ScreenToGif/Util/Converters/MaximumValue.cs

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using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Data;

namespace ScreenToGif.Util.Converters
{
    /// <summary>
    /// MaximumValue MultiValueConverter.
    /// [0]: Minimum based on itself.
    /// [1]: Maximum based on another control.
    /// [2]: Offset (It's used as Maximum - Offset).
    /// </summary>
    public class MaximumValue : IMultiValueConverter
    {
        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
        {
            if (values.Length < 2)
                return DependencyProperty.UnsetValue;

            var minVar = (int)Math.Round(values[0] as Double? ?? values[0] as Int32? ?? 0, MidpointRounding.AwayFromZero);
            var maxVar = (int)Math.Round(values[1] as Double? ?? values[1] as Int32? ?? 0, MidpointRounding.AwayFromZero);

            if (values.Length == 2)
                return minVar > maxVar || double.IsNaN(maxVar) ? minVar : maxVar;

            var offset = values[2] as Double? ?? values[2] as Int32? ?? 0;

            var result = (int)Math.Round(maxVar - offset, MidpointRounding.AwayFromZero);
            return minVar > result || double.IsNaN(maxVar) ? minVar : result;
        }

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