Dynamically Resize an Image using Response.BinaryWrite

Question

User-224188520 posted

Hey All I've been mucking around with this for a bit now and can't seem to find a code example of how to resize an image based on how I am generating an image.

I have banner images stored in an MS SQL database, the banners are selected for use at the top of webpages, when creating a new webpage the user is presented with a radio button list that has each banner generated in an image control. Currently I am just forcing the size of the image, with the image control and the page takes for ever for the images to load.

How can I force a resize of my images at render time to be more like thumbnails?, bellow is the code I am using on my page load event of the page that renders the images.

Imports System.Data.SqlClient

Imports System.IO

Partial Class imgDisplay

Inherits System.Web.UI.Page

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

Dim banner_id As String = Request.QueryString("banner_id")

Using ConnectionString As New SqlConnection(ConfigurationManager.ConnectionStrings("ConnectionString").ConnectionString)

Const SQL As String = "SELECT [banner_img], [MIMEType] FROM [tbl_banner] WHERE [banner_id] = @banner_id"

Dim myCommand As New SqlCommand(SQL, ConnectionString)myCommand.Parameters.AddWithValue("@banner_id", banner_id)

ConnectionString.Open()

Dim myReader As SqlDataReader = myCommand.ExecuteReader

If myReader.Read Then

Response.ContentType = myReader("MIMEType").ToString()

Response.BinaryWrite(myReader("banner_img"))

End If

myReader.Close()

ConnectionString.Close()

End Using

End Sub

End Class

Thanks,

Answer 1

User1396828672 posted

This is a method I used in C#. Do you need it in VB?

 

// this is how to call the resizeimage method from an upload form
// I believe you can convert the myreader("banner_img") to a stream
// and use the System.Drawing.Image.FromStream method

 private const int MAX_IMAGE_WIDTH_AND_HEIGHT = 200;

  byte[] fileArray = new Byte[profileImageUpload.PostedFile.ContentLength];
                profileImageUpload.PostedFile.InputStream.Read(fileArray, 0, profileImageUpload.PostedFile.ContentLength);

                System.Drawing.Image uploadedImage = System.Drawing.Image.FromStream(profileImageUpload.PostedFile.InputStream);
                if (uploadedImage.Height > MAX_IMAGE_WIDTH_AND_HEIGHT || uploadedImage.Width > MAX_IMAGE_WIDTH_AND_HEIGHT)
                    fileArray = ResizeImage(uploadedImage);


 private byte[] ResizeImage(System.Drawing.Image imageToResize)
        {
            Decimal percentageOfMaxWidth = (decimal)MAX_IMAGE_WIDTH_AND_HEIGHT / imageToResize.Width;
            Decimal percentageOfMaxHeight = (decimal)MAX_IMAGE_WIDTH_AND_HEIGHT / imageToResize.Height;

            Decimal whatPercentageToUse = percentageOfMaxWidth > percentageOfMaxHeight ? percentageOfMaxHeight : percentageOfMaxWidth;

            System.Drawing.Bitmap newImage = new System.Drawing.Bitmap(imageToResize, 
                new System.Drawing.Size(Convert.ToInt32(imageToResize.Width * whatPercentageToUse), 
                    Convert.ToInt32(imageToResize.Height * whatPercentageToUse)));

            MemoryStream stream = new MemoryStream();
            newImage.Save(stream, System.Drawing.Imaging.ImageFormat.Jpeg);

            byte[] resizedImageArray = new Byte[stream.Length];
            stream.Position = 0;
            stream.Read(resizedImageArray, 0, (int)stream.Length);
            stream.Close();

            return resizedImageArray;

        }

 

Answer 2

User-224188520 posted

Thanks Chris, I can convert it to VB, no problem. Let me have a look at it tonight and I will let you know how it works out for me.

Answer 3

User-224188520 posted

I used to think I was pretty good at figuring out code, but wow this one is really starting to bother me. I can not figure this out, there is a lot of code examples out there and they all seem massive just to do a simple little re-size job. Also most of the code out there deals with images stored in a file folder and not in a database.

I am truely stumped on how to get a full sized image from my sql database, resize it to a much smaller version then display it using VB. Why does this seem so difficult and labour intensive. The code above shows the extraction of the full sized image.

Answer 4

User-224188520 posted

Maybe I should re-phrase the question.

Is there a way to get this

Response.BinaryWrite(mySQLReader("banner_img"))

Into an Image.FileStream so I then can use the many code examples to resize the image when being rendered from an Image.FileStream.