Win32 Tk JPEG from memory problem

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

Hi. I need some help with displaying a JPEG via TK using ActiveState Perl.

Pulling the image from a file works fine:

use strict;
use Tk;
use Tk::JPEG;

my $fname = "rock.jpg";
my $win = new MainWindow;
my $image = $win->Photo('-format' => 'jpeg',
            '-file' => $fname);
$win->Label(-image=>$image)->pack;

MainLoop;
[download]

But I can seem to load images from a data string (as the images will eventually be pulled from a database). That is, this doesn't work:


use strict;
use Tk;
use Tk::JPEG;

my $fname = "rock.jpg";
open(F, $fname) or die "cant open $fname";
binmode(F);
undef $/;
my $jpeg = <F>;
close(F);

my $win = new MainWindow;
my $image = $win->Photo('-format' => 'jpeg',
            '-data' => $jpeg);
$win->Label(-image=>$image)->pack;

MainLoop;
[download]

It dies with this error:

couldn't recognize image data at C:/Perl/site/lib/Tk/Image.pm line 21.
[download]

Can anyone offer advice? Am I reading the JPEG in wrong, or am I sending it to TK wrong?

Thanks

nop

Comment on Win32 Tk JPEG from memory problem Select or Download Code

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(crazyinsomniac) Re: Win32 Tk JPEG from memory problem by crazyinsomniac (Prior) on Nov 11, 2001 at 14:23 UTC
Not too long ago I ran into the same problem, and the only place I found a solution was pVoice and pStory. It's probably documented somewhere, but I couldn't find it at the moment (in my perl Tk documentation; it's prolly documented in the c or whatever other lang Tk is available originally in). It turns out, that when you specify a -data string, it has to be base64 encoded, and that is why the following works; `#!/usr/bin/perl -w $^W=1; use strict; use Tk; use Tk::JPEG; use MIME::Base64 qw( encode_base64 ); my $fname = "rock.jpg"; open(F, $fname) or die "cant open $fname"; binmode(F); undef $/; my $jpeg = <F>; close(F); my $win = new MainWindow; my $image = $win->Photo( -data => encode_base64($jpeg), -format => 'JPEG', ,); $win->Label(-image=>$image)->pack; MainLoop;` [download] I gotta say is thanks Jouke, no wonder you got that perl GUI book deal. update: after some "testing" :D, it turns out you don't really need to specify -format, as it will pick it up from the -data. ___crazyinsomniac_______________________________________ `Disclaimer: Don't blame. It came from inside the void` `perl -e "$q=$_;map({chr unpack qq;H;,$_}split(q;;,qH*));print;$q/$q;"`	[reply] [d/l]

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(crazyinsomniac) Re: Win32 Tk JPEG from memory problem
by crazyinsomniac (Prior) on Nov 11, 2001 at 14:23 UTC

pVoice

pStory

#!/usr/bin/perl -w
$^W=1;
use strict;
use Tk;
use Tk::JPEG;
use MIME::Base64 qw( encode_base64 );

my $fname = "rock.jpg";
open(F, $fname) or die "cant open $fname";
binmode(F);
undef $/;
my $jpeg = <F>;
close(F);

my $win = new MainWindow;
my $image = $win->Photo( -data => encode_base64($jpeg),
                         -format => 'JPEG',
                       ,);
$win->Label(-image=>$image)->pack;

MainLoop;
[download]

Jouke

update: after some "testing" :D, it turns out you don't really need to specify -format, as it will pick it up from the -data.

___crazyinsomniac_______________________________________
Disclaimer: Don't blame. It came from inside the void
perl -e "$q=$_;map({chr unpack qq;H*;,$_}split(q;;,q*H*));print;$q/$q;"

[reply]
[d/l]