QScrollView and repaint

[munna]

Can you please do me a favor ?

Can you try it with the following code ? It should draw red horizontal lines, right ?

[CODE]

void drawContents(QPainter *p, int cx, int cy, int cw, int ch)
{
//p->setClipRect(cx,cy,cw,ch);
// p->setClipping(true);
p->fillRect(0,0,600,300, Qt::white);
p->setPen(Qt::red);
for(int i = 0; i < 300; i+=25){
p->drawLine(0,i, 600, i);
}
}

[CODE]

Once you have the drawing, resize your browser( or any other window) and move it around this drawing.

Are the lines getting drawn as the new area is shown and the window is moved ?

Thanks a lot.

[wysota]

No, they don't.

[munna]

Shouldn't the lines be drawn as I move the window ? I mean, shouldn't the drawContents be called and the drawing should be updated?

Now, since we know that drawContents is not called, is there a way be which I can detect this and call repaint()

Thanks a lot for your time.
Thanks a lot

[munna]

Any ideas on this one ?

Thanks.

[wysota]

A simple way around this is to add a child widget to the scrollview and do all the drawing in the paint event of the widget.

class MyWidget : public QWidget{
public:
  MyWidget(QWidget *parent = 0) : QWidget(parent){}
protected:
  void paintEvent(QPaintEvent *pe){
    //...
  }
};
//...
wid = new MyWidget(viewport());
wid.resize(600, 400);
//...

class MyWidget : public QWidget{
public:
  MyWidget(QWidget *parent = 0) : QWidget(parent){}
protected:
  void paintEvent(QPaintEvent *pe){
    //...
  }
};
//...
wid = new MyWidget(viewport());
wid.resize(600, 400);
//...

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