public IAsyncOperationWithProgress <IBuffer, uint> ReadAsync(IBuffer buffer, uint count, InputStreamOptions options) { if (buffer == null) { // Mapped to E_POINTER. throw new ArgumentNullException(nameof(buffer)); } if (count < 0 || int.MaxValue < count) { ArgumentOutOfRangeException ex = new ArgumentOutOfRangeException(nameof(count)); ex.SetHResult(E_INVALIDARG); throw ex; } if (buffer.Capacity < count) { ArgumentException ex = new ArgumentException(global::Windows.Storage.Streams.SR.Argument_InsufficientBufferCapacity); ex.SetHResult(E_INVALIDARG); throw ex; } if (!(options == InputStreamOptions.None || options == InputStreamOptions.Partial || options == InputStreamOptions.ReadAhead)) { ArgumentOutOfRangeException ex = new ArgumentOutOfRangeException(nameof(options), global::Windows.Storage.Streams.SR.ArgumentOutOfRange_InvalidInputStreamOptionsEnumValue); ex.SetHResult(E_INVALIDARG); throw ex; } Stream str = EnsureNotDisposed(); IAsyncOperationWithProgress <IBuffer, uint> readAsyncOperation; switch (_readOptimization) { case StreamReadOperationOptimization.MemoryStream: readAsyncOperation = StreamOperationsImplementation.ReadAsync_MemoryStream(str, buffer, count); break; case StreamReadOperationOptimization.AbstractStream: readAsyncOperation = StreamOperationsImplementation.ReadAsync_AbstractStream(str, buffer, count, options); break; // Use this pattern to add more optimisation options if necessary: //case StreamReadOperationOptimization.XxxxStream: // readAsyncOperation = StreamOperationsImplementation.ReadAsync_XxxxStream(str, buffer, count, options); // break; default: Debug.Fail("We should never get here. Someone forgot to handle an input stream optimisation option."); readAsyncOperation = null; break; } return(readAsyncOperation); }