Creating a thumbnail image

[ShawnMolloy]

Hello,

I have an image control on a web form. On page load I'd like to programatically set the source of the image (I guess using the Image.ImageUrl property) to a function that returns an Image, without first saving the image to the file system.

Any idea how I can do this?

 

[BoulderBum]

Create a page that generates the thumbnail and set the ImageUrl to that page.

For instance:

myImage.ImageUrl = "~/Thumbnail.aspx?imageId=whatever";

Then in Thumbnail.aspx generate the thumbnail using GDI+ and write it to the response stream.

//page load in Thumbnail.aspx
string imageId = Request.QueryString["imageId"];

//load image into MemoryStream

//write MemoryStream to Response
Response.Write( /*image*/ );

There's more to it than that, but you get the idea.

 

[ShawnMolloy]

Ok, thats a great way of doing it. I was hoping to keep all the functionality in one class, but I suppose this is as close as I can get.

Thanks alot!

-- shawn

 

[tperri]

here is some code I use to create thumbnails on the fly (when a user uses a dialog to upload)

                if (bResize == true)
                {
                    StrFileName = SaveThumbnail(strCompleteFilePath, Convert.ToInt32(NewImageHeight), Convert.ToInt32(NewImageWidth), iUserID, StrFileName);

                }

    private string SaveThumbnail(string strFilePath, int fHeight, int fWidth, int iUserID, string strFileName)
    {

        Bitmap myPic = new Bitmap(strFilePath);

        System.Drawing.Image myThumb = myPic.GetThumbnailImage(Convert.ToInt32(fWidth), Convert.ToInt32(fHeight), null, new IntPtr());

        string strNewPath = Server.MapPath(".\\images\\uploaded\\" + "UserID" + iUserID + "new" + strFileName);
        myThumb.Save(strNewPath, System.Drawing.Imaging.ImageFormat.Jpeg);

        return "new" + strFileName;


    }

Maybe you'll want to look at working with the object myThumb after the bitmap is loaded into it and see if that Image can be displayed. I don't see why it couldn't. Let me know if you try this and how it goes.