尝试将边框放到所有PDF页面会引发IO.Exception

Question

我有一个包含多个页面的现有pdf文件,我想为所有页面添加边框.

所以我创建了一个继承自PdfPageEventHelper的类,我重写了OnEndPage并将该类的实例分配给PdfWriter实例的PageEvent:

using iTextSharp.text;
using iTextSharp.text.pdf;

namespace My.Apps.WPF.Classes
{
    public class PdfEventHelper : PdfPageEventHelper
    {
        public override void OnEndPage(PdfWriter writer, iTextSharp.text.Document document)
        {
            // Add border to page
            PdfContentByte content = writer.DirectContent;
            iTextSharp.text.Rectangle rectangle = new iTextSharp.text.Rectangle(document.PageSize);
            rectangle.Left += document.LeftMargin;
            rectangle.Right -= document.RightMargin;
            rectangle.Top -= document.TopMargin;
            rectangle.Bottom += document.BottomMargin;
            content.SetColorStroke(BaseColor.BLACK);
            content.Rectangle(rectangle.Left, rectangle.Bottom, rectangle.Width, rectangle.Height);
            content.Stroke();
        }
    }
}

然后在主程序中我有一个方法,它返回一个带有所有页面边框的新PDF(源文件pdf文档'pdfFilePath'是横向的,所以我保持新的方向):

private string PutBorderToPdfPages(string pdfFilePath)
{
    string newPdf = @"C:\Output.pdf";

    using (var reader = new PdfReader(pdfFilePath))
    {
        using (var fileStream = new FileStream(newPdf, FileMode.Create, FileAccess.Write))
        {
            iTextSharp.text.Document document = new iTextSharp.text.Document(reader.GetPageSizeWithRotation(1));
            PdfEventHelper pdfEvent = new PdfEventHelper();

            PdfWriter writer = PdfWriter.GetInstance(document, fileStream);
            writer.PageEvent = pdfEvent;

            document.Open();

            document.Close(); // here it crashes, see below in post exception thrown
            writer.Close();
        }
    }

    return newPdf;
}

在运行时,在线:

document.Close();

我得到一个IO.Exception,说:

该文件没有页面.

在这种情况下,Pdf文档只有1页.

我究竟做错了什么？我不想在现有的pdf文件中写任何东西,我只想创建一个与源完全相同但在其所有页面中都有边框的新PDF文件.

更新:

ATTEMPT#1:

我在下面做了,但我得到所有页面都是黑色的(我不知道怎么做未填充的矩形):

private string PutBorderToPdfPages(string pdfFilePath)
{
    string newPdf = @"C:\Output.pdf";

    using (var reader = new PdfReader(pdfFilePath))
    {
        using (var fileStream = new FileStream(newPdf, FileMode.Create, FileAccess.Write))
        {
            using (var pdfStamper = new PdfStamper(reader, fileStream))
            {
                int PageCount = reader.NumberOfPages;   

                for (int p = 1; p <= PageCount; p++)
                {
                    // Add border to page                                
                    PdfContentByte cb = pdfStamper.GetOverContent(p);
                    iTextSharp.text.Rectangle rectangle = pdfReader.GetPageSizeWithRotation(p);
                    rectangle.BackgroundColor = iTextSharp.text.BaseColor.BLACK;                                
                    cb.Rectangle(rectangle);
                }                            
            }
        }
    }

    return newPdf;
}

ATTEMPT#2:

在这次尝试中,我得到一个ObjectDisposedException:

无法访问已关闭的文件.

退出使用pdfStamper时:

private string PutBorderToPdfPages(string pdfFilePath)
{
    string newPdf = @"C:\Output.pdf";

    using (var reader = new PdfReader(pdfFilePath))
    {
        using (var fileStream = new FileStream(newPdf, FileMode.Create, FileAccess.Write))
        {
                    iTextSharp.text.Document document = new iTextSharp.text.Document(reader.GetPageSizeWithRotation(1));                        
                    PdfWriter writer = PdfWriter.GetInstance(document, fileStream);

                    document.Open();

                    using (var pdfStamper = new PdfStamper(reader, fileStream))
                    {                            
                        for (int p = 0; p < pdfStamper.Reader.NumberOfPages; p++)                            
                        {
                            // Add border to page
                            PdfContentByte content = writer.DirectContent;
                            iTextSharp.text.Rectangle rectangle = new iTextSharp.text.Rectangle(document.PageSize);
                            rectangle.Left += document.LeftMargin;
                            rectangle.Right -= document.RightMargin;
                            rectangle.Top -= document.TopMargin;
                            rectangle.Bottom += document.BottomMargin;
                            content.SetColorStroke(iTextSharp.text.BaseColor.BLACK);
                            content.Rectangle(rectangle.Left, rectangle.Bottom, rectangle.Width, rectangle.Height);
                            content.Stroke();
                        }
                        document.Close();
                        writer.Close();
                    }
        }
    }

    return newPdf;
}

Answer 1

你做

document.Open();

document.Close(); // here it crashes, see below in post exception thrown

即你开始一个新文档,不添加任何内容,然后关闭它.因此,iText响应它将是空的The document has no pages.

因此,例外是完全正确的.

正确的方式"把一个边界的所有页面"的"现有的PDF文件"是

• 打开文件PdfReader,
• 创建一个PdfStamper操作PdfReader,
• 迭代它的页面并添加边框,
• 并关闭PdfStamper.

例如,对于源文件source和目标文件dest:

using (PdfReader reader = new PdfReader(source))
using (PdfStamper stamper = new PdfStamper(reader, new FileStream(dest, FileMode.Create)))
{
    for (int pageNumber = 1; pageNumber <= reader.NumberOfPages; pageNumber++)
    {
        Rectangle cropBox = reader.GetCropBox(pageNumber);
        Rectangle rectangle = new Rectangle(cropBox);
        rectangle.Left += 20;
        rectangle.Right -= 20;
        rectangle.Top -= 20;
        rectangle.Bottom += 20;

        PdfContentByte content = stamper.GetOverContent(pageNumber);
        content.SetColorStroke(iTextSharp.text.BaseColor.BLACK);
        content.Rectangle(rectangle.Left, rectangle.Bottom, rectangle.Width, rectangle.Height);
        content.Stroke();
    }
}