QScrollView and repaint

[wysota]

Maybe you reimplemented drawContents incorrectly? QScrollView should trigger a paint event (and eventually drawContents) after part of the widget gets obscured. Could you give more details, what exactly did you do?

[munna]

Here is my code :

void Paper::drawContents(QPainter *p, int cx, int cy, int cw, int ch)
{
	QPixmap pm(cw, ch);
	QPainter *pmp = new QPainter( &pm );
	pmp->setBrush( white );
	pmp->setPen( NoPen );
	pmp->drawRect( 0, 0, cw, ch);
	pmp->setPen( black );
	pmp->translate( -cx, -cy );
 
        //My drawing code. Everything is done useing pmp
 
        pmp->end();
	p->drawPixmap( cx, cy, pm );
	p->end();
       delete pmp;
}

void Paper::drawContents(QPainter *p, int cx, int cy, int cw, int ch)
{
	QPixmap pm(cw, ch);
	QPainter *pmp = new QPainter( &pm );
	pmp->setBrush( white );
	pmp->setPen( NoPen );
	pmp->drawRect( 0, 0, cw, ch);
	pmp->setPen( black );
	pmp->translate( -cx, -cy );

        //My drawing code. Everything is done useing pmp

        pmp->end();
	p->drawPixmap( cx, cy, pm );
	p->end();
       delete pmp;
}

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Thanks a lot

[wysota]

I think the translation might be messing the things up (I think the code is incorrect). Try getting rid of the pixmap at all and draw the whole viewport directly. If it helps, you can then optimise some things to get better results.

[munna]

Here is the new code :

void Paper::drawContents(QPainter *pmp, int cx, int cy, int cw, int ch)
{
	//QPixmap pm(cw, ch);
	//QPainter *pmp = new QPainter( &pm );
	pmp->setBrush( white );
	pmp->setPen( NoPen );
	pmp->drawRect( 0, 0, cw, ch);
	//pmp->setPen( black );
	//pmp->translate( -cx, -cy );
 
       //My drawing code
}

void Paper::drawContents(QPainter *pmp, int cx, int cy, int cw, int ch)
{
	//QPixmap pm(cw, ch);
	//QPainter *pmp = new QPainter( &pm );
	pmp->setBrush( white );
	pmp->setPen( NoPen );
	pmp->drawRect( 0, 0, cw, ch);
	//pmp->setPen( black );
	//pmp->translate( -cx, -cy );

       //My drawing code
}

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It did not solve the first problem. Also, now flickering is introduced.
Does this has to do something with contentsHeight and contentsWidth ?

Thanks a lot for your time

[wysota]

How about:

void Paper::drawContents(QPainter *pmp, int cx, int cy, int cw, int ch)
{
    pmp->setClipRect(cx,cy,cw,ch);
    pmp->setClipping(true);
    pmp->fill(Qt::white);
     //Your drawing code
}

void Paper::drawContents(QPainter *pmp, int cx, int cy, int cw, int ch)
{
    pmp->setClipRect(cx,cy,cw,ch);
    pmp->setClipping(true);
    pmp->fill(Qt::white);
     //Your drawing code
}

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[munna]

It does not work.

Also, if I do not translate, and when scrollbars appear, all the drawing is messed up.

Please Help
Thanks a lot

[wysota]

It should work. Did you reimplement some other methods too? Maybe the viewport isn't set up correctly?