Hacking樂無窮-為ReportViewer匯出PDF檔加上浮水印

using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Text;

using System.Web;

public class ExpFileFilterStream : MemoryStream

{

    private Stream output = null;

    Func<byte[], byte[]> modifier = null;

    private HttpResponse response = null;

    private bool firstFlush = false;

    public ExpFileFilterStream(HttpResponse resp, Func<byte[], byte[]> modifier)

    {

        response = resp;

        output = resp.Filter;

        this.modifier = modifier;

    }

    public override void Write(byte[] buffer, int offset, int count)

    {

        //由於ReportViewer會關閉BufferOutput，並分成多段Flush傳回前端，

        //在此重新啟用Buffer功能(因必須得到檔案完整內容再處理)，

        //但會漏掉第一次的Flush()，藉以以下邏輯避免第一次部分Flush()

        //註: ReportViewer在分段Flush的大小為81920，當少於此值表示不需略過Flush

        if (!response.BufferOutput && count == 81920)

        {

            response.BufferOutput = true;

            firstFlush = true;

        }

        base.Write(buffer, offset, count);

    }

    public override void Flush()

    {

        if (firstFlush)

        {

            firstFlush = false;

            return;

        }

        //Flush時，將要傳回內容byte[]交由外部邏輯處理後再取回

        byte[] buff = base.ToArray();

        if (modifier != null)

            buff = modifier(buff);

        output.Write(buff, 0, buff.Length);

    }

}

using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

using System.Text;

using System.Web;

using iTextSharp.text.pdf;

using iText = iTextSharp.text;

using iTextSharp.text;

using System.IO;

namespace ReportViewerHacking

{

    public class WaterMarkModule : IHttpModule

    {

        #region IHttpModule Members

        public void Dispose()

        {

        }

        public void Init(HttpApplication context)

        {

            context.BeginRequest += context_BeginRequest;

        }

        void context_BeginRequest(object sender, EventArgs e)

        {

            HttpApplication app = sender as HttpApplication;

            string url = app.Context.Request.RawUrl;

            var context = app.Context;

            if (url.Contains("Reserved.ReportViewerWebControl.axd"))

            {

                var req = context.Request;

                var resp = context.Response;

                string opType = req["OpType"];

                string name = req["Name"];

                string format = req["Format"];

                if (opType == "Export" && format == "PDF")

                {

                    resp.BufferOutput = true;

                    resp.Filter = new ExpFileFilterStream(resp, (buff) =>

                    {

                        //輸入PDF內容，加上浮水印

                        PdfReader pr = new PdfReader(buff);

                        iText.Rectangle dimension = pr.GetPageSize(1);

                        MemoryStream ms = new MemoryStream();

                        PdfStamper stmp = new PdfStamper(pr, ms);

                        //REF: http://bit.ly/10qirzK

                        BaseFont bf =

                            BaseFont.CreateFont(BaseFont.TIMES_ROMAN, BaseFont.CP1252, false);

                        iText.Font fnt = new iText.Font(bf, 6, iText.Font.NORMAL, BaseColor.BLACK);

                        PdfContentByte cb = stmp.GetOverContent(1);

                        //設定半透明文字

                        PdfGState gstate = new PdfGState();

                        gstate.FillOpacity = 0.2f;

                        gstate.StrokeOpacity = 0.2f;

                        cb.SetGState(gstate);

                        cb.BeginText();

                        cb.SetFontAndSize(bf, 6);

                        cb.SetColorFill(BaseColor.BLACK);

                        cb.ShowTextAligned(PdfContentByte.ALIGN_LEFT,

                            string.Format("PDF {0:yyyy-MM-dd HH:mm:ss}", DateTime.Now),

                            dimension.GetLeft(1), dimension.GetTop(5), 0);

                        cb.EndText();

                        stmp.Close();

                        pr.Close();

                        return ms.ToArray();

                    });

                }

            }

        }

        #endregion

    }

}