[Development] QPA / QWindow / QPainter

Thiago Macieira thiago.macieira at intel.com
Fri Mar 7 23:56:04 CET 2014

Em sex 07 mar 2014, às 22:41:35, Martin Koller escreveu:
> I'm implementing a QPA plugin (now with 5.3 snapshot) and there's something
> I do not understand: When I use native widgets, every widget creates a
> QPlatformWindow, but only a toplevel window creates a
> QPlatformBackingStore, which is the class which delivers the paintDevice
> implementation.
> Question: when a QWidget now creates a QPainter on it, how does my QPA
> plugin know onto which QWindow it is currently acting, when there's only
> one paintDevice/one backing store ?

By "native widgets", do you mean "using one native window per widget", the 
opposite of the "alien" project?

Are you even sure that mode of operation even works in Qt 5? During the QPA 
port of 5.0, we might have lost that ability and it shows in the API you've 

In any case, each non-top-level QWidget has a link to the top level window 
(TLW) it's connected to and stores state there.
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center

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