/// <summary>
/// Creates an enumerator for the current browse position.
/// </summary>
/// <param name="sources">if set to <c>true</c> then sources are enumerated.</param>
/// <returns>The wrapped enumerator.</returns>
private EnumString CreateEnumerator(bool sources)
{
IEnumString unknown = null;
string methodName = "IOPCEventAreaBrowser.BrowseOPCAreas";
try
{
IOPCEventAreaBrowser server = BeginComCall <IOPCEventAreaBrowser>(methodName, true);
OPCAEBROWSETYPE browseType = OPCAEBROWSETYPE.OPC_AREA;
if (sources)
{
browseType = OPCAEBROWSETYPE.OPC_SOURCE;
}
server.BrowseOPCAreas(browseType, String.Empty, out unknown);
}
catch (Exception e)
{
ComCallError(methodName, e);
return(null);
}
finally
{
EndComCall(methodName);
}
// wrapper the enumrator. hardcoding a buffer size of 256.
return(new EnumString(unknown, 256));
}
/// <summary>
/// Gets the qualified name for the source.
/// </summary>
/// <param name="name">The name.</param>
/// <returns>The qualified name for the area.</returns>
private string GetQualifiedSourceName(string name)
{
string methodName = "IOPCEventAreaBrowser.GetQualifiedSourceName";
string qualifiedName = null;
try
{
IOPCEventAreaBrowser server = BeginComCall <IOPCEventAreaBrowser>(methodName, true);
server.GetQualifiedSourceName(name, out qualifiedName);
}
catch (Exception e)
{
ComCallError(methodName, e);
return(null);
}
finally
{
EndComCall(methodName);
}
return(qualifiedName);
}
/// <summary>
/// Changes the browse position.
/// </summary>
/// <param name="direction">The direction.</param>
/// <param name="qualifiedName">The qualified area name.</param>
private bool ChangeBrowsePosition(OPCAEBROWSEDIRECTION direction, string qualifiedName)
{
string methodName = "IOPCEventAreaBrowser.CreateAreaBrowser";
try
{
IOPCEventAreaBrowser server = BeginComCall <IOPCEventAreaBrowser>(methodName, true);
server.ChangeBrowsePosition(direction, qualifiedName);
return(true);
}
catch (Exception e)
{
if (ComUtils.IsUnknownError(e, ResultIds.E_FAIL))
{
ComCallError(methodName, e);
}
return(false);
}
finally
{
EndComCall(methodName);
}
}
