internal static IAsyncOperationWithProgress <IBuffer, uint> ReadAsync_MemoryStream(Stream stream, IBuffer buffer, uint count)
{
Debug.Assert(stream != null);
Debug.Assert(stream is MemoryStream);
Debug.Assert(stream.CanRead);
Debug.Assert(stream.CanSeek);
Debug.Assert(buffer != null);
Debug.Assert(0 <= count);
Debug.Assert(count <= int.MaxValue);
Debug.Assert(count <= buffer.Capacity);
// We will return a different buffer to the user backed directly by the memory stream (avoids memory copy).
// This is permitted by the WinRT stream contract.
// The user specified buffer will not have any data put into it:
buffer.Length = 0;
MemoryStream memStream = stream as MemoryStream;
Debug.Assert(memStream != null);
try
{
IBuffer dataBuffer = memStream.GetWindowsRuntimeBuffer((int)memStream.Position, (int)count);
if (dataBuffer.Length > 0)
{
memStream.Seek(dataBuffer.Length, SeekOrigin.Current);
}
return(AsyncInfo.CreateCompletedOperation <IBuffer, uint>(dataBuffer));
}
catch (Exception ex)
{
return(AsyncInfo.CreateFaultedOperation <IBuffer, uint>(ex));
}
} // ReadAsync_MemoryStream