I don't know about AutoCAD 2014 or if this may be addressing your specific issue with starting it up, so this may be all I can do to help, but who knows! 🙂
I had an issue using this approach with 2015 and found out the issue was related to the fact that Microsoft has chosen not to support nested message loops in WPF.... Kean Wamsley wrote about it here
Below is some sample code for startup which may or may not address your particular issue. Note though that what gasty was getting at is that you don't have to have the COM Interop references if you don't plan to interact with the session, but be aware that without them, AutoCAD will start in the background and you can't make it visible without them. See my code sample below... Hope this helps...
btw... equivalent 2012 Interop references (COM tab of VS) is "AutoCAD 2012 Type Library" and "AcObjClassImp 1.0 Type Library". I'm not sure how this varies on 2014 if there's been changes, but something to look for...
/*
For more information on IMessageFilter: http://msdn.microsoft.com/en-us/library/ms693740(VS.85).aspx
This is used to handle a “problem” that was introduced as Autodesk
addressed an issue with the WPF components in AutoCAD handle inbound messages,
largely due to Microsoft’s decision not to support nested message loops in WPF.
If WPF is in the middle of performing some kind of layout processing operation
(which leads to Dispatcher.DisableProcessing() being called) and there’s an incoming COM call,
then AutoCAD was respecting it which could lead to a crash.
Now they do the right thing and reject the COM call: effectively asking the caller to try again later.
The problem is that – while the VB6 runtime was very good at automatically retrying calls such as CreateObject() – WinForm applications are not.
We need to implement an additional interface from our WinForm application to make sure it can handle failure
*/
[ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("00000016-0000-0000-C000-000000000046")]
public interface IMessageFilter
{
[PreserveSig]
int HandleInComingCall(int dwCallType, IntPtr hTaskCaller, int dwTickCount, IntPtr lpInterfaceInfo);
[PreserveSig]
int RetryRejectedCall(IntPtr hTaskCallee, int dwTickCount, int dwRejectType);
[PreserveSig]
int MessagePending(IntPtr hTaskCallee, int dwTickCount, int dwPendingType);
}
public class StartAutoCAD : IMessageFilter
{
#region P/Invoke Declarations and Delegates
//IMessageFilter support, see the IMessageFilter interface file for more information
//Note: The IMessage helps support opening AutoCAD externally while supporting conflict issues
[DllImport("ole32.dll")]
static extern int CoRegisterMessageFilter(IMessageFilter lpMessageFilter, out IMessageFilter lplpMessageFilter);
#endregion
#region Constructors
public StartAutoCAD()
{
//IMessageFilter support
IMessageFilter oldFilter;
CoRegisterMessageFilter(this, out oldFilter);
}
#endregion
#region Starting new instance
public void StartNew()
{
//Trying to get a currently open instance first
object objectACADApplication=null;
try
{
objectACADApplication = Marshal.GetActiveObject("AutoCAD.Application.18");
}
catch (COMException)
{
//If not found, try getting with reflection
if (objectACADApplication == null)
{
Type acadSessionType = Type.GetTypeFromProgID("AutoCAD.Application.18");
objectACADApplication = Activator.CreateInstance(acadSessionType, true);
//I give a little time for it to settle out, probably not necessary though
Thread.Sleep(125);
}
}
//Reference the AutoCAD Interop dll's so that you can cast acadApplication as AcadApplication
//if you want to communicate with the instance directly with COM... Shouldn't be necessary otherwise
//Make visible... sorry, but to my knowledge this does require the interop dlls otherwise AutoCAD
//remains in the background
if (objectACADApplication != null)
{
AcadApplication acadApplication = (AcadApplication)objectACADApplication;
acadApplication.Visible = true;
}
}
#endregion
#region IMessageFilter Members
//For more information, see comments in the IMessageFilter file.
int IMessageFilter.HandleInComingCall(int dwCallType, IntPtr hTaskCaller, int dwTickCount, IntPtr lpInterfaceInfo)
{
return 0; // SERVERCALL_ISHANDLED
}
int IMessageFilter.RetryRejectedCall(IntPtr hTaskCallee, int dwTickCount, int dwRejectType)
{
/* return values:
* -1: the call should be cancelled. COM then returns RPC_E_CALL_REJECTED from the original method call
* value >= 0 and < 100: the call is to be retried immediately
* value >= 100: COM will wait for this many milliseconds and then retry the call
*/
return 1000; // Retry in a second
}
int IMessageFilter.MessagePending(IntPtr hTaskCallee, int dwTickCount, int dwPendingType)
{
return 1; // PENDINGMSG_WAITNOPROCESS
}
#endregion
}
