BSG Corner Clipper

To celebrate the end of BSG this weekend, and to learn how ASP.NET services work, I have written a web service that will clip off the corners of your images (JPEG or PNG) in a BSG stylie. Behold:

I've added the source code below in case you are interested. It was written very quickly, so don't expect production quality, but it illustrates how easy these services are to write:

<%@ WebHandler Language="C#" Class="Handler" %>

using System;
using System.Web;
using System.Net;
using System.Drawing;
using System.Drawing.Imaging;

public class Handler : IHttpHandler 
{
    ImageFormat ParseImageExtension(string src)
    {
        string ext = src.Substring(src.LastIndexOf('.') + 1);
        if (ext == "gif")
        {
            return ImageFormat.Gif;
        }
        else if (ext == "png")
        {
            return ImageFormat.Png;
        }
        else if (ext == "jpg")
        {
            return ImageFormat.Jpeg;
        }
        else if (ext == "jpeg")
        {
            return ImageFormat.Jpeg;
        }
        return null;
    }

    string ImageFormat2ContentType(ImageFormat imageFormat)
    {
        return "image/" + imageFormat.ToString();
    }
    
    public void ProcessRequest (HttpContext context) 
    {
        // Get the src parameter
        var src = context.Request.Params["src"];

        // Get the corner color (optional)
        var color = context.Request.Params["color"];
        if (color == null)
        {
            color = "White";
        }
        // Get the size of the corner
        var corner = context.Request.Params["corner"];
        int cornerSize = -1;
        if (corner != null)
        {
            Int32.TryParse(corner, out cornerSize);
        }
        if (cornerSize < 1)
        {
            cornerSize = 20;
        }
        
        if (src != null)
        {
            // Extract the image type
            var imageFormat = ParseImageExtension(src);
            if(imageFormat != null)
            {
                // Request the source image
                HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(src);
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                try
                {
                    // Make a bitmap from the source image
                    using(var bitmap = Bitmap.FromStream(response.GetResponseStream()))
                    using(var b = new SolidBrush(Color.FromName(color)))
                    {                    
                        ClipCorners(bitmap, b, cornerSize);
                        System.IO.MemoryStream buffer = new System.IO.MemoryStream();
                        bitmap.Save(buffer, imageFormat);
                        context.Response.ContentType = ImageFormat2ContentType(imageFormat);
                        context.Response.BinaryWrite(buffer.ToArray());
                        context.Response.End();                      
                    }                        
                }
                finally
                {
                    response.Close();
                }
            }
        }
    }

    void ClipCorners(Image image, Brush b, int r)
    {
        using (var g = Graphics.FromImage(image))
        {
            g.CompositingMode = System.Drawing.Drawing2D.CompositingMode.SourceCopy;
            int w = image.Width;
            int h = image.Height;
            if (r >= w)
            {
                r = w / 10;
            }
            if (r >= h)
            {
                r = h / 10;
            }
            if (r > 0)
            {
                g.FillPolygon(b, new Point[]
                {
                    new Point(0, 0),
                    new Point(0, r),
                    new Point(r, 0)
                });
                g.FillPolygon(b, new Point[]
                {
                    new Point(w, 0),
                    new Point(w - r, 0),
                    new Point(w, r)
                });
                g.FillPolygon(b, new Point[]
                {
                    new Point(0, h),
                    new Point(0, h - r),
                    new Point(r, h)
                });
                g.FillPolygon(b, new Point[]
                {
                    new Point(w, h),
                    new Point(w, h - r),
                    new Point(w - r, h)
                });
            }
        }        
    }
    
    public bool IsReusable {
        get {
            return false;
        }
    }

}