QWidget::render() paint to painter with wrong offset.

Hi,

I made a custom delegate to my view (list view in a icon mode).

This is a paint method of the delegate:

Code:

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void PreviewWidget::paint(QPainter *painter, const QStyleOptionViewItem &option,
		   const QModelIndex &index) const
{
	painter->save();
 
	QBrush brush;
	int r = ((double)qrand()/ static_cast<double>( RAND_MAX )) * 255;
	int g= ((double)qrand()/ static_cast<double>( RAND_MAX )) * 255;
	int b = ((double)qrand()/ static_cast<double>( RAND_MAX )) * 255;
	brush.setColor(QColor(r,g,b));
	brush.setStyle(Qt::SolidPattern);
	painter->fillRect(option.rect, brush);
 
	ImagePrev i;
	i.render(painter, option.rect.topLeft());
 
	painter->restore();
}

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Results of rendering widget onto the painter is wrong. Filling painter with random color rect is only to show where widget should be located.

Attachment 8764

Why this offset occur?

Quote:

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Why this offset occur?

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Probably because you are passing option.rect.topLeft() into the render() call instead of (0,0).

But option.rect.topLeft() is a good position for every item. First will get (0,0), next will get another position according to size of a item (given by sizeHint()). So unfortunately your comment is very wrong.

Here's a bug report on this: QTBUG-26694

Try the workaround in the attachment:

Code:

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i.render( painter, painter->deviceTransform().map(option.rect.topLeft()));

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Quote:

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Originally Posted by norobro

Here's a bug report on this: QTBUG-26694

Try the workaround in the attachment:

Code:

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i.render( painter, painter->deviceTransform().map(option.rect.topLeft()));

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It works. Thanks a lot! :)