In many cases you may want to create a smaller version of your images. maybe for mobile devices or for images view on your page.

One known way is to use the "ready-made" GetThumbnailImage function. That will generally do the job (another way is below):

int Width;
int Height;
int ThumbWidth;
int ThumbHeight;
string SavePath = "[Some save path"];
string FilenameWOext = "[]";
string FileExtention;

Bitmap btmp1 = new Bitmap(SavePath + FilenameWOext + FileExtention); 

Width = btmp1.Width;
Height = btmp1.Height;

System.Drawing.Image.GetThumbnailImageAbort myCallBack =
new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback);
         
if (ThumbWidth > Width && ThumbHeight > Height)
{
      ThumbWidth = Width;
      ThumbHeight = Height;
}

System.Drawing.Image myThumbnail1 = btmp1.GetThumbnailImage(ThumbWidth,
ThumbHeight, myCallBack, IntPtr.Zero);
myThumbnail1.Save(SavePath + ThumbFile);

btmp1.Dispose();

Bitmap resized = new Bitmap(ThumbWidth, ThumbHeight);
            Graphics g = Graphics.FromImage(resized);
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            g.DrawImage(btmp1, new Rectangle(0, 0, resized.Width, resized.Height));

g.Dispose();

The Adobe p2p and Stratus are not that new. its sample application is cool and shows more than just textual p2p connection like other tutorials, but actually shows a good enough voice and image transfer.


BUT, as a .Net programmer, the registration Python code was a bit wierd to work with. Moreover, the application is literally poor in user management, so I needed a good start point to have that registration use real DB.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;

namespace P2PRegistration
{
    /// 

    /// Summary description for $codebehindclassname$
    /// 
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    public class reg : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            RegistrationDBDataContext db = new RegistrationDBDataContext();

            string user = context.Request.QueryString["username"];
            string identity = context.Request.QueryString["identity"];
            string friendsString = context.Request.QueryString["friends"];

            List friends = new List();

            if (friendsString != null && friendsString != "")
            {
                friends = friendsString.Split(',').ToList();
            }

            context.Response.ContentType = "text/plain";
            context.Response.Write(@"");
            context.Response.Write(@"");

            if (user != null && user != "" && identity != null && identity != "")
            {
                context.Response.Write(@"");
                try
                {
                    var rUser = from p in db.registrations where (p.m_username == user) select p;
                    if (rUser.Count() > 0)
                    {
                        //update
                        rUser.First().m_username = user;
                        rUser.First().m_identity = identity;
                        rUser.First().m_updatetime = DateTime.Now;
                        
                        
                    }
                    else
                    {
                        registration newReg = new registration();
                        newReg.m_username = user;
                        newReg.m_identity = identity;
                        newReg.m_updatetime = DateTime.Now;

                        db.registrations.InsertOnSubmit(newReg);
                    }

                    db.SubmitChanges();

                    context.Response.Write("true");
                }
                catch
                {
                    context.Response.Write("false");
                }
                context.Response.Write(@"");
            }

            foreach (string f in friends)
            {
                context.Response.Write(@"");

                context.Response.Write(@"");
                context.Response.Write(context.Server.UrlEncode(f));
                context.Response.Write(@"");

                
                var rFriends = from p in db.registrations where p.m_username == f && p.m_updatetime > DateTime.Now.AddHours(-1) select p;
                foreach (registration r in rFriends)
                {
                    string ident = r.m_identity;
                    if (ident == null) ident = "";

                    context.Response.Write(@""+context.Server.UrlEncode(ident)+@"");

                    if (f != r.m_username)
                    {
                        context.Response.Write(@""+r.m_username+"");
                    }
                }

                context.Response.Write(@"");
            }

            context.Response.Write(@"");
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[registrations]') AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[registrations](
    [m_username] [varchar](100) NOT NULL,
    [m_identity] [varchar](100) NULL,
    [m_updatetime] [datetime] NULL,
 CONSTRAINT [PK__registrations__7C8480AE] PRIMARY KEY CLUSTERED 
(
    [m_username] ASC
)WITH (PAD_INDEX  = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END

...
    // please insert your webservice URL here for exchanging
    private const WebServiceUrl:String = "http://[your domain here]/reg.ashx"; 
...