/Code/Foundation.Build.VisualBasic6.VisualStudioIntegration/ProjectBase/SelectionListener.cs

/* ****************************************************************************

 *

 * Copyright (c) Microsoft Corporation. 

 *

 * This source code is subject to terms and conditions of the Apache License, Version 2.0. A 

 * copy of the license can be found in the License.html file at the root of this distribution. If 

 * you cannot locate the Apache License, Version 2.0, please send an email to 

 * ironpy@microsoft.com. By using this source code in any fashion, you are agreeing to be bound 

 * by the terms of the Apache License, Version 2.0.

 *

 * You must not remove this notice, or any other, from this software.

 *

 * ***************************************************************************/



using System;

using System.Diagnostics;

using Microsoft.VisualStudio;

using Microsoft.VisualStudio.Shell;

using Microsoft.VisualStudio.Shell.Interop;

using ShellConstants = Microsoft.VisualStudio.Shell.Interop.Constants;



namespace Microsoft.VisualStudio.Project

{



	[CLSCompliant(false)]

	public abstract class SelectionListener : IVsSelectionEvents, IDisposable

	{

		#region fields

		private uint eventsCookie;

		private IVsMonitorSelection monSel;

		private ServiceProvider serviceProvider;

		private bool isDisposed;

		/// <summary>

		/// Defines an object that will be a mutex for this object for synchronizing thread calls.

		/// </summary>

		private static volatile object Mutex = new object();

		#endregion



		#region ctors

		protected SelectionListener(ServiceProvider serviceProviderParameter)

		{

            if (serviceProviderParameter == null)

            {

                throw new ArgumentNullException("serviceProviderParameter");

            }



            this.serviceProvider = serviceProviderParameter;

            this.monSel = this.serviceProvider.GetService(typeof(SVsShellMonitorSelection)) as IVsMonitorSelection;



			if(this.monSel == null)

			{

				throw new InvalidOperationException();

			}

		}

		#endregion



		#region properties

		protected uint EventsCookie

		{

			get

			{

				return this.eventsCookie;

			}

		}



		protected IVsMonitorSelection SelectionMonitor

		{

			get

			{

				return this.monSel;

			}

		}



		protected ServiceProvider ServiceProvider

		{

			get

			{

				return this.serviceProvider;

			}

		}

		#endregion



		#region IVsSelectionEvents Members



		public virtual int OnCmdUIContextChanged(uint dwCmdUICookie, int fActive)

		{

			return VSConstants.E_NOTIMPL;

		}



		public virtual int OnElementValueChanged(uint elementid, object varValueOld, object varValueNew)

		{

			return VSConstants.E_NOTIMPL;

		}



		public virtual int OnSelectionChanged(IVsHierarchy pHierOld, uint itemidOld, IVsMultiItemSelect pMISOld, ISelectionContainer pSCOld, IVsHierarchy pHierNew, uint itemidNew, IVsMultiItemSelect pMISNew, ISelectionContainer pSCNew)

		{

			return VSConstants.E_NOTIMPL;

		}



		#endregion



		#region IDisposable Members

		/// <summary>

		/// The IDispose interface Dispose method for disposing the object determinastically.

		/// </summary>

		public void Dispose()

		{

			this.Dispose(true);

			GC.SuppressFinalize(this);

		}

		#endregion



		#region methods

		public void Init()

		{

			if(this.SelectionMonitor != null)

			{

				ErrorHandler.ThrowOnFailure(this.SelectionMonitor.AdviseSelectionEvents(this, out this.eventsCookie));

			}

		}



		/// <summary>

		/// The method that does the cleanup.

		/// </summary>

		/// <param name="disposing"></param>

		[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA1806:DoNotIgnoreMethodResults", MessageId = "Microsoft.VisualStudio.Shell.Interop.IVsMonitorSelection.UnadviseSelectionEvents(System.UInt32)")]

		protected virtual void Dispose(bool disposing)

		{

			// Everybody can go here.

			if(!this.isDisposed)

			{

				// Synchronize calls to the Dispose simulteniously.

				lock(Mutex)

				{

					if(disposing && this.eventsCookie != (uint)ShellConstants.VSCOOKIE_NIL && this.SelectionMonitor != null)

					{

						this.SelectionMonitor.UnadviseSelectionEvents((uint)this.eventsCookie);

						this.eventsCookie = (uint)ShellConstants.VSCOOKIE_NIL;

					}



					this.isDisposed = true;

				}

			}

		}

		#endregion



	}

}