HomeDownloadsSource Code LibraryMiscellaneous (23)How to build a paragraph collection

How to build a paragraph collection

Author:	TX Text Control Support Department
Language:	Visual Basic
Version:	1.0
Released:	June 06, 2005
Last modified:	January 11, 2008
Requirements:	TX Text Control .NET with Visual Basic .NET
Download code:	tx_sample_dotnet_par.zip  [20.59 KB, ZIP]

TX Text Control .NET offers a Line and a Chars collection to access the text in TX Text Control .NET. This makes sense as the Selection class uses the character index, which is returned by these collections. Anyway, sometimes it is required to have a collection that contains all paragraphs. This sample shows how to build a paragraph collection to iterate through all paragraphs in a document.

First, we created the Paragraph Class with the properties Text, Start, Length, Style and Page. The last two are particularly interesting for further processing. For example in order to create a a table of contents.

Secondly, we need a collection, which holds the Paragraph objects. The class Paragraphs contains a collection (in fact an ArrayList). The read only Paragraphs property returns this collection with all Paragraph objects.

Public ReadOnly Property Paragraphs() As Collection
	Get
		Dim startPos As Integer = 0
		Dim newPos As Integer
 
		Do
			newPos = TX.Find(Chr(10), startPos, _
			TXTextControl.FindOptions.NoMessageBox)
 
			If newPos = -1 Then Exit Do
 
			Dim newPar As New Paragraph
 
			newPar.Start = startPos
			newPar.Length = newPos - startPos
 
			TX.Select(startPos, newPos - startPos)
 
			If newPos <> startPos Then
				newPar.Text = TX.Selection.Text
			Else
				newPar.Text = ""
			End If
 
			newPar.Style = TX.Selection.FormattingStyle
			newPar.Page = TX.InputPosition.Page
 
			m_par.Add(newPar)
			startPos = newPos + 1
		Loop
 
		Return m_par
	End Get
End Property

We utilize the Find method to search for the next carriage return control character. The text between two carriage returns is the text of the new Paragraph object which is stored in the collection. Additionally, we store the start position and the length of the text for later communication with the Selection class.

There are two different interpretations for a paragraph. In this sample, a valid paragraph must end with a carriage return. Additionally, an empty paragraph (just a carriage return) is a valid paragraph with no text. This can be changed, if required.

In this sample, we use the paragraph collection to display a simple document summary. We can iterate through all paragraphs using a For Each statement.

Dim myParagraphs As New Paragraphs
myParagraphs.TX = TextControl1
 
For Each par As Paragraph In myParagraphs.Paragraphs
	debug.WriteLine(par.Text)
	[...]
Next

The sample requires Visual Studio 2003 and at least a TX Text Control .NET 11.0 trial version.

top