HiDPI scaling is not respected for menu icons and padding

[paulmcauley]

I have a HiDPI display at 250% scaling.

Here is a screenshot of how the Material menu looks:

Here is a screenshot of how a normal menu looks:

As you can see, the menu's icon size and padding are too small when scaling is used.

[Zren]

Was planning to refactor the TextButton::horzPadding from a hardcoded 4px anyways, so I just made it use smallSpacing.

As for why the QMenu doesn't scale, I'm not sure.

Here's what 200% scaling looks like for me to confirm the bug.

[Zren]

Hmm, if I uncomment the code to display the normal "Application Menu" icon button that tells KWin to display the menu, it draws the entire menu at 100%. Even the text is at 100% scaling.

Even breeze seems to have this bug. Can you confirm this @paulmcauley?

[paulmcauley]

No, I don't have the problem with a normal application menu in Breeze (Plasma 5.21.2). Here is what 250% with a normal application menu looks like for me:

[SeptemberHX]

It is possible to fix the small icon with QProxyStyle.

    int pixelMetric(PixelMetric metric, const QStyleOption *option, const QWidget *widget) const override {
        qCDebug(category) << metric;
        if (metric == QStyle::PM_ButtonIconSize) {
            return QProxyStyle::pixelMetric(metric, option, widget) * pixelRatio;
        }
        return QProxyStyle::pixelMetric(metric, option, widget);
    }

Then appMenu->setStyle(xxx) should works.
But I don't know how to get the pixelRatio in a decoration.