Revit api 创建楼梯图元

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using Autodesk.Revit.Attributes;
 using Autodesk.Revit.DB;
 using Autodesk.Revit.UI;
 using Autodesk.Revit.DB.Architecture;

 namespace CreateStairs
 {
     [Transaction(TransactionMode.Manual)]
     public class Class1:IExternalCommand
     {
         public Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
         {
             Document doc = commandData.Application.ActiveUIDocument.Document;
             Transaction trans = new Transaction(doc,"new level");
             trans.Start();
             Level blvl = Level.Create(doc, );
             Level tlvl = Level.Create(doc, );
             trans.Commit();
             CreateStairs(doc, blvl, tlvl);
             return Result.Succeeded;
         }
         private ElementId CreateStairs(Document document, Level levelBottom, Level levelTop)
         {
             ElementId newStairsId = null;
             using (StairsEditScope newStairsScope = new StairsEditScope(document, "New Stairs"))
             {
                 newStairsId = newStairsScope.Start(levelBottom.Id, levelTop.Id);
                 using (Transaction stairsTrans = new Transaction(document, "Add Runs and Landings to Stairs"))
                 {
                     stairsTrans.Start();

                     // Create a sketched run for the stairs
                     IList<Curve> bdryCurves = new List<Curve>();
                     IList<Curve> riserCurves = new List<Curve>();
                     IList<Curve> pathCurves = new List<Curve>();
                     XYZ pnt1 = new XYZ(, , );
                     XYZ pnt2 = new XYZ(, , );
                     XYZ pnt3 = new XYZ(, , );
                     XYZ pnt4 = new XYZ(, , );
                     // boundaries
                     bdryCurves.Add(Line.CreateBound(pnt1, pnt2));
                     bdryCurves.Add(Line.CreateBound(pnt3, pnt4));
                     // riser curves
                     const int riserNum = ;
                     for (int ii = ; ii <= riserNum; ii++)
                     {
                         XYZ end0 = (pnt1 + pnt2) * ii / (double)riserNum;
                         XYZ end1 = (pnt3 + pnt4) * ii / (double)riserNum;
                         XYZ end2 = new XYZ(end1.X, , );
                         riserCurves.Add(Line.CreateBound(end0, end2));
                     }

                     //stairs path curves
                     XYZ pathEnd0 = (pnt1 + pnt3) / 2.0;
                     XYZ pathEnd1 = (pnt2 + pnt4) / 2.0;
                     pathCurves.Add(Line.CreateBound(pathEnd0, pathEnd1));
                     StairsRun newRun1 = StairsRun.CreateSketchedRun(document, newStairsId, levelBottom.Elevation, bdryCurves, riserCurves, pathCurves);
                     // Add a straight run
                     Line locationLine = Line.CreateBound(new XYZ(, -, newRun1.TopElevation), new XYZ(, -, newRun1.TopElevation));
                     StairsRun newRun2 = StairsRun.CreateStraightRun(document, newStairsId, locationLine, StairsRunJustification.Center);
                     newRun2.ActualRunWidth = ;
                     // Add a landing between the runs
                     CurveLoop landingLoop = new CurveLoop();
                     XYZ p1 = new XYZ(, , );
                     XYZ p2 = new XYZ(, , );
                     XYZ p3 = new XYZ(, -, );
                     XYZ p4 = new XYZ(, -, );
                     Line curve_1 = Line.CreateBound(p1, p2);
                     Line curve_2 = Line.CreateBound(p2, p3);
                     Line curve_3 = Line.CreateBound(p3, p4);
                     Line curve_4 = Line.CreateBound(p4, p1);
                     landingLoop.Append(curve_1);
                     landingLoop.Append(curve_2);
                     landingLoop.Append(curve_3);
                     landingLoop.Append(curve_4);
                     StairsLanding newLanding = StairsLanding.CreateSketchedLanding(document, newStairsId, landingLoop, newRun1.TopElevation);
                     stairsTrans.Commit();
                 }
                 // A failure preprocessor is to handle possible failures during the edit mode commitment process.
                 newStairsScope.Commit(new FailuresPreprocessor());//new StairsFailurePreprocessor());
             }
             return newStairsId;
         }

     }
     public class FailuresPreprocessor : IFailuresPreprocessor
     {
         public FailureProcessingResult PreprocessFailures(FailuresAccessor failuresAccessor)
         {
             IList<FailureMessageAccessor> listFma = failuresAccessor.GetFailureMessages();
             if (listFma.Count == )
                 return FailureProcessingResult.Continue;
             foreach (FailureMessageAccessor fma in listFma)
             {
                 if (fma.GetSeverity() == FailureSeverity.Error)
                 {
                     if (fma.HasResolutions())
                         failuresAccessor.ResolveFailure(fma);
                 }
                 if (fma.GetSeverity() == FailureSeverity.Warning)
                 {
                     failuresAccessor.DeleteWarning(fma);
                 }
             }
             return FailureProcessingResult.ProceedWithCommit;
         }
     }
 }