Qt emit signal problem

[katana]

Hi everyone here
i'm new in here and Qt.(having a lot problems)
what im doing is to draw a point (later a line a circle maybe) in a graphicsview mit mouse click
what ive done is like that:

mainwindow.h

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private slots:
    void paintEvent(QPaintEvent *ev);

private:
    Ui::MainWindow *ui;
    myview view;
};

myview.h

#include <QGraphicsView>
#include <QMouseEvent>
#include <QEvent>

class myview : public QGraphicsView
{
    //Q_OBJECT
public:
    myview(QWidget *parent = 0);

    int x,y;

protected:
    void mousePressEvent(QMouseEvent *ev);

signals:
    void Mousepressed();
};

myview.cpp

#include <QMouseEvent>

myview::myview(QWidget *parent) : QGraphicsView(parent)
{
}
void myview::mousePressEvent(QMouseEvent *ev)
{
    x = ev->pos().x();
    y = ev->pos().y();
    emit Mousepressed();
}

mainwindow.cpp

#include <QPainter>
#include <myview.h>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    QObject::connect(ui->graphicsView,SIGNAL(Mousepressed()),this,SLOT(paintEvent(QPaintEvent *ev)));
}

MainWindow::~MainWindow()
{
    delete ui;
}
void MainWindow::paintEvent(QPaintEvent *ev)
{
    QPainter p(this);
    QPen pen(Qt::black);
    pen.setWidth(6);
    p.setPen(pen);
    p.drawPoint(view.x,view.y);
}

when i bild the project i get this error:
undefined reference to myview::Mousepressed()

Thanks in advance

[edit: corrected coding tags: use ```before and after SGaist]

[SGaist]

Hi and welcome to devnet,

You commented out the Q_OBJECT macro from your myview class so moc doesn't run thus your signals are not implemented like they should be.

On a side note, your connection statement is invalid for two reasons:

• list item paintEvent is not a slot
• you can't connect a parameterless signal to a slot with parameters.

[katana]

@SGaist Thank U so much. The Signal emit problem is solved perfect. I wanna ask how can I call the paintevent with a mouse click?

thanks in advance

[SGaist]

You can't. paintEvent is called when needed, you can ask for a repaint but it doesn't mean it will be done immediately