Default Style Not Applying

Question

I'm creating a ListViewEx control based off the ListView Control. The Code works but the Default Style I made for it does not work when I run the app (though it shows in the VS 2008 designer). Instead I get the normal ListView Style.

 

It will work if I do this though:

Code Snippet

Code SnippetStyle style = (Style)Application.Current.FindResource(typeof(ListViewEx));

lv.Style = style;

 

 

 

It's not taking the Default Style on its own and I don't know why.

Here's the VS 2008 Solution.  I've never made a control library before. Any help fixing this would be appreciated.

 

http://www.sendspace.com/file/3ixznw

Answer 1

Hi Emanon,

 

your style is applying. The problem is located in the GridView. :-)

 

Just set your Listbox like this without specifying the gridView:

 

Code Snippet

<ctrl:ListViewEx Name="lv" Margin="10"/>

 

 

You'll see, that your template applies. Let's get further and write a custom View for your ListBox. :-)

Answer 2

Yeah, I have noticed not setting a view allows the style to show. But it doesn't make sense to me that setting a view would effect the style of its parent control. It also doesn't make sense to me that

 

Code Snippet

Style style = (Style)Application.Current.FindResource(typeof(ListViewEx));

lv.Style = style;

 

 

 

 

...will have the style of the ListViewEx show up despite having put in a GridView. It is also strange that the style shows up in the designer including the GridView's column headers w/ my style, but doesn't when the app is run. I would like to use the GridView. It already does what I'd like it to. Why would I want to rewrite it? I'd just like to have my style apply to my derived ListView control and still have it be compatible w/ the GridView.

 

Do you know how to do this?

Answer 3

The problem is, that setting a View overrides the Style of the ListView. So you have to re-set the style explicit.

Below some code out of the ListView-Class (Just debugged with microsofts symbols, really cool. :-))

There you see that the DefaultStyleKey of the ListView is set to the DefaultStyleKey specified in the GridView.

 

Code Snippet

private void ApplyNewView()

{

  ViewBase newView = View;

  if (newView != null)

  {

    // update default style key of ListView

    DefaultStyleKey = newView.DefaultStyleKey;

  }

  ...

}

 

 

 

So what to do... you could create a subclass from GridView that only overrides the DefaultStyleKey-Property:

 

Code Snippet

public class MyGridView:GridView

{

  protected override object DefaultStyleKey

  {

    get

    {

      return typeof(ListViewEx);

    }

  }

}

 

Then it'll work, if you use the MyGridView:

 

Code Snippet

<ctrl:ListViewEx Name="lv" Margin="10">

  <ctrl:ListViewEx.View>

    <ctrl:MyGridView>

      <ctrl:SortableGVC Header="FirstName" SortPropertyName="FirstName" DisplayMemberBinding="{Binding Path=FirstName}" IsDefaultSortColumn="True"/>

      <ctrl:SortableGVC Header="LastName" SortPropertyName="LastName" DisplayMemberBinding="{Binding Path=LastName}"/>

    </ctrl:MyGridView>

  </ctrl:ListViewEx.View>

</ctrl:ListViewEx>

 

 

 

 

Answer 4

Ahh, I see you are right. That's a great idea and it works really well. Thank you very much !

 

Another thing I had tried to just get the headerStyle to work was :

 

Code Snippet

public GridViewEx()

{

StreamResourceInfo sri = Application.GetResourceStream(new Uri("Themes/ListViewEx.xaml", UriKind.Relative));

System.Windows.Markup.XamlReader reader = new System.Windows.Markup.XamlReader();

ResourceDictionary dic = (ResourceDictionary)reader.LoadAsync(sri.Stream);

 

this.ColumnHeaderContainerStyle = (Style)dic["ListViewExGridViewColumnHeader"];

}

 

 

It didn't work. I'm doing it wrong, I think. I was just curious, is it possible to have something like a GridView which is not a control pull up a Style from a xaml file in code behind and assign it to one of its properties like I was trying to do here?