iTextSharp - 某些页面未按预期标记

Question

我正在使用 iTextSharp 5.0.6 读取现有的 PDF，迭代每个页面，在每个页面上标记文本，然后写出新标记的 PDF。我面临的问题是这并不是 100% 有效。对于某些 PDF，每个页面都按预期加盖了印记，而对于其他 PDF，大多数页面都加盖了印记，而有些则没有。似乎存在潜在的问题，即压模的 GetOverContent() 没有返回最顶层，但这只是一个假设。有人遇到过类似的问题吗？

using iTextSharp.text;
using iTextSharp.text.pdf;
const string WATERMARK_TEXT = "John Doe";

static void Main(string[] args)
{
    string masterPdf = "master.pdf";
    string pdfToCreate = "watermark.pdf";

    byte[] bytes = StampPDF(masterPdf);
    using (FileStream stream = new FileStream(pdfToCreate, FileMode.Create))
    {
        stream.Write(bytes, 0, bytes.Length);
    }

}

static byte[] StampPDF(string PdfPath)
{
    using (MemoryStream memoryStream = new MemoryStream())
    {
        PdfReader reader = new PdfReader(PdfPath);
        int pageCount = reader.NumberOfPages;
        PdfStamper stamper = new PdfStamper(reader, memoryStream);

        float fontSize = 9;
        float textAngle = 0f;
        BaseFont font = BaseFont.CreateFont(BaseFont.TIMES_ROMAN, BaseFont.WINANSI, BaseFont.EMBEDDED);
        BaseColor backgroundColor = new BaseColor(0, 0, 0);
        BaseColor fontColor = new BaseColor(255, 255, 255);
        float padding = 2f;
        float fontWidth = font.GetWidthPoint(WATERMARK_TEXT, fontSize);
        iTextSharp.text.Rectangle pageSize;
        PdfContentByte pageContents;
        for (int i = 1; i <= pageCount; i++)
        {
            pageSize = reader.GetPageSize(i);
            pageContents = stamper.GetOverContent(i);
            //draw a rectangle
            pageContents.SetColorFill(backgroundColor);
            pageContents.MoveTo(pageSize.Width - (fontWidth + padding), 0f);
            pageContents.LineTo(pageSize.Width, 0f);
            pageContents.LineTo(pageSize.Width, 14f);
            pageContents.LineTo(pageSize.Width - (fontWidth + padding), 14f);
            pageContents.Fill();
            //drop our watermark on top of the rectangle we just created
            pageContents.BeginText();
            pageContents.SetColorFill(fontColor);
            pageContents.SetFontAndSize(font, fontSize);
            pageContents.ShowTextAligned(PdfContentByte.ALIGN_LEFT, WATERMARK_TEXT, pageSize.Width - fontWidth, 4, textAngle);
            pageContents.EndText();
        }
        stamper.Close();
        reader.Close();

        return memoryStream.ToArray();
    }
}

Answer 1

对于那些可能遇到同样问题的人来说，关键是检查 CropBox。由于 PDF 的 CropBox 的尺寸可能小于其 PageSize 的尺寸，因此您需要有条件地使用其中之一。因此，根据上面的代码示例，for 循环将更改为:

for (int i = 1; i <= pageCount; i++)
{
    mediaBox = reader.GetPageSize(i);
    cropBox = reader.GetCropBox(i);
    overContent = stamper.GetOverContent(i);

    if (cropBox != null && (cropBox.Width < mediaBox.Width || cropBox.Height < cropBox.Height))
        mediaBox = cropBox;

    //draw a rectangle
    overContent.SetColorFill(backgroundColor);
    overContent.MoveTo(mediaBox.Right - (fontWidth + fontPadding), mediaBox.Bottom);
    overContent.LineTo(mediaBox.Right, mediaBox.Bottom);
    overContent.LineTo(mediaBox.Right, mediaBox.Bottom + rectangleHeight);
    overContent.LineTo(mediaBox.Right - (fontWidth + fontPadding), mediaBox.Bottom + rectangleHeight);
    overContent.ClosePathFillStroke();
    //drop our watermark on top of the rectangle we just created
    overContent.BeginText();
    overContent.SetColorFill(fontColor);
    overContent.SetFontAndSize(font, fontSize);
    overContent.ShowTextAligned(PdfContentByte.ALIGN_LEFT, WATERMARK_TEXT, mediaBox.Right - fontWidth, mediaBox.Bottom + (rectangleHeight - fontSize), textAngle);
    overContent.EndText();
}