How to access controls in header style

[Peter Meinl]

I have defined ComboBoxes for filtering in the grid header style (see XAML below).
How can I access the ComboBoxes from code?

a)
I do not understand how to loop through the grids columns an access the ComboBox in each columns header.

b)
I the ComboBoxes SelectionChanged event I do not understand how to determine the grid column of the ComboBox raising the event.

       <Style x:Key="GridViewHeaderCellFilterStyle" TargetType="{x:Type telerik:GridViewHeaderCell}">
                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate TargetType="{x:Type telerik:GridViewHeaderCell}">
                            <Grid x:Name="PART_HeaderCellGrid">

                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition Width="*"/>
                                    <ColumnDefinition Width="Auto"/>
                                </Grid.ColumnDefinitions>

                     <!-- Modification Start-->
                            <Grid.RowDefinitions>
                                <RowDefinition Height="Auto" />
                                <RowDefinition Height="*" />
                            </Grid.RowDefinitions>
                            <Grid Grid.Row="1" Grid.ColumnSpan="2" Height="20">
                                    <Grid.ColumnDefinitions>
                                        <ColumnDefinition Width="Auto"/>
                                        <ColumnDefinition Width="*"/>
                                    </Grid.ColumnDefinitions>
                                <telerik:RadComboBox Grid.Column="0" x:Name="cboOperator" SelectionChanged="cboOperator_SelectionChanged"  FontWeight="Normal">
                                        <telerik:RadComboBoxItem Content="=" IsSelected="True"></telerik:RadComboBoxItem>
                                        <telerik:RadComboBoxItem Content="&lt;"></telerik:RadComboBoxItem>
                                        <telerik:RadComboBoxItem Content="&lt;="></telerik:RadComboBoxItem>
                                        <telerik:RadComboBoxItem Content="&gt;"></telerik:RadComboBoxItem>
                                        <telerik:RadComboBoxItem Content="&gt;="></telerik:RadComboBoxItem>
                                        <telerik:RadComboBoxItem Content="in"></telerik:RadComboBoxItem>
                                        <telerik:RadComboBoxItem Content="like"></telerik:RadComboBoxItem>
                                    </telerik:RadComboBox>
                                <telerik:RadComboBox Grid.Column="1" x:Name="cboValue"  HorizontalAlignment="Stretch" IsEditable="True" IsReadOnly="False" FontWeight="Normal"></telerik:RadComboBox>

                            </Grid>

                      <!-- Modification End -->


                            <Border x:Name="GridViewHeaderCell" Grid.ColumnSpan="2" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}">
                                    <Border Background="{TemplateBinding Background}" BorderBrush="#FF4B4B4B" BorderThickness="1"/>
                                </Border>
                                <Border x:Name="GridViewHeaderCell_Over" Opacity="0" Grid.ColumnSpan="2" BorderBrush="#FFFFC92B" BorderThickness="{TemplateBinding BorderThickness}">
                                    <Border BorderBrush="White" BorderThickness="1">
                                        <Border.Background>
                                            <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                                                <GradientStop Color="#FFFFFBA3" Offset="1"/>
                                                <GradientStop Color="#FFFFFBDA" Offset="0"/>
                                                <GradientStop Color="#FFFFD25A" Offset="0.43"/>
                                                <GradientStop Color="#FFFEEBAE" Offset="0.42"/>
                                            </LinearGradientBrush>
                                        </Border.Background>
                                    </Border>
                                </Border>
                                <Border x:Name="GridViewHeaderCell_Selected" Opacity="0" Grid.ColumnSpan="2" BorderThickness="{TemplateBinding BorderThickness}">
                                    <Border.BorderBrush>
                                        <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                                            <GradientStop Color="#FF616161" Offset="0"/>
                                            <GradientStop Color="#FF989898" Offset="1"/>
                                        </LinearGradientBrush>
                                    </Border.BorderBrush>
                                    <Border BorderThickness="1">
                                        <Border.Background>
                                            <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                                                <GradientStop Color="#FFFFD74E" Offset="0.996"/>
                                                <GradientStop Color="#FFFFDCAB" Offset="0.17"/>
                                                <GradientStop Color="#FFFFB062" Offset="0.57"/>
                                                <GradientStop Color="#FFFFD18F" Offset="0.56"/>
                                                <GradientStop Color="#FFFFBA74"/>
                                            </LinearGradientBrush>
                                        </Border.Background>
                                        <Border.BorderBrush>
                                            <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                                                <GradientStop Color="#FFB69A78"/>
                                                <GradientStop Color="#FFFFE17A" Offset="0.126"/>
                                            </LinearGradientBrush>
                                        </Border.BorderBrush>
                                    </Border>
                                </Border>
                                <ContentControl x:Name="ContentPresenter" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" Content="{TemplateBinding Content}" ContentTemplate="{TemplateBinding ContentTemplate}" Foreground="{TemplateBinding Foreground}" Grid.Column="0"/>
                                <Path x:Name="PART_SortIndicator" Fill="Black" Stretch="Fill" HorizontalAlignment="Center" Margin="0,3,0,0" VerticalAlignment="Top" Width="5" Height="3" Opacity="0" RenderTransformOrigin="0.5,0.5" Grid.ColumnSpan="2" Data="M0,0L1,0 2,0 3,0 4,0 5,0 5,1 4,1 4,2 3,2 3,3 2,3 2,2 1,2 1,1 0,1 0,0z">
                                    <Path.RenderTransform>
                                        <TransformGroup>
                                            <ScaleTransform ScaleX="1" ScaleY="-1"/>
                                            <SkewTransform AngleX="0" AngleY="0"/>
                                            <RotateTransform Angle="0"/>
                                            <TranslateTransform X="0" Y="0"/>
                                        </TransformGroup>
                                    </Path.RenderTransform>
                                </Path>
                                <!--<telerik:FilteringDropDown x:Name="PART_DistinctFilterControl" Margin="0,0,8,0" IsTabStop="False" Visibility="{TemplateBinding FilteringUIVisibility}" Grid.Column="1">
                                    <telerik:StyleManager.Theme>
                                        <telerik:Office_BlackTheme/>
                                    </telerik:StyleManager.Theme>
                                </telerik:FilteringDropDown>-->
                                <Thumb x:Name="PART_LeftHeaderGripper" HorizontalAlignment="Left" Grid.ColumnSpan="2">
                                    <Thumb.Style>
                                        <Style TargetType="{x:Type Thumb}">
                                            <Setter Property="Width" Value="8"/>
                                            <Setter Property="Background" Value="Transparent"/>
                                            <Setter Property="BorderBrush" Value="Transparent"/>
                                            <Setter Property="BorderThickness" Value="0"/>
                                            <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
                                            <Setter Property="VerticalContentAlignment" Value="Stretch"/>
                                            <Setter Property="Padding" Value="0"/>
                                            <Setter Property="Cursor" Value="SizeWE"/>
                                            <Setter Property="Template">
                                                <Setter.Value>
                                                    <ControlTemplate TargetType="{x:Type Thumb}">
                                                        <Border HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}"/>
                                                    </ControlTemplate>
                                                </Setter.Value>
                                            </Setter>
                                        </Style>
                                    </Thumb.Style>
                                </Thumb>
                                <Thumb x:Name="PART_RightHeaderGripper" HorizontalAlignment="Right" Grid.ColumnSpan="2">
                                    <Thumb.Style>
                                        <Style TargetType="{x:Type Thumb}">
                                            <Setter Property="Width" Value="8"/>
                                            <Setter Property="Background" Value="Transparent"/>
                                            <Setter Property="BorderBrush" Value="Transparent"/>
                                            <Setter Property="BorderThickness" Value="0"/>
                                            <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
                                            <Setter Property="VerticalContentAlignment" Value="Stretch"/>
                                            <Setter Property="Padding" Value="0"/>
                                            <Setter Property="Cursor" Value="SizeWE"/>
                                            <Setter Property="Template">
                                                <Setter.Value>
                                                    <ControlTemplate TargetType="{x:Type Thumb}">
                                                        <Border HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}"/>
                                                    </ControlTemplate>
                                                </Setter.Value>
                                            </Setter>
                                        </Style>
                                    </Thumb.Style>
                                </Thumb>
                            </Grid>
                            <ControlTemplate.Triggers>
                                <MultiTrigger>
                                    <MultiTrigger.EnterActions>
                                        <BeginStoryboard>
                                            <Storyboard>
                                                <DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="GridViewHeaderCell_Over" Storyboard.TargetProperty="Opacity">
                                                    <SplineDoubleKeyFrame KeyTime="00:00:00.2000000" Value="1"/>
                                                </DoubleAnimationUsingKeyFrames>
                                            </Storyboard>
                                        </BeginStoryboard>
                                    </MultiTrigger.EnterActions>
                                    <MultiTrigger.ExitActions>
                                        <BeginStoryboard>
                                            <Storyboard>
                                                <DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="GridViewHeaderCell_Over" Storyboard.TargetProperty="Opacity">
                                                    <SplineDoubleKeyFrame KeyTime="00:00:00.2000000" Value="0"/>
                                                </DoubleAnimationUsingKeyFrames>
                                            </Storyboard>
                                        </BeginStoryboard>
                                    </MultiTrigger.ExitActions>
                                    <MultiTrigger.Conditions>
                                        <Condition Property="IsMouseOver" Value="True"/>
                                        <Condition Property="SortingState" Value="None"/>
                                    </MultiTrigger.Conditions>
                                    <Setter Property="Foreground" Value="Black"/>
                                </MultiTrigger>
                                <Trigger Property="SortingState" Value="Ascending">
                                    <Setter Property="Foreground" Value="Black"/>
                                    <Setter Property="Opacity" TargetName="PART_SortIndicator" Value="1"/>
                                    <Setter Property="LayoutTransform" TargetName="PART_SortIndicator">
                                        <Setter.Value>
                                            <ScaleTransform ScaleX="1" ScaleY="1"/>
                                        </Setter.Value>
                                    </Setter>
                                    <Setter Property="Opacity" TargetName="GridViewHeaderCell_Selected" Value="1"/>
                                </Trigger>
                                <Trigger Property="SortingState" Value="Descending">
                                    <Setter Property="Foreground" Value="Black"/>
                                    <Setter Property="Opacity" TargetName="PART_SortIndicator" Value="1"/>
                                    <Setter Property="LayoutTransform" TargetName="PART_SortIndicator">
                                        <Setter.Value>
                                            <ScaleTransform ScaleX="1" ScaleY="-1"/>
                                        </Setter.Value>
                                    </Setter>
                                    <Setter Property="Opacity" TargetName="GridViewHeaderCell_Selected" Value="1"/>
                                </Trigger>
                                <Trigger Property="SortingState" Value="None">
                                    <Setter Property="Opacity" TargetName="PART_SortIndicator" Value="0"/>
                                </Trigger>
                            </ControlTemplate.Triggers>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
                <Setter Property="Background">
                    <Setter.Value>
                        <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                            <GradientStop Color="#FF5B5B5B" Offset="1"/>
                            <GradientStop Color="#FF868686"/>
                            <GradientStop Color="#FF4F4F4F" Offset="0.42"/>
                            <GradientStop Color="#FF0E0E0E" Offset="0.43"/>
                        </LinearGradientBrush>
                    </Setter.Value>
                </Setter>
                <Setter Property="BorderBrush" Value="#FF848484"/>
                <Setter Property="BorderThickness" Value="0,0,1,1"/>
                <Setter Property="VerticalContentAlignment" Value="Center"/>
                <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
                <Setter Property="Padding" Value="5,0,3,0"/>
                <Setter Property="Foreground" Value="White"/>
                <Setter Property="DropMarkPen">
                    <Setter.Value>
                        <Pen Brush="White" Thickness="2"/>
                    </Setter.Value>
                </Setter>
                <Setter Property="SnapsToDevicePixels" Value="True"/>
            </Style>

[Vlad]

Hello,

You can use both ParentOfType<> and ChildrenOfType<> to access controls in the cell visual tree. For example ParentOfType<GridViewHeaderCell> in SelectionChanged will get the parent header cell of the combo.

Greetings,
Vlad
the Telerik team

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