Can't create instance of AcadApplication from C#.

[durgesh]

Hello Everyone,

I am new to programming AutoCad using .Net. I am trying to create a standalone C#/.Net Application to manipulate the dwg files.

While creating an instance of AcadApplication using following code, I am getting a crash which I can't comprehend completely.

Type acType = Type.GetTypeFromProgID("AutoCAD.Application.18.1");
AcadApplication acApp = null;
acApp = (AcadApplication)Activator.CreateInstance(acType,true);

 I get the followng error message.

Unable to cast COM object of type 'Autodesk.AutoCAD.Interop.AcadApplicationMinorVersion1Class' to interface type 'AutoCAD.AcadApplication'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{070AA05D-DFC1-4E64-8379-432269B48B07}' failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)).

Although, I can see an instance of acad.exe getting started in taskmanager, but value of acApp is still null.

Other informations:

Visual Studio Version : VS 2012 Express Edition

AutoCaD Version : AutoCAD 2012 x64 version

OS : Windows 7, x64 version.

Thanks in advance,

Durgesh

[mcicognani]

To avoid referencing a specific AutoCAD version, you can try late binding.

This works for any version of AutoCAD, 32 or 64bit:

public static List<String> GetOpenFiles()
{
    List<String> result = new List<String>();
 
    try
    {
        // retrieve running AutoCAD, generic class
        Object acadApp = Marshal.GetActiveObject("AutoCAD.Application");
        if (acadApp == null) return null;
 
        // Recupera active document list
        object objDoc = acadApp.GetType().InvokeMember("Documents", BindingFlags.IgnoreCase | BindingFlags.GetProperty, null, acadApp, null);
        if (objDoc == null) return null;
 
        Int64 iCount = Convert.ToInt64(objDoc.GetType().InvokeMember("Count", BindingFlags.IgnoreCase | BindingFlags.GetProperty, null, objDoc, null));
 
        for (int i = 0; i < iCount; i++)
        {
            object[] dataArray = new object[1];
            dataArray[0] = i;
 
            object obj = objDoc.GetType().InvokeMember("Item", BindingFlags.IgnoreCase | BindingFlags.InvokeMethod, null, objDoc, dataArray);
            if (obj != null)
            {
                object objName = obj.GetType().InvokeMember("FullName", BindingFlags.IgnoreCase | BindingFlags.GetProperty, null, obj, null);
                String szName = objName.ToString();
 
                //object objRead = obj.GetType().InvokeMember("ReadOnly", BindingFlags.IgnoreCase | BindingFlags.GetProperty, null, obj, null);
                //bool bReadOnly = Convert.ToBoolean(objRead);
 
                if (szName.Length > 0) result.Add(szName);
            }
        }
    }
    catch (System.Exception ex)
    {
        result = null;
    }
 
    return result;
}

[durgesh]

Hi,

I better switch back to VB6 for AutoCAD Programming. Late binding is looking very scary and difficult to implement. 

Anyways Thanks, Is there any way I can implement it as COM Interop.

Regards,

Durgesh