/// <summary>
/// Read() reads from an offset in the file. A PP_ArrayOutput must be
/// provided so that output will be stored in its allocated buffer. This
/// function might perform a partial read.
/// </summary>
/// <param name="buffer">An ArraySegment<byte> to hold the specified number of bytes read.</param>
/// <param name="offset">The offset into the file.</param>
/// <param name="bytesToRead">The number of bytes to read from <code>offset</code>.</param>
/// <returns>Error code. If the return value is 0, then end-of-file was reached.</returns>
public PPError Read(ArraySegment <byte> buffer, int offset, int bytesToRead)
{
var readToArrayAction = new Action <PPError, byte[]>(
(result, bytes) =>
{
Array.Copy(bytes, buffer.Array, Math.Min(bytes.Length, buffer.Count));
OnReadData(result);
}
);
var arrayOutput = new CompletionCallbackWithOutput <byte[]>(new CompletionCallbackWithOutputFunc <byte[]>(readToArrayAction));
return((PPError)PPBFileIO.ReadToArray(this, offset, bytesToRead, ref arrayOutput.ArrayOutput, arrayOutput));
}
private async Task <FileIOResult> ReadAsyncCore(ArraySegment <byte> buffer, int offset, int size, MessageLoop messageLoop = null)
{
var tcs = new TaskCompletionSource <FileIOResult>();
EventHandler <FileIOResult> handler = (s, e) => { tcs.TrySetResult(e); };
try
{
HandleReadData += handler;
if (MessageLoop == null && messageLoop == null)
{
Read(buffer, offset, size);
}
else
{
Action <PPError> action = new Action <PPError>((e) =>
{
using (var arrayOutput = new ArrayOutputAdapterWithStorage <byte[]>())
{
PPArrayOutput ao = arrayOutput.PPArrayOutput;
var result = (PPError)PPBFileIO.ReadToArray(this, offset, size, ref ao,
new BlockUntilComplete());
var bytes = arrayOutput.Output;
Array.Copy(bytes, buffer.Array, Math.Min(bytes.Length, buffer.Count));
tcs.TrySetResult(new FileIOResult((int)result, (int)result == 0));
}
}
);
InvokeHelper(action, messageLoop);
}
return(await tcs.Task);
}
catch (Exception exc)
{
Console.WriteLine(exc.Message);
tcs.SetException(exc);
return(new FileIOResult((int)PPError.Aborted, true));
}
finally
{
HandleReadData -= handler;
}
}