CtrEditor/Converters/SubtractConverter.cs

using System;
using System.Globalization;
using System.Windows.Data;

namespace CtrEditor.Converters
{
    /// <summary>
    /// Converter that subtracts a parameter value from the input value
    /// Useful for calculations like width - margin, etc.
    /// </summary>
    public class SubtractConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            try
            {
                if (value != null && parameter != null)
                {
                    var inputValue = System.Convert.ToDouble(value);
                    var subtractValue = System.Convert.ToDouble(parameter);
                    
                    var result = inputValue - subtractValue;
                    return Math.Max(0, result); // Ensure result is not negative
                }
            }
            catch (Exception ex)
            {
                System.Diagnostics.Debug.WriteLine($"SubtractConverter.Convert: Exception - {ex.Message}");
            }
            
            return 0.0;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            try
            {
                if (value != null && parameter != null)
                {
                    var inputValue = System.Convert.ToDouble(value);
                    var addValue = System.Convert.ToDouble(parameter);
                    
                    return inputValue + addValue;
                }
            }
            catch (Exception ex)
            {
                System.Diagnostics.Debug.WriteLine($"SubtractConverter.ConvertBack: Exception - {ex.Message}");
            }
            
            return 0.0;
        }
    }
}