#!/usr/bin/perl

use strict;
use warnings;
# Use the Windows Registry
Win32::Registry;

# Dir of all useable Wallpapapers
my $base_dir = 'C:\Dokumente und Einstellungen\Ricco\Lokale Einstellungen\Anwendungsdaten\Microsoft\Wallpaper\\';

# get the actual Wallpaper from Registry
my $filename=$HKEY_CURRENT_USER->Open('Control Panel\Desktop')->GetValue('Wallpaper');

# Get all wallpapers in dir
my @files=sort glob("${base_dir}*.*");

# find next wallpaper
my $pos=0;
# last if the actual walpaper is found in list
while($pos<@files)
{
  last if ($filename eq $files[$pos]);
  $pos++;
}
# at end of list begin at start.
$pos=-1 if($pos>=$#files)

# get the next wallpaper in list
$pos++;
$filename=$files[$pos];

# set the path in registry
my $type=$HKEY_CURRENT_USER->Open('Control Panel\Desktop')->GetType('Wallpaper');
my $filename=$HKEY_CURRENT_USER->Open('Control Panel\Desktop')->SetValue('Wallpaper',$type,$filename);