Solved How to proxy style QPlastiqueStyle which is a proxy style

[Matt Penman]

Qt ver: 5.6.1
OS: Linux, Ubuntu 18.04.3

I have a case where I'm trying to apply a style to a widget with a complex proxy style hierarchy:

Style inherits QProxyStyle
    baseStyle = QPlastiqueStyle

QPlastique inherits QProxyStyle
    baseStyle = QWindowsStyle

The widget in question is a QTabBar, my Style class does not override drawControl for CE_TabBarTab, so the chain of style class traversal should be:

Style -> QProxyStyle -> QPlastiqueStyle -> QProxyStyle -> QWindowsStyle -> QCommonStyle

to the implementation of:

    case CE_TabBarTab:
        if (const QStyleOptionTab *tab = qstyleoption_cast<const QStyleOptionTab *>(opt)) {
            proxy()->drawControl(CE_TabBarTabShape, tab, p, widget);
            proxy()->drawControl(CE_TabBarTabLabel, tab, p, widget);
        }
        break;

As you can see, QCommonStyle immediately calls the proxy style's drawControl for both the CE_TabBarTabShape and the CE_TabBarTabLabel (which is great!) but that immediately hits QPlastiqueStyle's implementation and does not ever get to my Style's implementation (which is not great).

As a result, the QTabBar looks like QPlastiqueStyle rather than the custom Style.

Is there a prescribed workflow that I'm missing here? In qt4 Style inheritance chain is much simpler (of course):

Style -> QPlastiqueStyle -> QWindowsStyle -> QCommonStyle

Any pointers would be greatly appreciated :)

Thanks,
Matt

[VRonin]

@matt-penman said in How to proxy style QPlastiqueStyle which is a proxy style:

In qt4 Style inheritance chain is much simpler (of course):
Style -> QPlastiqueStyle -> QWindowsStyle -> QCommonStyle

This still works in Qt5 with a minor extra step that is transparent to you why do you think it's impossible?

What I'm saying is that Style should inherit QPlastiqueStyle, not QProxyStyle

[Matt Penman]

@VRonin thanks for the reply!

Are you implying that I should be linking against qtstyleplugins? And deriving from QPlastiqueStyle directly?

[VRonin]

You are expanding that class so it would make sense, right?

[Matt Penman]

Correct. I'll give that a go, thank you