
// a member of ReimplementedQGraphicsItemGroup
QList<QGraphicsRectItem> m_ListRects;
}
void ReimplementedQGraphicsItemGroup::AddRectangle(QGraphicsRectItem rect)
{
addToGroup(rect);
m_ListRects.append(rect);
}