Resizing Image in ASP.NET -- Output as a Stream of the resized image for

Question

I got this block of code from link text and modified it a little because I want to use it with my AJAX Uploader that needs a Stream to be used for adding uploaded items into the attachments display;

public Stream ResizeFromStream(int MaxSideSize, Stream Buffer)
{
    int intNewWidth;
    int intNewHeight;
    System.Drawing.Image imgInput = System.Drawing.Image.FromStream(Buffer);

    // GET IMAGE FORMAT
    ImageFormat fmtImageFormat = imgInput.RawFormat;

    // GET ORIGINAL WIDTH AND HEIGHT
    int intOldWidth = imgInput.Width;
    int intOldHeight = imgInput.Height;

    // IS LANDSCAPE OR PORTRAIT ?? 
    int intMaxSide;

    if (intOldWidth >= intOldHeight)
    {
        intMaxSide = intOldWidth;
    }
    else
    {
        intMaxSide = intOldHeight;
    }


    if (intMaxSide > MaxSideSize)
    {
        // SET NEW WIDTH AND HEIGHT
        double dblCoef = MaxSideSize / (double)intMaxSide;
        intNewWidth = Convert.ToInt32(dblCoef * intOldWidth);
        intNewHeight = Convert.ToInt32(dblCoef * intOldHeight);
    }
    else
    {
        intNewWidth = intOldWidth;
        intNewHeight = intOldHeight;
    }

    // CREATE NEW BITMAP
    Bitmap bmpResized = new Bitmap(imgInput, intNewWidth, intNewHeight);

    // SAVE BITMAP TO STREAM
    MemoryStream imgStream = new MemoryStream();
    bmpResized.Save(imgStream, imgInput.RawFormat);

    // RELEASE RESOURCES
    imgInput.Dispose();
    bmpResized.Dispose();
    Buffer.Close();

    return imgStream;
}

and being called in this block of code;

private void ItemPicture_FileUploaded(object sender, UploaderEventArgs args)
{
    if (GetVisibleItemCount() >= 5)
        return;

    using (System.IO.Stream stream = args.OpenStream())
    {
        ImageResize ir = new ImageResize();
        // This returns a 0 byte stream
        ItemPictureAttachments.Upload(args.FileSize, args.FileName, ir.ResizeFromStream(640, stream));
        // This works fine
        // ItemPictureAttachments.Items.Add(args.FileSize, args.FileName, stream);
    }
}

Am I doing it wrong in returning the stream back to where it is being called from? Thanks!

Answer 1

Based on your code everything looks OK. I suggest you to put a break point at

Bitmap bmpResized = new Bitmap(imgInput, intNewWidth, intNewHeight);

and inspect whether imgInput is not empty. Or Perhaps there is something wrong with the ImageRawFormat.

Answer 2

I tested your ResizeFromStream method using the PostedFile.Inputstream property of a regular ASP.NET File control, and that worked fine. Perhaps the problem is with the component you are using to retrieve the file's stream (args.OpenStream())?