Qt-interest Archive, June 2007
QPainter::begin: Widget painting can only begin as a result of a paintEvent
Message 1 in thread
Hi, o wise ones :-)
I get the following error message with qt 4.2 and kdevelop 3.4.0
QPainter::begin: Widget painting can only begin as a result of a paintEvent
This is part of the code with the error:
QImage *image;
QFrame* imageFrame;
void qpixy::paintEvent( QPaintEvent * )
{
QPainter imagePainter( imageFrame );
imagePainter.drawImage( QPoint(0,0), *image);
}
But when i do
QPainter imagePainter( this );
instead of
QPainter imagePainter( imageFrame );
Then it works fine.
I have looked in the porting from qt3 to qt4.
There is something about reimplementing paintEvent, but i do not know how.
And can not find via google a way which i understand.
How can i paint the qimage in the qframe ?
I humbly bow my head and say : Thank you :-)
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Message 2 in thread
On 6/5/07, hihihi <hihihi@xxxxxxxxxx> wrote:
>
> Hi, o wise ones :-)
>
> I get the following error message with qt 4.2 and kdevelop 3.4.0
>
> QPainter::begin: Widget painting can only begin as a result of a paintEvent
>
> This is part of the code with the error:
>
> QImage *image;
> QFrame* imageFrame;
>
> void qpixy::paintEvent( QPaintEvent * )
> {
> QPainter imagePainter( imageFrame );
> imagePainter.drawImage( QPoint(0,0), *image);
> }
>
> But when i do
> QPainter imagePainter( this );
> instead of
> QPainter imagePainter( imageFrame );
> Then it works fine.
>
> I have looked in the porting from qt3 to qt4.
> There is something about reimplementing paintEvent, but i do not know how.
> And can not find via google a way which i understand.
>
> How can i paint the qimage in the qframe ?
You must paint a widget in its *own* paintEvent method, not *any*
widget's paintEvent method. Subclass the Qt widget on which you want
to paint and implement an appropriate paintEvent.
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[ signature omitted ]
