use strict;
use Tk;
use Tk::Pane;

my $mw = MainWindow->new;

my $sPane = $mw->Scrolled("Pane",
   -scrollbars => 'se',
   -sticky => 'nsew',
   -bg => 'black',
   -width => 300,
   -height => 300
)->pack(qw/-expand 1 -fill both/);
my $container = $sPane->Subwidget('scrolled');

foreach my $row (0 .. 3) {
   foreach my $col (0 .. 3) {
      createTile($container, $row, $col);
   }
}

foreach my $i (0 .. 3) {
   $container->gridRowconfigure($i, -weight => 1);
   $container->gridColumnconfigure($i, -weight => 1);
}

MainLoop;

## Each 'Tile' is a Frame containing a Scrolled Canvas +
## another Frame containing zoom controls.

sub createTile
{
   my ($parent, $x, $y) = @_;

   my $tileColor = "black";
   my $tile = $parent->Frame(-bg => $tileColor)->grid(
     -padx => 5,
     -pady => 5,
     -row => $x, 
     -column => $y, 
     -sticky => 'nsew'
   );

   my $sc = $tile->Scrolled('Canvas',
      -scrollbars => 'osoe',
      -scrollregion => [0, 0, 200, 200],
      -width => 125,
      -height => 125,
      -background => randColor()
   )->pack(qw/-fill both -side top -expand 1/);

   my $count = int(rand(6)) + 2;
   foreach my $i (1 .. $count) {
      my ($x, $y) = (randNumber(), randNumber());
      my $size = randNumber();
      $sc->createRectangle($x, $y, $x+$size, $y+$size,
         -fill => randColor(),
         -outline => 'black',
         -width => 2
      );
   }

   my $bFrame = $tile->Frame(-bg => $tileColor)->pack(qw/-side top/);
   $bFrame->Button(
       -text => " Zoom Out ",
       -command => sub { $sc->scale(qw/all 0 0 .5 .5/); }
   )->pack(qw/-side left -padx 5/);

   $bFrame->Button(
       -text => " Zoom In",
       -command => sub { $sc->scale(qw/all 0 0 2 2/); }
   )->pack(qw/-side right -padx 5/);
}

sub randColor {
   my @colors = qw(red yellow blue orange green purple);
   return $colors[rand($#colors + 1)];
}

sub randNumber {
   my ($max, $min) = (100, 10);
   my $size = int(rand($max));
   $size += $min if $size < $min;
   return $size;
}