Shrlalgo.RvKits/WPFluent/Controls/ListView/ListView..cs

namespace WPFluent.Controls;

/// <summary>
/// Extends <see cref="System.Windows.Controls.ListView"/>, and adds customized support <see
/// cref="ListViewViewState.GridView"/> or <see cref="ListViewViewState.Default"/>.
/// </summary>
/// <example>
/// <code lang="xml"> /// &lt;ui:ListView ItemsSource="{Binding ...}" &gt; ///     &lt;ui:ListView.View&gt; ///        
/// &lt;ui:GridView&gt; ///             &lt;GridViewColumn ///                 DisplayMemberBinding="{Binding
/// FirstName}" ///                 Header="First Name" /&gt; ///             &lt;GridViewColumn ///                
/// DisplayMemberBinding="{Binding LastName}" ///                 Header="Last Name" /&gt; ///        
/// &lt;/ui:GridView&gt; ///     &lt;/ui:ListView.View&gt; /// &lt;/ui:ListView&gt; ///</code>
/// </example>
public class ListView : System.Windows.Controls.ListView
{
    /// <summary>
    /// Identifies the <see cref="ViewState"/> dependency property.
    /// </summary>
    public static readonly DependencyProperty ViewStateProperty = DependencyProperty.Register(
        nameof(ViewState),
        typeof(ListViewViewState),
        typeof(ListView),
        new FrameworkPropertyMetadata(ListViewViewState.Default, OnViewStateChanged));
    private DependencyPropertyDescriptor? _descriptor;

    static ListView()
    { DefaultStyleKeyProperty.OverrideMetadata(typeof(ListView), new FrameworkPropertyMetadata(typeof(ListView))); }

    public ListView()
    {
        Loaded += OnLoaded;
        Unloaded += OnUnloaded;
    }

    private void OnLoaded(object sender, RoutedEventArgs e)
    {
        Loaded -= OnLoaded; // prevent memory leaks

        // Setup initial ViewState and hook into View property changes
        _descriptor = DependencyPropertyDescriptor.FromProperty(
            System.Windows.Controls.ListView.ViewProperty,
            typeof(System.Windows.Controls.ListView));
        _descriptor?.AddValueChanged(this, OnViewPropertyChanged);
        UpdateViewState(); // set the initial state
    }

    private void OnUnloaded(object sender, RoutedEventArgs e)
    {
        Unloaded -= OnUnloaded;

        _descriptor?.RemoveValueChanged(this, OnViewPropertyChanged);
    }

    private void OnViewPropertyChanged(object? sender, EventArgs e) { UpdateViewState(); }

    private static void OnViewStateChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if(d is not ListView self)
        {
            return;
        }

        self.OnViewStateChanged(e);
    }

    private void UpdateViewState()
    {
        ListViewViewState viewState = View switch
        {
            System.Windows.Controls.GridView => ListViewViewState.GridView,
            null => ListViewViewState.Default,
            _ => ListViewViewState.Default,
        };

        SetCurrentValue(ViewStateProperty, viewState);
    }

    protected override DependencyObject GetContainerForItemOverride() { return new ListViewItem(); }

    protected override bool IsItemItsOwnContainerOverride(object item) { return item is ListViewItem; }

    protected virtual void OnViewStateChanged(DependencyPropertyChangedEventArgs e)
    {
        // Hook for derived classes to react to ViewState property changes
    }

    /// <summary>
    /// Gets or sets the view state of the <see cref="ListView"/>, enabling custom logic based on the current view.
    /// </summary>
    /// <value>The current view state of the <see cref="ListView"/>.</value>
    public ListViewViewState ViewState
    {
        get => (ListViewViewState)GetValue(ViewStateProperty);
        set => SetValue(ViewStateProperty, value);
    }
}