How To Generate Indexes with TX Text Control

Brian Noyes from DevX (http://www.devx.com) has written a review about TX Text Control:

"Many applications need to provide some document editing and creation capabilities as part of their functionality. This is true whether it's the app's primary focus or just a secondary function (such as the ability to enter and record comments or descriptions of objects in the application). Depending on the application, you might be able to get away with the capabilities of Windows' simple edit or the rich-text edit controls, which are approachable to program from C++ because MFC provides wrapper classes for them. But if you want to provide complex document editing and formatting capabilities, you'll still end up writing and debugging a considerable amount of code."

Top TX Tip: How To Generate Indexes with TX Text Control

This example will show you how to generate an index for a document using TX Text Control. In an index you find keywords and on which page they are located in the text. Such an index can be easily generated automatically with a TX control.

First of all, you must give the user the ability to define a word in the text as a keyword. This is done by inserting a field in the sample (Menu Edit -> Insert Keyword).

Then when the document is set up and all the keywords have been inserted, the user should generate the index. In the sample a new form pops up with another TX Text Control that shows the index. The index is generated new every time the user opens the form, so it's always "up to date"...

So, the main thing happens when the user opens the form. Here is the Form_Load event:

Private Sub Form_Load()

Dim lID As Long
Dim lCurPos As Long
Dim lPage As Variant
Dim nTemp As Integer
Dim szCur As String
Dim szLast As String

TXTextControl1.ResetContents
TXTextControl1.LockWindowUpdate = True

TXTextControl1.FontBold = True
TXTextControl1.FontSize = 24
TXTextControl1.Alignment = 2
TXTextControl1.SelText = "Index" + vbCrLf + vbCrLf
TXTextControl1.FontBold = False
TXTextControl1.FontSize = 14
TXTextControl1.Alignment = 0

szCur = ""

With Form1

    ' Store the current input position
    lCurPos = .TXTextControl1.SelStart

    lID = .TXTextControl1.FieldNext(0, 0)
    List1.Clear

    ' Loop through all fields and store their text
    ' in a ListBox
    ' The Itemdata property is used to save the page on which the
      field is
    ' and the field ID (Page = HIWORD, ID = LOWORD)
    While lID <> 0
        If .TXTextControl1.FieldData(lID) = 1 Then
            .TXTextControl1.FieldCurrent = lID
            .TXTextControl1.SelStart = .TXTextControl1.FieldStart
            lPage = .TXTextControl1.CurrentInputPosition
            List1.AddItem .TXTextControl1.FieldText
            List1.ItemData(List1.NewIndex) = lPage(0) * 65536 + _
            .TXTextControl1.FieldCurrent
        End If

        lID = .TXTextControl1.FieldNext(lID, 0)
    Wend

    ' Restore old input position
    .TXTextControl1.SelStart = lCurPos

    ' Now loop through all list items and insert the indices
    For i = 0 To List1.ListCount - 1

        If (UCase(Left(List1.List(i), 1)) <> szCur) Then
            szCur = UCase(Left(List1.List(i), 1))
            TXTextControl1.FontBold = True
            TXTextControl1.FontSize = 18
            TXTextControl1.SelText = vbCrLf + vbCrLf + szCur + vbCrLf
            TXTextControl1.FontBold = False
            TXTextControl1.FontSize = 14
        End If

        ' Check here if the index has been inserted already
        ' If so, only append its page number
        If (szLast = List1.List(i)) Then
            TXTextControl1.SelText = ", "
        Else
            TXTextControl1.SelText = vbCrLf + List1.List(i) + " "
            szLast = List1.List(i)
        End If

        ' The page number is inserted as a field, so the user
        ' can click and scroll to that field
        nTemp = List1.ItemData(i) Mod 65536
        TXTextControl1.FieldInsert Str((List1.ItemData(i) - nTemp) /
        65536)
        TXTextControl1.FieldData(TXTextControl1.FieldCurrent) = nTemp

    Next i

End With

TXTextControl1.LockWindowUpdate = False

End Sub

The TX Text Control is cleared and the window update is locked, so the user won't see all the things we do. Then the text "Index" is inserted in big letters. Now, we loop through all the fields in the TX on the main form and get their field texts, i.e. the keywords. To store the keywords we use a common list box. So, the items will be sorted automatically. The page number and the field id are also stored. The ItemData property is used for this purpose.

After we have gathered all the keywords, we start looping through the list box items and append them to the index document. A larger letter is inserted every time a keyword starts with a new letter. The current letter is stored in the variable szCur.

The last thing we need to check is if the last word we added is equal to the word we want to add. Perhaps the same keyword is used several times in the document, so we insert only the page number on which the keyword is and not the whole word again. The page numbers are inserted as fields, so the user can click on them and the main TX scrolls to the keyword. That's why we stored the field IDs earlier.

TX Text Control Gets Reviewed by DevX

Top TX Tip: How To Generate Indexes with TX Text Control