draw points on mouse click shows error painter not active.

[athulms]

void MainWindow::mousePressEvent(QMouseEvent *e)
{
if(e->button()==Qt::LeftButton)
{
QPoint point = e->pos();
int x=point.rx();
int y=point.ry();
QPainter painter(this);
QPen linepen(Qt::red);
linepen.setWidth(30);
linepen.setCapStyle(Qt::RoundCap);
painter.setRenderHint(QPainter::Antialiasing,true) ;
painter.setPen(linepen);
painter.drawPoint(x,y);
}
}


What is the error in the code. Waiting for rply.

[MasterBLB]

The reason of the error is using QPainter not inside paintEvent().Move the drawing to the paintEvent(),here in mousePressEvent just save points to draw on some list or so.

[athulms]

void MainWindow:aintEvent(QPaintEvent *e)
{
QPainter painter(this);
QPen linepen(Qt::red);
linepen.setWidth(30);
linepen.setCapStyle(Qt::RoundCap);
painter.setRenderHint(QPainter::Antialiasing,true) ;
painter.setPen(linepen);
}


void MainWindow::mousePressEvent(QMouseEvent *e)
{
if(e->button()==Qt::LeftButton)
{
QPoint point = e->pos();
int x=point.rx();
int y=point.ry();
QPainter painter(this);
painter.drawPoint(x,y);
}
}


This also shows the same error

[MasterBLB]

Of course it shows the same error,as you have not corrected it

void MainWindow::mousePressEvent(QMouseEvent *e)
{
if(e->button()==Qt::LeftButton)
{
QPoint point = e->pos();
int x=point.rx();
int y=point.ry();
QPainter painter(this);//this is fckig wrong.QPainter instances may not be created outside the paintEvent
painter.drawPoint(x,y);
}
}

[athulms]

ya i have used the update(); method. now it worked