Maui: [BUG] Popup doesn't work with hot reload

@mavispuford IHotReloadabieView has nothing to do with XAML Hot Reload, it has to do with Comet. Implementing it won’t do anything for XAML Hot Reload.

@pictos For XAML Hot Reload to work, you need to implement IVisualTreeElement, https://github.com/dotnet/maui/blob/main/src/Core/src/Core/IVisualTreeElement.cs

Most base MAUI controls (Apart from ListView) implement this out of the box. XAML Hot Reload checks if the control implements this and uses it to then go through the children. If your control doesn’t implement this, it will not show up in the Live Visual Tree, and will then not be tracked at all for XAML Hot Reload.

Also, I would leave an issue in the MAUI repo about docs for this, since none of that is obvious unless you’re me, lol.

While I wouldn’t normally suggest this approach, given .NET 7 is not really going to change anything in this area of the code, it is probably safe enough to use some reflection if you really want to multitarget this support. Here’s what I used in Maui.VirtualListView before the methods were added in .NET 8:

internal static class LogicalChildrenHelpers
{
	static MethodInfo removeLogicalChildMethod = null;

	internal static void RemoveLogicalChild(this Element parent, IView view)
	{
		if (view is Element elem)
		{
			removeLogicalChildMethod ??= GetLogicalChildMethod(parent, "RemoveLogicalChildInternal", "RemoveLogicalChild");
			removeLogicalChildMethod?.Invoke(parent, new[] { elem });
		}
	}

	static MethodInfo addLogicalChildMethod = null;

	internal static void AddLogicalChild(this Element parent, IView view)
	{
		if (view is Element elem)
		{
			addLogicalChildMethod ??= GetLogicalChildMethod(parent, "AddLogicalChildInternal", "AddLogicalChild");
			addLogicalChildMethod?.Invoke(parent, new[] { elem });
		}
	}

	static MethodInfo GetLogicalChildMethod(Element parent, string internalName, string publicName)
	{
		var internalMethod = parent.GetType().GetMethod(
				internalName,
				BindingFlags.Instance | BindingFlags.NonPublic,
				new[] { typeof(Element) });

		if (internalMethod is null)
		{
			internalMethod = parent.GetType().GetMethod(
				publicName,
				BindingFlags.Instance | BindingFlags.Public,
				new[] { typeof(Element) });
		}

		return internalMethod;
	}
}

@LennoxP90 not yet

It depends on the control, but generally you should only need to place it on the top most level, unless the control handles child elements in a weird way. Basically, if you don’t see the child elements in the Live Visual Tree, it is not tracked and can’t be hot reloaded.

You may also need to make sure whenever the popup is invoked, that VisualDiagnostics OnVisualTree changes are fired, https://github.com/dotnet/maui/blob/main/src/Core/src/VisualDiagnostics/VisualDiagnostics.cs#L77-L80

I got a bit curious and looked at the .NET MAUI source code. Looks like classes have to implement IHotReloadableView in order to be reloaded.

The View class implements IHotReloadableView.

Same with ContentPage.

See also:

• https://github.com/dotnet/maui/blob/10be7d53f9fc8b3c7e1bc99fc6eb8528289b7085/src/Core/src/HotReload/HotReloadHelper.cs
• https://github.com/dotnet/maui/tree/10be7d53f9fc8b3c7e1bc99fc6eb8528289b7085/src/Core/src/HotReload