How to restyle TextBox of DataGridTextColumn?

Question

I am working with a Wpf application. I have created a custom style for wpf DataGrid (provided in Wpf Toolkit). It all works fine except that I am unable to apply a Style on the TextBox that comes on double clicking the cell(editable mode) in DataGridTextColumn. It display as default style and that doesn't match with my style and looks odd. I have applied a style on the ComboBox in DataGridComboBoxColumn and the CheckBox and all other controls, but this one is not working. Any help plz!!!

Edit:

I have a control library and every control is overridden here for customization (additional functionality) and restyling. These controls are used through out the application. I have to apply this style on the control in control library. So that I can get it reflected in my whole application.

Answer 1

Not perfect, but works...

<Style x:Key="DataGridTextBoxStyle"
    TargetType="TextBox">
    <Setter
        Property="SelectionBrush"
        Value="#FFF8D172" />
    <Setter
        Property="Padding"
        Value="0" />
    <Setter
        Property="VerticalContentAlignment"
        Value="Center" />
    <Setter
        Property="FontSize"
        Value="9pt" />
    <Setter
        Property="SelectionOpacity"
        Value="0.6" />
</Style>

<DataGridTextColumn
   x:Name="TextColumn"
   Header="Header"
   EditingElementStyle="{StaticResource ResourceKey=DataGridTextBoxStyle}"/>

Answer 2

This can also be achieved with the PreparingCellForEdit event of the DataGrid, if you don't want to override the system EditingElementStyle, or if use AutoGenerateColumns, or when you have multiple columns and can't afford to set them individually.

private void DataGrid_PreparingCellForEdit(object sender, 
  DataGridPreparingCellForEditEventArgs e)
{
  if (!(e.Column is DataGridTextColumn && e.EditingElement is TextBox textBox))
    return;

  var style = new Style(typeof(TextBox), textBox.Style);        
  style.Setters.Add(new Setter { Property = ForegroundProperty, Value = Brushes.Red });
  textBox.Style = style;      
}

If you want to apply app resources:

private void DataGrid_PreparingCellForEdit(object sender, 
  DataGridPreparingCellForEditEventArgs e)
{
  if (!(e.Column is DataGridTextColumn && e.EditingElement is TextBox textBox))
    return;

  var tbType = typeof(TextBox);
  var resourcesStyle = Application
    .Current
    .Resources
    .Cast<DictionaryEntry>()
    .Where(de => de.Value is Style && de.Key is Type styleType && styleType == tbType)
    .Select(de => (Style)de.Value)
    .FirstOrDefault();

  var style = new Style(typeof(TextBox), resourcesStyle);
  foreach (var setter in textBox.Style.Setters)
    style.Setters.Add(setter);

  textBox.Style = style;
}