Question

我正在尝试使用iTextSharp在PDF文档的每个页面上创建一个页脚，其格式为Page＃of＃，跟随iText页面和书籍上的教程。虽然我一直在cb.SetFontAndSize（helv，12）上得到一个例外; - 未将对象引用设置为对象。有谁能看到这个问题？代码如下。

谢谢，罗布

public class MyPdfPageEventHelpPageNo : iTextSharp.text.pdf.PdfPageEventHelper
{
    protected PdfTemplate total;
    protected BaseFont helv;
    private bool settingFont = false;

    public override void OnOpenDocument(PdfWriter writer, Document document)
    {
        total = writer.DirectContent.CreateTemplate(100, 100);
        total.BoundingBox = new Rectangle(-20, -20, 100, 100);

        helv = BaseFont.CreateFont(BaseFont.HELVETICA, BaseFont.WINANSI, BaseFont.NOT_EMBEDDED);
    }

    public override void OnEndPage(PdfWriter writer, Document document)
    {
        PdfContentByte cb = writer.DirectContent;
        cb.SaveState();
        string text = "Page " + writer.PageNumber + " of ";
        float textBase = document.Bottom - 20;
        float textSize = 12; //helv.GetWidthPoint(text, 12);
        cb.BeginText();
        cb.SetFontAndSize(helv, 12);
        if ((writer.PageNumber % 2) == 1)
        {
            cb.SetTextMatrix(document.Left, textBase);
            cb.ShowText(text);
            cb.EndText();
            cb.AddTemplate(total, document.Left + textSize, textBase);
        }
        else
        {
            float adjust = helv.GetWidthPoint("0", 12);
            cb.SetTextMatrix(document.Right - textSize - adjust, textBase);
            cb.ShowText(text);
            cb.EndText();
            cb.AddTemplate(total, document.Right - adjust, textBase);
        }
        cb.RestoreState();
    }

    public override void OnCloseDocument(PdfWriter writer, Document document)
    {
        total.BeginText();
        total.SetFontAndSize(helv, 12);
        total.SetTextMatrix(0, 0);
        int pageNumber = writer.PageNumber - 1;
        total.ShowText(Convert.ToString(pageNumber));
        total.EndText();
    }

}

Answer 1

以下是good example，用于向每个页面添加总页数。

编辑：以下是该网站的代码，以防它消失：

using System;
using System.Collections.Generic;
using System.Text;
using iTextSharp.text.pdf;
using iTextSharp.text;
namespace PDF_Tests
{
    public class TwoColumnHeaderFooter :PdfPageEventHelper
    {
        // This is the contentbyte object of the writer
        PdfContentByte cb;
        // we will put the final number of pages in a template
        PdfTemplate template;
        // this is the BaseFont we are going to use for the header / footer
        BaseFont bf = null;
        // This keeps track of the creation time
        DateTime PrintTime = DateTime.Now;
        #region Properties
        private string _Title;
        public string Title
        {
            get { return _Title; }
            set { _Title = value; }
        }

        private string _HeaderLeft;
        public string HeaderLeft
        {
            get { return _HeaderLeft; }
            set { _HeaderLeft = value; }
        }
        private string _HeaderRight;
        public string HeaderRight
        {
            get { return _HeaderRight; }
            set { _HeaderRight = value; }
        }
        private Font _HeaderFont;
        public Font HeaderFont
        {
            get { return _HeaderFont; }
            set { _HeaderFont = value; }
        }
        private Font _FooterFont;
        public Font FooterFont
        {
            get { return _FooterFont; }
            set { _FooterFont = value; }
        }
        #endregion
        // we override the onOpenDocument method
        public override void OnOpenDocument(PdfWriter writer, Document document)
        {
            try
            {
                PrintTime = DateTime.Now;
                bf = BaseFont.CreateFont(BaseFont.HELVETICA, BaseFont.CP1252, BaseFont.NOT_EMBEDDED);
                cb = writer.DirectContent;
                template = cb.CreateTemplate(50, 50);
            }
            catch (DocumentException de)
            {
            }
            catch (System.IO.IOException ioe)
            {
            }
        }

        public override void OnStartPage(PdfWriter writer, Document document)
        {
            base.OnStartPage(writer, document);
            Rectangle pageSize = document.PageSize;
            if (Title != string.Empty)
            {
                cb.BeginText();
                cb.SetFontAndSize(bf, 15);
                cb.SetRGBColorFill(50, 50, 200);
                cb.SetTextMatrix(pageSize.GetLeft(40), pageSize.GetTop(40));
                cb.ShowText(Title);
                cb.EndText();
            }
            if (HeaderLeft + HeaderRight != string.Empty)
            {
                PdfPTable HeaderTable = new PdfPTable(2);
                HeaderTable.DefaultCell.VerticalAlignment = Element.ALIGN_MIDDLE;
                HeaderTable.TotalWidth = pageSize.Width - 80;
                HeaderTable.SetWidthPercentage(new float[] { 45, 45 }, pageSize);

                PdfPCell HeaderLeftCell = new PdfPCell(new Phrase(8, HeaderLeft, HeaderFont));
                HeaderLeftCell.Padding = 5;
                HeaderLeftCell.PaddingBottom = 8;
                HeaderLeftCell.BorderWidthRight = 0;
                HeaderTable.AddCell(HeaderLeftCell);
                PdfPCell HeaderRightCell = new PdfPCell(new Phrase(8, HeaderRight, HeaderFont));
                HeaderRightCell.HorizontalAlignment = PdfPCell.ALIGN_RIGHT;
                HeaderRightCell.Padding = 5;
                HeaderRightCell.PaddingBottom = 8;
                HeaderRightCell.BorderWidthLeft = 0;
                HeaderTable.AddCell(HeaderRightCell);
                cb.SetRGBColorFill(0, 0, 0);
                HeaderTable.WriteSelectedRows(0, -1, pageSize.GetLeft(40), pageSize.GetTop(50), cb);
            }
        }
        public override void OnEndPage(PdfWriter writer, Document document)
        {
            base.OnEndPage(writer, document);
            int pageN = writer.PageNumber;
            String text = "Page " + pageN + " of ";
            float len = bf.GetWidthPoint(text, 8);
            Rectangle pageSize = document.PageSize;
            cb.SetRGBColorFill(100, 100, 100);
            cb.BeginText();
            cb.SetFontAndSize(bf, 8);
            cb.SetTextMatrix(pageSize.GetLeft(40), pageSize.GetBottom(30));
            cb.ShowText(text);
            cb.EndText();
            cb.AddTemplate(template, pageSize.GetLeft(40) + len, pageSize.GetBottom(30));

            cb.BeginText();
            cb.SetFontAndSize(bf, 8);
            cb.ShowTextAligned(PdfContentByte.ALIGN_RIGHT, 
            "Printed On " + PrintTime.ToString(), 
            pageSize.GetRight(40), 
            pageSize.GetBottom(30), 0);
            cb.EndText();
        }
        public override void OnCloseDocument(PdfWriter writer, Document document)
        {
            base.OnCloseDocument(writer, document);
            template.BeginText();
            template.SetFontAndSize(bf, 8);
            template.SetTextMatrix(0, 0);
            template.ShowText("" + (writer.PageNumber - 1));
            template.EndText();
        }
    }
}

附加它的适用代码：

// Our custom Header and Footer is done using Event Handler
TwoColumnHeaderFooter PageEventHandler = new TwoColumnHeaderFooter();
PDFWriter.PageEvent = PageEventHandler;
// Define the page header
PageEventHandler.Title = Title;
PageEventHandler.HeaderFont = FontFactory.GetFont(BaseFont.COURIER_BOLD, 10, Font.BOLD);
PageEventHandler.HeaderLeft = "Group";
PageEventHandler.HeaderRight = "1";

Answer 2

上面的代码是正确的，唯一的问题是，它没有被执行。为此，你必须在你编写下载PDf代码的地方创建一个实例。例如：

MyPdfPageEventHelpPageNo pageeventhandler = new MyPdfPageEventHelpPageNo();
writer.PageEvent = pageeventhandler;

writer是指PDF编写器（实例）。

Answer 3

在您覆盖的每个方法中，您都可以添加对其基本方法的调用：

base.OnStartPage(writer, document);
base.OnEndPage(writer, document);
base.OnCloseDocument(writer, document);

iTextSharp创建页脚＃of＃

3 个答案: