Dynamically resize image with maintain its ratio in asp.net

Task: Dynamically Re-size Image with maintain its ration using Asp.net and C# code.

Description: Many times we need to store different size images for a specific images as used in e-commerce website. for that we re-size the image and save multiple images as one small, medium and a full size image. But If we have issue regarding space and having good performance server then we can use dynamically re-sizing of image just save single big image and then when need to use re-size it at run time as you want.

For achieving this task I write a code which response the re-size image. I use it for jpg and png images not for gif.



Call the page where you code for image merging :

Image1.ImageUrl = "dynamicimage.aspx";

Dynamic Code for image generation and merging (dynamicimage.aspx/dynamicimage.aspx.cs)

using System.Drawing;

using System.Drawing.Drawing2D;

using System.Drawing.Imaging;

using System.IO;

protected void Page_Load(object sender, EventArgs e)

{

  string testimage = Server.MapPath(@"images/hemant_image.jpg");

  getimage(testimage, 400, 400); 

  // can set imageurl, max-width and max-height using query string...

}

public void getimage(string ThumbnailPath, int maxwidth, int maxheight)

{

    System.Drawing.Image image = System.Drawing.Image.FromFile(ThumbnailPath);

    Size ThumbNailSize = setimagesize(maxwidth, maxheight, image.Width, image.Height);

    System.Drawing.Image ImgThnail = new Bitmap(ThumbNailSize.Width, ThumbNailSize.Height);

    System.Drawing.Graphics graphics = System.Drawing.Graphics.FromImage(ImgThnail);

    graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;

    graphics.SmoothingMode = SmoothingMode.HighQuality;

    graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;

    graphics.CompositingQuality = CompositingQuality.HighQuality;

    graphics.DrawImage(image, 0, 0, ThumbNailSize.Width, ThumbNailSize.Height);

    ImageCodecInfo[] info = ImageCodecInfo.GetImageEncoders();

    EncoderParameters encoderParameters;

    encoderParameters = new EncoderParameters(1);

    encoderParameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);

    string sExt = System.IO.Path.GetExtension(ThumbnailPath);

    if (sExt.ToString() == ".png")

    {

        Response.ContentType = "image/png";

        ImgThnail.Save(Response.OutputStream, image.RawFormat);

    }

    else

    {

        Response.ContentType = "image/jpeg";

        ImgThnail.Save(Response.OutputStream, info[1], encoderParameters);

    }

    image.Dispose();

}

// below code is my old one for calculating height and width with maintain image ratio.

public Size setimagesize(int maxwidth, int maxheight, int OriginalWidth, int OriginalHeight)

{

    Size NewSize = new Size();

    int sNewWidth = OriginalWidth;

    int sNewHeight = OriginalHeight;

    int tempheight = 0;

    int tempwidht = 0;

    if (OriginalWidth >= OriginalHeight)

    {

        if (OriginalWidth >= maxwidth)

        {

            sNewWidth = maxwidth;

            sNewHeight = OriginalHeight * maxwidth / OriginalWidth;

        }

        if (sNewHeight > maxheight)

        {

            tempheight = sNewHeight;

            sNewHeight = maxheight;

            sNewWidth = sNewWidth * maxheight / tempheight;

        }

    }

    else

    {

        if (OriginalHeight >= maxheight)

        {

            sNewHeight = maxheight;

            sNewWidth = OriginalWidth * maxheight / OriginalHeight;

        }

        if (sNewWidth > maxwidth)

        {

            tempwidht = sNewWidth;

            sNewWidth = maxwidth;

            sNewHeight = sNewHeight * maxwidth / tempwidht;

        }

    }

    NewSize = new Size(sNewWidth, sNewHeight);

    return NewSize;

}