Image::Magick not printing all images

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

I've been messing around with this for ages now without finding a solution - I am taking a set of images from the internet and printing a thumbnail to my server. However when I run the script only a haphazard subset of the full set is written to file - I have to run the script a few times to get all the images

Could anyone test this to see if it an error in the code or otherwise what might be going wrong? Thanks.

#!/usr/bin/perl -w
use strict;
use Image::Magick;
use CGI::Carp qw(fatalsToBrowser warningsToBrowser);

print "Content-type: text/html\n\n"; 

my @names = qw(
http://www.coldwellbanker.com/imgs/property2002/205/14692047_1.jpg.266
+x200
http://www.coldwellbanker.com/imgs/property2002/78/14692047_2.jpg.266x
+200
http://www.coldwellbanker.com/imgs/property2002/463/14692047_3.jpg.266
+x200
http://www.coldwellbanker.com/imgs/property2002/336/14692047_4.jpg.266
+x200
http://www.coldwellbanker.com/imgs/property2002/209/14692047_5.jpg.266
+x200
http://www.coldwellbanker.com/imgs/property2002/82/14692047_6.jpg.266x
+200
http://www.coldwellbanker.com/imgs/property2002/467/14692047_7.jpg.266
+x200
http://www.coldwellbanker.com/imgs/property2002/340/14692047_8.jpg.266
+x200
);

my $count;
foreach my $item (@names) {
  $count++;
  my $photo = '../photo' . $count . '.jpg';
  my $image = Image::Magick->new(magick=>'JPEG');
  my $x = $image->Read($item);

$x = $image->Scale(width=>'50', height=> '50');

$x = $image->Write($photo);

print qq~<img src="http://www.mysite.com/$photo"><br>~;
}
exit();
[download]

Additional note: All of the lines are printed, 1 to 8, but some of the 'Write' are ignored, as mentioned previously, in haphazard manner.

Comment on Image::Magick not printing all images Download Code

Replies are listed 'Best First'.
Re: Image::Magick not printing all images by almut (Canon) on Dec 31, 2008 at 00:39 UTC
Do you get any error messages if you print out the three `$x`es? (see Handling Exceptions) Update: in particular, note that context (i.e. string/numeric) matters here. E.g. `$x = $image->Read(...); warn "$x" if "$x"; # string context: the error/warning message ( +if any) print 0+$x; # numeric context: the number of images read` [download]	[reply] [d/l] [select]
Re: Image::Magick not printing all images by oko1 (Deacon) on Dec 31, 2008 at 02:15 UTC
You may also be Suffering from Buffering. For myself, whenever I'm dealing with any external resource - e.g., a database or a web server - I disable buffering by habit. I find that it prevents a number of arbitrary-seeming and difficult to troubleshoot problems. `#!/usr/bin/perl -w use strict; # Ask Perl to pull the chain after every 'write' or 'print' $\|++; # Rest of code follows` [download] -- "Language shapes the way we think, and determines what we can think about." -- B. L. Whorf	[reply] [d/l]
Re: Image::Magick not printing all images by leocharre (Priest) on Dec 31, 2008 at 01:13 UTC
Yes, as almut mentioned very wisely.. I know Image::Magick is funny- some of the methods only return if there's an error. Ala unix. This is a little of the frustration of mixing c coders with perl code :-) So, those $x hold the error, if there is one.. so.. `my $count; foreach my $item (@names) { $count++; my $photo = '../photo' . $count . '.jpg'; my $image = Image::Magick->new(magick=>'JPEG'); my $x = $image->Read($item); $x = $image->Scale(width=>'50', height=> '50'); $x and die("Error scaling: $x"); $x = $image->Write($photo); $x and die("Error writing: $x"); print qq~<img src="http://www.mysite.com/$photo"><br>~; }` [download]	[reply] [d/l]
Re: Image::Magick not printing all images by zentara (Cardinal) on Dec 31, 2008 at 10:46 UTC
In addition to what has been said, I will point out that IM has a way of retaining images in an internal stack, so when you read an image in, with the same IM object, it gets pushed into an array of images. You might try to clean out the IM object after each loop run to be sure `...... $x = $image->Write($photo); undef @$image; ......` [download] Even though you are calling a new IM object each time thru the loop, it may be that the object is not "loop-safe" for some reason....possibly a bug or an old version that needs updating? But your symptoms point to this, and it's worth a try. I'm not really a human, but I play one on earth Remember How Lucky You Are	[reply] [d/l]