[Extensions] AlternateColor without item containers

[Avid29]

Fixes #712

PR Type

What kind of change does this PR introduce?

What is the current behavior?

If a ListViewBase does not use a container, for whatever reason, the item's background will not be altered.

What is the new behavior?

If the ItemContainer is not, the item itself will be used if the type is a Control.

PR Checklist

Please check if your PR fulfills the following requirements:

• Created a feature/dev branch in your fork (vs. submitting directly from a commit on main)
• Based off latest main branch of toolkit
• Tested code with current supported SDKs(https://github.com/CommunityToolkit/WindowsCommunityToolkit-design-assets)
• Tests for the changes have been added (if applicable)
• Contains NO breaking changes

Other information

[zubinqayam]

Avid29:fix/alt-color6

[AndrewKeepCoding]

Since you are already organizing code in this PR, this would be a good time to move OnListViewBaseUnloaded into its own file instead of keeping it in ListViewExtensions.AlternateRows.cs. That method handles unsubscribing from several features, so separating it would improve clarity and maintainability.

ListViewExtensions.cs

namespace CommunityToolkit.WinUI;

public static partial class ListViewExtensions
{
    private static void OnListViewBaseUnloaded(object sender, RoutedEventArgs e)
    {
        if (sender is not ListViewBase listViewBase)
            return;

        _itemsForList.Remove(listViewBase.Items);

        listViewBase.ContainerContentChanging -= ItemContainerStretchDirectionChanging;
        listViewBase.ContainerContentChanging -= ItemTemplateContainerContentChanging;
        listViewBase.ContainerContentChanging -= ColorContainerContentChanging;
        listViewBase.Items.VectorChanged -= ColorItemsVectorChanged;
        listViewBase.Unloaded -= OnListViewBaseUnloaded;
    }
}

[Avid29]

Thanks for the reminder. I had noticed this, but hadn't yet written an alternative because I was torn between your solution, and splitting the method for the different attached property types.

ListViewExtensions.AlternateRows.cs

private static void OnListViewBaseUnloaded_AltRow(object sender, RoutedEventArgs e)
{
    if (sender is not ListViewBase listViewBase)
        return;

    // Untrack the list view
    _trackedListViews.Remove(listViewBase.Items);

    // Unsubscribe from events
    listViewBase.ContainerContentChanging -= ItemTemplateContainerContentChanging;
    listViewBase.ContainerContentChanging -= ColorContainerContentChanging;
    listViewBase.Items.VectorChanged -= ColorItemsVectorChanged;
    listViewBase.Unloaded -= OnListViewBaseUnloaded_AltRow;
}

ListViewExtensions.StretchItemContainer.cs

private static void OnListViewBaseUnloaded_StretchDirection(object sender, RoutedEventArgs e)
{
    if (sender is not ListViewBase listViewBase)
        return;

    // Unsubscribe from events
    listViewBase.ContainerContentChanging -= ItemContainerStretchDirectionChanging;
    listViewBase.Unloaded -= OnListViewBaseUnloaded_StretchDirection;
}

[AndrewKeepCoding]

One vote for your solution then. We can still keep each feature on its own file unless we have other shared logic. 🙂