WPF: DataTrigger is not triggering inside DataTemplate - wpf

Question

My requirement is to change foreground color to white if the background color of the Grid cell is Red.
I am using below template for the cell. But, its not triggering.
<DataTemplate x:Key="NumericThreeDecimalCellTemplate">
<TextBlock HorizontalAlignment="Right"
VerticalAlignment="Center">
<TextBlock.Text>
<Binding Path="Value"
StringFormat="###,###,###,###,###,###,##0.000;(###,###,###,###,###,###,##0.000)" />
</TextBlock.Text>
<TextBlock.Foreground>
<Binding Path="Value"
Converter="{StaticResource negativeToBrushConvertor}" />
</TextBlock.Foreground>
</TextBlock>
<DataTemplate.Resources>
<Style TargetType="{x:Type TextBlock}">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=Background.Color,RelativeSource={RelativeSource Mode=Self}}" Value="#FF0000">
<Setter Property="Foreground" Value="White" />
</DataTrigger>
</Style.Triggers>
</Style>
</DataTemplate.Resources>
</DataTemplate>`
Let me know if am doing anything wrong.

Answer 1

A local value, such as the returned by your negativeToBrushConverter, takes precedence over a value set by a style setter: https://learn.microsoft.com/en-us/dotnet/framework/wpf/advanced/dependency-property-value-precedence
So no matter what you set the Foreground property to in your Style, it won't be applied unless you remove this part:
<TextBlock.Foreground>
<Binding Path="Value" Converter="{StaticResource negativeToBrushConvertor}" />
</TextBlock.Foreground>
You should set the default value for the Foreground property in the Style. And you should set the AncestorType of the {RelativeSource} to whatever the property of your cell is:
<DataTemplate>
<TextBlock HorizontalAlignment="Right" VerticalAlignment="Center">
<TextBlock.Text>
<Binding Path="Value" StringFormat="###,###,###,###,###,###,##0.000;(###,###,###,###,###,###,##0.000)" />
</TextBlock.Text>
<TextBlock.Style>
<Style TargetType="{x:Type TextBlock}">
<Setter Property="Foreground">
<Setter.Value>
<Binding Path="Value" Converter="{StaticResource negativeToBrushConvertor}" />
</Setter.Value>
</Setter>
<Style.Triggers>
<DataTrigger Binding="{Binding Path=Background.Color,RelativeSource={RelativeSource AncestorType=dxg:GridCellContentPresenter}}" Value="#FF0000">
<Setter Property="Foreground" Value="White" />
</DataTrigger>
</Style.Triggers>
</Style>
</TextBlock.Style>
</TextBlock>
</DataTemplate>