Generating image thumbnails in ASP.NET

To generate an image thumbnail in ASP.NET you can use the method below.

public static void CreateThumbnail(string filename, int desiredWidth, int desiredHeight, string outFilename)
{
    using (System.Drawing.Image img = System.Drawing.Image.FromFile(filename))
    {
        float widthRatio = (float)img.Width / (float)desiredWidth;
        float heightRatio = (float)img.Height / (float)desiredHeight;
        float ratio = heightRatio > widthRatio ? heightRatio : widthRatio;
        int newWidth = Convert.ToInt32(Math.Floor((float)img.Width / ratio));
        int newHeight = Convert.ToInt32(Math.Floor((float)img.Height / ratio));
        using (System.Drawing.Image thumb = img.GetThumbnailImage(newWidth, newHeight, new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailImageAbortCallback), IntPtr.Zero))
        {
            thumb.Save(outFilename, System.Drawing.Imaging.ImageFormat.Jpeg);
        }
    }
}

public static bool ThumbnailImageAbortCallback()
{
    return true;
}

You can use the way resize an image to create a thumbnail in c#.

public void GenerateImage(byte[] data, string extension, string filename)
{
    using (MemoryStream ms = new MemoryStream(data))
    {
        var image = Image.FromStream(ms);
        image.Save(filename);
        ResizeImage(image, 800, 600, "large-image.jpg");
        ResizeImage(image, 480, 320, "medium-image.jpg");
        ResizeImage(image, 192, 144, "small-image.jpg");
    }
}

public void ResizeImage(Image image, int width, int height, string filename)
{
    using (Bitmap newImage = new Bitmap(width, height))
    {
        var graphics = Graphics.FromImage(newImage);
        graphics.DrawImage(image, 0, 0, width, height);
        newImage.Save(filename, ImageFormat.Jpeg);
    }
}