SpellCheck As You Type with RadRichTextBox
| Date Posted | Product | Author |
|---|---|---|
| April 25, 2014 | RadRichTextBox | Georgi Georgiev |
How To
This article will demonstrate how to implement spellcheck as you type functionality in RadRichTextBox. Here is how our spell chcked RadRichTextBox will look like at the end:
Solution
First of all, we will need a derived class from RadRichTextBox:
public class SpellCheckRichTextBox : RadRichTextBox
{ }
Public Class SpellCheckRichTextBox
Inherits RadRichTextBox
End Class
Then we will need an instance of RadSpellChecker which will be used to check the words:
protected override void CreateChildItems(Telerik.WinControls.RadElement parent)
{
base.CreateChildItems(parent);
this.spellChecker = new RadSpellChecker();
this.controlSpellChecker = this.spellChecker.GetControlSpellChecker(typeof(RadRichTextBox));
this.controlSpellChecker.CurrentControl = this;
}
Protected Overrides Sub CreateChildItems(parent As Telerik.WinControls.RadElement)
MyBase.CreateChildItems(parent)
Me.spellChecker = New RadSpellChecker()
Me.controlSpellChecker = Me.spellChecker.GetControlSpellChecker(GetType(RadRichTextBox))
Me.controlSpellChecker.CurrentControl = Me
End Sub
Spell-checking will be performed when the Spacekey is pressed. We can override the OnKeyDown event and execute any spellchecking logic from there:
protected override void OnKeyDown(KeyEventArgs e)
{
if (e.KeyCode == Keys.Space)
{
this.SpellCheckCore(this.GetCurrentWord());
}
base.OnKeyDown(e);
}
Protected Overrides Sub OnKeyDown(e As KeyEventArgs)
If e.KeyCode = Keys.Space Then
Me.SpellCheckCore(Me.GetCurrentWord())
End If
MyBase.OnKeyDown(e)
End Sub
At this point, you are probably wondering what the SpellCheckCore and GetCurrentWord methods do. The GetCurrentWord method will get the word where the cursor is as a string by using the RadRichTextBox API:
private string GetCurrentWord()
{
DocumentPosition endPosition = new DocumentPosition(this.Document.CaretPosition);
DocumentPosition startPosition = new DocumentPosition(endPosition);
this.SelectCurrentWord(startPosition);
string lastWord = this.Document.Selection.GetSelectedText();
this.Document.Selection.Clear();
return lastWord;
}
Private Function GetCurrentWord() As String
Dim endPosition As New DocumentPosition(Me.Document.CaretPosition)
Dim startPosition As New DocumentPosition(endPosition)
Me.SelectCurrentWord(startPosition)
Dim lastWord As String = Me.Document.Selection.GetSelectedText()
Me.Document.Selection.Clear()
Return lastWord
End Function
On the other hand, the SpellCheckCore method will check whether a word is correct, and if it is not, it will be underlined. Also, if the word is a part of the IgnoredWords in the SpellChecker, it will be skipped:
protected virtual void SpellCheckCore(string word)
{
if (string.IsNullOrEmpty(word) || this.controlSpellChecker.IgnoredWords.ContainsWord(word))
{
return;
}
this.SelectCurrentWord(this.Document.CaretPosition);
if (this.AutoReplaceOnSpellCheck)
{
string[] suggestions = (string[])this.ControlSpellChecker.SpellChecker.GetSuggestions(this.Document.Selection.GetSelectedText());
if (suggestions.Length > 0)
{
this.Insert(suggestions[0]);
}
}
else
{
if (!controlSpellChecker.SpellChecker.CheckWordIsCorrect(word))
{
this.ChangeUnderlineDecoration(Telerik.WinControls.RichTextBox.UI.UnderlineType.Wave);
this.Document.Selection.Clear();
this.ChangeUnderlineDecoration(Telerik.WinControls.RichTextBox.UI.UnderlineType.None);
}
else
{
this.ChangeUnderlineDecoration(Telerik.WinControls.RichTextBox.UI.UnderlineType.None);
this.Document.Selection.Clear();
}
}
}
Protected Overridable Sub SpellCheckCore(word As String)
If String.IsNullOrEmpty(word) OrElse Me.controlSpellChecker.IgnoredWords.ContainsWord(word) Then
Return
End If
Me.SelectCurrentWord(Me.Document.CaretPosition)
If Me.AutoReplaceOnSpellCheck Then
Dim suggestions As String() = DirectCast(Me.ControlSpellChecker.SpellChecker.GetSuggestions(Me.Document.Selection.GetSelectedText()), String())
If suggestions.Length > 0 Then
Me.Insert(suggestions(0))
End If
Else
If Not controlSpellChecker.SpellChecker.CheckWordIsCorrect(word) Then
Me.ChangeUnderlineDecoration(Telerik.WinControls.RichTextBox.UI.UnderlineType.Wave)
Me.Document.Selection.Clear()
Me.ChangeUnderlineDecoration(Telerik.WinControls.RichTextBox.UI.UnderlineType.None)
Else
Me.ChangeUnderlineDecoration(Telerik.WinControls.RichTextBox.UI.UnderlineType.None)
Me.Document.Selection.Clear()
End If
End If
End Sub
The If statement, which checks the AutoReplaceOnSpellCheck property, is used to replace the current word, if it is incorrect with the first suggestion in the dictionary. After our Control is capable of spellchecking while we are typing, we can implement a context menu to see a list of suggestions and use the Copy/Paste/Undo/Delete/SelectAll actions. Here is how the context menu can be built in a single method:
private RadDropDownMenu BuildContextMenu(SpanLayoutBox spanBox)
{
RadDropDownMenu menu = new RadDropDownMenu();
RadMenuItem menuItem;
if (this.Document.Selection.IsEmpty && this.IsSpellCheckingEnabled && spanBox != null)
{
this.Document.CaretPosition.MoveToInline(spanBox, 0);
string spanBoxTextAlphaNumericOnly = String.Concat(spanBox.Text.TakeWhile(c => char.IsLetterOrDigit(c)));
if (spanBoxTextAlphaNumericOnly.Length > 0 && !this.ControlSpellChecker.SpellChecker.CheckWordIsCorrect(spanBoxTextAlphaNumericOnly))
{
string[] suggestions = (string[])this.ControlSpellChecker.SpellChecker.GetSuggestions(spanBox.Text);
if (suggestions.Length <= 0)
{
menuItem = new RadMenuItem("(No Spelling Suggestions)");
menuItem.Enabled = false;
menu.Items.Add(menuItem);
}
foreach (string suggestion in suggestions)
{
menuItem = new RadMenuItem(suggestion);
menuItem.Click += (object sender, EventArgs e) => { this.ReplaceCurrentWord(spanBox, (sender as RadMenuItem).Text); };
menu.Items.Add(menuItem);
}
menu.Items.Add(new SeparatorElement());
menuItem = new RadMenuItem("Add to Dictionary");
menuItem.Click += (object sender, EventArgs e) => { this.ControlSpellChecker.SpellChecker.AddWord(spanBoxTextAlphaNumericOnly); };
menu.Items.Add(menuItem);
menu.Items.Add(new SeparatorElement());
}
}
menuItem = new RadMenuItem("Undo");
menuItem.Click += (object sender, EventArgs e) => { this.Undo(); };
menu.Items.Add(menuItem);
menu.Items.Add(new SeparatorElement());
menuItem = new RadMenuItem("Cut");
menuItem.Click += (object sender, EventArgs e) => { this.Cut(); };
menu.Items.Add(menuItem);
menuItem = new RadMenuItem("Copy");
menuItem.Click += (object sender, EventArgs e) => { this.Copy(); };
menu.Items.Add(menuItem);
menuItem = new RadMenuItem("Paste");
menuItem.Click += (object sender, EventArgs e) => { this.Paste(); };
menu.Items.Add(menuItem);
menuItem = new RadMenuItem("Delete");
menuItem.Click += (object sender, EventArgs e) => { this.Delete(false); };
menu.Items.Add(menuItem);
menu.Items.Add(new SeparatorElement());
menuItem = new RadMenuItem("Select All");
menuItem.Click += (object sender, EventArgs e) => { this.Document.Selection.SelectAll(); };
menu.Items.Add(menuItem);
return menu;
}
Private Function BuildContextMenu(spanBox As SpanLayoutBox) As RadDropDownMenu
Dim menu As New RadDropDownMenu()
Dim menuItem As RadMenuItem
If Me.Document.Selection.IsEmpty AndAlso Me.IsSpellCheckingEnabled AndAlso spanBox IsNot Nothing Then
Me.Document.CaretPosition.MoveToInline(spanBox, 0)
Dim spanBoxTextAlphaNumericOnly As String = [String].Concat(spanBox.Text.TakeWhile(Function(c) Char.IsLetterOrDigit(c)))
If spanBoxTextAlphaNumericOnly.Length > 0 AndAlso Not Me.ControlSpellChecker.SpellChecker.CheckWordIsCorrect(spanBoxTextAlphaNumericOnly) Then
Dim suggestions As String() = DirectCast(Me.ControlSpellChecker.SpellChecker.GetSuggestions(spanBox.Text), String())
If suggestions.Length <= 0 Then
menuItem = New RadMenuItem("(No Spelling Suggestions)")
menuItem.Enabled = False
menu.Items.Add(menuItem)
End If
For Each suggestion As String In suggestions
menuItem = New RadMenuItem(suggestion)
AddHandler menuItem.Click, Sub(sender As Object, e As EventArgs)
Me.ReplaceCurrentWord(spanBox, TryCast(sender, RadMenuItem).Text)
End Sub
menu.Items.Add(menuItem)
Next
menu.Items.Add(New SeparatorElement())
menuItem = New RadMenuItem("Add to Dictionary")
AddHandler menuItem.Click, Sub(sender As Object, e As EventArgs)
Me.ControlSpellChecker.SpellChecker.AddWord(spanBoxTextAlphaNumericOnly)
End Sub
menu.Items.Add(menuItem)
menu.Items.Add(New SeparatorElement())
End If
End If
menuItem = New RadMenuItem("Undo")
AddHandler menuItem.Click, Sub(sender As Object, e As EventArgs)
Me.Undo()
End Sub
menu.Items.Add(menuItem)
menu.Items.Add(New SeparatorElement())
menuItem = New RadMenuItem("Cut")
AddHandler menuItem.Click, Sub(sender As Object, e As EventArgs)
Me.Cut()
End Sub
menu.Items.Add(menuItem)
menuItem = New RadMenuItem("Copy")
AddHandler menuItem.Click, Sub(sender As Object, e As EventArgs)
Me.Copy()
End Sub
menu.Items.Add(menuItem)
menuItem = New RadMenuItem("Paste")
AddHandler menuItem.Click, Sub(sender As Object, e As EventArgs)
Me.Paste()
End Sub
menu.Items.Add(menuItem)
menuItem = New RadMenuItem("Delete")
AddHandler menuItem.Click, Sub(sender As Object, e As EventArgs)
Me.Delete(False)
End Sub
menu.Items.Add(menuItem)
menu.Items.Add(New SeparatorElement())
menuItem = New RadMenuItem("Select All")
AddHandler menuItem.Click, Sub(sender As Object, e As EventArgs)
Me.Document.Selection.SelectAll()
End Sub
menu.Items.Add(menuItem)
Return menu
End Function
We can easily show it on Right Mouse Click:
protected override void OnMouseDown(System.Windows.Forms.MouseEventArgs e)
{
if (e.Button == System.Windows.Forms.MouseButtons.Right)
{
SpanLayoutBox spanBox = this.Document.GetLayoutBoxByPosition(e.Location) as SpanLayoutBox;
this.BuildContextMenu(spanBox).Show(this, e.Location);
}
base.OnMouseDown(e);
}
Protected Overrides Sub OnMouseDown(e As System.Windows.Forms.MouseEventArgs)
If e.Button = System.Windows.Forms.MouseButtons.Right Then
Dim spanBox As SpanLayoutBox = TryCast(Me.Document.GetLayoutBoxByPosition(e.Location), SpanLayoutBox)
Me.BuildContextMenu(spanBox).Show(Me, e.Location)
End If
MyBase.OnMouseDown(e)
End Sub
A complete solution in C# and VB.NET can be found here.