[Development] Foreign windows, embedding and transiency

Samuel Rødal samuel.rodal at digia.com
Tue Dec 11 12:33:41 CET 2012

On 12/11/2012 12:03 PM, Alberto Mardegan wrote:
> Hi all,
>     while digging a bit more deeply into the code of QX11EmbedWidget (in
> order to port it to Qt5), I started wondering if we really need a
> special API for embedding, or whether QWindow could already offer most
> of it:
> ==========
>     QWindow::QWindow(QWindow * parent)
>     Creates a window as a child of the given parent window.
>     The window will be embedded inside the parent window, its coordinates
>     relative to the parent.
> ==========
> What about adding an API to create QWindow objects for foreign windows
> as well? (by "foreign window" I mean a window created by another process)
> Then we could provide embedding functionality by using the QWindow
> constructor or the QWindow::setParent() method. Also, the
> QWindow::setTransientParent() could be use to set our QWindow as
> transient for a foreign window.
> Of course, this might not work in all platforms, but the documentation
> could explain where it works and where it doesn't.
> In order to create a QWindow for a foreign window, there might be a
> special subclass of QWindow (QForeignWindow?) or maybe it could just be
> a QWindow with a special Qt::ForeignWindow flag (and maybe a constructor
> like QWindow::QWindow(WinId foreignWindow)).
> Your opinions on which way foreign windows could be created (and on
> whether all of this sounds like a good idea to you) are very welcome. :-)

This worked for QWidgets in Qt 4 by passing a native window handle (WId) 
to create(). However, then we also knew at compile time what the native 
windowing system would be.

Is it possible to define a WId type that will work on X11, Wayland, and 
any other theoretical windowing system on Unix platforms?


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