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

• Mar 29, 2019
• 2 minutes to read

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

Note

A complete code sample is available at how-to-add-spell-check-menu-items-to-the-standard-text-controls repository in GitHub.

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 Lesson 1 - 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>