How do I customise the appearance of links in QLab

问题:

I have a QLabel with a Qt stylesheet that sets a dark background:

QLabel {
background: black;
color: white;
}

This works fine until I add text with an embedded URL and set the Qt::TextFormat to Qt::RichText. The link displays as the default dark blue, which is hard to read on a dark background.

I've tried customising it via a stylesheet such as:

a { color: white; }
QLabel!visited { color: white; }

but this doesn't have any effect. The one thing that does seem to work is changing the application's QPalette:

QPalette newPal(qApp->palette());
newPal.setColor(QPalette::Link, Qt::white);
newPal.setColor(QPalette::LinkVisited, Qt::white);
qApp->setPalette(newPal);

However this requires the colour to be hardcoded. Is there any way I can set the colour from a stylesheet instead?

EDIT:

I've discovered a further problem with customising the palette. If I want to just modify the palette of my widget (substituting widget for qApp in the sample above) then this doesn't work. I don't want to affect all the other QLabels in the app, so how do I limit the palette changes to this widget?

回答1:

Short answer is no. Recently I had to do this.

1. QLabel!visited doesn't work because Qt doesn't track whether QLabel were visited or not.
2. QLabel { color: ... } doesn't work for links. Can't find why but all I found is a suggestion to use QPallete in this case.

回答2:

I've had little success explicitly setting the QPalette -- it works if you set it for the entire application, but not if you set it in the widget. In the end though, the easiest thing for what I needed to do was use a QTextBrowser instead which supports a subset of HTML. I could then override the colour of links using a regular CSS stylesheet:

QTextBrowser browser;
// IMPORTANT! - set the stylesheet before the content
browser->document()->setDefaultStyleSheet("a {color: white; }");
browser->setText(html);

回答3:

One way is to add style="color: whatever" or a class to the inner <span> of the link. I haven't figured out yet how to apply this to the whole application but it's a good start.