Resize media library images to width of the mobile device

You may find this code useful if you do not want mobile users requesting images from the media library at a resolution which is larger than their device width, to save a bit of bandwidth.

    public class MobileMediaRequestHandler : MediaRequestHandler
{
    protected override bool DoProcessRequest(HttpContext context)
    {
        if (Sitecore.Context.Device.Name.Equals("Mobile", StringComparison.InvariantCultureIgnoreCase))
        {
            Assert.ArgumentNotNull(context, "context");
            MediaRequest mediaRequest = MediaManager.ParseMediaRequest(context.Request);
            if (mediaRequest == null)
            {
                return false;
            }
            Sitecore.Resources.Media.Media media = MediaManager.GetMedia(mediaRequest.MediaUri);
            if (media == null)
            {
                using (SecurityDisabler securityDisabler = new SecurityDisabler())
                {
                    media = MediaManager.GetMedia(mediaRequest.MediaUri);
                }
                string text;
                if (media == null)
                {
                    text = Settings.ItemNotFoundUrl;
                }
                else
                {
                    Assert.IsNotNull(Context.Site, "site");
                    text = ((Context.Site.LoginPage != string.Empty) ? Context.Site.LoginPage : Settings.NoAccessUrl);
                }
                if (Settings.RequestErrors.UseServerSideRedirect)
                {
                    HttpContext.Current.Server.Transfer(text);
                }
                else
                {
                    HttpContext.Current.Response.Redirect(text);
                }
                return true;
            }

            int screenHeight = HttpContext.Current.Request.Browser.ScreenPixelsHeight;

            int screenWidth = HttpContext.Current.Request.Browser.ScreenPixelsWidth;                

            int imageWidth = TypeGuard.Cast<int>(media.MediaData.MediaItem.InnerItem["width"], 0);

            if (imageWidth != 0 && (imageWidth > screenWidth))
            {
                mediaRequest.Options.MaxWidth = screenWidth;                   
                mediaRequest.Options.UseMediaCache = true;
            }

            return this.DoProcessRequest(context, mediaRequest, media);
        }

        return base.DoProcessRequest(context);
    }