LazyView - possible to use it to only load as a View becomes visible?

[jameslavery]

We've got a FlexLayout with a complex ItemTemplate. When we have a lot of items in the ItemsSource, the page takes too long to load.

Is it possible to use a LazyView to only trigger a full load of the the ItemTemplate's contents when an Item comes into view? I think we've got ItemAppearing available for a ListView, but I can't find an equivalent for a FlexLayout.

Any suggestions/ideas?

[jameslavery]

One solution I've come up with for Windows (we're only running on Windows) is to add a handler for the EffectiveViewPortChanged event in the OnHandlerChanged event for the Control.

        private void OnHandlerChanged(object sender, EventArgs e)
        {
            LazyFileCardContentView control = (LazyFileCardContentView)sender;
            Microsoft.Maui.Platform.ContentPanel platformControl = (Microsoft.Maui.Platform.ContentPanel)control.Handler.PlatformView;

            // Subscribe to EffectiveViewportChanged, so that we can detect if the control is at least partially visible.
            platformControl.EffectiveViewportChanged += PlatformControl_EffectiveViewportChanged;
        }

        private async void PlatformControl_EffectiveViewportChanged(Microsoft.UI.Xaml.FrameworkElement sender, Microsoft.UI.Xaml.EffectiveViewportChangedEventArgs args)
        {
            Microsoft.Maui.Platform.ContentPanel control = (Microsoft.Maui.Platform.ContentPanel)sender;

            // BringIntoViewDistanceX/Y = 0 if control is fully in viewport, or between 0 and ActualWidth/ActualHeight if partially in viewport.
            if ((args.BringIntoViewDistanceX == 0 && args.BringIntoViewDistanceY == 0) ||
                (args.BringIntoViewDistanceX > 0 && args.BringIntoViewDistanceX < control.ActualWidth) ||
                (args.BringIntoViewDistanceY > 0 && args.BringIntoViewDistanceY < control.ActualHeight)
                )

            {
               await LoadContent();
            }