C# IBaseFilter.IsNull方法代码示例

		/// <summary>
		/// Connect pins from two filters
		/// </summary>
		/// <param name="graphBuilder">the IGraphBuilder interface of the graph</param>
		/// <param name="upFilter">the upstream filter</param>
		/// <param name="sourcePinName">the upstream filter pin name</param>
		/// <param name="downFilter">the downstream filter</param>
		/// <param name="destPinName">the downstream filter pin name</param>
		/// <param name="useIntelligentConnect">indicate if the method should use DirectShow's Intelligent Connect</param>
		/// <exception cref="System.ArgumentNullException">Thrown if graphBuilder, upFilter or downFilter are null</exception>
		/// <exception cref="System.ArgumentException">Thrown if pin names are not found in filters</exception>
		/// <exception cref="System.Runtime.InteropServices.COMException">Thrown if pins can't connect</exception>
		/// <remarks>
		/// If useIntelligentConnect is true, this method can add missing filters between the two pins.<br/>
		/// If useIntelligentConnect is false, this method works only if the two media types are compatible.
		/// </remarks>

		public static void ConnectFilters(IGraphBuilder graphBuilder, IBaseFilter upFilter, string sourcePinName, IBaseFilter downFilter, string destPinName, bool useIntelligentConnect)
		{
			if (graphBuilder.IsNull())
				throw new ArgumentNullException("graphBuilder");

			if (upFilter.IsNull())
				throw new ArgumentNullException("upFilter");

			if (downFilter.IsNull())
				throw new ArgumentNullException("downFilter");

			IPin sourcePin, destPin;

			sourcePin = DsFindPin.ByName(upFilter, sourcePinName);
			if (sourcePin.IsNull())
				throw new ArgumentException("The source filter has no pin called : " + sourcePinName, sourcePinName);

			destPin = DsFindPin.ByName(downFilter, destPinName);
			if (destPin.IsNull())
				throw new ArgumentException("The downstream filter has no pin called : " + destPinName, destPinName);

			try
			{
				ConnectFilters(graphBuilder, sourcePin, destPin, useIntelligentConnect);
			}
			finally
			{
				Marshal.ReleaseComObject(sourcePin);
				Marshal.ReleaseComObject(destPin);
			}
		}

		public static void ShowFilterPropertyPage(IBaseFilter filter, IntPtr parent)
		{
			int hr = 0;
			FilterInfo filterInfo;
			DsCAUUID caGuid;
			object[] objs;

			if (filter.IsNull())
				throw new ArgumentNullException("filter");

			if (HasPropertyPages(filter))
			{
				hr = filter.QueryFilterInfo(out filterInfo);
				DsError.ThrowExceptionForHR(hr);

				if (filterInfo.pGraph.NotNull())
					Marshal.ReleaseComObject(filterInfo.pGraph);

				hr = (filter as ISpecifyPropertyPages).GetPages(out caGuid);
				DsError.ThrowExceptionForHR(hr);

				try
				{
					objs = new object[1];
					objs[0] = filter;

					NativeMethods.OleCreatePropertyFrame(
						parent, 0, 0,
						filterInfo.achName,
						objs.Length, objs,
						caGuid.cElems, caGuid.pElems,
						0, 0,
						IntPtr.Zero
						);
				}
				finally
				{
					Marshal.FreeCoTaskMem(caGuid.pElems);
				}
			}
		}

		public static void DisconnectPins(IBaseFilter filter)
		{
			int hr = 0;

			if (filter.IsNull())
				throw new ArgumentNullException("filter");

			IEnumPins enumPins;
			IPin[] pins = new IPin[1];

			hr = filter.EnumPins(out enumPins);
			DsError.ThrowExceptionForHR(hr);

			try
			{
				while (enumPins.Next(pins.Length, pins, IntPtr.Zero) == 0)
				{
					try
					{
						hr = pins[0].Disconnect();
						DsError.ThrowExceptionForHR(hr);
					}
					finally
					{
						Marshal.ReleaseComObject(pins[0]);
					}
				}
			}
			finally
			{
				Marshal.ReleaseComObject(enumPins);
			}
		}

		/// <summary>
		/// Check if a DirectShow filter can display Bits Pages
		/// </summary>
		/// <param name="filter">A DirectShow Filter</param>
		/// <exception cref="System.ArgumentNullException">Thrown if filter is null</exception>
		/// <seealso cref="ShowFilterPropertyPage"/>
		/// <returns>true if the filter has Bits Pages, false if not</returns>
		/// <remarks>
		/// This method is intended to be used with <see cref="ShowFilterPropertyPage">ShowFilterPropertyPage</see>
		/// </remarks>

		public static bool HasPropertyPages(IBaseFilter filter)
		{
			if (filter.IsNull())
				throw new ArgumentNullException("filter");

			return ((filter as ISpecifyPropertyPages).NotNull());
		}

		public static bool RenderPin(IGraphBuilder graphBuilder, IBaseFilter source, string pinName)
		{
			int hr = 0;

			if (graphBuilder.IsNull())
				throw new ArgumentNullException("graphBuilder");

			if (source.IsNull())
				throw new ArgumentNullException("source");

			IPin pin = DsFindPin.ByName(source, pinName);

			if (pin.NotNull())
			{
				hr = graphBuilder.Render(pin);
				Marshal.ReleaseComObject(pin);

				return (hr >= 0);
			}

			return false;
		}