Question

When I select several QGraphicsItem (with Ctrl key) I can move them together, but the mouseMoveEvent is triggered only for the item that actually receives the event. Is there a way to make every selected items receive the event ? I can’t find it in Qt’s doc.

Could I group selected items together and handle it within QGraphicsView’s mouseMoveEvent ?

Thanks a lot for any help 🙂

Answer 1

No there is no default way to do what you want as far as I know. Something you could do is the following:

• Subclass QGraphicsScene and implement the mouseMoveEvent
• In the mouse move event check if there is an item at the event position using the itemAt function
• If there is an item and it is selected (isSelected), get all selected items of the scene.
• For all selected items call the same function you would call.

Sample code follows:

void mouseMoveEvent(QGraphicsSceneMouseEvent * mouseEvent) 
{
    QPointF mousePosition = mouseEvent->scenePos();
    QGraphicsItem* pItem = itemAt(mousePosition.x(), mousePosition.y());
    if (pItem == NULL)
    {
        QGraphicsScene::mouseMoveEvent(mouseEvent);
        return;
    }

    if (pItem->isSelected() == false)  
    {
        QGraphicsScene::mouseMoveEvent(mouseEvent);
        return;
    }

    // Get all selected items
    QList<QGraphicsItem *> items = selectedItems();

    for (unsinged i=0; i<items.count(); i++)
        // Do what you want to do when a mouse move over a selected item.
        items[i]->doSomething(); 

    QGraphicsScene::mouseMoveEvent(mouseEvent);  
}