QFrame: official shape/shadow to not fill background ?

dextermagnific

Hi all,
I'm the author of QSvgStyle, and I would like to know if QFrame is just about drawing a frame without background ?
Currently I'm using the color of the frame's backgroundRole() to fill it with color. But I see other style engines like fusion do not fill it.
Is there a way to tell through shape/shadow whether we want the frame to be filled ?
I know about autoFillBackground() but this is managed by qt itself by filling the background with Window palette, regardless of the backgroundRole set to the frame.

Thanks

dextermagnific

Thanks. Do you know how the officiel Qt Fusion style handles frame fills ? Maybe I should follow it since it's made by Qt itself.

SGaist

Hi,

To the best of my knowledge, I would say no. QFrame is a base widget for anything that requires a frame but it does not mean it needs to be transparent.

Axel Spoerl

You could use QMetaObject to figure out whether a frame is a plain QFrame (in which case you could fill it) or inherits from it (in which case you might rather leave it untouched).

dextermagnific

So in which case of shape/shadow should I fill the frame with its background color ?

Axel Spoerl

I am not maintaining QSvgStyle.
Without knowing it's principles: I'd probably add a flag to the style itself, to toggle whether frame background will be applied only to QFrame or to everything that inherits from it. Then I'd evaluate Qt::WA_NoSystemBackground and paint the background if the widget attribute is unset.

dextermagnific

Thanks. Do you know how the officiel Qt Fusion style handles frame fills ? Maybe I should follow it since it's made by Qt itself.

Axel Spoerl

QFusionStyle::drawPrimitive() doesn't explicitly draw a background for PE_Frame. It draws backgrounds only for classes inheriting from it to the extent needed. Drawing that frame without explicit background, however, draws it on the default window background. If you have a frame as a top level widget, it looks as if its background had been explicitly drawn.

dextermagnific

Thank you, I'll have a look at its code to mimic its behavior.