ITEXTSHARP学习整理
学习的版本iTextSharp.5.5.5。
关于获取PDF中的图片资源
/// <summary> /// 将PDF中的图片资源转换成二进制 /// </summary> /// <param name="filePath"></param> /// <returns></returns> public List<byte[]> ConvertImageData(string filePath) { List<byte[]> lst = new List<byte[]>(); using (PdfReader pdf = new PdfReader(filePath)) { for (int i = 1; i <= pdf.NumberOfPages; i++) { byte[] result = null; PdfDictionary page = pdf.GetPageN(pageNum); PdfObject obj = FindImageInPDFDictionary(page); if (obj != null) { PdfImageObject imageObj = null; int XrefIndex = Convert.ToInt32(((PRIndirectReference)obj).Number.ToString(System.Globalization.CultureInfo.InvariantCulture)); PdfObject pdfObj = pdf.GetPdfObject(XrefIndex); PRStream pdfStrem = (PRStream)pdfObj; imageObj = new PdfImageObject(pdfStrem); result = imageObj.GetImageAsBytes(); } lst.Add(result); } } return lst; }
/// <summary> /// 提取图片元素 /// </summary> /// <param name="pg"></param> /// <returns></returns> private static PdfObject FindImageInPDFDictionary(PdfDictionary pg) { PdfDictionary res = pg.GetAsDict(PdfName.RESOURCES); PdfDictionary xobj = res.GetAsDict(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)) { return obj; }// image inside a form else if (PdfName.FORM.Equals(type) || PdfName.GROUP.Equals(type)) { return FindImageInPDFDictionary(tg); } } } } return null; }