Question

i am trying to create one dependency property in a class called
"FocusBehaviour" that is in Class library.. I have added the
namespaces like below.. But it showing error in line 1) return
(bool)control.GetValue(FocusFirstProperty);

error: System.windows.Controls.Control Doesn’t have a method
‘GetValue" that accepts the First argument of type
System.windows.Controls.Control. 2) The same error is coming from
SetValue() also…below that… 3) Control control = dpObj as Control;
error:Cann’t convert System.DependencyObject To
System.windows.Controls.Control

I Also Added the WindowsBase Reference..

  using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;

namespace MyOrgBI
{
    public static class FocusBehavior:DependencyObject
    {

        public static readonly DependencyProperty FocusFirstProperty = 
        DependencyProperty.RegisterAttached("FocusFirst", 
                                            typeof(bool),
                                            typeof(Control),
                                            new PropertyMetadata(OnFocusFirstPropertyChanged));

    public static bool GetFocusFirst(Control control)
    {
        return (bool)control.GetValue(FocusFirstProperty);
    }
    public static void SetFocusFirst(Control control, bool value)
    {
        control.SetValue(FocusFirstProperty, value);
    }
    static void OnFocusFirstPropertyChanged(DependencyObject dpObj, DependencyPropertyChangedEventArgs args)
    {
        Control control = dpObj as Control;
        if (control == null || !(args.NewValue is bool))
        {
            return;
        }
        if ((bool)args.NewValue)
        {
            control.Loaded += (sender, e) => control.MoveFocus(new TraversalRequest(FocusNavigationDirection.First));
        }
    }
}

}

Previously I created a dependency property in a WpfApplication project. It worked fine but when I create one in another class library it shows this error.

Why these errors Coming ? And how should I write this code?

Answer 1

You need to add a reference to the WindowsBase Assembly. DependencyObject is located there.