[Lazarus] JPEG Dimensions

[Mattias Gaertner]

On Sun, 2 Oct 2011 13:26:09 +0200
"ADTEC (Pty) Ltd" <adtec at adtec.co.za> wrote:

> Does anyone know of a simple way to determine the picture dimensions
> for a JPEG file? I can determine them using the LazJPG unit and
> loading the file into a variable. The problem is that when I'm trying
> to determine the dimensions on a whole directory of files, the time
> taken to load each file makes the process unuseable.
> 
> I've tried to understand the file layout for jpg files (wikipedia and
> jpeg.org) but don't see where the final dimensions are stored. What I
> would like to do is read just enough of each file to get the height
> and width of the final image. Any suggestions?

Maybe you can alter the fpreadjpeg unit and add a property to read only
the header.
I need a quick jpeg dimension function too.

Mattias