用程序自动替换PDF文件中的图像

from:
[url]http://itext.ugent.be/library/question.php?id=66[/url]

要使用Java代码，应该调用iText库。
要使用C#代码，应该调用iTextSharp库。


Here's the code to replace images in PDFs, in Java and C#. It will replace the first image in the first page.

Java代码

PdfReader pdf = new PdfReader( "in.pdf");
PdfStamper stp = new PdfStamper(pdf, new FileOutputStream( "c:\\out.pdf"));
PdfWriter writer = stp.getWriter();
Image img = Image.getInstance( "image.png");
PdfDictionary pg = pdf.getPageN(1);
PdfDictionary res =
    (PdfDictionary)PdfReader.getPdfObject(pg.get(PdfName.RESOURCES));
PdfDictionary xobj =
    (PdfDictionary)PdfReader.getPdfObject(res.get(PdfName.XOBJECT));
if (xobj != null) {
     for (Iterator it = xobj.getKeys().iterator(); it.hasNext(); ) {
        PdfObject obj = xobj.get((PdfName)it.next());
         if (obj.isIndirect()) {
            PdfDictionary tg = (PdfDictionary)PdfReader.getPdfObject(obj);
            PdfName type =
                (PdfName)PdfReader.getPdfObject(tg.get(PdfName.SUBTYPE));
             if (PdfName.IMAGE.equals(type)) {
                PdfReader.killIndirect(obj);
                Image maskImage = img.getImageMask();
                 if (maskImage != null)
                    writer.addDirectImageSimple(maskImage);
                writer.addDirectImageSimple(img, (PRIndirectReference)obj);
                 break;
            }
        }
    }
}
stp.close();

C#代码：

PdfReader pdf = new PdfReader( "in.pdf");
PdfStamper stp = new PdfStamper(pdf, new FileStream( "out.pdf",
FileMode.Create));
PdfWriter writer = stp.Writer;
Image img = Image.GetInstance( "image.png");
PdfDictionary pg = pdf.GetPageN(1);
PdfDictionary res =
    (PdfDictionary)PdfReader.GetPdfObject(pg.Get(PdfName.RESOURCES));
PdfDictionary xobj =
    (PdfDictionary)PdfReader.GetPdfObject(res.Get(PdfName.XOBJECT));
if (xobj != null) {
     foreach (PdfName name in xobj.Keys) {
        PdfObject obj = xobj.Get(name);
         if (obj.IsIndirect()) {
            PdfDictionary tg = (PdfDictionary)PdfReader.GetPdfObject(obj);
            PdfName type =
                (PdfName)PdfReader.GetPdfObject(tg.Get(PdfName.SUBTYPE));
             if (PdfName.IMAGE.Equals(type)) {
            PdfReader.KillIndirect(obj);
            Image maskImage = img.ImageMask;
             if (maskImage != null)
                writer.AddDirectImageSimple(maskImage);
                writer.AddDirectImageSimple(img, PRIndirectReference)obj);
                 break;
            }
        }
    }
}
stp.Close();