extend RadComboBox item

[Roman]

Hi, I need extend RadComboBoxItem to prevent DropDownClose (in some cases).
I added this class:

public class CustomComboItem : RadComboBoxItem
{
    protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
    {
        var parentComboBox = ItemsControl.ItemsControlFromItemContainer(this) as RadComboBox;
        if (parentComboBox != null)
        {
            var collection = parentComboBox.ItemsSource as ICustomCollection;
            if (collection != null)
            {
                var item =
                    collection[parentComboBox.ItemContainerGenerator.IndexFromContainer(this)] as ICustomItem;
                if (item != null && !item.IsSelectable)
                    return;
            }
        }
        base.OnMouseLeftButtonUp(e);
    }
}

Idea is to trigger base implementation of MouseLeftButtonUp only if necessary.
But when I try use this class in XAML:

<Style x:Key="CustomComboBoxItem" TargetType="controls:CustomComboItem"></Style>

 

<Style x:Key="ComboBase" TargetType="controls:CustomCombo">
//other styles

    <Setter Property="ItemContainerStyle" Value="{StaticResource CustomComboBoxItem}"></Setter>       
//other styles


</Style>

I get XamlParseException in RadComboBox PrepareContainerForItemOverride. I don't apply any styles or bindings in CustomComboBoxItem (but I also use DataTemplate), why I get this error? Is it possible to do such things?

Thanks for help!

[Vladi]

Hello Roman,

If you want to customize the RadComboBoxItem by creating a class that inherits RadComboBoxItem you will need to create a custom RadComboBox and override its GetContainerForItemOverride() method in which you should return the custom RadComboBoxItem that you have created.

You will need to do the following steps:

1. Create a class MyComboBoxItem that inherits RadComboBoxItem.
2. Override its OnMouseLeftButtonUp() method with your custom logic.
3. Create a class MyRadComboBox that inherits RadComboBox.
4. Override its GetContainerForItemOverride() method to return the newly created MyComboBoxItem.

Hope this is helpful.

Greetings,
Vladi
the Telerik team

[Roman]

I didn't know about GetContainerForItemOverride.
Now everything works great!
Thanks, Vladi for help!