CODEWITHSUNDEEP
c++qt
Radwa
Radwa

Reputation: 117

How to execute the mouseevent of qgraphicsitem only ? (ignoring the rest of mouseevent of qgraphicsview)

I know how to pass events from qgraphicsview to qgraphicsitem. But the problem is after executing the mouseEvent of item ,i have to execute the mouse event of the view which is not desirable in my case. so,the question is: "Is there a smart way to know if mousePress is on an item or on an empty space?"

Edit:The working code:

#include <QtGui>

class CustomView : public QGraphicsView
{

protected:
    void mousePressEvent(QMouseEvent *event)
    {
        QGraphicsView::mousePressEvent(event);
        qDebug() << "Custom view clicked.";

    }
};

class CustomItem : public QGraphicsRectItem
{
protected:
    void mousePressEvent(QGraphicsSceneMouseEvent *event)
    {
        qDebug() << "Custom item clicked.";
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    CustomItem item;
    item.setRect(20, 20, 60, 60);

    QGraphicsScene scene(0, 0, 100, 100);
    scene.addItem(&item);

    CustomView view;
    view.setScene(&scene);
    view.show();
    return a.exec();
}

Appling the same concept in a qgraphics scene instead of view 

#include <QtGui>
class CustomScene : public QGraphicsScene
{
protected:
    void mousePressEvent(QGraphicsSceneMouseEvent *event)
    {
        if(itemAt(event->scenePos()))
            QGraphicsScene::mousePressEvent((event));
        else
        qDebug() << "Custom view clicked.";
    }
};
class CustomItem : public QGraphicsRectItem
{
protected:
    void mousePressEvent(QGraphicsSceneMouseEvent *event)
    {
        qDebug() << "Custom item clicked.";
    }
};
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    CustomItem item;
    item.setRect(20, 20, 60, 60);
    CustomScene scene;
    //scene().set
    scene.addItem(&item);
    QGraphicsView view;
    view.setScene(&scene);
    view.show();
    return a.exec();
}

Upvotes: 0

Views: 1234

Answers (2)

Oleg Shparber
Oleg Shparber

Reputation: 2752

To determine wether mouse event occured on item or not you can use QGraphicsView::itemAt:

void CustomView::mousePressEvent(QMouseEvent *event)
{
    if (itemAt(event->pos()))
        // Click on item
    else
        // Click on empty space
    ...
}

Upvotes: 2

Pavel Strakhov
Pavel Strakhov

Reputation: 40512

There are 3 correct ways to solve your task:

1. Reimplement QGraphicsView::mousePressEvent and use QGraphicsView::itemAt to find clicked item.

2. Subclass QGraphicsScene and reimplement QGraphicsScene::mousePressEvent. Its argument event contains position in scene coordinates, and you can use QGraphicsScene::itemAt to determine which item has been clicked.

3. Subclass QGraphicsItem (or any derived class) and reimplement QGraphicsItem::mousePressEvent. It will be called only if this element was clicked.

Upvotes: 3

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