Add SizeChanged event

[johannesegger]

I would like to store the size of an AbsoluteLayout control within my model, because based on that I can tell whether some controls (i.e. players) within this layout are touching the border. Xamarin.Forms has VisualElement.SizeChanged, but in Fabulous I couldn't find something similar. The only thing I found was OnSizeAllocatedCallback which only works when attached to a ContentPage.

Would it be possible for you to enable SizeChanged events for ViewElements or how else could I store the size of a specific control within my Elmish model?

[TimLariviere]

Thanks for reporting.
We will add SizeChanged and the other missing events from VisualElement.

[johannesegger]

Awesome, thanks a lot for adding this so fast.

[johannesegger]

Hm, not sure if this helps me a lot, though:

View.AbsoluteLayout(...)
|> sizeChanged (fun _ -> dispatch (SetSceneSize ???))

How do I get the size now from within the event handler? I neither get the sender nor do I get useful event args.

[TimLariviere]

Ah. Xamarin.Forms does not send the new size...

SizeChanged?.Invoke(this, EventArgs.Empty);

As I would prefer not to pass the sender, I think we can create a new type SizeChangedEventArgs which will store the width and height of the control.
This will allow this kind of code:

View.AbsoluteLayout(...)
|> sizeChanged (fun args -> dispatch (SetSceneSize (args.Width, args.Height)))

[johannesegger]

Yeah, I would also prefer that, thanks a lot.