sbox-public/game/addons/base/code/UI/Controls/SwitchControl.razor

@using System
@namespace Sandbox.UI
@inherits BaseControl
@attribute [CustomEditor( typeof(bool) )]

<root class="switchcontrol @StateClass">

    <div class="switch-frame">
        <div class="switch-inner">
        </div>
    </div>

    @if ( Label != null )
    {
        <div class="switch-label">
            @Label
        </div>
    }

</root>

@code
{
    public override bool SupportsMultiEdit => true;

    public RenderFragment Label { get; set; }

    public Action<bool> OnValueChanged { get; set; }

    string StateClass => Value ? "active" : "inactive";

    bool _value;

    public bool Value
    {
        get => Property?.As.Bool ?? _value;

        set
        {
            if ( Property is not null )
            {
                Property.As.Bool = value;
                StateHasChanged();
                return;
            }

            if (_value == value)
                return;

            _value = value;
            StateHasChanged();
        }
    }

    public SwitchControl()
    {

    }

    protected override void OnMouseDown( MousePanelEvent e )
    {
        base.OnMouseDown( e );

        Value = !Value;
        OnValueChanged?.Invoke( Value );
        e.StopPropagation();
    }
}