在EXCEL中插入内存中的图片（VSTO）

    Excel中一般是通过Worksheet.Shapes.AddPicture方法添加图片，方法的参数格式为：
    AddPicture([In] string Filename,    [In] MsoTriState LinkToFile,    [In] MsoTriState SaveWithDocument,    [In] float Left,    [In] float Top,    [In] float Width,    [In] float Height);
    其中Filename必须是一个uri路径，内存中的图片对象则没有办法使用此方法插入。
    我们的项目是一个SmartClient的VSTO项目，当时总有一个意识在支配我，那就是尽可能不要访问本地资源，而如果内存中的图片不写到本地又该如何插入到EXCEL中呢？Google吧，结果搜到一个连他自己都说“Heavyweight”的解决方案，那就是在本地临时创建一个最小型的HTTP Server，将内存中的图片数据交给它，然后由它再展交给AddPicture，代码如下：

using System;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;

namespace YourNameSpace
{
    public class LocalWebServer:IDisposable
    {
        private TcpListener myListener;
        private static readonly Guid terminationGuid = new Guid("{7b0d9a9d-fbec-4fe5-8ea7-fc3b313510fc}");
        byte[] contentsToServe;
        Thread thread;
        string fileName;
        int myPort;

        //The constructor which makee the TcpListener start listening on the
        //given port. It also creates a Thread on the method StartListen(). 

        public LocalWebServer(int port, string fileName, byte[] contents)
        {
            try
            {
                //start listing on the given port
                myListener = new TcpListener(IPAddress.Parse("127.0.0.1"), port);
                contentsToServe = contents;
                this.fileName = fileName;
                this.myPort = port;

                myListener.Start();
                System.Diagnostics.Debug.WriteLine("Web Server Running Press ^C to Stop");

                //start the thread which calls the method 'StartListen'
                Thread th = new Thread(new ThreadStart(StartListen));
                this.thread = th;
                th.Start();
            }
            catch (Exception e)
            {
                System.Diagnostics.Debug.WriteLine("An Exception Occurred while Listening :" + e.ToString());
            }
        }

        public void SendHeader(string sHttpVersion, string sMIMEHeader, int iTotBytes, string sStatusCode, TcpClient tcpClient)
        {
            StringBuilder sBuffer = new StringBuilder();
            // if Mime type is not provided set default to text/html

            if (string.IsNullOrEmpty(sMIMEHeader))
            {
                sMIMEHeader = "text/xml";  // Default Mime Type is text/xml
            }

            sBuffer.Append(sHttpVersion);
            sBuffer.AppendLine(sStatusCode);
            sBuffer.AppendLine("Server: VSTOServer");
            sBuffer.Append("Content-Type: ");
            sBuffer.AppendLine(sMIMEHeader);
            sBuffer.AppendLine("Accept-Ranges: bytes");
            sBuffer.Append("Content-Length: ");
            sBuffer.AppendLine(iTotBytes.ToString());
            sBuffer.AppendLine("");

            Byte[] bSendData = Encoding.ASCII.GetBytes(sBuffer.ToString());
            SendToBrowser(bSendData, tcpClient);
            System.Diagnostics.Debug.WriteLine("Total Bytes : " + iTotBytes.ToString());
        }

        public void SendToBrowser(Byte[] bSendData, TcpClient tcpClient)
        {
            try
            {
                if (tcpClient.Connected)
                {
                    NetworkStream stream = tcpClient.GetStream();
                    stream.Write(bSendData, 0, bSendData.Length);
                    stream.Flush();
                }
                else
                {
                    System.Diagnostics.Debug.WriteLine("Connection Dropped.");
                }
            }
            catch (Exception e)
            {
                System.Diagnostics.Debug.WriteLine(String.Format("Error Occurred : {0} ", e));
            }
        }

        public void StartListen()
        {

            int iStartPos = 0;
            String sErrorMessage;
            while (true)
            {
                //Accept a new connection
                using (TcpClient tcpClient = myListener.AcceptTcpClient())
                {
                    if (tcpClient.Connected)
                    {
                        System.Diagnostics.Debug.WriteLine(String.Format("\nClient Connected!!\n==================\nClient IP {0}\n", tcpClient.Client.RemoteEndPoint));
                        NetworkStream stream = tcpClient.GetStream();
                        //make a byte array and receive data from the client 
                        Byte[] bReceive = new Byte[1024];
                        int i = stream.Read(bReceive, 0, bReceive.Length);
                        //Convert Byte to String
                        string sBuffer = Encoding.ASCII.GetString(bReceive);
                        // Look for HTTP request
                        iStartPos = sBuffer.IndexOf("HTTP", 1);
                        // Get the HTTP text and version e.g. it will return "HTTP/1.1"
                        string sHttpVersion = sBuffer.Substring(iStartPos, 8);
                        //At present we will only deal with GET type
                        // if OPTION received, still OK
                        if (!sBuffer.StartsWith("GET"))
                        {
                            System.Diagnostics.Debug.WriteLine("Only Get Method is supported..");
                            SendHeader(sHttpVersion, null, 0, " 501 Not Implemented", tcpClient);
                            continue;
                        }
                        if (sBuffer.Contains(terminationGuid.ToString()))
                        {
                            SendHeader(sHttpVersion, null, 0, " 200 OK", tcpClient);
                            break;
                        }
                        if (!sBuffer.Contains(fileName))
                        {
                            sErrorMessage = "<H2>404 Error! File Does Not Exist</H2>";
                            SendHeader(sHttpVersion, "", sErrorMessage.Length, " 404 Not Found", tcpClient);
                            SendToBrowser(Encoding.ASCII.GetBytes(sErrorMessage), tcpClient);
                            continue;
                        }

                        SendHeader(sHttpVersion, null, contentsToServe.Length, " 200 OK", tcpClient);
                        SendToBrowser(contentsToServe, tcpClient);
                    }
                }
            }
            myListener.Stop();
        }

        IDisposable Members#region IDisposable Members
        public void Dispose()
        {
            // Send a termination request to stop the web server
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://localhost:" + myPort + "/" + terminationGuid.ToString());
            WebResponse response = request.GetResponse();
        }
        #endregion

    }
}

    调用时可以使用这个方法：

        private void AddPictureByWeb(Excel.Worksheet worksheet, string fileName, byte[] contents, float left, float top, float width, float height)
        {
            // Use any private port in the range 49152–65535
            int portNumber = 50213;
            fileName = System.Web.HttpUtility.UrlEncode(fileName);
            using (new LocalWebServer(portNumber, fileName, contents))
            {
                // the request will land with the WebServer object in this process
                string url = @"http://localhost:" + portNumber + "/" + fileName;
                worksheet.Shapes.AddPicture(url, Office.MsoTriState.msoFalse, Office.MsoTriState.msoTrue,
                                   left, top, width, height);
            }
        }

    内存的图片数据交给byte[] contents即可。
    当这个方案成功后，我却突然开了窍，既然是VSTO的项目，一般来说需要客户端FullTrust许可，那么写到本地临时目录中根本不成问题呀，何苦如此大动干戈呢？于是：

.
Bitmap image = new Bitmap(new MemoryStream(buffer))
image.Save(filePath, ImageFormat.Jpeg);
worksheet.Shapes.AddPicture(filePath, Office.MsoTriState.msoFalse,  Office.MsoTriState.msoTrue, left, top, width, height);
File.Delete(filePath);
.