private static void InitializeMessage()
{
if (null == outputMessageFunction)
{
lock (outputMessageFunctionLock)
{
if (null == outputMessageFunction)
{
FreeImage.ValidateAvailability();
try
{
// Create a delegate (function pointer) to 'OnMessage'
outputMessageFunction =
delegate(FREE_IMAGE_FORMAT fif, string message)
{
LastErrorMessage = message;
// Get a local copy of the multicast-delegate
OutputMessageFunction m = FreeImageEngine.message;
// Check the local copy instead of the static instance
// to prevent a second thread from setting the delegate
// to null, which would cause a nullreference exception
if (m != null)
{
// Invoke the multicast-delegate
m.Invoke(fif, message);
}
};
// Set the callback
FreeImage.SetOutputMessage(outputMessageFunction);
}
catch
{
outputMessageFunction = null;
throw;
}
}
}
}
}