problem in eventFilter of QGraphicsView()

[wagmare]

hi friends,
in QGraphicsView i am try to install event filter to an item .. to capture a key ...

RecRepView::RecRepView(QWidget *parent)
         : QGraphicsView(parent)
{
QRectF bounds(0, -20, 700, 500);
        scene = new QGraphicsScene(bounds, this);
        setScene(scene);
 //this is the QGraphicsItem      
     logout = new BackItem(QRectF(0, 0, 70, 65));
        logout->setPos(20, 405);
        logout->setFlag(QGraphicsItem::ItemIsSelectable);
        logout->installEventFilter(this);
        connect(logout, SIGNAL(closeSignal()), qApp, SLOT(quit()));
        scene->addItem(logout);
}

RecRepView::RecRepView(QWidget *parent)
         : QGraphicsView(parent)
{
QRectF bounds(0, -20, 700, 500);
        scene = new QGraphicsScene(bounds, this);
        setScene(scene);
 //this is the QGraphicsItem      
     logout = new BackItem(QRectF(0, 0, 70, 65));
        logout->setPos(20, 405);
        logout->setFlag(QGraphicsItem::ItemIsSelectable);
        logout->installEventFilter(this);
        connect(logout, SIGNAL(closeSignal()), qApp, SLOT(quit()));
        scene->addItem(logout);
}

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and in event filter

bool RecRepView:: eventFilter(QObject *ob, QEvent *e)
{
        printf("is it coming inside ..\n");
        if(ob == logout && e->type() == QEvent::KeyPress) {
                const QKeyEvent *ke = static_cast<QKeyEvent *>(e);
                if(ke->key()==Qt::Key_F1){
                        some  cond ..... 
                }
                return true;
        }
         return QWidget::eventFilter(ob, e);
}

bool RecRepView:: eventFilter(QObject *ob, QEvent *e)
{
        printf("is it coming inside ..\n");
        if(ob == logout && e->type() == QEvent::KeyPress) {
                const QKeyEvent *ke = static_cast<QKeyEvent *>(e);
                if(ke->key()==Qt::Key_F1){
                        some  cond ..... 
                }
                return true;
        }
         return QWidget::eventFilter(ob, e);
}

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but even the printf output is not displaying .....
i dont know where i done the mistake ... please help ....

[Lykurg]

Install the filter on the scene or view, not on the item.

this->installEventFilter(this);
//...
return QGraphicsView::eventFilter(ob, e);

this->installEventFilter(this);
//...
return QGraphicsView::eventFilter(ob, e);

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[wagmare]

Install the filter on the scene or view, not on the item.

this->installEventFilter(this);
//...
return QGraphicsView::eventFilter(ob, e);

this->installEventFilter(this);
//...
return QGraphicsView::eventFilter(ob, e);

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of course i try that one too ....

my full code

RecRepView::RecRepView(QWidget *parent)
         : QGraphicsView(parent)
{
 setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
        setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
        setFrameShape(QFrame::NoFrame);
        setCacheMode(CacheBackground);
        setViewportUpdateMode(FullViewportUpdate);
        setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform);
        setStyleSheet("background:#00002E");
        QRectF bounds(0, -20, 700, 500);
        scene = new QGraphicsScene(bounds, this);
        setScene(scene);
        this->installEventFilter(this);
        signalMapper =  new QSignalMapper();
int i =0;
        mapValue[i] = STARTVALUE;
        button1 = new GraphButton(QRectF(0,0, 150, 40), 1);
        button1->setFlag(QGraphicsItem::ItemIsSelectable);
        button1->setPos(475, 330);
        scene->addItem(button1);
        connect(button1, SIGNAL(activated()), signalMapper, SLOT(map()));
        signalMapper->setMapping(button1,mapValue[i]);
        i++;
 
 
        mapValue[i] = STOPVALUE;
        button2 = new GraphButton(QRectF(0,0, 150, 40), 2);
        button2->setFlag(QGraphicsItem::ItemIsSelectable);
        button2->setPos(475, 400);
        scene->addItem(button2);
        connect(button2, SIGNAL(activated()), signalMapper, SLOT(map()));
        signalMapper->setMapping(button2,mapValue[i]);
 
        logout = new BackItem(QRectF(0, 0, 70, 65));
        logout->setPos(20, 405);
        logout->setFlag(QGraphicsItem::ItemIsSelectable);
//      log connect(logout, SIGNAL(closeSignal()), qApp, SLOT(quit()));
        scene->addItem(logout);
 
        connect(signalMapper, SIGNAL(mapped(int )), this, SIGNAL(activated(int)));
 
        connect(this, SIGNAL(activated(int )), this, SLOT(recRepSlot(int )));
 
}
 
void RecRepView ::resizeEvent(QResizeEvent *event)
{
        QGraphicsView::resizeEvent(event);
        fitInView(scene->sceneRect(), Qt::KeepAspectRatio);
}
 
void RecRepView::drawBackground(QPainter *painter, const QRectF &rect)
{
        Q_UNUSED(rect);
 
        QRectF rects(450,310, 200, 160);
        QPen pen(QColor(211, 210, 212), 0.5);
        painter->setBrush(QColor(128, 128, 128));
        painter->setPen(pen);
        painter->drawRect(rects);
 
}bool RecRepView:: eventFilter(QObject *ob, QEvent *e)
{
        if(ob == logout && e->type() == QEvent::KeyPress) {
                const QKeyEvent *ke = static_cast<QKeyEvent *>(e);
                if(ke->key()==Qt::Key_F1){
                        printf("is it coming inside ..\n");
 
                }
                return true;
        }
         return QWidget::eventFilter(ob, e);
}
void RecRepView::recRepSlot(int value)
{
        printf("the value coming inside :%d \n", value);
 
}

RecRepView::RecRepView(QWidget *parent)
         : QGraphicsView(parent)
{
 setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
        setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
        setFrameShape(QFrame::NoFrame);
        setCacheMode(CacheBackground);
        setViewportUpdateMode(FullViewportUpdate);
        setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform);
        setStyleSheet("background:#00002E");
        QRectF bounds(0, -20, 700, 500);
        scene = new QGraphicsScene(bounds, this);
        setScene(scene);
        this->installEventFilter(this);
        signalMapper =  new QSignalMapper();
int i =0;
        mapValue[i] = STARTVALUE;
        button1 = new GraphButton(QRectF(0,0, 150, 40), 1);
        button1->setFlag(QGraphicsItem::ItemIsSelectable);
        button1->setPos(475, 330);
        scene->addItem(button1);
        connect(button1, SIGNAL(activated()), signalMapper, SLOT(map()));
        signalMapper->setMapping(button1,mapValue[i]);
        i++;


        mapValue[i] = STOPVALUE;
        button2 = new GraphButton(QRectF(0,0, 150, 40), 2);
        button2->setFlag(QGraphicsItem::ItemIsSelectable);
        button2->setPos(475, 400);
        scene->addItem(button2);
        connect(button2, SIGNAL(activated()), signalMapper, SLOT(map()));
        signalMapper->setMapping(button2,mapValue[i]);

        logout = new BackItem(QRectF(0, 0, 70, 65));
        logout->setPos(20, 405);
        logout->setFlag(QGraphicsItem::ItemIsSelectable);
//      log connect(logout, SIGNAL(closeSignal()), qApp, SLOT(quit()));
        scene->addItem(logout);

        connect(signalMapper, SIGNAL(mapped(int )), this, SIGNAL(activated(int)));

        connect(this, SIGNAL(activated(int )), this, SLOT(recRepSlot(int )));

}

void RecRepView ::resizeEvent(QResizeEvent *event)
{
        QGraphicsView::resizeEvent(event);
        fitInView(scene->sceneRect(), Qt::KeepAspectRatio);
}

void RecRepView::drawBackground(QPainter *painter, const QRectF &rect)
{
        Q_UNUSED(rect);

        QRectF rects(450,310, 200, 160);
        QPen pen(QColor(211, 210, 212), 0.5);
        painter->setBrush(QColor(128, 128, 128));
        painter->setPen(pen);
        painter->drawRect(rects);

}bool RecRepView:: eventFilter(QObject *ob, QEvent *e)
{
        if(ob == logout && e->type() == QEvent::KeyPress) {
                const QKeyEvent *ke = static_cast<QKeyEvent *>(e);
                if(ke->key()==Qt::Key_F1){
                        printf("is it coming inside ..\n");
                       
                }
                return true;
        }
         return QWidget::eventFilter(ob, e);
}
void RecRepView::recRepSlot(int value)
{
        printf("the value coming inside :%d \n", value);

}

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GraphButton::GraphButton(const QRectF &rect, int itemNo)
            : QGraphicsRectItem(rect)
{
}
 
void GraphButton::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
        if(event->button() != Qt::LeftButton)
        {
                QGraphicsRectItem::mousePressEvent(event);
                return;
        }
        emit activated();
}

GraphButton::GraphButton(const QRectF &rect, int itemNo)
            : QGraphicsRectItem(rect)
{
}

void GraphButton::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
        if(event->button() != Qt::LeftButton)
        {
                QGraphicsRectItem::mousePressEvent(event);
                return;
        }
        emit activated();
}

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please help ....

[wysota]

What is the point of installing an event filter on "this"? Why do you need the event filter in the first place? Can't you use the regular means of handling events?

[wagmare]

when the user press key <F1> .. i have to close the application or else user can click logout item .. like wise there are seven buttons <F2>, <F3> ,<F4> ... , each having different functions ... so i am planning to catch the event of pressing F1 ,... and try to do the option ....
why this one is not working ..? shall i use QAction instead for this ..?

[Lykurg]

when the user press key <F1> .. i have to close the application or else user can click logout item .. like wise there are seven buttons <F2>, <F3> ,<F4> ... , each having different functions ... so i am planning to catch the event of pressing F1 ,... and try to do the option ....
why this one is not working ..? shall i use QAction instead for this ..?

well the item has to be focused to get the event - I guess. If you whant a global short cut - seems to me you whant one - use a QAction with QAction::setShortcutContext(Qt::ApplicationShortcut).

[wysota]

At "worst" you can reimplement QGraphicsView::keyPressEvent(). Event filters are for something else.

[wagmare]

we have to install event filter on QGraphicsScene() not in QGraphicsView() itself ..

scene->installEventFilter(this);

now the above code working perfectly .