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c#comocx

Calling OCX(COM) method using C#

I am using an OCX library from C#. I have added COM reference from Visual Studio. When I try to create an object in this class I am getting,

var ocxCls = new MyOCXClass();

CS1729  'MyOCXClass' does not contain a constructor that takes 0 arguments

If I use reflection to see the parameters and constructor count,

        Type tt = typeof(MyOCXClass);
        var  flags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance;
        var cs = tt.GetConstructors(flags)[0].GetParameters().Count();

The constructor's count is 1 and parameters 0? What's happening?

Update: When I opened OCX inside OLEView I got,

enter image description here

Solution

  • Instead of using the Console application, I have used a WinForm application. Now Visual Studio generates a class that I am able to instantiate.

    In Console the class generated was,

    [ClassInterfaceAttribute(0)]
[ComSourceInterfaces("OCX.__OCX")]
[Guid("SomeGuid")]
[TypeLibType(32)]
public class OCXClass : _OCX, OCX, __OCX_Event
{
    [DispId(1610809349)]
    public virtual void OCXMethod1(ref short milliseconds);
    [DispId(1610809350)]
    public virtual bool OCXMethod2();
}

    While in WinForms it shows,

    [Clsid("{SomeGuid}")]
[DesignTimeVisible(true)]
public class OCXClass : OCXClassHost
{
    public OCXClass();
    public virtual void OCXMethod1(ref short milliseconds);
    public virtual bool OCXMethod2();
}

    When I use JustDeCompile I also see,

    [ClassInterfaceAttribute(0)]
[ComSourceInterfaces("OCX.__OCX")]
[Guid("SomeGuid")]
[TypeLibType(32)]
public class OCXClass : _OCX, OCX, __OCX_Event
{
    [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType=MethodCodeType.Runtime)]
    internal extern OCXClass();

    Note the internal extern constructor which I think stopping me to create an object.