Error displaying PNGs

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

Heres my code, I run it using localhost/script.cgi from my browser -

#!C:/Perl/bin/perl -w

use strict;
use CGI::Carp qw(fatalsToBrowser);
use GD;

#createanewimage
my $im=new GD::Image(100,100);

#allocatesomecolors
my $white=$im->colorAllocate(255,255,255);
my $black=$im->colorAllocate(0,0,0);
my $red=$im->colorAllocate(255,0,0);
my $blue=$im->colorAllocate(0,0,255);

#makethebackgroundtransparentandinterlaced
$im->transparent($white);
$im->interlaced('true');

#Putablackframearoundthepicture
$im->rectangle(0,0,99,99,$black);

#Drawablueoval
$im->arc(50,50,95,75,0,360,$blue);

#Andfillitwithred
$im->fill(50,50,$red);

#makesurewearewritingtoabinarystream
binmode STDOUT;

#ConverttheimagetoPNGandprintitonstandardoutput
print $im->png;
[download]

When I try to run this from my browser, I get an Internal server error, and in my error log I get -

[Sat Mar 15 20:58:45 2003] [error] [client 127.0.0.1] malformed header
+ from script. Bad header=‰PNG: script.cgi
[download]

I can open gen.png fine from the browser using localhost/gen.png. I'm running on Win XP, and I have Apache installed. Maybe Apache is the problem? The script works fine on the command line. ANy ideas?

Comment on Error displaying PNGs Select or Download Code

Replies are listed 'Best First'.
Re: Error displaying PNGs by pfaut (Priest) on Mar 15, 2003 at 21:11 UTC
You need to output HTTP headers indicating a proper Content-Type for a PNG image. Before the binmode, you want something like `print "Content-type: image/x-png\n\n";` [download] `--- print map { my ($m)=1<<hex($_)&11?' ':''; $m.=substr('AHJPacehklnorstu',hex($_),1) } split //,'2fde0abe76c36c914586c';` [download]	[reply] [d/l] [select]
Wrong MIME type (was: Error displaying PNGs) by Aristotle (Chancellor) on Mar 16, 2003 at 01:09 UTC
The right MIME type is `image/png` though. All else will result in undefined behaviour, even if some browsers will work. Makeshifts last the longest.	[reply]
Re: Wrong MIME type (was: Error displaying PNGs) by pfaut (Priest) on Mar 16, 2003 at 01:45 UTC
Thanks, Aristotle. I've long since lost my pointer to a list of valid content types. I posted what I last remembered seeing which was likely a long time ago before PNG files were popular. `--- print map { my ($m)=1<<hex($_)&11?' ':''; $m.=substr('AHJPacehklnorstu',hex($_),1) } split //,'2fde0abe76c36c914586c';` [download]	[reply] [d/l]