I have a template for a DataGrid located in a ResourceDictionary.

BlockStyles.xaml

<Style TargetType="DataGrid" x:Key="SearchExpGrid">
    <Setter Property="AlternatingRowBackground" Value="#4C87C6ff"/>
    <Setter Property="GridLinesVisibility" Value="None"/>
    <Setter Property="FontSize" Value="15"/>
    <Setter Property="HeadersVisibility" Value="Column"/>
    <Setter Property="CellStyle">
        <Setter.Value ... />
    </Setter>
    <Setter Property="RowStyle">
        <Setter.Value ... />
    </Setter>
    <Setter Property="ColumnHeaderStyle">
        <Setter.Value>
            <Style TargetType="DataGridColumnHeader">
                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate>
                            <Border 
                                x:Name="Border" Background="White" BorderBrush="#4C87C6" BorderThickness="1" >
                                <StackPanel Orientation="Horizontal" Margin="5,5" HorizontalAlignment="Center">
                                    <TextBlock 
                                        x:Name="TxtB"  Text="{Binding}"
                                        Foreground="#4C87C6" FontWeight="DemiBold" HorizontalAlignment="Center"/>
                                    <Image Source="../Images/dropdown.png"
                                               Width="10" Height="10" Margin="5,0,5,0"
                                              MouseEnter="DropdownButton_MouseEnter"
                                              MouseLeave="DropdownButton_MouseLeave"
                                              MouseEnter="DropdownButton_Click"/>
                                </StackPanel>
                            </Border>
                            <ControlTemplate.Triggers>
                                <Trigger Property="IsMouseOver" Value="True">
                                    <Setter TargetName="Border" Property="Background" Value="#4C87C6"/>
                                    <Setter TargetName="TxtB" Property="Foreground" Value="White"/>
                                </Trigger>
                            </ControlTemplate.Triggers>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
            </Style>
        </Setter.Value>
    </Setter>
</Style>

I always have an error because the function can't find it's definition.

I first implemented the function in the View file where the style is used but it doesn't work.

I tried this method from StackOverflow using a resource class inheriting ResourceDictionnary but got the same error.

I then tried to use ICommand and RelayCommand to execute the function from the ViewModel but didn't got any result.

I also didn't find where I could add an EventHandler ImgDropdownButton.MouseEnter = new MouseEventHandler(MouseEnter_DropdownButton); using MVVM.

Is there a better solution for this kind of behaviour or if adding an EventHandler is the best solution, where sould be the best place to add it ?

Thanks in advance

Edit :

I managed to handle the function using a code-behind file for my ResourceDictionary following this.

BlockStyles.xaml.cs

private void DropdownButton_MouseEnter(object sender, System.Windows.Input.MouseEventArgs e)
{
    Mouse.OverrideCursor = Cursors.Hand;
}

private void DropdownButton_MouseLeave(object sender, System.Windows.Input.MouseEventArgs e)
{
    Mouse.OverrideCursor = Cursors.Arrow;
}

private void DropdownButton_Click(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
    //Function to show the popup
}

The MouseEnter and MouseLeave function are working, but I don't understand how to use the function to make my popup appear.

What I'm trying to do is that when I click on the Dropdown Image on the column header, I want to display a Popup, like an Excel one. This will allow the user to filter the columns values.

The file where my Grid and Popup are : (SearchExpView.xaml)

<Grid Grid.Row="2" Grid.Column="1">
    <searchcomponents:ExpListView x:Name="ExpDatagrid"
        DataContext="{Binding OExpListVM}" 
        Width="auto" Height="auto"/>
</Grid>

<Popup x:Name="PopupFiltre">
    PopupFiltre content
</Popup>

Definition of my Datagrid : (ExpListView.xaml)

<Grid>
    <DataGrid x:Name="ExpGrid" Style="{StaticResource SearchExpGrid}"
                  BorderThickness="0" BorderBrush="#4C87C6"
                  HorizontalAlignment="Left" VerticalAlignment="Top" 
                  MinHeight="200" Height="auto" Margin="10,10,0,0"
                  MinWidth="780" Width="auto"
                  ItemsSource="{Binding}" DataContext="{Binding tableExpertise.DefaultView}"
                  AutoGenerateColumns="True" CanUserAddRows="False" IsReadOnly="True">
        <DataGrid.InputBindings>
            <MouseBinding MouseAction="LeftDoubleClick"
                              Command="{Binding DataContext.OnRowDoubleClickedCommand, RelativeSource={RelativeSource AncestorType=UserControl}}"
                              CommandParameter="{Binding ElementName=ExpGrid, Path=CurrentItem}"/>
        </DataGrid.InputBindings>
        <DataGrid.ContextMenu>
            <ContextMenu Name="dgctxmenu">
                <Separator></Separator>
            </ContextMenu>
        </DataGrid.ContextMenu>
    </DataGrid>
</Grid>

I'm looking for a way to be able to implement this popup fonction but I can't find out how to link everything together.

CodePudding user response：

My Window is SearchExpView.xaml (with the Datagrid and the Popup). My Datagrid component is defined in ExpListView.xaml and styled in BlockStyles.xaml, which is not a window. I want to make the Popup (in SearchExpView.xaml) visible by clicking on the dropdown button (defined in BlockStyles.xaml)

Then you need to get a reference to the Popup in the window from the ResourceDictionary somehow.

You could for example use the static Application.Current.Windows property:

var window = Application.Current.Windows.OfType<SearchExpView>().FirstOrDefault();
if (window != null)
    window.PopupFiltre.IsOpen = true;

Also make sure that you make the Popup accessible from outside the SearchExpView class:

<Popup x:Name="PopupFiltre" x:FieldModifier="internal">
...