Spell Checking

A red zigzag line under a word tells the user that it is misspelled. TXTextControl draws that line, counts the misspelled words and replaces them with corrections, but it does not decide which words are wrong: since version 16.0, it hands the changed text to your code, and your code asks a spell checker and reports the misspelled words back.

What follows explains this interface, fills it with a simple check of your own and then with TX Spell .NET, the spell checker of Text Control, through the TX Spell .NET ActiveX Package. The last sections correct misspelled words from a context menu and from a spelling dialog box of your own.

How Spell Checking Works

TX Text Control ActiveX has no dictionary of its own. Its spell checker interface lets you connect any spell checker to a TXTextControl, and it works in three steps:

1. You switch spell checking on with the EnableSpellChecking property.
2. Each time the text of the document changes, the control raises the SpellCheckText event. Its Text parameter holds the text to check.
3. Your event handler checks the text and returns the positions of the misspelled words in the MisspelledWordPositions parameter. TXTextControl underlines these words with a red zigzag line.

MisspelledWordPositions is an array of Long values that your handler creates. It holds two entries for each misspelled word, the start position and the end position, and both are one-based indexes into Text. For the text "This iss an exxample", with the misspelled words "iss" and "exxample", the array holds the four values 6, 8, 13 and 20.

After that, the control keeps track of the misspelled words. Your code reads their number with MisspelledWords, their position and length with MisspelledWordStart and MisspelledWordLength, and corrects or ignores a word with MisspelledWordDelete. All of these members count the misspelled words from the beginning to the end of the document, starting with 1.

Since version 20.0, a piece of text can be formatted for a language, which spell checking and hyphenation use. The Locale property sets it for the selected text as a Windows locale identifier (LCID), and the LocaleDialog method lets the user choose it.

Turn On Spell Checking

EnableSpellChecking is a Boolean property. Set it to True in the Properties window of Visual Basic, as the samples of the TX Spell .NET ActiveX Package do, or in code, for instance when the form loads:

Private Sub Form_Load()
    ' Raise the SpellCheckText event when the text changes
    TXTextControl1.EnableSpellChecking = True
End Sub

As long as EnableSpellChecking is False, the SpellCheckText event does not occur.

Report Misspelled Words to the Control

The following handler shows what the control expects from the SpellCheckText event. It splits the text at spaces and asks the function IsMisspelled about each word. In a real application, IsMisspelled calls a spell checker; here it knows two misspelled words, so you can try the handler with the text "This iss an exxample":

Private Sub TXTextControl1_SpellCheckText(ByVal Text As String, MisspelledWordPositions As Variant)
    Dim Positions() As Long
    Dim Count As Long
    Dim WordStart As Long
    Dim I As Long

    WordStart = 1
    For I = 1 To Len(Text) + 1
        ' A space or the end of the text ends a word
        If I > Len(Text) Or Mid$(Text, I, 1) = " " Then
            If IsMisspelled(Mid$(Text, WordStart, I - WordStart)) Then
                ReDim Preserve Positions(Count + 1)
                Positions(Count) = WordStart     ' one-based start
                Positions(Count + 1) = I - 1     ' one-based end
                Count = Count + 2
            End If
            WordStart = I + 1
        End If
    Next I

    ' Report the misspelled words, if there are any
    If Count > 0 Then MisspelledWordPositions = Positions
End Sub

Private Function IsMisspelled(Word As String) As Boolean
    ' Stand-in for a call to a spell checker
    IsMisspelled = (Word = "iss" Or Word = "exxample")
End Function

The code works as follows:

• The handler declaration is the one the samples of the TX Spell .NET ActiveX Package use: Text is passed by value as a String, and MisspelledWordPositions is a Variant that the handler assigns the array to.
• Positions collects two Long values for each misspelled word. The start is the one-based position of the word's first character in Text, and the end is the position of its last character.
• For "This iss an exxample", the handler returns 6, 8, 13 and 20, and TXTextControl underlines "iss" and "exxample".

Check With TX Spell .NET

TX Spell .NET is the spell checking component of Text Control for .NET applications, available as TX Spell .NET for Windows Forms. To use it from Visual Basic 6, Text Control released the TX Spell .NET ActiveX Package in January 2012, as the blog article TX Spell .NET ActiveX Package Released - Spell Checking in VB6 announced. It is a Visual Studio project that wraps TX Spell .NET for Windows Forms in a COM-visible control, AxTXSpellChecker, whose members Visual Basic 6 can call.

The package comes as source code, and you need TX Spell .NET for Windows Forms to build it. Since November 2012 the source has been open for changes by its users, as TX Spell .NET ActiveX Package Goes CodePlex explains; today it is the GitHub repository TXSpell.ActiveX-Package. The repository holds the wrapper project AxTXSpell and two Visual Basic 6 samples, Simple and DialogAndContextMenu. Its first_steps.md file describes how to build the wrapper in Visual Studio, register its type library with regasm and open the samples. The wrapper project references TX Spell .NET for Windows Forms 10.0 and targets .NET Framework 4.0.

With a reference to the wrapper's type library, which the samples list as TX Spell .NET ActiveX Package among their references, the whole spell checking code of the Simple sample is this:

Dim TXSpell1 As AxTXSpell.AxTXSpellChecker

Private Sub Form_Load()
    Set TXSpell1 = New AxTXSpellChecker
End Sub

Private Sub TXTextControl1_SpellCheckText(ByVal Text As String, MisspelledWordPositions As Variant)
    TXSpell1.Check (Text)
    MisspelledWordPositions = TXSpell1.MisspelledWordPositions
End Sub

The code works as follows:

• Form_Load creates one AxTXSpellChecker for the form. EnableSpellChecking is set to True in the Properties window of TXTextControl1.
• In the SpellCheckText event, the wrapper's Check method checks the text.
• The wrapper's MisspelledWordPositions property returns the start and end positions in the format that the event expects, so the handler assigns them directly.

The members of AxTXSpellChecker come from the source code of the package, not from TX Text Control ActiveX. Besides Check, the samples use CreateSuggestions and GetSuggestions for correction suggestions and OptionsDialog for the options dialog box of TX Spell .NET.

Correct a Word From a Context Menu

The DialogAndContextMenu sample opens a context menu with suggestions when the user right-clicks a misspelled word. Its MouseUp handler moves the input position, the place where the caret stands, to the clicked point, selects the misspelled word there and fills three menu items with suggestions:

Private Sub TXTextControl1_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)
    On Error Resume Next

    If Button = 2 Then
        TXTextControl1.SelStart = TXTextControl1.InputPosFromPoint(X, Y)
    End If

    If TXTextControl1.MisspelledWordAtInputPos = 0 Or Button <> 2 Then
        Exit Sub
    End If

    ' Select the misspelled word
    TXTextControl1.SelStart = TXTextControl1.MisspelledWordStart(TXTextControl1.MisspelledWordAtInputPos)
    TXTextControl1.SelLength = TXTextControl1.MisspelledWordLength(TXTextControl1.MisspelledWordAtInputPos)

    ' Get suggestions from TX Spell .NET
    TXSpell1.CreateSuggestions (TXTextControl1.SelText)
    suggestionsArray = TXSpell1.GetSuggestions

    mnuWord1.Caption = suggestionsArray(0)
    mnuWord2.Caption = suggestionsArray(1)
    mnuWord3.Caption = suggestionsArray(2)

    PopupMenu mnu_Spell
End Sub

Private Sub mnuWord1_Click()
    TXTextControl1.MisspelledWordDelete TXTextControl1.MisspelledWordAtInputPos, mnuWord1.Caption
End Sub

The sample also hides empty menu items and shows "No suggestions found." when there is no suggestion; the excerpt leaves this out. The code works as follows:

• A right click (Button = 2) moves the input position to the clicked point with InputPosFromPoint.
• MisspelledWordAtInputPos returns the number of the misspelled word at the input position. If there is none there, the property returns the next misspelled word, or the first one when none follows.
• To select a misspelled word, you assign MisspelledWordStart to SelStart and MisspelledWordLength to SelLength. SelText then returns the word.
• When the user chooses a suggestion, MisspelledWordDelete replaces the word's text with the suggestion and removes the word from the list of misspelled words.

Build a Spelling Dialog Box

The second form of the DialogAndContextMenu sample, a dialog box named Spelling, goes through the misspelled words of the document one by one. It always works on misspelled word number 1: once that word has been corrected or ignored, it leaves the list, and the next word becomes number 1. The excerpt below shows the Change and Ignore Once buttons. It is adapted from the sample: it leaves out the preview of the word in its line and the list of suggestions, and it ignores a word with an empty string, as the reference describes.

Private Sub NextMisspelledWord()
    If TXTextControl1.MisspelledWords = 0 Then
        MsgBox "Spell checking complete."
    Else
        ' Select the first remaining misspelled word
        TXTextControl1.SelStart = TXTextControl1.MisspelledWordStart(1)
        TXTextControl1.SelLength = TXTextControl1.MisspelledWordLength(1)
    End If
End Sub

Private Sub btnChange_Click()
    ' Replace the word with the selected suggestion
    TXTextControl1.MisspelledWordDelete 1, listSuggestions.Text
    NextMisspelledWord
End Sub

Private Sub btnIgnoreOnce_Click()
    ' Keep the word's text, remove it from the list
    TXTextControl1.MisspelledWordDelete 1, ""
    NextMisspelledWord
End Sub

The code works as follows:

• MisspelledWords returns the number of misspelled words in the document. When it is 0, the check is complete.
• MisspelledWordDelete takes the number of the word and a corrected text. With a corrected text, it replaces the word's text. With an empty string, the word's text stays as it is, and the word is only removed from the list of misspelled words.
• The method returns True when it could remove the word.

In the sample, the dialog box also sets HideSelection of the document's TXTextControl to False when it loads, so that the selected word stays visible while the dialog box has the input focus. The list of suggestions comes from the CreateSuggestions and GetSuggestions members of the wrapper.

Spell Checkers of Earlier Versions

Before the spell checker interface of version 16.0, TX Text Control ActiveX left spell checking to components of other vendors, which a special API of the control let them build for it, as the blog article Spell Checking in TX Text Control ActiveX of 2004 describes. The obsolete VTSpellCheck method and VTSpellDictionary property started the VT Speller of VisualTools, which was not part of the Text Control package and is no longer available. Use the spell checker interface described above instead.

Key Members

The programming category Spell Checking lists all members of the spell checker interface.

Related Pages

• Selections, Clipboard and Undo: selecting text in code with SelStart, SelLength and SelText.
• Character and Paragraph Formatting: the character attributes of the selected text, which the language belongs to.
• Version 16.0: the release that introduced the spell checker interface.
• Spell Checking: all members for spell checking.