Question

I am writing a WinForms application in C# .NET and want to update the listview from the worker thread. I have read just about every post here on this but don’t really fully understand the use of Invoke and delegates. In fact a few examples on here won’t even compile as it complains of calling a non-static control from a static function.

I have a ListViewItem which I just want to pass to the UI thread via AddListItem(…). What is the best way to do this?

At present I have

this.lvcontrol.Invoke(new Action(() => lvcontrol.Items.Add(item)));

This is from MyForm::AddListView() which is a static function. But of course the compiler complains that you can’t call “this” or just “lvcontrol” from a static method. If the method isn’t static I can’t call the method from the static worker thread which is a member function of the Form.

Answer 1

You need a reference to the lvcontrol in order for the code to know which one you are trying to update (you could have two copies of the form open!).

If lvcontrol is a variable then drop the this at the begining eg

lvcontrol.Invoke(new Action(() => lvcontrol.Items.Add(item))

If it isn’t your code is going to either all have to be non-static or you will need to pass a reference to the form around (and use that reference instead of the this, eg if frm is a reference to the form

frm.lvcontrol.Invoke(new Action(() => frm.lvcontrol.Items.Add(item))