iTextSharp生成的PDF显示“Page X of Y”的效果，IPdfPageEvent的应用一例

网友来信提出这个需求，看到iText的另外一个版本的教程中有这么个demo，就把它转换成C#，贴出来了，有需要的朋友可以根据自己的需求再进行适当的修改就可以。原java代码见如下地址：
http://itextdocs.lowagie.com/tutorial/directcontent/pageevents/
注，运行下面的程序，你需要个叫logo.gif的图片(http://itextdocs.lowagie.com/tutorial/directcontent/pageevents/logo.gif)

using System;
using iTextSharp.text;
using iTextSharp.text.pdf;
using System.IO;

namespace iTextSharp.Demo
{
    /**//// <summary>
    /// Making a document with a header containing 'page x of y' and with a watermark on every page.
    /// </summary>
    public class PageNumbersWatermark : IPdfPageEvent
    {
        /**//** An Image that goes in the header. */
        public Image headerImage;
        /**//** The headertable. */
        public PdfPTable table;
        /**//** The Graphic state */
        public PdfGState gstate;
        /**//** A template that will hold the total number of pages. */
        public PdfTemplate tpl;
        /**//** The font that will be used. */
        public BaseFont helv;

        public PageNumbersWatermark()
        {
            try 
            {
                // step 1: creating the document
                Document doc = new Document(PageSize.A4, 50, 50, 100, 72);
                // step 2: creating the writer
                
                PdfWriter writer = PdfWriter.GetInstance(doc, new FileStream("pageNumbersWatermark.pdf",FileMode.Create));
                // step 3: initialisations + opening the document
                writer.PageEvent =new PageNumbersWatermark();
                doc.Open();
                // step 4: adding content
                string text = "some padding text ";
                for (int k = 0; k < 10; ++k)
                    text += text;
                Paragraph p = new Paragraph(text);
                p.Alignment=(Element.ALIGN_JUSTIFIED);
                doc.Add(p);
                // step 5: closing the document
                doc.Close();
            }
            catch ( Exception e ) 
            {
                System.Diagnostics.Debug.WriteLine(e.StackTrace);
            }
        }
        IPdfPageEvent Members#region IPdfPageEvent Members

        public void OnOpenDocument(PdfWriter writer, Document document)
        {
            try 
            {
                // initialization of the header table
                headerImage = Image.GetInstance("logo.gif");
                table = new PdfPTable(2);
                Phrase p = new Phrase();
                Chunk ck = new Chunk("lowagie.com\n", new Font(Font.TIMES_ROMAN, 16, Font.BOLDITALIC, Color.BLUE));
                p.Add(ck);
                ck = new Chunk("Ghent\nBelgium", new Font(Font.HELVETICA, 12, Font.NORMAL, Color.DARK_GRAY));
                p.Add(ck);
                table.DefaultCell.BackgroundColor=(Color.YELLOW);
                table.DefaultCell.BorderWidth=(0);
                table.AddCell(p);
                table.DefaultCell.HorizontalAlignment=(Element.ALIGN_RIGHT);
                table.AddCell(new Phrase(new Chunk(headerImage, 0, 0)));
                // initialization of the Graphic State
                gstate = new PdfGState();
                gstate.FillOpacity=(0.3f);
                gstate.StrokeOpacity=(0.3f);
                // initialization of the template
                tpl = writer.DirectContent.CreateTemplate(100, 100);
                tpl.BoundingBox=(new Rectangle(-20, -20, 100, 100));
                // initialization of the font
                helv = BaseFont.CreateFont("Helvetica", BaseFont.WINANSI, false);
            }
            catch(Exception e) 
            {
                throw e;
            }
        }

        public void OnCloseDocument(PdfWriter writer, Document document)
        {
            tpl.BeginText();
            tpl.SetFontAndSize(helv, 12);
            tpl.SetTextMatrix(0, 0);
            tpl.ShowText("" + (writer.PageNumber - 1));
            tpl.EndText();
        }

        public void OnParagraph(PdfWriter writer, Document document, float paragraphPosition)
        {
            // TODO:  Add PageNumbersWatermark.OnParagraph implementation
        }

        public void OnEndPage(PdfWriter writer, Document document)
        {
            PdfContentByte cb = writer.DirectContent;
            cb.SaveState();
            // write the headertable
            table.TotalWidth=(document.Right - document.Left);
            table.WriteSelectedRows(0, -1, document.Left, document.PageSize.Height - 50, cb);
            // compose the footer
            String text = "Page " + writer.PageNumber + " of ";
            float textSize = helv.GetWidthPoint(text, 12);
            float textBase = document.Bottom - 20;
            cb.BeginText();
            cb.SetFontAndSize(helv, 12);
            // for odd pagenumbers, show the footer at the left
            if ((writer.PageNumber & 1) == 1) 
            {
                cb.SetTextMatrix(document.Left, textBase);
                cb.ShowText(text);
                cb.EndText();
                cb.AddTemplate(tpl, document.Left + textSize, textBase);
            }
                // for even numbers, show the footer at the right
            else 
            {
                float adjust = helv.GetWidthPoint("0", 12);
                cb.SetTextMatrix(document.Right - textSize - adjust, textBase);
                cb.ShowText(text);
                cb.EndText();
                cb.AddTemplate(tpl, document.Right - adjust, textBase);
            }
            cb.SaveState();
            // draw a Rectangle around the page
            cb.SetColorStroke(Color.ORANGE);
            cb.SetLineWidth(2);            
            cb.Rectangle(20, 20, document.PageSize.Width - 40, document.PageSize.Height - 40);
            cb.Stroke();
            cb.RestoreState();
            // starting on page 3, a watermark with an Image that is made transparent
            if (writer.PageNumber >= 3) 
            {
                cb.SetGState(gstate);
                cb.SetColorFill(Color.RED);
                cb.BeginText();
                cb.SetFontAndSize(helv, 48);
                cb.ShowTextAligned(Element.ALIGN_CENTER, "Watermark Opacity " + writer.PageNumber, document.PageSize.Width / 2, document.PageSize.Height / 2, 45);
                cb.EndText();
                try 
                {
                    cb.AddImage(headerImage, headerImage.Width, 0, 0, headerImage.Height, 440, 80);
                }
                catch(Exception e) 
                {
                    throw e;
                }
                cb.RestoreState();
            }
        }

        public void OnSection(PdfWriter writer, Document document, float paragraphPosition, int depth, Paragraph title)
        {
            // TODO:  Add PageNumbersWatermark.OnSection implementation
        }

        public void OnSectionEnd(PdfWriter writer, Document document, float paragraphPosition)
        {
            // TODO:  Add PageNumbersWatermark.OnSectionEnd implementation
        }

        public void OnParagraphEnd(PdfWriter writer, Document document, float paragraphPosition)
        {
            // TODO:  Add PageNumbersWatermark.OnParagraphEnd implementation
        }

        public void OnGenericTag(PdfWriter writer, Document document, Rectangle rect, string text)
        {
            // TODO:  Add PageNumbersWatermark.OnGenericTag implementation
        }

        public void OnChapterEnd(PdfWriter writer, Document document, float paragraphPosition)
        {
            // TODO:  Add PageNumbersWatermark.OnChapterEnd implementation
        }

        public void OnChapter(PdfWriter writer, Document document, float paragraphPosition, Paragraph title)
        {
            // TODO:  Add PageNumbersWatermark.OnChapter implementation
        }

        public void OnStartPage(PdfWriter writer, Document document)
        {
            if (writer.PageNumber < 3) 
            {
                PdfContentByte cb = writer.DirectContentUnder;
                cb.SaveState();
                cb.SetColorFill(Color.PINK);
                cb.BeginText();
                cb.SetFontAndSize(helv, 48);
                cb.ShowTextAligned(Element.ALIGN_CENTER, "My Watermark Under " + writer.PageNumber, document.PageSize.Width / 2, document.PageSize.Height / 2, 45);
                cb.EndText();
                cb.RestoreState();
            }
        }

        #endregion
    }
}

更多iTextSharp的教程请访问：
iTextSharp (iText#) tutorial update version,VB.NET version
iTextSharp (iText#) tutorial update version

以上两份教程你可以在http://iTextSharp.sf.net获得：

		iTextSharp.tutorial.01.zip	663592	1859	i386	Source .zip
		iTextSharp.tutorial.VB.NET.01.zip	675764	835	i386	Source .zip