insaniac has asked for the wisdom of the Perl Monks concerning the following question:

Hey Monkies,

I'm trying to load the EXIF thumbnail from images, when they are present in the EXIF header, within Gtk2. The perldoc of Gtk2::Gdk::Pixbuf says I have to use pack(), so I can pass the data to Gtk2::Gdk::Pixbuf->new_from_data();


This is my code: 
my $thumb = pack('a*',${ $image->get_exif->{ThumbnailImage} });
        my $pixbuf = Gtk2::Gdk::Pixbuf->new_from_data($thumb,'rgb',TRU
+E,8,160,120,640);

[download]

$image is an object which retrieves EXIF information, it works... I've already dumped the output to a file, it's an image. That's how I found out what the width and height were.
Now, my problem is that all thumbs are 'mangled'.. they're snowy black :-/

Any help, tips, pointers to URLs/docs is greatly appreciated!

Thanks,
a confused monkie..

to ask a question is a moment of shame
to remain ignorant is a lifelong shame

Replies are listed 'Best First'.
Re: How to use pack() with Gtk2::Gdk::Pixbuf
by zentara (Cardinal) on Sep 13, 2005 at 11:16 UTC
[reply]
      yeah... was thinking about that already ;-)
      thanks for the advice tho...

      to ask a question is a moment of shame
      to remain ignorant is a lifelong shame

[reply]
Re: How to use pack() with Gtk2::Gdk::Pixbuf
by insaniac (Friar) on Sep 13, 2005 at 13:21 UTC
    muppet on the gtk-perl mailinglist found the solution ;-)
    here's his message (well, at least the solution part ;) ): 

    Is the image data actually raw, packed, 24-bit pixels?  If it's in a  
compressed format, you'll have to do incremental loading with a  
PixbufLoader.

/me pokes google for EXIF thumbnail format

According to http://park2.wakwak.com/~tsuruzoh/Computer/Digicams/exif-
+ 
e.html#ExifThumbs the thumbnail will be JPEG or TIFF, not raw bits.

Do this, instead:

   my $loader = Gtk2::Gdk::PixbufLoader->new;
   $loader->write ($data);
   $loader->close ();
   my $pixbuf = $loader->get_pixbuf ();

(That code is from memory, check for yourself to make sure i'm not  
telling lies.)

    [download]

    It works like a charm now ;-)

    to ask a question is a moment of shame
    to remain ignorant is a lifelong shame

[reply]
[d/l]

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