4C/Gumming/Modules/FloatBox.cs

using System;
using System.Globalization;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Input;

namespace Gumming
{
    public class FloatBox : TextBox
    {
        #region MaxValue

        public static readonly DependencyProperty MaxValueProperty =
            DependencyProperty.Register("MaxValue", typeof(Decimal), typeof(FloatBox),
                                        new PropertyMetadata(100000000m, OnMaxValueChanged,
                                                             CoerceMaxValue));

        public Decimal MaxValue
        {
            get { return (Decimal)GetValue(MaxValueProperty); }
            set { SetValue(MaxValueProperty, value); }
        }

        private static void OnMaxValueChanged(DependencyObject element,
                                              DependencyPropertyChangedEventArgs e)
        {
            var control = (FloatBox)element;
            var maxValue = (Decimal)e.NewValue;
        }

        private static object CoerceMaxValue(DependencyObject element, Object baseValue)
        {
            var maxValue = (Decimal)baseValue;

            if (maxValue == Decimal.MaxValue)
            {
                return DependencyProperty.UnsetValue;
            }

            return maxValue;
        }

        #endregion

        #region Constructors
        /*
         * The default constructor
         */
        public FloatBox()
        {
            TextChanged += new TextChangedEventHandler(OnTextChanged);
            KeyDown += new KeyEventHandler(OnKeyDown);
        }
        #endregion

        #region Properties
        new public String Text
        {
            get { return base.Text; }
            set
            {
                base.Text = LeaveOnlyNumbers(value);
            }
        }

        #endregion

        #region Functions
        private bool IsNumberKey(Key inKey)
        {
            if (inKey == System.Windows.Input.Key.OemPeriod)
            {
                return true;
            }
            if (inKey == System.Windows.Input.Key.Decimal)
            {
                return true;
            }
            if ((inKey < Key.D0 || inKey > Key.D9) && inKey != Key.OemMinus)
            {
                if (inKey < Key.NumPad0 || inKey > Key.NumPad9)
                {
                    return false;
                }
            }
            return true;
        }

        private bool IsDelOrBackspaceOrTabKey(Key inKey)
        {
            return inKey == Key.Delete || inKey == Key.Back || inKey == Key.Tab;
        }

        private string LeaveOnlyNumbers(String inString)
        {
            String tmp = inString;
            foreach (char c in inString.ToCharArray())
            {
                if (!System.Text.RegularExpressions.Regex.IsMatch(c.ToString(), @"^\+?(:?(:?\d+\.\d+)|(:?\d+))|(-?\d+)(\.\d+)?$") && c != '.' && c != '-')
                {
                    tmp = tmp.Replace(c.ToString(), "");
                }
            }
            if (tmp.Count(x => x == '.') > 1)
            {
                int firstdot = tmp.IndexOf('.');
                string header = tmp.Substring(0, firstdot + 1);
                string strEnd = tmp.Substring(firstdot + 1);
                tmp = header + strEnd.Replace(".", "");
            }
            return tmp;
        }
        #endregion

        #region Event Functions
        protected void OnKeyDown(object sender, KeyEventArgs e)
        {
            e.Handled = !IsNumberKey(e.Key) && !IsDelOrBackspaceOrTabKey(e.Key);
        }

        protected void OnTextChanged(object sender, TextChangedEventArgs e)
        {            
            if (!System.Text.RegularExpressions.Regex.IsMatch(Text, @"^\+?(:?(:?\d+\.\d+)|(:?\d+))|(-?\d+)(\.\d+)?$"))
            {
                base.Text = LeaveOnlyNumbers(Text);
            }
            decimal value = 0;
            decimal.TryParse(Text, out value);
            if (value > MaxValue)
            {
                base.Text = MaxValue.ToString();
            }
            this.Select(this.Text.Length, 0);
        }
        #endregion
    }
}