Vixed Vixed - 22 days ago 7
ASP.NET (C#) Question

How can I execute an aspx from url returning an ContentType Image?

This function return an resized and centered image.
I would like tu execute it like thumb.aspx?image=test.jpg&width=100&height=50&needToFill=tru‌​e to get a ContentType = "image/jpeg"

public static System.Drawing.Image FixedSize(Image image, int Width, int Height, bool needToFill)
{
int sourceWidth = image.Width;
int sourceHeight = image.Height;
int sourceX = 0;
int sourceY = 0;
double destX = 0;
double destY = 0;
double nScale = 0;
double nScaleW = 0;
double nScaleH = 0;
nScaleW = ((double)Width / (double)sourceWidth);
nScaleH = ((double)Height / (double)sourceHeight);
if (!needToFill)
{
nScale = Math.Min(nScaleH, nScaleW);
}
else
{
nScale = Math.Max(nScaleH, nScaleW);
destY = (Height - sourceHeight * nScale) / 2;
destX = (Width - sourceWidth * nScale) / 2;
}
if (nScale > 1)
nScale = 1;
int destWidth = (int)Math.Round(sourceWidth * nScale);
int destHeight = (int)Math.Round(sourceHeight * nScale);

System.Drawing.Bitmap bmPhoto = null;
try
{
bmPhoto = new System.Drawing.Bitmap(destWidth + (int)Math.Round(2 * destX), destHeight + (int)Math.Round(2 * destY));
}
catch (Exception ex)
{
throw new ApplicationException(string.Format("destWidth:{0}, destX:{1}, destHeight:{2}, desxtY:{3}, Width:{4}, Height:{5}",
destWidth, destX, destHeight, destY, Width, Height), ex);
}
using (System.Drawing.Graphics grPhoto = System.Drawing.Graphics.FromImage(bmPhoto))
{
grPhoto.InterpolationMode = InterpolationMode.HighQualityBicubic;
grPhoto.CompositingQuality = CompositingQuality.HighQuality;
grPhoto.SmoothingMode = SmoothingMode.HighQuality;
Rectangle to = new System.Drawing.Rectangle((int)Math.Round(destX), (int)Math.Round(destY), destWidth, destHeight);
Rectangle from = new System.Drawing.Rectangle(sourceX, sourceY, sourceWidth, sourceHeight);
grPhoto.DrawImage(image, to, from, System.Drawing.GraphicsUnit.Pixel);
return bmPhoto;
}
}


Can I just add this in somehow?

void Page_Load(Object sender, EventArgs e){

Answer

You can use an HTTP Handler to satisfy such requirement. An ASP.NET HTTP handler is the process (frequently referred to as the "endpoint") that runs in response to a request made to an ASP.NET Web application. To learn more, take a look at HTTP Handlers and HTTP Modules Overview

ASHX Example

To process a request like this: http://localhost:19610/ImageHandler.ashx?width=200&height=200

  1. Add a new Generic Handler (.ashx) to project and name it ImageHandler.ashx
  2. Write code to get parameters from query string and perform processing and return suitable response:
using System;
using System.Collections.Generic;
using System.Web;
using System.Drawing;

namespace WebApplication1 /*use your application namespace*/
{
    public class ImageHandler: IHttpHandler
    {
        public void ProcessRequest(HttpContext context)
        {
            int width = 0;
            int.TryParse(context.Request.QueryString["width"], out width);
            var height = 0;
            int.TryParse(context.Request.QueryString["height"], out height);
            if (width <= 0) width = 100;
            if (height <= 0) height = 100;
            using (var image = new Bitmap(width, height))
            {
                using (var g = Graphics.FromImage(image))
                    g.Clear(Color.Red);
                byte[] buffer = 
                    (byte[])new ImageConverter().ConvertTo(image, typeof(byte[]));
                context.Response.ContentType = "image/bmp";
                context.Response.OutputStream.Write(buffer, 0, buffer.Length);
            }
        }
        public bool IsReusable { get { return false; } }
    }
}

ASPX Example

If for any reason you want to use an aspx instead, you can create a aspx file without any code behind file like this:

<%@ Page Title="Home Page" Language="C#" %>
<script language="C#" runat="server">
    protected void Page_Load(object sender, EventArgs e)
    {
        int width = 0;
        int.TryParse(Request.QueryString["width"], out width);
        var height = 0;
        int.TryParse(Request.QueryString["height"], out height);
        if (width <= 0) width = 100;
        if (height <= 0) height = 100;
        using (var image = new System.Drawing.Bitmap(width, height))
        {
            using (var g = System.Drawing.Graphics.FromImage(image))
                g.Clear(System.Drawing.Color.Red);
            byte[] buffer =
            (byte[])new System.Drawing.ImageConverter().ConvertTo(image, typeof(byte[]));
            Response.ContentType = "image/bmp";
            Response.OutputStream.Write(buffer, 0, buffer.Length);
        }
    }
</script>