129 lines
3.8 KiB
C#
129 lines
3.8 KiB
C#
#region Copyright (c) 2011-2023 Technosoftware GmbH. All rights reserved
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//-----------------------------------------------------------------------------
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// Copyright (c) 2011-2023 Technosoftware GmbH. All rights reserved
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// Web: https://www.technosoftware.com
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//
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// The source code in this file is covered under a dual-license scenario:
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// - Owner of a purchased license: SCLA 1.0
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// - GPL V3: everybody else
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//
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// SCLA license terms accompanied with this source code.
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// See SCLA 1.0: https://technosoftware.com/license/Source_Code_License_Agreement.pdf
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//
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// GNU General Public License as published by the Free Software Foundation;
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// version 3 of the License are accompanied with this source code.
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// See https://technosoftware.com/license/GPLv3License.txt
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//
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// This source code is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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// or FITNESS FOR A PARTICULAR PURPOSE.
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//-----------------------------------------------------------------------------
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#endregion Copyright (c) 2011-2023 Technosoftware GmbH. All rights reserved
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#region Using Directives
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using System;
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using System.Runtime.InteropServices;
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using Technosoftware.OpcRcw.Comn;
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#endregion
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namespace Technosoftware.DaAeHdaClient.Com
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{
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/// <summary>
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/// A wrapper for the COM IEnumString interface.
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/// </summary>
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internal class EnumString : IDisposable
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{
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/// <summary>
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/// A reference to the remote COM object.
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/// </summary>
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private IEnumString m_enumerator = null;
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/// <summary>
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/// Initializes the object with an enumerator.
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/// </summary>
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public EnumString(object enumerator)
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{
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m_enumerator = (IEnumString)enumerator;
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}
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/// <summary>
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/// Releases the remote COM object.
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/// </summary>
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public void Dispose()
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{
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Utilities.Interop.ReleaseServer(m_enumerator);
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m_enumerator = null;
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}
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//=====================================================================
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// IEnumString
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/// <summary>
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/// Fetches the next subscription of strings.
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/// </summary>
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public string[] Next(int count)
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{
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try
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{
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// create buffer.
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var buffer = Marshal.AllocCoTaskMem(Marshal.SizeOf(typeof(IntPtr))*count);
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try
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{
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// fetch next subscription of strings.
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var fetched = 0;
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m_enumerator.RemoteNext(
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count,
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buffer,
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out fetched);
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// return empty array if at end of list.
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if (fetched == 0)
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{
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return new string[0];
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}
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return Interop.GetUnicodeStrings(ref buffer, fetched, true);
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}
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finally
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{
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Marshal.FreeCoTaskMem(buffer);
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}
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}
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// return null on any error.
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catch (Exception)
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{
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return null;
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}
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}
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/// <summary>
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/// Skips a number of strings.
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/// </summary>
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public void Skip(int count)
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{
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m_enumerator.Skip(count);
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}
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/// <summary>
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/// Sets pointer to the start of the list.
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/// </summary>
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public void Reset()
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{
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m_enumerator.Reset();
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}
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/// <summary>
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/// Clones the enumerator.
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/// </summary>
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public EnumString Clone()
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{
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IEnumString enumerator;
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m_enumerator.Clone(out enumerator);
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return new EnumString(enumerator);
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}
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}
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}
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