Problem drowing in tabWidget...

**dspfen** · 9th December 2009, 02:43

Problem drowing in tabWidget...
I'm having a problem with a simple QWidget program that draws an ellipse inside a child tabWidget (in sоme of tabs).

I have Main ui form and a tabWidget in it.

Here is part of the code:

Qt Code:

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void MainWindow::paintEvent(QPaintEvent *event) 
{ 
QPainter painter(ui->tab_2); 
painter.setRenderHint(QPainter::Antialiasing, true); 
painter.setPen(QPen(Qt::black, 12, Qt::ashDotLine, Qt::RoundCap)); 
painter.setBrush(QBrush(Qt::green, Qt::olidPattern)); 
painter.drawEllipse(80, 80, 400, 240); 
}

void MainWindow::paintEvent(QPaintEvent *event) 
{ 
QPainter painter(ui->tab_2); 
painter.setRenderHint(QPainter::Antialiasing, true); 
painter.setPen(QPen(Qt::black, 12, Qt::ashDotLine, Qt::RoundCap)); 
painter.setBrush(QBrush(Qt::green, Qt::olidPattern)); 
painter.drawEllipse(80, 80, 400, 240); 
}

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Line 3 QPainter painter(ui->tab_2); doesn't do anything. The program draws the ellipse only if I replace line 3 with QPainter painter(this); but that draws on the parent QWidget (Main form) and not on the child QWidget (tabWidget) as desired.

Any Suggestion?

Thanks!

**Tanuki-no Torigava** · 9th December 2009, 05:27

Hi,
can you enclose the code with \[CODE\]\[\/CODE\] next time and where is the ui declaration?

**wysota** · 9th December 2009, 08:27

Originally Posted by dspfen

Line 3 QPainter painter(ui->tab_2); doesn't do anything.

Yes it does. It issues a warning on your console stating that you can only paint on a widget from within its paint event. And currently you are in paint event of a different widget.

Any Suggestion?

Install an event filter on the child widget and intercept its paint event there. You can draw from within the intercepted event.

**dspfen** · 9th December 2009, 09:44

Marci for your replay, but I don't know how to install an event filter on the child widget and intercept its paint event in my project.
In the link below is my project.