Include XAML Trigger To ControlTemplate - wpf

Question

I am pretty new with WPF and am doing some custom control stuff...
My problem is that the code in one file is going to be way to much, so i want
to split the code in seperate files, so other people looking in that code aren´t going to be overwhelmed.
Okay to my question...
I got a ResourceDictionary... the "Generic.xaml"
In this file a got the template of an DataGrid:
<Style TargetType="{x:Type local:BADataGrid}">
<Style.Setters>
<Setter Property="Control.Template">
<Setter.Value>
<ControlTemplate TargetType="local:BADataGrid">
<Border BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Background="{TemplateBinding Background}"
Padding="{TemplateBinding Padding}"
SnapsToDevicePixels="True">
<!-- *SOME TEMPLATE CODE* -->
</Border>
<ControlTemplate.Triggers>
<Trigger Property="GridStyle" Value="CUSTOMER">
<Trigger.Setters>
<Setter Property="ColumnHeaderStyle">
<Setter.Value>
<Style TargetType="{x:Type DataGridColumnHeader}">
<Setter Property="Background">
<Setter.Value>
<ImageBrush>
<ImageBrush.ImageSource>
<Binding Path="HeaderBackground" RelativeSource="{RelativeSource AncestorType=local:BADataGrid}">
<Binding.TargetNullValue>
<ImageSource>
headerBack.png
</ImageSource>
</Binding.TargetNullValue>
</Binding>
</ImageBrush.ImageSource>
</ImageBrush>
</Setter.Value>
</Setter>
</Style>
</Setter.Value>
</Setter>
</Trigger.Setters>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style.Setters>
</Style>
Now I want the "ControlTemplate.Triggers" part of the code above in another .XAML File.
Is this even possible?

Answer 1

it´s me again. Sorry it took me so long to answer.
I am a few steps ahead now... I got the Trigger in an additional ResourceDictionary, and if I impletment it in the "Window.Resources" where I implement the control everything works just fine.
My problem now is... I don´t want to implement the ResourceDictionary in the "Window.Resources" but in the "ControlTemplate.Resources" of my custom control. But when I do so it tell´s me :
"Unable to cast object of type 'Microsoft.Expression.Markup.DocumentModel.DocumentCompositeNode' to type 'System.Windows.ResourceDictionary'.
<ControlTemplate.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary
Source="Customer.xaml" />
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</ControlTemplate.Resources>
If I copy the code inside the Customer.xaml ResourceDictionary into the ControlTemplate.Resources it works... but I want it in an additional file...
Any ideas?

Answer 2

Look into Resource Dictionaries. That should allow you to split styles across files.

Answer 3

Did it with a nasty workaround... I´ll just share it with you.
I just implemented an event that is fired when the DataGrid is loaded.
In this event I load the ResourceDictionarys i wanted to add to the control template
in ResourceDictionary object´s. Then i iterate through all entrys in the ResourceDictionary object and add each seperate to the ControlTemplate´s resources...
Here´s the code:
void DataGridLoaded(object sender, RoutedEventArgs e)
{
BADataGrid dg = (BADataGrid)VisualTreeHelper.GetParent((DependencyObject)sender);
List<string> resourceList = new List<string>();
resourceList.Add(Properties.Resources.Customer);
foreach (string s in resourceList)
{
System.Xml.XmlReader xmlReader = new System.Xml.XmlTextReader(new System.IO.StringReader(s));
ResourceDictionary resource = (ResourceDictionary)XamlReader.Load(xmlReader);
foreach (System.Collections.DictionaryEntry item in resource)
{
dg.Resources.Add(item.Key, item.Value);
}
}