Image demensions from Blob field?

matman

Is there a way to get the width and height of an image stored in a blob field. I'm working with images in a table that the creator did not add fields for width and height.

using phps getimagesize() works if you have a path to an image on a server, but it does not work for me when using something like getimagesize($row['BLOB_FILE']) where blob_file is an actual blob.

Is there a way to get the image width and height before displaying it on a webpage?

Thanks for any tips...

NogDog

I'm thinking if you have a separate file for serving up images from the DB, then you could reference it as a URL (assuming allow_url_fopen is enabled):

$sizeInfo = getimagesize('http://localhost/image_server.php?id='.$pic_id);

matman

Thanks, but that does not return any values. But, no errors. :o)

I also tried:
list($width,$height,$x,$y) = getimagesize("get-image.html?id=123");
print "<p>w $width, h $height</p>";

w, h,

I cannot display the actual url as the pages are on an intranet and you wouldn't be able to see them. But the image I'm testing with has a width=250, height=350. I am getting nothing.

Thanks for the help.

NogDog

The only other option I can think of is to fetch the image data, save it as a file, then run the getimagesize() against that file. (You could then unlink() the file when done.) This would have obvious performance issues for regular usage, but could perhaps be worthwhile to update the database with the dimension info so you don't need to do it any more.

bradgrafelman

As NogDog points out, it might be beneficial to add two columns to your database to hold the width and height of the image.

Alternatively, you'd have to retrieve the BLOB field from the database, use [man]imagecreatefromstring/man to create an image resource, and then use [man]imagesx/man and [man]imagesy/man to get the width/height respectively.

Weedpacket

Another option is to write a stream wrapper (see [man]stream_wrapper_register[/man]) that can be used to hide blob access behind an internal URL. If the wrapper was registered as "db" say, then - depending on how those URLs were converted into database queries, writing something like getimagesize("db://tablename/2343/image"); would work (which would imply that file_get_contents("db://tablename/2343/image") would fetch the blob data itself).

Obviously, if you were going to write such a wrapper for this one task, it would make sense to come up with some scheme for the URLs that would make it useful in other contexts. No doubt there is other data stored in the record (and it would be a reasonable sacrifice of normalisation in favour of efficiency to store the image dimensions directly as their own fields instead of having to having to derive them from first principles every time). So you might, for example, have "db://tablename/2343/foo" return the value of the "foo" field of record #2343; or "db://tablename/2343" to return an array of all of the (at least non-blob) data in that record; and other especially common queries could also be specified by suitably-designed URLs.