Control created in code behind does not have it's default Style

Question

I am trying to instantiate a control in my window's code behind (for Frame Navigation). Unfortunately, it's not getting the default style applied to it.

I would expect that when a control is first rendered, the renderer would set the control's Style/Template to either (the explicitly supplied one -> the default one supplied in the resources -> null).

Is my mental model of how default styles are applied wrong? Is it actually like how

class Whatever
{
    int value = 5;
}

is really syntactic sugar for

class Whatever
{
    public Whatever()
    {
        this.value = 5;
    }

    int value;
}

And thus the Style is being set at compile time?

Could it be a problem stemming from how I'm accessing the Styles and Templates for the control (unlikely as I can make a control of it's type on my main window and it has the default Style)?

MainWindow.xaml

<Window>
    <Window.Resources>
        <ResourceDictionary>
            </ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="DataLogPage/Themes.xaml" />
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Window.Resources>
    <!-- Data here... -->
</Window>

DatalogPage/Themes.xaml

<ResourceDictionary>
    <ResourceDictionary.MergedDictionaries>
        <ResourceDictionary Source="Themes/Styles/DefaultStyle.xaml" />
    </ResourceDictionary.MergedDictionaries>
</ResourceDictionary>

DatalogPage/Themes/Styles/DefaultStyle.xaml

<ResourceDictionary>
    <ResourceDictionary.MergedDictionaries>
        <ResourceDictionary Source="../Templates/DefaultTemplate.xaml" />
    </ResourceDictionary.MergedDictionaries>
    <Style TargetType="this:DataLog">
        <Setter Property="Template"
                Value="{StaticResource DefaultTemplateForDataLog}" />
    </Style>
</ResourceDictionary>

DatalogPage/Themes/Templates/DefaultTemplate.xaml

<ResourceDictionary>
    <ControlTemplate x:Key="DefaultTemplateForDataLog"
                     TargetType="this:DataLog">
        <!-- Data here... -->
    </ControlTemplate>
</ResourceDictionary>

MainWindow.xaml.cs (where I'm creating the control in the code behind)

private void currentContext_ContextChangeRequested()
{
    //Other bits of logic for context switching

    //User wants to go to the Data Log Page
    this.MainFrame.Navigate(new DataLogPage.DataLog());
    return;
}

To reiterate:

Problem: Control created in code behind does not have it's default Style.

Possible ideas on why this may be:

1)My user model for how default styles are applied is wrong and I must set it explicitly.
2)I may be referencing the style incorrectly.

If I have to explicitly set the Style/Template, is there a best-of-both-worlds where I can make something in the MainWindow's xaml that I can programmatically reference like so: new DataLogPage.DataLog(){Style = this.DataLogStyle};?

Answer 1

App.xaml

If you really want stuff shared you may inject them into the shared application resources, or you may merge them in app.xaml

<Application x:Class="BlaBla"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         StartupUri="MainWindow.xaml">
   <Application.Resources>
     <ResourceDictionary>
       <ResourceDictionary.MergedDictionaries>
          <ResourceDictionary Source="A.xaml"/>
          <ResourceDictionary Source="B.xaml"/>
       </ResourceDictionary.MergedDictionaries>
    </ResourceDictionary>
  </Application.Resources>
</Application>

Using a global ResourceDictionary in a UserControl Library

WPF - Global Style?

Templates and cust controls

Applies to customcontrols only (**)

First off I would never start merging or using dictionaries that way in a window(That's if you go the cc way, your rather merge these dictionaries in the generic files described below, note they must be in scope though). You have a folder called Generic, which must have a file called Themes.xaml present. Personally I merge alot of dictionaries here and also do some "manual labor". Typically i call my cust control Foo's theme ThemeName.generic.xaml, but that's just my preference. :).

A customcontrol should derrive from control and it must have the following static constructor, for having it's template applied.

public class Whatever : Control // from scratch or something you want to extend
   static Whatever()
   {
       DefaultStyleKeyProperty.OverrideMetadata(typeof (Whatever), new FrameworkPropertyMetadata(typeof (Whatever)));
   }
}

<Style TargetType="{x:Type local:Whatever}">
    <!-- Do whatever here ;) -->
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:Whatever}">
                <Border Background="{TemplateBinding Background}"
                        BorderBrush="{TemplateBinding BorderBrush}"
                        BorderThickness="{TemplateBinding BorderThickness}">
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

Override OnApplyTemplate to see if the template is applied. (*)

Styles

Applies to styling.

To override an existing controls template you do the following in themes.xaml. This will make all your button controls have this style by default.

 <Style TargetType="{x:Type Button}">
    <Setter Property="Background" Value="Green"/> 
 </Style>

I often just put styles directly in ie a usercontrol's resources, but mostly data,itemptemplates etc if they don't belong in a cust control, anyways this is how to do that:

<UserControl.Resources>
    <!-- usuallly  just datatemplates, itemtemplates etc.. -->
    <Style x:Key="SomeStyle" TargetType="{x:Type Button}">
        <!--whatever -->
        <Setter Property="Background" Value="Black"/>
    </Style>
</UserControl.Resources>
<Button Style="{StaticResource SomeStyle}"></Button>

BTW: You may load most things dynamicly and even from other assemblies. Resources, templates the works. But that's another subject :)

Hope it helped you some,

Cheers

Stian