Question

Trying to get a thread to change form controls in Windows Mobile.

Throws an unsupported exception.

Does this mean it cant be done at all?

If not, how do I go about this? Forms are created in the Parent/Main thread then a thread is created to do some work in the background but I want to make it so the Background thread can update the form to show its completed…

Answer 1

You cannot access GUI items on a non-GUI thread. You will need to determine if an invocation is required to the GUI thread. For example (here’s some I made earlier):

public delegate void SetEnabledStateCallBack(Control control, bool enabled);
public static void SetEnabledState(Control control, bool enabled)
{
    if (control.InvokeRequired)
    {
        SetEnabledStateCallBack d = new SetEnabledStateCallBack(SetEnabledState);
        control.Invoke(d, new object[] { control, enabled });
    }
    else
    {
        control.Enabled = enabled;
    }
}

Or

public delegate void AddListViewItemCallBack(ListView control, ListViewItem item);
public static void AddListViewItem(ListView control, ListViewItem item)
{
    if (control.InvokeRequired)
    {
        AddListViewItemCallBack d = new AddListViewItemCallBack(AddListViewItem);
        control.Invoke(d, new object[] { control, item });
    }
    else
    {
        control.Items.Add(item);
    }
}

You can then set the enabled property (from my first example) using ClassName.SetEnabledState(this, true);.