QGraphicsSvgItem and mousePressEvent troubles



  • The following program draws a red SVG rectangle in a white window.
    When you click on the white area, you'll see a messagebox with the text "QGraphicsView (White)".
    When you click on the red rectangle, I'd expect to see a messagebox with the text "QGraphicsSvgItem (Red)".
    However, I see "QGraphicsView (White)" instead.
    Can anyone point out what I'm doing wrong here ?

    [code]

    //------------------------------------------------------------------------------
    #include <QtGui/QApplication>
    #include <QtGui/QGraphicsView>
    #include <QtGui/QMessageBox>
    #include <QtGui/QMouseEvent>
    #include <QtSvg/QGraphicsSvgItem>
    #include <QtSvg/QSvgRenderer>
    //------------------------------------------------------------------------------
    class View : public QGraphicsView
    {
    Q_OBJECT
    public:
    View() : QGraphicsView()
    {
    }

    protected:

    void mousePressEvent(QMouseEvent *event)
    {
    QMessageBox::warning(0, "QGraphicsView (White)",
    "QGraphicsView (White)",
    QMessageBox::Ok,
    QMessageBox::Ok);
    }
    };
    //------------------------------------------------------------------------------
    class SvgItem : public QGraphicsSvgItem
    {
    public:
    SvgItem(QGraphicsItem * p = NULL ) :
    QGraphicsSvgItem( p )
    {
    setFlag( QGraphicsItem::ItemIsSelectable );
    setFlag( QGraphicsItem::ItemIsMovable );

    QSvgRenderer* mySvgRenderer;
    QByteArray svgData = QByteArray("<svg><rect x="0" y="0" width="50" height="50" fill="red" stroke="black" /></svg>");
    mySvgRenderer = new QSvgRenderer(svgData, this);

    QRect svgSize = mySvgRenderer->viewBox();
    this->setSharedRenderer(mySvgRenderer);

    }
    ~SvgItem()
    {
    }
    protected:
    void mousePressEvent(QGraphicsSceneMouseEvent *event)
    {
    QGraphicsItem::mousePressEvent(event);
    QMessageBox::warning(0, "QGraphicsSvgItem (Red)",
    "QGraphicsSvgItem (Red)",
    QMessageBox::Ok,
    QMessageBox::Ok);
    }
    };
    //------------------------------------------------------------------------------
    #include "main.moc"
    //------------------------------------------------------------------------------
    int main( int argc, char ** argv )
    {
    QApplication app(argc, argv );

    View * view = new View();

    QGraphicsScene * scene = new QGraphicsScene( 0, 0, 150, 150 );

    SvgItem * rect = new SvgItem();
    scene->addItem( rect );

    rect->setAcceptDrops( true );
    rect->setAcceptHoverEvents( true );
    rect->setPos(50,50);

    view->setScene( scene );
    view->show();

    return( app.exec() );
    }
    //------------------------------------------------------------------------------
    [/code]



  • This is easy to understand. QGraphicsView is a QWidget, but QGraphicsSvgItem is not a QWidget, it just a item located in QGraphicsScene.

    QGraphicsView(Receive mouseEvent) ==>QGraphicsScene ==> QGraphicsXXXItem

    In your View class, you have override the mousePressEvent, but you forget to call mousePressEvent of it's base class.



  • I got it.
    Thanks


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