in reply to Downloading KeyForge image

On Windows, STDOUT applies "\n" to CRLF conversion by default, breaking binary data. Add binmode STDOUT before writing data to STDOUT and it will work. The same is true for any file you open without binmode (or I/O layers like :raw). See also binmode.

Alexander

--
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)

Replies are listed 'Best First'.
Re^2: Downloading KeyForge image
by Stamm (Sexton) on May 21, 2019 at 19:10 UTC
    Thank you for your answers. I just figured out how to save the image (with binmode). But it was only for debugging. The real purpose is to display it in Tk. And still can't make it to work. Here is the whole program: 
    use 5.010;
use strict;
use warnings;

use LWP::UserAgent;
use Tk;
use Tk::PNG;

my $url = "https://cdn.keyforgegame.com/media/card_front/en/341_1_7C85
+4VPW72RH_en.png";

my $ua = LWP::UserAgent->new(agent => '');
my $response = $ua->get($url);
die $response->status_line if not $response->is_success;
my $data = $response->decoded_content(charset => 'none');

my $mw = MainWindow->new;
$mw->Photo(-data => $data, -format => 'PNG');

    [download]
    I have the error 'couldn't recognize image data at ...../perl/vendor/lib/Tk/Image.pm line 21'. Why is that?
[reply]
[d/l]

      Seems to only work if you base64 encode the binary

      use 5.010;
use strict;
use warnings;

use LWP::UserAgent;
use Tk;
use Tk::PNG;
use MIME::Base64;

my $url = 'http://www.perl.com/images/ads/tpcip_banner-1200x150.png';
my $ua = LWP::UserAgent->new(agent => '');
my $response = $ua->get($url);
die $response->status_line if not $response->is_success;
my $data = MIME::Base64::encode_base64($response->decoded_content());

my $mw = MainWindow->new;
my $photo = $mw->Photo(-data => $data, -format => 'PNG');
$mw->Label(-image => $photo)->pack();
MainLoop;

      [download]
      poj
[reply]
[d/l]

        Thank you! Yes it works with Base64. It's weird, the doc says it accepts binary in addition to Base64.

        Thanks again.

[reply]

      Are you sure the image is a PNG? Just because a URL ends in .png, the file does not have to be a PNG. Browsers and image viewers generally accept anything that roughly looks like an image, more or less ignoring file extensions, URL parts, and MIME types.

      Check the first few bytes: They should be 0x89 0x50 0x4E 0x47 0x0D 0x0A 0x1A 0x0A, according to both Portable_Network_Graphics and http://www.libpng.org/pub/png/spec/1.2/PNG-Contents.html.

      Alexander

      --
      Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)
[reply]
[d/l]

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