Problems with drawing image in paintEvent of QTreeView

[jpn]

The problem is that item views (or delegates) fill the background with QPalette::Base. You can set the view background as transparent with good old palette:

QPalette pal = viewport()->palette();
pal.setColor(QPalette::Base, Qt::transparent);
viewport()->setPalette(pal);

QPalette pal = viewport()->palette();
pal.setColor(QPalette::Base, Qt::transparent);
viewport()->setPalette(pal);

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or with style sheets:

viewport()->setStyleSheet("background: transparent");

viewport()->setStyleSheet("background: transparent");

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Once you've done that, you can paint the image like you want before calling the base class implementation of paintEvent(). If you want to re-enable the base background you can do it for example like this:

void TreeView::paintEvent(QPaintEvent *event)
{
    QPainter painter(viewport());
    painter.fillRect(event->rect(), palette().base()); // <---
    painter.drawImage(imageLeftMargin, imageTopMargin, image);
    painter.end();
    QTreeView::paintEvent(event);
}

void TreeView::paintEvent(QPaintEvent *event)
{
    QPainter painter(viewport());
    painter.fillRect(event->rect(), palette().base()); // <---
    painter.drawImage(imageLeftMargin, imageTopMargin, image);
    painter.end();
    QTreeView::paintEvent(event);
}

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[Tito Serenti]

Wonderful, it's working just like I wanted it to! Thank you for your help!