Question

I have code that runs in a different thread than the UI’s one, and it has to create a control (windows forms). However, I don’t have a reference to any control from the UI (that way, I could use myControl.Invoke( methodThatAddsControlToUI ) ). Is there a way to do it in the .net compact framework?

I would be interested in a solution that doesn’t use references to other controls, if possible (tracking all created forms, for example, would not be a good workaround, as my code will be in a library). In the full framework version, there is the Application.OpenForms property, but this doesn’t exit in the CF.

EDIT:

The main purpose of this is calling a method on the UI thread:

class Worker
{
    public MyMethod()
    {
        // I need to call a method on the UI (this code doesn't run in the UI thread), 
        // but I don't have any field  in this object holding an UI control
        // value. So, I can't write myControlField.Invoke(...),
        // but I still need to call a method on the UI thread
    }
}

Any suggestions?

Answer 1

From a library there’s really no way to guarantee your thread context, so your safest bet is to have the consume provide the invoker and leave it to them to ensure it was created in the proper context. Something like this pattern:

class Foo
{
    private Control m_invoker;

    public Foo()
        : this(null)
    {
    }

    public Foo(Control invoker)
    {
        if (invoker == null)
        {
            // assume we are created on the UI thread, 
            // if not bad things will ensue
            m_invoker = new Control();
        }
        else
        {
            m_invoker = invoker;
        }
    }

    public void Bar()
    {
        m_invoker.Invoke(new Action(delegate
        {
            // do my UI-context stuff here
        }));
    }
}