This example illustrates how to resize the row header column in WPF DataGrid (SfDataGrid).
DataGrid does not provide the direct support to resize the row header column. You can resize the row header column by overriding the GridRowHeaderCell and GridRowHeaderIndentCell by triggering the Thumb.DragDelta event.
<Window.Resources>
<Style TargetType="syncfusion:GridRowHeaderCell">
<Setter Property="Background" Value="Transparent" />
<Setter Property="BorderBrush" Value="Gray" />
<Setter Property="BorderThickness" Value="0,0,1,1" />
<Setter Property="Padding" Value="0,0,0,0" />
<Setter Property="FocusVisualStyle" Value="{x:Null}" />
<Setter Property="IsTabStop" Value="False" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="syncfusion:GridRowHeaderCell">
<Grid>
<Border x:Name="PART_RowHeaderCellBorder"
Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="BorderStates">
<VisualState x:Name="NormalCell"/>
<VisualState x:Name="TableSummaryCell">
<Storyboard BeginTime="0">
<ThicknessAnimationUsingKeyFrames Storyboard.TargetName="PART_RowHeaderCellBorder" Storyboard.TargetProperty="(Border.BorderThickness)">
<EasingThicknessKeyFrame KeyTime="0" Value="0" />
</ThicknessAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Fixed_NormalCell">
<Storyboard BeginTime="0">
<ThicknessAnimationUsingKeyFrames BeginTime="0"
Duration="1"
Storyboard.TargetName="PART_RowHeaderCellBorder"
Storyboard.TargetProperty="BorderThickness">
<EasingThicknessKeyFrame KeyTime="0" Value="0, 1, 1, 1" />
</ThicknessAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="IndicationStates">
<VisualState x:Name="Normal">
</VisualState>
<VisualState x:Name="Error_CurrentRow">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="PART_RowHeaderIndicator" Storyboard.TargetProperty="Data">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Geometry>F1 M 397.333,276.552L 395.445,274.666L 392,278.112L 388.555,274.666L 386.667,276.552L 390.113,279.999L 386.667,283.445L 388.555,285.334L 392,281.887L 395.445,285.334L 397.333,283.445L 393.887,279.999L 397.333,276.552 Z</Geometry>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ColorAnimationUsingKeyFrames Storyboard.TargetName="PART_RowHeaderIndicator" Storyboard.TargetProperty="(Shape.Fill).(SolidColorBrush.Color)">
<EasingColorKeyFrame KeyTime="0" Value="#FFFF3D2E" />
</ColorAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Error">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="PART_RowHeaderIndicator" Storyboard.TargetProperty="Data">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Geometry>F1 M 397.333,276.552L 395.445,274.666L 392,278.112L 388.555,274.666L 386.667,276.552L 390.113,279.999L 386.667,283.445L 388.555,285.334L 392,281.887L 395.445,285.334L 397.333,283.445L 393.887,279.999L 397.333,276.552 Z</Geometry>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ColorAnimationUsingKeyFrames Storyboard.TargetName="PART_RowHeaderIndicator" Storyboard.TargetProperty="(Shape.Fill).(SolidColorBrush.Color)">
<EasingColorKeyFrame KeyTime="0" Value="#FFEC777C" />
</ColorAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="CurrentRow">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="PART_RowHeaderIndicator" Storyboard.TargetProperty="Data">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Geometry>F1 M 390.741,274.667L 387.928,274.667L 393.048,280L 387.927,285.333L 390.741,285.333L 396.073,280L 390.741,274.667 Z</Geometry>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="PART_ToolTip" Storyboard.TargetProperty="(UIElement.Visibility)">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Collapsed</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="EditingRow">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="PART_RowHeaderIndicator" Storyboard.TargetProperty="Data">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Geometry>M6.8007798,1.7332839 L8.97791,3.9143763 2.8868401,10.034073 0,10.666874 0.70837402,7.8491302 z M9.1967516,0.00016105175 C9.5903473,-0.0053596497 9.9693098,0.13107061 10.251301,0.41431141 10.856801,1.0224026 10.794301,2.067961 10.110801,2.7515601 L7.9219999,0.5588423 C8.2858057,0.19500291 8.7506762,0.0064178705 9.1967516,0.00016105175z</Geometry>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="PART_ToolTip" Storyboard.TargetProperty="(UIElement.Visibility)">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Collapsed</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="AddNewRow">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="PART_RowHeaderIndicator" Storyboard.TargetProperty="Data">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Geometry>F1 M 397.333,278.825L 393.176,278.825L 393.176,274.667L 390.824,274.667L 390.824,278.825L 386.667,278.825L 386.667,281.175L 390.824,281.175L 390.824,285.333L 393.176,285.333L 393.176,281.175L 397.333,281.175L 397.333,278.825 Z</Geometry>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="PART_ToolTip" Storyboard.TargetProperty="(UIElement.Visibility)">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Collapsed</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="FilterRow">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="PART_RowHeaderIndicator" Storyboard.TargetProperty="Data">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Geometry>F1M12,6L12,7L13,7L13,8L14,8L14,9L15,9L15,13L17,14L17,9L18,9L18,8L19,8L19,7L20,7L20,6z</Geometry>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="PART_ToolTip" Storyboard.TargetProperty="(UIElement.Visibility)">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Collapsed</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Path x:Name="PART_RowHeaderIndicator"
Width="8.146"
Height="8.146"
HorizontalAlignment="Center"
VerticalAlignment="Center"
Fill="#FF303030"
Stretch="Fill">
<ToolTipService.ToolTip>
<ToolTip x:Name="PART_ToolTip"
Background="#FFDB000C"
Placement="Left"
PlacementRectangle="20,0,0,0"
Tag="{TemplateBinding RowErrorMessage}"/>
</ToolTipService.ToolTip>
</Path>
</Border>
<Thumb x:Name="PART_RightHeaderGripper" HorizontalAlignment="Right" DragDelta="PART_RightHeaderGripper_DragDelta" Tag="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type syncfusion:SfDataGrid}}}">
<Thumb.Style>
<Style TargetType="{x:Type Thumb}">
<Setter Property="Width" Value="8"/>
<Setter Property="Background" Value="Transparent"/>
<Setter Property="Cursor" Value="SizeWE"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Thumb}">
<Border Background="{TemplateBinding Background}" Padding="{TemplateBinding Padding}"/>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Thumb.Style>
</Thumb>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style TargetType="syncfusion:GridRowHeaderIndentCell">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="syncfusion:GridRowHeaderIndentCell">
<Grid>
<Border Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}" />
<Thumb x:Name="PART_RightHeaderGripper" HorizontalAlignment="Right" DragDelta="PART_RightHeaderGripper_DragDelta" Tag="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type syncfusion:SfDataGrid}}}">
<Thumb.Style>
<Style TargetType="{x:Type Thumb}">
<Setter Property="Width" Value="8"/>
<Setter Property="Background" Value="Transparent"/>
<Setter Property="Cursor" Value="SizeWE"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Thumb}">
<Border Background="{TemplateBinding Background}" Padding="{TemplateBinding Padding}"/>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Thumb.Style>
</Thumb>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Window.Resources>private void PART_RightHeaderGripper_DragDelta(object sender, System.Windows.Controls.Primitives.DragDeltaEventArgs e)
{
SfDataGrid sfDataGrid = (sender as Thumb).Tag as SfDataGrid;
var width = sfDataGrid.RowHeaderWidth + e.HorizontalChange;
if (width >= 24)
sfDataGrid.RowHeaderWidth = width;
}