=head1 NAME

newbg - Set wallpaper like no-one's business

=head1 SYNOPSIS

  newbg [-d|-D subdir] [-v] [-n] [--list] [keywords...]

  echo 'root: /home/user/wallpapers' >> ~/.newbg

  newbg                # random wallpaper
  newbg -d animals     # random wallpaper from animals subdir
  newbg dinosaur       # random wallpaper with dinosaur in filename

  # Adjust brightness
  newbg --darken [10] | --lighten [10]

  # View current wallpaper or history
  newbg [--current | --history]

  # Restore previous wallpaper on startup
  newbg -r

=head1 DESCRIPTION

C<newbg> is a simple utility to set the desktop wallpaper.
Given a directory of wallpaper images, it will pick a random image subject
to the subdirectory or filename restrictions you provide, and set it as
background. It keeps track of previously set images and will cycle through
them to avoid duplicates.

C<newbg> keeps track of how long a wallpaper has been active and will be
less likely to suggest wallpapers you change after a short amount of time.

Additionally, C<newbg> can normalise the brightness of wallpapers and
output a history of previously set images.

=head1 OPTIONS

=head2 I<keywords>

Pick wallpapers in which the filename contains at least one of the keywords
provided. Case-insensitive.

=head2 C<-d>, C<--dir> I<subdir>

Specify the directory in which to look for a wallpaper. This directory is
assumed to be a sub-directory of the root directory (see above), unless
it begins with a slash ('/'). 

=head2 C<-D> I<subdir>

As C<-d>, except assume the directory is relative to the current working
directory if it does not begin with a slash.

=head2 C<-r>, C<--restore>

Restore previously set wallpaper, without counting statistics. This
is intended for use at startup.

=head2 C<--darken[=adjustment]>

Darken the current wallpaper. The default adjustment is 10, but can
be set. Your adjustment will be saved and applied when the wallpaper is
picked again.

=head2 C<--brighten[=adjustment]>

Brighten the current wallpaper (as above).

=head2 C<-n>, C<--no-stats>

Usually C<newbg> will remember if you immedately switch to another
wallpaper (by re-running the command) or seem to be happy with a
wallpaper (but not re-running for a while) and factor this into
future selections. This option disables this behaviour for the current
invocation.

=head2 C<-l>, C<--list>

List wallpapers that could be picked, but don't set any.

=head2 C<--history>

Show current and previously set wallpapers, with time since they were
set.

=head2 C<--current>

Print path of current wallpaper.

=head2 C<-v>, C<--verbose>

Output the filename of the selected wallpaper, and some other
information.

=head2 C<--config> I<path>

Override path to the C<newbg> config file.

=head1 CONFIGURATION

C<newbg>'s configuration is by default stored in C<$HOME/.newbg> in YAML
format. You can override this via either the C<--config> option or the
C<NEWBG_CONFIG> environment variable.

The config file is used to store data about previous wallpaper
selections and user preferences e.g. brightness adjustments. The
following top-level keys may be set:

=head2 root

Path to the root directory of the user's wallpapers. Required.

=head2 brightness

Target average intensity of pixels in the wallpaper, as a floating
point number [0,1]. If this config is set, images will have their
brightness adjusted such that the average intensity becomes this
value.

=head2 data.$hash

Holds configuration for each wallpaper, by SHA-1 hash of its
contents. Relevant keys are 'good' (number of good votes), 'bad'
(number of bad votes) and 'bright_adjust' (user-specified brightness
adjustment for image).

=head1 AUTHOR

Richard Harris <richardjharris@gmail.com>

=head1 COPRIGHT AND LICENSE

This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.