Strange thing after override paintEvent function

[Sheng]

I override paintEvent function for a QDialog project. After that, in QDialog, I can not put label which load bitmap image any more. If I do so, there is "Segmentation error".
Is that normal?
Thanks

[talk2amulya]

would you mind sharing the code with us?

[Sheng]

would you mind sharing the code with us?

void myDialog::paintEvent(QPaintEvent *event)
{
 QPainter painter(this);
 painter.setRenderHint(QPainter::Antialiasing,true);
  painter.setPen(QPen(Qt::black,1,Qt::SolidLine));
 painter.drawLine(27,450,630,450);
 painter.drawLine(30,50,30,453);
 painter.drawLine(180,450,180,453);
 painter.drawLine(330,450,330,453);
 painter.drawLine(480,450,480,453);
 painter.drawText(QPoint(570,470),tr("Time (Sec)"));
 painter.drawText(QPoint(170,470),tr("75"));
 painter.drawText(QPoint(470,470),tr("225"));
 painter.drawText(QPoint(320,470),tr("150"));
 painter.drawText(QPoint(10,40),tr("Force (lbs)"));
}

void myDialog::paintEvent(QPaintEvent *event)
{
 QPainter painter(this);
 painter.setRenderHint(QPainter::Antialiasing,true);
  painter.setPen(QPen(Qt::black,1,Qt::SolidLine));
 painter.drawLine(27,450,630,450);
 painter.drawLine(30,50,30,453);
 painter.drawLine(180,450,180,453);
 painter.drawLine(330,450,330,453);
 painter.drawLine(480,450,480,453);
 painter.drawText(QPoint(570,470),tr("Time (Sec)"));
 painter.drawText(QPoint(170,470),tr("75"));
 painter.drawText(QPoint(470,470),tr("225"));
 painter.drawText(QPoint(320,470),tr("150"));
 painter.drawText(QPoint(10,40),tr("Force (lbs)"));
}

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and in Qt designer, I put a label and load a bitmap.
After successfully compiled, when I run the application, it shows segmentation error.
After I remove the label, it works fine.

[aamer4yu]

Had you promoted you dialog properly ?

Also try calling QDialog:aintEvent(event); before your code.

[Sheng]

Had you promoted you dialog properly ?

Also try calling QDialog:aintEvent(event); before your code.

I think it is crashed when constructor is called.

myDialog::myDialog()
{
 setupUi(this);
 updateTimer=new QTimer(this);
 currentPoint=0;
 connect(btnClose,SIGNAL(clicked()),this,SLOT(onClose()));
 connect(updateTimer,SIGNAL(timeout()),this,SLOT(update()));
}

myDialog::myDialog()
{
 setupUi(this);
 updateTimer=new QTimer(this);
 currentPoint=0;
 connect(btnClose,SIGNAL(clicked()),this,SLOT(onClose()));
 connect(updateTimer,SIGNAL(timeout()),this,SLOT(update()));
}

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Now instead of adding image in designer, I load image in paintEvent function, it works fine.

[Sheng]

I tried put a bitmap button in myDialog using designer, it also crashed.
Is it a bug of Qt? Any ideas?

[aamer4yu]

Can u post a code which reproduces the problem ?

[Sheng]

Can u post a code which reproduces the problem ?

It basically same as putting label in Dialog. To me it seems after overriding paintEvent, you can not use designer to handle image anymore, I can only do it through overrided paintEvent function.

[talk2amulya]

well, paintEvent() is the event called to draw the dialog after all..whenever u call update(), evth is erased and drawing starts from scratch..so if u r reimplementing it, u should do all the drawing there only..it makes sense..u can try it with smth other than QDialog, i believe same thing will happen

[Sheng]

well, paintEvent() is the event called to draw the dialog after all..whenever u call update(), evth is erased and drawing starts from scratch..so if u r reimplementing it, u should do all the drawing there only..it makes sense..u can try it with smth other than QDialog, i believe same thing will happen

Thanks, that makes sense. Hopefully in the future the error will be pointed out during compilation instead of during run-time.