'''' This code is part of Document Solutions for PDF .NET demos.'' Copyright (c) MESCIUS inc. All rights reserved.''Imports System.IOImports System.DrawingImports GrapeCity.Documents.PdfImports GrapeCity.Documents.TextImports GrapeCity.Documents.Pdf.StructureImports GrapeCity.Documents.Pdf.MarkedContent
'' This sample shows how To create tagged (structured) PDF And attach'' tags to individual paragraphs in a TextLayout that is used to render'' them together, splitting between pages.'' The code generating the document is similar to that used in PaginatedText,'' but adds tags.'' To see/explore the tags, open the document in Adobe Acrobat Pro and go to'' View | Navigation Panels | Tags.Public Class TagTextLayout    Function CreatePDF(ByVal stream As Stream) As Integer        Dim doc = New GcPdfDocument()
        '' Create a Part element, it will contain P (paragraph) elements:        Dim sePart = New StructElement("Part")        doc.StructTreeRoot.Children.Add(sePart)
        '' Create and set up a TextLayout to render paragraphs:        Dim tl = New TextLayout(72)        tl.DefaultFormat.Font = StandardFonts.Times        tl.DefaultFormat.FontSize = 12        tl.FirstLineIndent = 72 / 2        tl.MaxWidth = doc.PageSize.Width        tl.MaxHeight = doc.PageSize.Height        tl.MarginAll = tl.Resolution        ''        '' Append the text (20 paragraphs so they would not fit on a single page)        '' (note that TextLayout interprets vbCrLf as paragraph delimiter):        ''        '' Get the text (20 paragraphs):        Dim text = Util.LoremIpsum(20)        '' In order to tag the individual paragraphs, we need to split the text into paragraphs,        '' and use each paragraph format's Tag property (which is not related to PDF tags,         '' it is just an arbitrary data that can be associated with a TextFormat) to add the        '' paragraph's index to the paragraph:        Dim pars = text.Split(New Char() {vbCr, vbLf}, StringSplitOptions.RemoveEmptyEntries)        For i = 0 To pars.Length - 1            Dim tf = New TextFormat(tl.DefaultFormat) With {.Tag = i}            tl.AppendLine(pars(i), tf)        Next
        '' Layout the text:        tl.PerformLayout(True)        '' Use split options to provide widow/orphan control:        Dim tso = New TextSplitOptions(tl) With {            .MinLinesInFirstParagraph = 2,            .MinLinesInLastParagraph = 2        }        '' TextLayoutHandler implements ITextLayoutHandler, which        '' allows tagging the text as it is rendered:        Dim tlh = New TextLayoutHandler() With {.ParentElement = sePart}
        '' In a loop, split and render the text:        While True            '' 'rest' will accept the text that did not fit:            Dim rest As TextLayout = Nothing            Dim splitResult = tl.Split(tso, rest)            Dim page = doc.Pages.Add()            Dim g = page.Graphics            '' Tell the TextLayoutHandler which page we're on:            tlh.Page = page            '' ..and associate it with the graphics:            g.TextLayoutHandler = tlh            '' Draw the text that fits on the current page, and advance to next page unless we're done:            g.DrawTextLayout(tl, PointF.Empty)            If splitResult <> SplitResult.Split Then                Exit While            End If            tl = rest        End While        '' Mark document as tagged:        doc.MarkInfo.Marked = True        ''        '' Done:        doc.Save(stream)        Return doc.Pages.Count    End Function
    '' Custom class that allows tagging content as it is rendered by TextLayout:    Private Class TextLayoutHandler : Implements ITextLayoutHandler        Private _tagIndex As Integer        Private _currentParagraphIndex As Integer = -1        Private _currentparagraphElement As StructElement        Public Property ParentElement As StructElement        Public Property Page As Page
        Public Sub TextTagBegin(ByVal graphics As GcPdfGraphics, ByVal textLayout As TextLayout, ByVal tag As Object) Implements ITextLayoutHandler.TextTagBegin            Dim paragraphIndex As Integer            If TypeOf tag Is Integer Then                paragraphIndex = CInt(tag)            Else                paragraphIndex = -1            End If
            Dim paragraphElement As StructElement            If _currentParagraphIndex = paragraphIndex Then                paragraphElement = _currentparagraphElement            Else                paragraphElement = New StructElement("P")                ParentElement.Children.Add(paragraphElement)                _currentparagraphElement = paragraphElement                _currentParagraphIndex = paragraphIndex            End If            ''            graphics.BeginMarkedContent(New TagMcid("P", _tagIndex))            Dim mcil = New McrContentItemLink()            mcil.MCID = _tagIndex            mcil.Page = Page            paragraphElement.ContentItems.Add(mcil)            _tagIndex += 1        End Sub
        Public Sub TextTagEnd(ByVal graphics As GcPdfGraphics, ByVal textLayout As TextLayout, ByVal tag As Object) Implements ITextLayoutHandler.TextTagEnd            graphics.EndMarkedContent()        End Sub
        Public Sub AddTextArea(ByVal bounds As RectangleF) Implements ITextLayoutHandler.AddTextArea        End Sub    End ClassEnd Class