Is DisplayInformation no longer supported?

[ThomasArdal]

After having upgraded my project to Uno.UI version 3.7.3 the following code causes my application to crash:

var displayInfo = DisplayInformation.GetForCurrentView();
if (displayInfo != null)
{
    var orientation = displayInfo.CurrentOrientation; // <-- the code doesn't fail if I comment out this line
}

This worked fine previously but now crashes as soon as I use any of the properties on displayInfo.

Does anyone know what the problem could be there?

[pkar70]

For what platform? iOS/macOS/Android/WASM/... ?

[ThomasArdal]

Thank you for creating the issue, @jeromelaban.

Just a few comments. The __ANDROID__ constant isn't available from class libraries as I understand it. Or am I wrong there?

Wrapping the code in try/catch doesn't help since it's a stack overflow exception that causes the entire thing to crash.

Thank you so much for looking into this.

[ThomasArdal]

And in addition to your sample. Should look like this, right?

if (Uno.UI.ContextHelper.Current != null)
{
    ...
}

[jeromelaban]

The library you've built is a cross-targeted library, which builds for monoandroid10.0, making __ANDROID__ available as well.

That said, it makes sense that the stack overflow would still happen because accessing the ContextHelper will log unconditionally if the context is null. This makes me notice that the fix I made for this will not fix your issue, as the log will still happen. I'll adjust that.

[ThomasArdal]

I'm not sure I understand the workaround specified in a previous comment:

#if __ANDROID__
if(Uno.UI.ContextHelper != null)
{
   ...
}
#endif

That code doesn't compile since ContextHelper is a class and I cannot check a class for null. I was suggesting using ContextHelper.Current but that doesn't seem to work either.

[jeromelaban]

Yes, that's correct, it'd be

#if __ANDROID__
if(Uno.UI.ContextHelper.Current != null)
{
   ...
}
#endif

but it'd fail anyways because the getter logs a warning. This will be fixed by the associated PR.

[ThomasArdal]

I can verify that it doesn't work. If you're interested I have updated the sample: https://github.com/elmahio/Elmah.Io.Uno/blob/crash/src/Elmah.Io.Uno/ElmahIoLogger.cs#L78

No worries, I'll wait for the bugfix, I believe.

[ThomasArdal]

Is this not in the newest version of Uno.UI on NuGet? I upgraded to 3.8.0-dev.302 and include the following in my code:

#if __ANDROID__
if (UnoUI.ContextHelper.Current != null)
{
#endif
try
{
    var displayInfo = DisplayInformation.GetForCurrentView();
    // ...
}
catch {}
#if __ANDROID__
}
#endif

The app still crashes on startup.

[jeromelaban]

You do not need to use the UnoUI.ContextHelper.Current != null around.

[ThomasArdal]

I see. I'll remove that. But I guess it still crashes?

[jeromelaban]

DisplayInformation.GetForCurrentView(); will always fail when executed too early, which is why you need the try/catch.

The original reason logging failed in a loop is because of UnoUI.ContextHelper.Current is logging a failure which causes the loop.

Let us know if this helps.

[ThomasArdal]

Sorry, I believe you already explained that to me 🙈 It works perfectly without the ContextHelper.Current call. Thank you so much for your help here.