Retrieving an items position in global screen coordinates and keep it up to date

[DuBu]

Hi all,

what's the best way to retrieve the position of an item in global screen coordinates and get notified when it changes (i.e. to show the position in a label)?

MainWindow {
  Item {
    Item {
      Text {
        // text: x coordinate + ", " + y coordinate
      }
    }
  }
}

The text should get updated when the MainWindow is moved, one of the parent items or the text item itself.

Cheers!

[raven-worx]

@DuBu
there is simply no generic way to achieve that (in QML)

[DuBu]

@raven-worx To bad. Thx, anyway!

[DuBu]

And what's the best way to do it without keeping it up to date (i.e. at button click)?

Cheers!

[GrecKo]

To do it on demand you can use : http://doc.qt.io/qt-5/qml-qtquick-item.html#mapToGlobal-method

If you absolutely need it updated live, I believe it's possible to do it in c++ by listening to all the ancestors xChanged, yChanged, widthChanged, heightChanged signals up to the root window.

or you can call mapToGlobal on a timer.

[DuBu]

@GrecKo I tried it with mapToGlobal, mapFromGlobal, mapToItem, mapFromItem already with no luck.
But now that you mentioned mapToGlobal again I gave it another try: Now it works and the timer was also a good hint. It's just a hack but anyway.
Thanks!

[red.green]

@DuBu Could you please hint a code snippet of me how you implemented getting the global coordinates correctly using mapToGlobal?

Thanks.