Step 4 - Adding Jumps to External Targets

Finally, in this step, jumps to other documents and jumps to targets in these documents are added.

Again the Hypertext Link dialog box is extended to choose an external file. A Choose File... button is placed on the form that triggers a common dialog.

After the user has chosen a file, its name is displayed in the text box and the file is searched for internal targets:

[Visual Basic 6]
Private Sub CheckFileForTargets(file As String)
   tx(1).LoadSaveAttribute(txEnableLinks) = True
   tx(1).Load file, 0, 4
   FillListboxWithTargets (1)
   optSelFile.Value = True
   loadedFile = file
End Sub

For this purpose the file is loaded in a second, invisible Text Control. Then the FieldNext method is used as in step 3 to list all targets.

To implement the jump to an external link, the code added to the FieldLinkClicked event in step 3 must be extended. The following code does not handle jumps to internet addresses, it only implements jumps to targets in other files. To separate a file from a name of a target, Text Control uses the '#' character. The following code separates the file name and the target's name, loads the file with the Load method and jumps to the target with the TargetGoto method:

[Visual Basic 6]
ElseIf FieldType = txFieldExternalLink Then
   'This sample does not feature links to www sites,
   'so exit sub
   If Left(TypeData, 7) = "http://" Then
      Exit Sub
   End If
   TXTextControl1.LoadSaveAttribute(txEnableLinks) = True
   pos = InStr(TypeData, "#")
   'File name includes an internal link
   If pos >= 0 Then
      'Ask the user to save changes, if any
      If bDocDirty Then
      ret = MsgBox("Save changes?", vbYesNoCancel, _
               "Question")
         If ret = vbYes Then
            mnuFile_SaveAs_Click
         ElseIf ret = vbCancel Then
            Exit Sub
         End If
   End If
      'Extract file name & path from full path
   str = Left(TypeData, pos - 1)
      TXTextControl1.Load str, 0, 4
      'Extract file position from full path
      str = Mid(TypeData, pos + 1)
      TXTextControl1.TargetGoto str
   Else
      'File name doesn't include an internal link
      TXTextControl1.Load TypeData, 0, 4
   End If
End If

When an HTML, RTF or Microsoft Word document is loaded, Text Control must convert containing hypertext links to appropriate marked text fields as described above. To perform this, a programmer must set the LoadSaveAttribute (txEnableLinks) before using the Load method. Otherwise hypertext links and target fields are not converted. When a document is saved, marked text fields that represent hypertext links, are always converted to the appropriate format.

If Text Control's proprietary format is used, setting LoadSaveAttribute is not necessary.