#!/usr/bin/perl -w
# Generate characters in a sparsely filled area.

use strict;
use constant WIDTH => 1024;
use constant HEIGHT => 1024;

# Convert code point to character
sub EncodeChar($)
{
   my ($code) = @_;

   if( $code <= (1 << 7) - 1 )
   {
      return chr($code);
   }
   if( $code <= (1 << (5 + 6)) - 1 )
   {
      return chr(0xc0 | (($code >> 6) & 0x1f)) .
             chr(0x80 | ($code & 0x3f));
   }
   if( $code <= (1 << (4 + 6 + 6)) - 1 )
   {
      return chr(0xe0 | (($code >> 12) & 0x0f)) .
             chr(0x80 | (($code >> 6) & 0x3f)) .
             chr(0x80 | ($code & 0x3f));
   }
   return chr(0xf0 | (($code >> 18) & 0x07)) .
          chr(0x80 | (($code >> 12) & 0x3f)) .
          chr(0x80 | (($code >> 6) & 0x3f)) .
          chr(0x80 | ($code & 0x3f));
}

for(my $y = 0; $y < HEIGHT; $y++)
{
   for(my $x = 0; $x < WIDTH - 2;)
   {
      if( rand() < 0.01 )
      {
         # Generate a full-width character.
         #
         # Select among the fish CJK characters or emojis.
         if( rand() > 0.5 )
         {
            use constant FISH_START => 0x9b58;
            use constant FISH_END => 0x9c7b;
            print EncodeChar(int(rand(FISH_END - FISH_START + 1)) + FISH_START);
         }
         else
         {
            use constant EMOJI_START => 0x1f600;
            use constant EMOJI_END => 0x1f635;
            print EncodeChar(int(rand(EMOJI_END - EMOJI_START + 1)) +
                             EMOJI_START);
         }
         $x += 2;
      }
      else
      {
         # Generate a single space
         print " ";
         $x++;
      }
   }
   print "\n";
}