Traverse focus after selection

[Marcel]

Hello,

I have a question about traversing the focus when a selection is made in the RadComboBox.

I have the following requirement:

When the user enters the combobox, the drop down should automatically open (I set OpenDropDownOnFocus= true) , the user will select an item and confirm the selection by using the enter key. After that the item should be set, the drop down should be closed and the focus should automatically traverse to the next field. Travesersing focus to the next field should be done by the enter-key, I already implemented this for textboxes.

 

I have used below code with the regular WPF ComboBox, but this gave some unexpected behavior in the past.

Sometimes the warning was shown ("Couldn't move the focus.......) and the user was not able anymore to traverse the focus in the whole screen using the enter key, he needed to close the screen and open it again to re-enable this functionality.

 

public class CustomComboBox : ComboBox
{
    #region Fields

    private bool _focused = false;

    #endregion

    #region Methods

    protected override void OnGotKeyboardFocus(KeyboardFocusChangedEventArgs e)
    {
        base.OnGotKeyboardFocus(e);

        _focused = true;
    }

    protected override void OnDropDownClosed(EventArgs e)
    {
        if (_focused)
        {
            var uie = this as UIElement;

            _focused = false;
        }
        else
        {
            base.OnDropDownClosed(e);
        }
    }

    protected override void OnKeyDown(KeyEventArgs e)
    {
        if ((e.Key == System.Windows.Input.Key.Enter))
        {
            base.OnKeyDown(e);


            var comboBoxItem = e.OriginalSource as FrameworkElement;
            var comboBox = ItemsControl.ItemsControlFromItemContainer(comboBoxItem) as ComboBox;

            if (comboBox != null)
                comboBox.MoveFocus(new TraversalRequest(FocusNavigationDirection.Next));
            else
            {
                LogManager.GetLog(this.GetType()).Warn("Couldn't move the focus to the next field, source: {0}.", e.OriginalSource);
            }
        }
        else
            base.OnKeyDown(e);

    }
    #endregion
}

 

 What is the best way to accomplish this, or is this functionality already in the RadComboBox?

 

Regards,

 

Marcel

[Nasko]

Hello Chris,

In order to move the focus from RadComboBox to another control as soon as a selection is made we suggest you to use the MoveFocus method. You could call it inside the SelectionChanged event of the ComboBox control instead of implementing a custom a logic for the KeyDown event- that event will fire as soon as a selection is made. Please, check the attached sample project that demonstrates the described above approach - it seems everything works as expected on our side. Give it a try and let us know if it worked for you.

Hopes this helps.

Regards,
Nasko
Telerik

[Marcel]

Hello Nasko,

Thanks for your reply, I checked out the solution.

It works well when there is no item selected yet.

But when there is already an item selected the user cant comfirm the already selected item with enter and traverse to the next field.

How can I combine this solution with that functionality?

Regards,

 

Marcel

 

[Nasko]

Hello Marcel,

In order to achieve the desired behavior you need also to handle the PreviewKeyUp event - we suggest you to handle that event because the KeyDown event could fire too early while there is still no selected item. Inside the event you need to implement the following logic:

private void combo_PreviewKeyUp(object sender, KeyEventArgs e)
{
    if (e.Key == Key.Enter)
    {
        this.combo.MoveFocus(new TraversalRequest(FocusNavigationDirection.Down));
    }
}

We hope this will help you.

Regards,
Nasko
Telerik