Question

我使用以下代码为我的pdf添加了水印。我的实际要求是在用户尝试打印pdf时显示水印。（打印预览和打印副本应该有水印而不是在观众的原始文件上）

我设置了标志ShowsOnScreen（false）和ShowsOnPrint（true），但它显示在打印预览上，但也显示在查看器上。另一个问题是可以选择此水印并执行其他注释，例如突出显示。

请建议我解决方法。要么我需要隐藏查看器中的水印，只显示打印预览/打印要么告诉我一种水印在观察者上显示的方式，但它必须是只读的。

using (Stamper st = new Stamper(StamperSizeType.e_relative_scale, 0.9, 0.9)) 
                { 
                    pdfDoc.InitSecurityHandler(); 

                    st.SetAlignment(StamperHorizontalAlignment.e_horizontal_center, StamperVerticalAlignment.e_vertical_center); 
                    st.SetFontColor(new ColorPt(0, 0, 0));                    st.SetOpacity(0.3); 
                    st.SetAsBackground(false); 
                    st.ShowsOnScreen(false); 

                    st.SetRotation(-45); 
                    st.ShowsOnPrint(true); 

                    st.SetAsAnnotation(false); 

                    st.StampText(pdfDoc, "If you are reading this\nthis is an even page", new PageSet(1, pdfDoc.GetPageCount())); 
                }

Answer 1

在PDFTron团队的帮助下排序。这是代码

public async Task<PDFDoc> SetWatermark(PDFDoc pdfDoc)
    {
        try
        {
            #region Solution 1
            var text = "Sample Watermark\nSample Watermark";

            pdfDoc.InitSecurityHandler();
            Image img1 = null;

            // Create a dummy document
            using (PDFDoc tempDoc = new PDFDoc())
            using (Stamper st = new Stamper(StamperSizeType.e_relative_scale, 0.9, 0.9))
            {
        // Add a page to the dummy doc.
                tempDoc.PagePushBack(tempDoc.PageCreate());
                st.SetAlignment(StamperHorizontalAlignment.e_horizontal_center, StamperVerticalAlignment.e_vertical_center);

                // Set text color to black
                st.SetFontColor(new ColorPt(0, 0, 0));

                // Add a text to the dummy page. This text will be the watermark you going to apply on your original document.
                st.StampText(tempDoc, text, new PageSet(1, tempDoc.GetPageCount()));
        // Reduce PDF page to minimal size
                tempDoc.GetPage(1).SetMediaBox(tempDoc.GetPage(1).GetVisibleContentBox());

        // Require a sepaprate license
                PDFDraw draw = new PDFDraw();
                // Adjust image output quality
                draw.SetDPI(100);
                draw.SetPageTransparent(true);

                // Export the dummy page's text as an image
                var pngImageData = await draw.ExportAsStreamAsync(tempDoc.GetPage(1), "PNG");
                img1 = await Image.CreateAsync(pdfDoc.GetSDFDoc(), pngImageData);
            }

            // Create a new stamper to embed the above created image to the original doc
            using (Stamper st = new Stamper(StamperSizeType.e_relative_scale, 0.9, 0.9))
            {
                // Adjust final stamp positioning
                st.SetAlignment(StamperHorizontalAlignment.e_horizontal_center, StamperVerticalAlignment.e_vertical_center);
                st.SetOpacity(0.3);
                st.SetAsBackground(false);
                st.ShowsOnScreen(true);
                st.SetRotation(-45);
                st.ShowsOnPrint(true);
                st.SetAsAnnotation(false); //Make it true if you want to add this watermark to the XFDF file

                st.StampImage(pdfDoc, img1, new PageSet(1, pdfDoc.GetPageCount()));
            }
            #endregion
        }
        catch (Exception ex)
        {
            throw;
        }
        return pdfDoc; //Retrun the watermark embeded document
    }

在PDFTron UWP上使用Stamper添加文本水印

1 个答案: