Revit API创建标高，单位转换

一业内朋友让我写个快速创建标高的插件。

//创建标高
[TransactionAttribute(Autodesk.Revit.Attributes.TransactionMode.Manual)]
public class cmdDrawLevel : IExternalCommand
{
    public Result Execute(ExternalCommandData commandData, ref string messages, ElementSet elements)
    {
        UIApplication app = commandData.Application;
        Document doc = app.ActiveUIDocument.Document;
        Selection sel = app.ActiveUIDocument.Selection;
        try
        {
            Transaction ts = new Transaction(doc, "revit");
            ts.Start();
            //起始，间距，数量，前缀
            double dStart = RevitTools.Unit.CovertToAPI(double.Parse(XmlTools.levelStart), DisplayUnitType.DUT_METERS);
            double dDis = RevitTools.Unit.CovertToAPI(double.Parse(XmlTools.levelDis), DisplayUnitType.DUT_METERS);
            int iNum = int.Parse(XmlTools.levelNum);
            //创建起始标高
            Level levelStart = doc.Create.NewLevel(dStart);
            levelStart.Name = XmlTools.levelPre + 1;
            //
            for (int i = 1; i <= iNum; i++)
            {
                Level level = doc.Create.NewLevel(dStart + i * dDis);
                level.Name = XmlTools.levelPre + (i + 1);
            }

            ts.Commit();
        }
        catch (Exception ex)
        {
            TaskDialog.Show("error", "请检查是否命名重复。");
        }

        return Result.Succeeded;
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace RevitCodes
{
    class XmlTools
    {
        public static string levelStart = "4";
        public static string levelDis = "4";
        public static string levelNum = "10";
        public static string levelPre = "F";
    }
}

//
// (C) Copyright 2003-2010 by Autodesk, Inc.
//
// Permission to use, copy, modify, and distribute this software in
// object code form for any purpose and without fee is hereby granted,
// provided that the above copyright notice appears in all copies and
// that both that copyright notice and the limited warranty and
// restricted rights notice below appear in all supporting
// documentation.
//
// AUTODESK PROVIDES THIS PROGRAM "AS IS" AND WITH ALL FAULTS.
// AUTODESK SPECIFICALLY DISCLAIMS ANY IMPLIED WARRANTY OF
// MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. AUTODESK, INC.
// DOES NOT WARRANT THAT THE OPERATION OF THE PROGRAM WILL BE
// UNINTERRUPTED OR ERROR FREE.
//
// Use, duplication, or disclosure by the U.S. Government is subject to
// restrictions set forth in FAR 52.227-19 (Commercial Computer
// Software - Restricted Rights) and DFAR 252.227-7013(c)(1)(ii)
// (Rights in Technical Data and Computer Software), as applicable.
//


using System;
using System.Collections.Generic;
using System.Text;
using Autodesk.Revit.DB;
using System.Configuration;
using System.Reflection;

namespace RevitTools
{
    /// <summary>
    /// Provides static functions to convert unit
    /// </summary>
    static class Unit
    {
        #region Methods
        /// <summary>
        /// Convert the value get from RevitAPI to the value indicated by DisplayUnitType
        /// </summary>
        /// <param name="to">DisplayUnitType indicates unit of target value</param>
        /// <param name="value">value get from RevitAPI</param>
        /// <returns>Target value</returns>
        public static double CovertFromAPI(DisplayUnitType to, double value)
        {
            return value *= ImperialDutRatio(to);
        }

        /// <summary>
        /// Convert a value indicated by DisplayUnitType to the value used by RevitAPI
        /// </summary>
        /// <param name="value">Value to be converted</param>
        /// <param name="from">DisplayUnitType indicates the unit of the value to be converted</param>
        /// <returns>Target value</returns>
        public static double CovertToAPI(double value, DisplayUnitType from )
        {
            return value /= ImperialDutRatio(from);
        }

        /// <summary>
        /// Get ratio between value in RevitAPI and value to display indicated by DisplayUnitType
        /// </summary>
        /// <param name="dut">DisplayUnitType indicates display unit type</param>
        /// <returns>Ratio </returns>
        private static double ImperialDutRatio(DisplayUnitType dut) 
        {
            switch (dut)
            {
                case DisplayUnitType.DUT_DECIMAL_FEET: return 1;
                case DisplayUnitType.DUT_FEET_FRACTIONAL_INCHES: return 1;
                case DisplayUnitType.DUT_DECIMAL_INCHES: return 12;
                case DisplayUnitType.DUT_FRACTIONAL_INCHES: return 12;
                case DisplayUnitType.DUT_METERS: return 0.3048;
                case DisplayUnitType.DUT_CENTIMETERS: return 30.48;
                case DisplayUnitType.DUT_MILLIMETERS: return 304.8;
                case DisplayUnitType.DUT_METERS_CENTIMETERS: return 0.3048;
                default: return 1;
            }
        }
        #endregion
    }
}

url:http://greatverve.cnblogs.com/p/revit-api-create-level.html