﻿// VirtualTreeView - a TreeView that *actually* allows virtualization
// https://github.com/picrap/VirtualTreeView

namespace VirtualTreeView
{
    using System;
    using System.Globalization;
    using System.Windows;
    using System.Windows.Data;

    /// <summary>
    /// Margin creation based on item depth and item margin
    /// </summary>
    /// <seealso cref="System.Windows.Data.IMultiValueConverter" />
    public class MarginConverter : IMultiValueConverter
    {
        /// <summary>
        /// Converts source values to a value for the binding target. The data binding engine calls this method when it propagates the values from source bindings to the binding target.
        /// </summary>
        /// <param name="values">The array of values that the source bindings in the <see cref="T:System.Windows.Data.MultiBinding" /> produces. The value <see cref="F:System.Windows.DependencyProperty.UnsetValue" /> indicates that the source binding has no value to provide for conversion.</param>
        /// <param name="targetType">The type of the binding target property.</param>
        /// <param name="parameter">The converter parameter to use.</param>
        /// <param name="culture">The culture to use in the converter.</param>
        /// <returns>
        /// A converted value.If the method returns null, the valid null value is used.A return value of <see cref="T:System.Windows.DependencyProperty" />.<see cref="F:System.Windows.DependencyProperty.UnsetValue" /> indicates that the converter did not produce a value, and that the binding will use the <see cref="P:System.Windows.Data.BindingBase.FallbackValue" /> if it is available, or else will use the default value.A return value of <see cref="T:System.Windows.Data.Binding" />.<see cref="F:System.Windows.Data.Binding.DoNothing" /> indicates that the binding does not transfer the value or use the <see cref="P:System.Windows.Data.BindingBase.FallbackValue" /> or the default value.
        /// </returns>
        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
        {
            return new GridLength(System.Convert.ToDouble(values[0]) * System.Convert.ToDouble(values[1]), GridUnitType.Pixel);
        }

        /// <summary>
        /// Converts a binding target value to the source binding values.
        /// </summary>
        /// <param name="value">The value that the binding target produces.</param>
        /// <param name="targetTypes">The array of types to convert to. The array length indicates the number and types of values that are suggested for the method to return.</param>
        /// <param name="parameter">The converter parameter to use.</param>
        /// <param name="culture">The culture to use in the converter.</param>
        /// <returns>
        /// An array of values that have been converted from the target value back to the source values.
        /// </returns>
        /// <exception cref="InvalidOperationException"></exception>
        public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
        {
            throw new InvalidOperationException();
        }
    }
}