using System.Windows.Controls;
using System.Windows.Input;

namespace MuchInfo.Chart.FormulaEdit
{
    public class NumberTextBox : TextBox
    {

        protected override void OnKeyDown(KeyEventArgs e)
        {
            base.OnKeyDown(e);
        

            if (!IsNumber((byte)e.Key))
            {
                e.Handled = true;
            }
        }

        protected override void OnTextChanged(TextChangedEventArgs e)
        {
            if (!string.IsNullOrEmpty(this.Text))
            {
                double number = 0d;
                if (!double.TryParse(this.Text, out number))
                {
                    this.Text = string.Empty;
                }
            }
            base.OnTextChanged(e);
        }

        /// <summary>
        /// 输入 是否为数字
        /// </summary>
        /// <param name="key"></param>
        /// <returns></returns>
        private bool IsNumber(byte key)
        {
            // 数字 
            if (key >= 34 && key <= 43) return true;
            // 小数字键盘 
            if (key >= 74 && key <= 83) return true;
            // Backspace键 
            if (key == 2) return true;
            return false;
        }
    }
}