how can i multibind rect in wpf?

Question

hello I've tried to multibind of rectangle. but i've got System.InvalidCastException: ‘Unable to cast object of type ‘MS.Internal.NamedObject’ to type ‘System.Boolean’.’ error

public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{

        SolidColorBrush color = new SolidColorBrush(Colors.Transparent);

        if (values == null)
        {
            return color;
        }
        bool A= (bool)(values[0]);
        bool B= (bool)values[1];

        if (A&& B)
        {
            color = new SolidColorBrush(Colors.Red);
        }

        else if (A== true && B== false)
        {
            color = new SolidColorBrush(Colors.Gray);

        }
        else if (A== true && B== true)
        {
            color = new SolidColorBrush(Colors.Green);
        }
        
        else
        {
            color = new SolidColorBrush(Colors.LightBlue);
        }
        return color;

    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

I Want to change colors of rectangle depending on conditions.

xaml

<Rectangle.Fill>
                    <MultiBinding Converter="{StaticResource BackGroundColorConverters}">
                        <Binding Path="CheckAStatus"/>
                        <Binding Path="CheckDStatus"/>
                    </MultiBinding>
                </Rectangle.Fill>
            </Rectangle>

private bool _checkAStatus; public bool CheckAStatus { get => _checkAStatus; set => SetProperty(ref _checkAStatus, value);

}

private bool _checkDStatus; public bool CheckDStatus { get => _checkDStatus; set => SetProperty(ref _checkDStatus, value); } public ViewModel() { this.CheckAstatus = false; this.CheckDstats = true; }

Answer 1

You should validate the arguments in your Convert method and do nothing when an MS.Internal.NamedObject is passed as an argument:

public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
    if (values == null || values.Length < 2 || !(values[0] is bool A) || !(values[1] is bool B)
        return Binding.DoNothing;

    SolidColorBrush color = new SolidColorBrush(Colors.Transparent);

    if (values == null)
    {
        return color;
    }

    if (A && B)
    {
        color = new SolidColorBrush(Colors.Red);
    }

    else if (A == true && B == false)
    {
        color = new SolidColorBrush(Colors.Gray);

    }
    else if (A == true && B == true)
    {
        color = new SolidColorBrush(Colors.Green);
    }

    else
    {
        color = new SolidColorBrush(Colors.LightBlue);
    }
    return color;
}