How to: Add Spell Check Items to the Standard Text Controls' Context Menu

• Jul 16, 2021
• 2 minutes to read

The following code example shows how to add spell check items for the .NET RichTextBox control’s context menu.

View Example

Create Binding to the RichTextEditor’s Context Menu

Create a new MenuItems property in code-behind and bind it to the RichTextBox’s ContextMenu property in XAML, as shown below:

C#

public MainWindow()
{
    DataContext = this;
    InitializeComponent();
}

public ObservableCollection<object> MenuItems { get; } = new ObservableCollection<object>();

VB.NET

Public Sub New()
    DataContext = Me
    InitializeComponent()
End Sub

Public ReadOnly Property MenuItems As ObservableCollection(Of Object) = New ObservableCollection(Of Object)()

XAML

<RichTextBox x:Name="richTextBox">
    <RichTextBox.ContextMenu>
        <ContextMenu ItemsSource="{Binding Path=MenuItems}"/>
    </RichTextBox.ContextMenu>
</RichTextBox>

Add SpellChecker Behavior

Add the SpellChecker behavior to the RichTextBox in XAML. Refer to the Configure Spell-Checking Behavior lesson for more information about the SpellChecker behavior and an example on how to add dictionaries.

XAML

<RichTextBox x:Name="richTextBox">
    <RichTextBox.ContextMenu>
        <ContextMenu ItemsSource="{Binding Path=MenuItems}"/>
    </RichTextBox.ContextMenu>
    <dxmvvm:Interaction.Behaviors>
        <dxspch:DXSpellChecker Culture="en-US" CheckAsYouType="True"/>
    </dxmvvm:Interaction.Behaviors>
</RichTextBox>

Handle the PreviewMouseRightButtonUp Event

Call the GetErrorOperationCommands method to obtain a list of available commands and assign it to the MenuItems property in the PreviewMouseRightButtonUp event handler. The SpellCheckerCommand.DoCommand method executes the retrieved command.

C#

void RichTextBox_PreviewMouseRightButtonUp(object sender, MouseButtonEventArgs e)
{
    MenuItems.Clear();
    var commands = this.richTextBox.GetErrorOperationCommands(e.GetPosition(this.richTextBox));
    foreach (var command in commands)
    {
        var menuItem = new MenuItem();
        menuItem.Header = command.Caption;
        menuItem.Click += (s, args) => command.DoCommand();
        menuItem.IsEnabled = command.Enabled;
        MenuItems.Add(menuItem);
    }
    if (MenuItems.Count == 0)
        MenuItems.Add(new MenuItem() { Header = "No Error", IsEnabled = false });
}

VB.NET

Private Sub RichTextBox_PreviewMouseRightButtonUp(ByVal sender As Object, ByVal e As MouseButtonEventArgs)
    MenuItems.Clear()
    Dim commands = Me.richTextBox.GetErrorOperationCommands(e.GetPosition(Me.richTextBox))
    For Each command In commands
        Dim menuItem = New MenuItem()
        menuItem.Header = command.Caption
        AddHandler menuItem.Click, Sub(s, args) command.DoCommand()
        menuItem.IsEnabled = command.Enabled
        MenuItems.Add(menuItem)
    Next command
    If MenuItems.Count = 0 Then
        MenuItems.Add(New MenuItem() With {.Header = "No Error", .IsEnabled = False})
    End If
End Sub

XAML

<RichTextBox x:Name="richTextBox" PreviewMouseRightButtonUp="RichTextBox_PreviewMouseRightButtonUp">
...
</RichTextBox>