Issue with Application.Current.MainPage.Width Returning -1 in .NET MAUI

Question

I am migrating my project from Xamarin to .NET MAUI. In Xamarin, I use Application.Current.MainPage.Width to get the width of the main page, and it works as expected.

However, in .NET MAUI, when I try to access Application.Current.MainPage.Width, it always returns -1. It seems like the layout hasn't been fully loaded when I try to access it.

I have explored using DeviceDisplay.MainDisplayInfo as a workaround to get the screen dimensions, but I specifically need to use Application.Current.MainPage.Width since my use case involves layout calculations that depend on the actual page dimensions.

Is there a specific lifecycle or event in .NET MAUI where I should access the width property to ensure it has been initialized? Why does this behavior differ from Xamarin?

Any guidance or best practices would be greatly appreciated!

Answer 1

Hello,

However, in .NET MAUI, when I try to access Application.Current.MainPage.Width, it always returns -1

Maui has optimized the initialization order of controls. Now if you want to get the width of the Page, you need to wait until OnSizeAllocated is executed to get the correct width.

Please refer to the following code:

protected override void OnSizeAllocated(double width, double height)
{
    base.OnSizeAllocated(width, height);
    var w = Application.Current.MainPage.Width;
    Console.WriteLine(w);
}

Updated:

For Shell-based applications, you need to obtain the page width through the Shell API.

var w = AppShell.Current.Window.Width;

Best Regards,

Alec Liu.

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