CODEWITHSUNDEEP
qtqgraphicsviewqgraphicssceneqmouseevent
Wagmare
Wagmare

Reputation: 1416

graphicsview receives mouse event before the item

I have implemented the panning view on the QGraphicsView, using the mouse move event using

void View::mouseMoveEvent(QMouseEvent* event) {
pan();
QGraphicsView::mouseMoveEvent(event);
}

and in the scene of this view I have added few items where some of the items are resizable, so I implemented 

void Item::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
 if(m_resizeMode)
    {
      resize();
      e->accept();
    }
}

I tried to filter the mouse move not to propagate to any further using e->accept() but my View mouseMove event has been called first , so when ever I tried to resize the item, the view started to pan all the way.

How can I avoid this event propagation from view to scene.

Upvotes: 1

Views: 477

Answers (2)

thuga
thuga

Reputation: 12931

You can call the base class implementation of the QGraphicsView and check if the event is accepted. However I would do this in the mousePressEvent instead of the mouseMoveEvent. After all this is where you determine if you should resize an item or do some panning. This is how I do something similar in my project:

void View::mousePressEvent(QMouseEvent *event)
{
    ...
    QGraphicsView::mousePressEvent(event);
    if(event->isAccepted())
        move = false;
    else
        move = true;
}

void View::mouseMoveEvent(QMouseEvent *event)
{
    if(!move)
    {
        QGraphicsView::mouseMoveEvent(event);
        return;
    }
    ... // you would do the panning here

    QGraphicsView::mouseMoveEvent(event);
}

void View::mouseReleaseEvent(QMouseEvent *event)
{
    if(!move)
    {
        QGraphicsView::mouseReleaseEvent(event);
        return;
    }
    else
    {
        ...
        move = false;
    }
    QGraphicsView::mouseReleaseEvent(event);
}

Upvotes: 1

TheDarkKnight
TheDarkKnight

Reputation: 27639

The view will always receive the mouse event first.

So, in the view, check to see if the mouse is over an item before allowing it to pan by getting the mouse pos in scene coordinates and retrieving the items at that position with QGraphicsScene::items( )

Upvotes: 1

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