vb.net参考程序集WithEvents无法正常工作

Question

I have been searching this for forever and have not been able to find an answer so any help would be greatly appreciated!

I am originally using this dll as an activeX control through .asp pages and it works perfectly. I am now having to rewrite it as a class because my boss asked me too. So in my project I have right clicked and added reference name.dll. The FileType of this is Assembly.

so i created a variable

Friend WithEvents scan As name.Integration.ActiveX.ActiveXObject

With this I am able to call its methods and it works perfectly at this point. However, after I call a method it runs a process and starts waiting for a card to be inserted into the scanner. When a card is inserted into the scanner it is suppose to throw an event and then start scanning.

Once I insert a card it scans but the issue I'm having is my program is not catching any of the 50 events it is throwing. Does anyone know how or why? I'm desperately needing to fix this.

Answer 1

If I understand you correctly (and I'm reading between the lines here) you have an ActiveX control from a third party. Your previous web page used this control. You now instead reference the dll that contains the ActiveX control, so VS automatically creates a .net wrapper around the ActiveX component. Is that correct?

If yes, confirm you are referencing the correct type from the correct libary.

1. Use the Object Browser to view the dll's types. I think you'll find you have two libraries associated with the dll. For example, assume your library is named "ThirdParty". You may see "AxThirdParty" as well as "Interop.ThirdParty". The "interop" library contains most classes. However, the "Ax..." library is key to handling events. Your object that declares events from be from this library. If you don't see this libary, you may need to add the control to a Windows .net form to get VS to create it for you.

2. Don't try to handle events in the "Ax..." library that are hidden. Note that handling hidden events does not cause compile errors, but nor do they ever get raised. Do you see the event your trying to handle in the "Ax..." library? If so, is it shown in light gray? Note that VS will rename any interop event that conflicts with standard control events. For example, the ActiveX control's click event gets named "ClickEvent" and it is the ClickEvent event you want to handle, not the Click event.

Note that above applies to Windows forms. I think Hans is right about the message loop.