使用itextsharp重新排序pdf文件中的页面 [英] Reorder pages in a pdf file using itextsharp

问题描述

我正在尝试重新排序PDF文件中的多个页面。我在博客中发现了一些代码但无法使其工作。我有两页pdf，我想让最后一页显示为第一页。我总是得到一个例外，说页码必须与订单匹配。当我检查文档对象时，它显示0页。但传入的PDF有两页。

I'm trying to reorder several pages in a PDF file. I found some code in a blog but couldn't get it to work. I have a two page pdf, and I want to get the last page to appear as first. I always get an exception saying that page number has to match with order. When I checked the document object, it shows 0 pages. But the PDF passed into has two pages.

public void reOrder(string inputFile)
{ 
    Document document = new Document();
    FileStream fs = new FileStream(inputFile, FileMode.Open);
    PdfWriter writer = PdfWriter.GetInstance(document, fs);
    document.AddDocListener(writer);                
    writer.SetLinearPageMode();
    int[] order = {2,1};
    writer.ReorderPages(order);
}

推荐答案

每当你用iTextSharp写的时候您需要创建新文档，它永远不会写入现有文档。在您的情况下，页面重新排序需要编写，因此您需要创建一个新文档，将页面重新排序然后重新排序。 （当然，你也可以在导入时重新排序它们。）

Whenever you use iTextSharp to write something you need to create a new document, it will never write to an existing document. In your case, page reordering would require writing so you need create a new document, bring over the pages and then reorder them. (Of course, you could also just reorder them upon import, too.)

        var inputFile = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "Test.pdf");
        var output = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "Output.pdf");

        //Bind a reader to our input file
        var reader = new PdfReader(inputFile);

        //Create our output file, nothing special here
        using (FileStream fs = new FileStream(output, FileMode.Create, FileAccess.Write, FileShare.None)) {
            using (Document doc = new Document(reader.GetPageSizeWithRotation(1))) {
                //Use a PdfCopy to duplicate each page
                using (PdfCopy copy = new PdfCopy(doc, fs)) {
                    doc.Open();
                    copy.SetLinearPageMode();
                    for (int i = 1; i <= reader.NumberOfPages; i++) {
                        copy.AddPage(copy.GetImportedPage(reader, i));
                    }
                    //Reorder pages
                    copy.ReorderPages(new int[] { 2, 1 });
                    doc.Close();
                }
            }
        }

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