C# .NET
Framework 4.0 MVVM Light Toolkit
In my WPF (MVVM)
application, I want to use the Listbox SelectedItems property but this property
has no setter and for this reason it’s not “bindable“ to my view model.
I have
tried to use the property (IsSelected) in my object and in the XAML this item
container style.
<ListBox.ItemContainerStyle>
<Style TargetType="{x:Type ListBoxItem}">
<Setter
Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay,
UpdateSourceTrigger=PropertyChanged}" />
</Style>
</ListBox.ItemContainerStyle>
This solution
works fine if the Listbox SelectionMode property is set to Single but if the
selection mode is “Extended” (SelectionMode="Extended") it doesn’t work correctly,
sometimes a few items remain selected.
Finally, I
found a solution that works for me. I use the MenuItem’s CommandParameter for accessing
to the Listbox SelectedItems property.
Like this.
<ListBox.ContextMenu>
<ContextMenu>
<MenuItem
Command="{Binding
AddImagesSelectedCommand}" CommandParameter="{Binding
PlacementTarget.SelectedItems,
RelativeSource={RelativeSource
AncestorType={x:Type
ContextMenu}}}" Header="{Binding Source={StaticResource
CustomResources}, Path=LocalizedStrings.mnuAddImagesSelected}"
/>
</ContextMenu>
</ListBox.ContextMenu>
Then in the view model:
AddImagesSelectedCommand
= new RelayCommand<object>(OnAddImagesSelected,
CanAddImagesSelected);
private void
OnAddImagesSelected(object param)
{
var
selectedImages = ((IEnumerable)param).Cast<CaptureImage>().ToList();
//To do
something …
}
private bool
CanAddImagesSelected(object param)
{
if
(param != null)
{
var
selectedImages = ((IEnumerable) param).Cast<CaptureImage>().ToList();
return (selectedImages != null && selectedImages.Count
> 0);
}
return false;
}
We must use the PlacementTarget object because
the ContextMenu is not in the same part of the Visual Tree, so that
is why you cannot use ElementName etc. to reference the ListBox.
See you soon for the next trick!
