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/// <summary>视频输入设备信息</summary>
    internal class Device : IDisposable
    {
        #region API
        [DllImport("ole32.dll")]
        static extern int CreateBindCtx(int reserved, out IBindCtx ppbc);        [DllImport("ole32.dll", CharSet = CharSet.Unicode)]
        static extern int MkParseDisplayName(IBindCtx pbc, string szUserName, ref int pchEaten, out IMoniker ppmk);
        #endregion        #region GUID
        static readonly Guid SystemDeviceEnum = new Guid(0x62BE5D10, 0x60EB, 0x11D0, 0xBD, 0x3B, 0x00, 0xA0, 0xC9, 0x11, 0xCE, 0x86);        static readonly Guid VideoInputDevice = new Guid(0x860BB310, 0x5D01, 0x11D0, 0xBD, 0x3B, 0x00, 0xA0, 0xC9, 0x11, 0xCE, 0x86);
        #endregion        /// <summary>枚举本机上的视频设备</summary>
        public static IEnumerable<Device> Devices
        {
            get
            {
                IMoniker[] ms = new IMoniker[5];
                ICreateDevEnum enumD = Activator.CreateInstance(Type.GetTypeFromCLSID(SystemDeviceEnum)) as ICreateDevEnum;
                IEnumMoniker moniker;
                Guid g = VideoInputDevice;
                if (enumD.CreateClassEnumerator(g, out moniker, 0) == 0)
                {
                    while (true)
                    {
                        int r = moniker.Next(1, ms, IntPtr.Zero);
                        if (r != 0 || ms[0] == null)
                            break;
                        yield return new Device(ms[0]);
                        ms[0] = null;
                    }
                }
            }
        }        /// <summary>根据设备路径创建设备</summary>
        /// <param name="path">设备路径</param>
        /// <returns>视频设备</returns>
        public static Device Create(string path)
        {
            IBindCtx bindCtx = null;
            IMoniker moniker = null;
            int n = 0;            if (CreateBindCtx(0, out bindCtx) == 0)
            {
                int hr = MkParseDisplayName(bindCtx, path, ref n, out moniker);
                hr.ThrowExceptionForHR();
                Marshal.ReleaseComObject(bindCtx);
                bindCtx = null;
            }
            if (moniker != null)
                return new Device(moniker);
            else
                return null;
        }        /// <summary>设备名称</summary>
        public string Name { get; private set; }        /// <summary>设备路径</summary>
        public string DevicePath { get; private set; }        public IMoniker Moniker { get; private set; }        private Device(IMoniker moniker)
        {
            Moniker = moniker;
            DevicePath = GetMonikerString(moniker);
            Name = GetName(moniker);
        }        internal IBaseFilter CreateFilter()
        {
            object filterObject = null;
            IBindCtx bindCtx = null;            if (CreateBindCtx(0, out bindCtx) == 0)
            {
                Guid filterId = typeof(IBaseFilter).GUID;
                Moniker.BindToObject(null, null, ref filterId, out filterObject);
                Marshal.ReleaseComObject(bindCtx);
            }
            return filterObject as IBaseFilter;
        }        private string GetMonikerString(IMoniker moniker)
        {
            string str;
            moniker.GetDisplayName(null, null, out str);
            return str;
        }        private string GetName(IMoniker moniker)
        {
            Object bagObj = null;
            IPropertyBag bag = null;            try
            {
                Guid bagId = typeof(IPropertyBag).GUID;
                moniker.BindToStorage(null, null, ref bagId, out bagObj);
                bag = (IPropertyBag)bagObj;                object val = "";
                int hr = bag.Read("FriendlyName", out val, null);
                if (hr != 0)
                    Marshal.ThrowExceptionForHR(hr);                string ret = (string)val;
                if ((ret == null) || (ret.Length < 1))
                    throw new ApplicationException();                return ret;
            }
            catch (Exception)
            {
                return "";
            }
            finally
            {
                bag = null;
                if (bagObj != null)
                {
                    Marshal.ReleaseComObject(bagObj);
                    bagObj = null;
                }
            }
        }        public override string ToString()
        {
            return Name;
        }        #region IDisposable 成员        public void Dispose()
        {
            Marshal.ReleaseComObject(Moniker);
            GC.SuppressFinalize(this);
        }        #endregion        ~Device() 
        {
            Dispose();
        }
    }