change rect of parent when child's boundingrect is changed or new child is added

Hi,

I want to implement grid using qgraphicsrectitem in which each cell can has multiple child and grandchildren. i.e. I have outer rectangle R1 with rect as R(0,0,300,300). This rect will have 3 child qgraphicsrectitem as RC1(0,0,300,100), RC2(0,100,300,100), RC3(0,200,300,100)
when I will add 2 children in RC1 as RGC1(0,0,300,75) and RGC1(0,75,300,75), it should change bounding rect as belows.

RGC1 - (0,0,300,75)
RGC2 - (0,75,300,75)
RC1 - (0,0,300,150),
RC2 - (0,150,300,100)
RC3 - (0,250,300,100)
R - (0,0,300,250)

This means basically, I want to implement that if child is added or resized all its parents and super parents to get re-shaped so that all children remain inside the bounding rect of parent and will not be out of border.

Any idea for this

Manish

Code:

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#include <QtWidgets>
 
class GraphicsRectItem : public QGraphicsRectItem
{
public:
    explicit GraphicsRectItem(const QString & name, QGraphicsItem * parent = 0)
        : QGraphicsRectItem(parent)
        , text(new QGraphicsSimpleTextItem(this))
    {
        setData(0, name);
    }
 
    void setSize(const QRect & r)
    {
        setRect(r);
 
        GraphicsRectItem * parent = dynamic_cast<GraphicsRectItem *>(parentItem());
 
        if(parent)
            parent->adjust();
 
        // Showing rect size in text
        text->setText(QString("%5-{%1,%2,%3,%4}").arg(r.x()).arg(r.y()).arg(r.width()).arg(r.height()).arg(data(0).toString()));
        text->setPos(rect().center());
        text->moveBy(-text->boundingRect().width()/2, -text->boundingRect().height()/2);
    }
 
private:
    void adjust()
    {
        QRect rect;
 
        foreach(const QGraphicsItem * child, childItems())
            if(dynamic_cast<const GraphicsRectItem *>(child))
                rect = rect.united(child->boundingRect().toRect());
 
        setSize(rect);
    }
 
    QGraphicsSimpleTextItem * const text;
};
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
 
    GraphicsRectItem * R = new GraphicsRectItem("R");
 
    GraphicsRectItem * RC1 = new GraphicsRectItem("RC1", R);
    GraphicsRectItem * RC2 = new GraphicsRectItem("RC2", R);
    GraphicsRectItem * RC3 = new GraphicsRectItem("RC3", R);
 
    GraphicsRectItem * RGC1 = new GraphicsRectItem("RGC1", RC1);
    GraphicsRectItem * RGC2 = new GraphicsRectItem("RGC2", RC1);
 
    RGC1->setSize(QRect(0,0,300,75));
    RGC2->setSize(QRect(0,75,300,75));
 
    RC2->setSize(QRect(0,150,300,100));
    RC3->setSize(QRect(0,250,300,100));
 
    QGraphicsScene scene;
    scene.addItem(R);
 
    QGraphicsView view;
    view.setScene(&scene);
    view.show();
 
    return app.exec();
}

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