Check uploaded image's dimensions

Question

I'm using asp.net 3.5 and c# on my web site. Here is my question:

I have an upload button and asp:Image on a page. An user can upload an image from his computer and that image will be displayed in the asp:image. But before I display the image, I would like to check the width and height of the uploaded image. How do I do this?

Answer 1

In ASP.NET you typically have the byte[] or the Stream when a file is uploaded. Below, I show you one way to do this where bytes is the byte[] of the file uploaded. If you're saving the file fisrt then you have a physical file. and you can use what @Jakob or @Fun Mun Pieng have shown you.

Either ways, be SURE to dispose your Image instance like I've shown here. That's very important (the others have not shown this).

  using (Stream memStream = new MemoryStream(bytes))
  {
    using (Image img = System.Drawing.Image.FromStream(memStream))
    {
      int width = img.Width;
      int height = img.Height;
    }
  }

Answer 2

Try the following:

public bool ValidateFileDimensions()
{
    using(System.Drawing.Image myImage =
           System.Drawing.Image.FromStream(FileUpload1.PostedFile.InputStream))
    {
        return (myImage.Height == 140 && myImage.Width == 140);
    }
}