Changing Border of WPF Tab Control Dynamically - wpf

Question

I'm using my own control template for the TabControl and TabItem in the application resource of my project.
In the template, the selected TabItem is colored depending on a property 'SelectedBrush' which returns a Brush. I would also like the Border of the Tab Control (boTabControl, the border around the content presenter) to do be the same color as the selected TabItem.
Is this a code thing, or can it be done in the application resource?
<Style TargetType="{x:Type TabControl}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TabControl}">
<Grid Margin="0">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<TabPanel Grid.Row="0" Panel.ZIndex="1" Margin="0,3,0,0" IsItemsHost="True" Background="Transparent"/>
<Border x:Name="boTabControl" Grid.Row="1" BorderThickness="1,3,0,0" CornerRadius="0" Padding="0" Margin="0" BorderBrush="{DynamicResource SelectedBrush}">
<ContentPresenter ContentSource="SelectedContent" Margin="0"/>
</Border>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsEnabled" Value="True">
<Setter TargetName="boTabControl" Property="BorderBrush" Value="{Binding SelectedBrush}" />
</Trigger>
<Trigger Property="IsEnabled" Value="False">
<Setter TargetName="boTabControl" Property="BorderBrush" Value="Blue" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style TargetType="{x:Type TabItem}">
<Setter Property="IsTabStop" Value="False"/>
<Setter Property="FontSize" Value="20"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TabItem}">
<Grid x:Name="Panel" Background="Transparent">
<Border x:Name="Border" Margin="0,0,-3,0" BorderThickness="1,1,1,0" CornerRadius="10,30,0,0">
<ContentPresenter x:Name="ContentSite" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" ContentSource="Header" Margin="10"/>
</Border>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter Property="FontWeight" Value="Bold" />
<Setter TargetName="Border" Property="Background" Value="{Binding SelectedBrush}" />
<Setter Property="Foreground" Value="White" />
</Trigger>
<Trigger Property="IsSelected" Value="False">
<Setter TargetName="Border" Property="Background" Value="LightGray" />
<Setter Property="FontWeight" Value="Normal" />
</Trigger>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="FontWeight" Value="Bold" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
Public ReadOnly Property SelectedBrush As Brush
Get
If Me.tcMain.SelectedItem Is Nothing Then
Return Brushes.Aquamarine
Exit Property
End If
Dim myTabItem As TabItem = Me.tcMain.SelectedItem
Dim myBrush As Brush = Brushes.Blue
Select Case myTabItem.Name
Case Me.tiSale.Name
myBrush = Brushes.Green
Case Me.tiReturn.Name
myBrush = Brushes.Red
Case Me.tiStock.Name
myBrush = Brushes.Black
Case Me.tiAdmin.Name
myBrush = Brushes.Purple
End Select
Return myBrush
End Get
End Property

Answer 1

here is an approach with an attached property SelectedBrush of type Brush
add Attached class to project (and make build):
public class Attached
{
public static DependencyProperty SelectedBrushProperty = DependencyProperty.RegisterAttached("SelectedBrush", typeof(Brush), typeof(Attached));
public static Brush GetSelectedBrush(DependencyObject obj)
{
return (Brush) obj.GetValue(SelectedBrushProperty);
}
public static void SetSelectedBrush(DependencyObject obj, Brush value)
{
obj.SetValue(SelectedBrushProperty, value);
}
}
then assign colors to each TabItem:
<TabControl>
<TabItem Name="tiSale" local:Attached.SelectedBrush="Green" Header="123"/>
<TabItem Name="tiReturn" local:Attached.SelectedBrush="Red" Header="abc"/>
<TabItem Name="tiStock" local:Attached.SelectedBrush="Black" Header="XYZ"/>
</TabControl>
change TabControl template to use Attached.SelectedBrush:
<Style TargetType="{x:Type TabControl}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TabControl}">
<Grid Margin="0">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<TabPanel Grid.Row="0" Panel.ZIndex="1" Margin="0,3,0,0" IsItemsHost="True" Background="Transparent"/>
<Border x:Name="boTabControl" Grid.Row="1"
BorderThickness="1,3,0,0"
BorderBrush="{Binding Path=SelectedItem.(local:Attached.SelectedBrush), RelativeSource={RelativeSource TemplatedParent}}"
CornerRadius="0" Padding="0" Margin="0">
<ContentPresenter ContentSource="SelectedContent" Margin="0"/>
</Border>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
to use the same brush for TabItem, change Background setter like this:
<Setter TargetName="Border" Property="Background"
Value="{Binding (local:Attached.SelectedBrush), RelativeSource={RelativeSource TemplatedParent}}" />
SelectedBrush property from code behind is not used here