public static extern ReturnCode DsmWinNew(
[In, Out] TWIdentity origin,
[In, Out] TWIdentity destination,
DataGroups dg,
DataArgumentType dat,
Message msg,
[In, Out] TWCallback data);
public static ReturnCode DsmEntry(
TWIdentity origin,
TWIdentity destination,
Message msg,
TWCallback data)
{
if (PlatformInfo.Current.IsWindows)
{
if (PlatformInfo.Current.UseNewWinDSM)
{
return(NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.Callback, msg, data));
}
else
{
return(NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, DataArgumentType.Callback, msg, data));
}
}
else if (PlatformInfo.Current.IsLinux)
{
return(NativeMethods.DsmLinux(origin, destination, DataGroups.Control, DataArgumentType.Callback, msg, data));
}
throw new PlatformNotSupportedException();
}
void ITwainSessionInternal.UpdateCallback()
{
if (State < 4)
{
_callbackObj = null;
}
else
{
ReturnCode rc = ReturnCode.Failure;
// per the spec (8-10) apps for 2.2 or higher uses callback2 so try this first
if (_appId.ProtocolMajor > 2 || (_appId.ProtocolMajor >= 2 && _appId.ProtocolMinor >= 2))
{
var cb = new TWCallback2(HandleCallback);
rc = ((ITwainSessionInternal)this).DGControl.Callback2.RegisterCallback(cb);
if (rc == ReturnCode.Success)
{
PlatformInfo.Current.Log.Debug("Registered callback2 OK.");
_callbackObj = cb;
}
}
if (rc != ReturnCode.Success)
{
// always try old callback
var cb = new TWCallback(HandleCallback);
rc = ((ITwainSessionInternal)this).DGControl.Callback.RegisterCallback(cb);
if (rc == ReturnCode.Success)
{
PlatformInfo.Current.Log.Debug("Registered callback OK.");
_callbackObj = cb;
}
}
}
}
/// <summary>
/// This triplet is sent to the DSM by the Application to register the application’s entry point with
/// the DSM, so that the DSM can use callbacks to inform the application of events generated by the
/// DS.
/// </summary>
/// <param name="callback">The callback.</param>
/// <returns></returns>
public ReturnCode RegisterCallback(TWCallback callback)
{
Session.VerifyState(4, 4, DataGroups.Control, DataArgumentType.Callback, Message.RegisterCallback);
return(Dsm.DsmEntry(Session.AppId, Session.CurrentSource.Identity, Message.RegisterCallback, callback));
}
