TableViewColumnHeader.OptionComamnds.cs

using Microsoft.UI.Xaml.Controls;
using Microsoft.UI.Xaml.Input;
using SD = WinUI.TableView.SortDirection;

namespace WinUI.TableView;

partial class TableViewColumnHeader
{
    private bool _commandsInitialized;
    private readonly StandardUICommand _sortAscendingCommand = new() { Label = TableViewLocalizedStrings.SortAscending };
    private readonly StandardUICommand _sortDescendingCommand = new() { Label = TableViewLocalizedStrings.SortDescending };
    private readonly StandardUICommand _clearSortingCommand = new() { Label = TableViewLocalizedStrings.ClearSorting };
    private readonly StandardUICommand _clearFilterCommand = new() { Label = TableViewLocalizedStrings.ClearFilter };    

    /// <summary>
    /// Sets commands to option menu items.
    /// </summary>
    private void SetOptionCommands()
    {
        InitializeCommands();

        if (GetTemplateChild("SortAscendingMenuItem") is MenuFlyoutItem sortAscendingMenuItem)
            sortAscendingMenuItem.Command = _sortAscendingCommand;
        if (GetTemplateChild("SortDescendingMenuItem") is MenuFlyoutItem sortDescendingMenuItem)
            sortDescendingMenuItem.Command = _sortDescendingCommand;
        if (GetTemplateChild("ClearSortingMenuItem") is MenuFlyoutItem clearSortingMenuItem)
            clearSortingMenuItem.Command = _clearSortingCommand;
        if (GetTemplateChild("ClearFilterMenuItem") is MenuFlyoutItem clearFilterMenuItem)
            clearFilterMenuItem.Command = _clearFilterCommand;
    }

    /// <summary>
    /// Initializes the commands.
    /// </summary>
    private void InitializeCommands()
    {
        if (_commandsInitialized)
        {
            return;
        }

        _sortAscendingCommand.ExecuteRequested += delegate { DoSort(SD.Ascending); };
        _sortAscendingCommand.CanExecuteRequested += (_, e) => e.CanExecute = CanSort && Column?.SortDirection != SD.Ascending;

        _sortDescendingCommand.ExecuteRequested += delegate { DoSort(SD.Descending); };
        _sortDescendingCommand.CanExecuteRequested += (_, e) => e.CanExecute = CanSort && Column?.SortDirection != SD.Descending;

        _clearSortingCommand.ExecuteRequested += delegate { ClearSortingWithEvent(); };
        _clearSortingCommand.CanExecuteRequested += (_, e) => e.CanExecute = Column?.SortDirection is not null;

        _clearFilterCommand.ExecuteRequested += delegate { ClearFilter(); };
        _clearFilterCommand.CanExecuteRequested += (_, e) => e.CanExecute = Column?.IsFiltered is true;
        
        _commandsInitialized = true;
    }
}