RevitSdkSamples/SDK/Samples/ExternalCommand/CS/ExternalCommandRegistration/AvailabilityClass.cs

//
// (C) Copyright 2003-2019 by Autodesk, Inc.
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Autodesk.Revit.UI;

namespace Revit.SDK.Samples.ExternalCommandRegistration.CS
{
   /// <summary>
   /// Implements the Revit add-in interface IExternalCommandAvailability, 
   /// determine when to enable\disable the corresponding external command by 
   /// return value from IsCommandAvailable function.
   /// Corresponding command will be disabled when a wall selected by user in this case.
   /// </summary>
   class WallSelection : IExternalCommandAvailability
   {
      #region IExternalCommandAvailability Members

      public bool IsCommandAvailable(UIApplication applicationData, 
         Autodesk.Revit.DB.CategorySet selectedCategories)
      {
         System.Collections.IEnumerator iterCategory = selectedCategories.GetEnumerator();
         iterCategory.Reset();
         while (iterCategory.MoveNext())
         {
            Autodesk.Revit.DB.Category category = (Autodesk.Revit.DB.Category)(iterCategory.Current);
            if (category.Name == "Walls")
            {
               return false;
            } 
         }
         return true;
      }

      #endregion
   }

   /// <summary>
   /// Implements the Revit add-in interface IExternalCommandAvailability, 
   /// determine when to enable\disable the corresponding external command by 
   /// return value from IsCommandAvailable function.
   /// Corresponding command will be disabled if active document is not a 3D view.
   /// </summary>
   class View3D : IExternalCommandAvailability
   {
      #region IExternalCommandAvailability Members

      public bool IsCommandAvailable(UIApplication applicationData, 
         Autodesk.Revit.DB.CategorySet selectedCategories)
      {
         Autodesk.Revit.DB.View activeView = applicationData.ActiveUIDocument.Document.ActiveView;
         if (Autodesk.Revit.DB.ViewType.ThreeD == activeView.ViewType)
         {
            return true;
         }
         else 
         {
            return false;
         }
      }

      #endregion
   }
}