Custom QGraphicsItem That Contains Child QGraphicsItems

Custom QGraphicsItem That Contains Child QGraphicsItems

By : wiifunky
Date : November 23 2020, 04:01 AM
This might help you to @replete, from the example at http://doc.qt.io/qt-5/qtwidgets-graphicsview-dragdroprobot-example.html I was able to create a custom QGraphicsItem with clickable sub-parts in it. In code below BboxItem represents container QGraphicsItem and BboxItemContent represents childs of it. By emitting signals whith mause click events I was able to implement button like features. And I can move the BboxItem by setting its bounding rectangle.
BboxItem related source code:
code :
BboxItemContent::BboxItemContent(QGraphicsItem *parent, int type, QColor color,QRectF *rect)
    : QGraphicsObject(parent)
    content_rectangle = rect;
    content_type = type;
    switch (type)
    case 0:
        rectangle_color = color;
        icon = 0;
    case 1:
        icon = new  QImage(":/resource/assets/info_btn.png");
    case 2:
        icon = new  QImage(":/resource/assets/close_btn.png");

    delete icon;

QRectF BboxItemContent::boundingRect() const
    return QRectF(content_rectangle->x(), content_rectangle->y(), content_rectangle->width(), content_rectangle->height());

void BboxItemContent::paint(QPainter *painter,
    const QStyleOptionGraphicsItem *option, QWidget *widget)
    if (icon == 0)
        QPen pen(rectangle_color, 3);

        painter->drawImage(*content_rectangle, *icon);

void BboxItemContent::mousePressEvent(QGraphicsSceneMouseEvent * event)
    emit bboxContentClickedSignal();

void BboxItemContent::setRect(QRectF *rect)
    content_rectangle = rect;

BboxItem::BboxItem(QGraphicsItem *parent,QRectF *itemRect) : BboxItemContent(parent,0,Qt::red, itemRect)
    bbox_area = new BboxItemContent(this, 0, Qt::red, itemRect);
    info_btn = new BboxItemContent(this, 1, Qt::red, new QRectF(itemRect->x() - 30, itemRect->y(), 30, 30));
    connect(info_btn, &BboxItemContent::bboxContentClickedSignal, this, &BboxItem::onInfoClickedSlot);
    delete_btn= new BboxItemContent(this, 2, Qt::red, new QRectF((itemRect->x()+itemRect->width()), itemRect->y(), 30, 30));
    connect(delete_btn, &BboxItemContent::bboxContentClickedSignal, this, &BboxItem::onDeleteClickedSlot);

void BboxItem::onDeleteClickedSlot()
    //delete clicked actions
void BboxItem::onInfoClickedSlot()
    //info clicked actions

void BboxItem::setRect(QRectF *rect)
    info_btn->setRect(new QRectF(rect->x() - 30, rect->y(), 30, 30));
    delete_btn->setRect(new QRectF((rect->x() + rect->width()), rect->y(), 30, 30));
class BboxItemContent : public QGraphicsObject
    BboxItemContent(QGraphicsItem *parent = 0, int type = 0, QColor color = Qt::red, QRectF *rect=nullptr);
    // Inherited from QGraphicsItem
    QRectF boundingRect() const override;
    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0) override;
    void setRect(QRectF *rect);
    void bboxContentClickedSignal();
    void mousePressEvent(QGraphicsSceneMouseEvent *event);
    QImage *icon;
    QColor rectangle_color;
    QRectF *content_rectangle;
    int content_type;

class BboxItem : public BboxItemContent {
    BboxItem(QGraphicsItem *parent = 0,QRectF *itemRect=nullptr);
    void setRect(QRectF *rect);
private slots:
    void onDeleteClickedSlot();
    void onInfoClickedSlot();
    BboxItemContent *delete_btn;
    BboxItemContent *bbox_area;
    BboxItemContent *info_btn;

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error: C2248: 'QGraphicsItem::QGraphicsItem' : cannot access private member declared in class 'QGraphicsItem'

error: C2248: 'QGraphicsItem::QGraphicsItem' : cannot access private member declared in class 'QGraphicsItem'

By : Mack Helldalgo
Date : March 29 2020, 07:55 AM
will be helpful for those in need Providing your own copy constructor may help.
The default copy constructor tries to copy all data members from your class and its parents.
Moveable QGraphicsItem parent but not child QGraphicsItem

Moveable QGraphicsItem parent but not child QGraphicsItem

By : jayasuriya
Date : March 29 2020, 07:55 AM
With these it helps Marek R's answer is the cleanest I've found. Simply implement the mousePressEvent in the child to prevent it from causing moveable behavior of the parent:
code :
class Child(QtGui.QGraphicsItem):
  def __init__(self, name):
    super(Child, self).__init__()

  def mousePressEvent(self, event):
How can I skip QGraphicsItems obscured by identical QGraphicsItems?

How can I skip QGraphicsItems obscured by identical QGraphicsItems?

By : Subu
Date : March 29 2020, 07:55 AM
This might help you
If I increase slightly the size of the rectangle on top, the isObscured function works (either version). But with identical shapes, one on top of the other, logically the bottom one would still be obscured...
Qt/C++ Cast QGraphicsItem to custom QGraphicsItem without using dynamic_cast

Qt/C++ Cast QGraphicsItem to custom QGraphicsItem without using dynamic_cast

By : Aguilar Melody
Date : March 29 2020, 07:55 AM
it fixes the issue Qt has its own casting function for QGraphicsItem: qgraphicsitem_cast. From the documentation:
Fixed QGraphicsItem position, without changing behaviour of other QGraphicsItems in scene

Fixed QGraphicsItem position, without changing behaviour of other QGraphicsItems in scene

By : Jaganatha Rao
Date : March 29 2020, 07:55 AM
wish helps you I think this is what you are looking for:
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