The Tk::WorldCanvas in CPAN looks like a very useful tool. However, I have a problem using it that I am not sure how to solve. I am trying to make a scrolling list of thumbnail images, each scaled and centered. I want to place them on a scrolling canvas so I can add labels next to them, etc.

The problem is that the first few images come out centered properly and the last ones don't. I think it's because they are outside the scrolled region and they don't have proper size information. Is there a way to work around this? Thanks.

use strict;
use Tk;
use Tk::WorldCanvas;

my $can_height = 50;
my $can_spacing = $can_height + 2;
my $can_label_padx = 2;
my $can_width = 50;
my $can_total = 5;
my @canvasList = ();

my $mainwin = MainWindow->new();
my $thumbholder = $mainwin->Scrolled('Canvas',
   -scrollbars => "e",
   -scrollregion => [0, 0, 0, $can_total*$can_spacing],
   -height => 2*$can_spacing,
   -width => 3*$can_width,
   -yscrollincrement=> $can_height,
   )->pack(-side => 'top');

for (my $i = 0; $i < $can_total; $i++) {
   makeThumbnail($i);
}

# Now let the WorldCanvas objects do a smart rescale.
$mainwin->update();
foreach my $can (@canvasList) {
   $can->viewAll;
}

MainLoop;

sub makeThumbnail {
   my $i = shift;
   my $thumbcan = $thumbholder->WorldCanvas(-height => $can_height,
      -width => $can_width);
   $thumbholder->createWindow(0, $can_spacing*$i,
                              -anchor => "nw",
                              -window => $thumbcan);
   $thumbholder->createText($can_width + $can_label_padx,
                            $can_spacing*$i,
                            -anchor => "nw",
                            -text => "Image " . $i);

   # Fake triangle object for illustration purposes.
   my $color = 'black';
   my $width = 1;
   my @path = (10,50,40,-20,66,80,10,50);
   $thumbcan->createLine(@path, -fill => $color, -width => $width);
   push @canvasList,$thumbcan;
}
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