A wallpaper changer for various Linux (and NetBSD) desktop environments.
Version 2.0c
LBC is a simple utility that runs quietly in the background and, at regular intervals, instructs the Linux desktop environment to change the background (wallpaper) image. LBC is more flexible than the mechanisms built into most desktops, for a number of reasons.
- LBC allows recursive directory searches, or arbitrary lists of files and directories, or any combination of these;
- it allows some control over what kind of images to include. For example, you can avoid putting potrait-orientation images on a landscape screen;
- it uses a simple, text-based configuration file, or just command-line options.
Note that I wrote LBC for Linux, but it also works to some extent with NetBSD. FOr example, if you're running the XFCE4 desktop, you can use LBC with the "-m xfce4" option. I do not know if any of the other screen-changing methods work with NetBSD.
$ lbc --method gnome2 --width 1024 --aspect landscape $HOME/Pictures/
Use images in $HOME/Pictures and all its subdirectories,
that are in landscape aspect
ratio, at least 1024 pixels wide. Use the gnome2 background method.
Change interval remains at the default of two minutes. Up to the
default number of images (1000) will be included.
Just the development headers for libjpeg. E.g.:
# apt-get install jpeglib-dev
To support all the various background-changing methods, you will need:
xview(apt-get install xloadimage) (for thexviewmethod)xfconf-query(for Xfce4 support)gsettings(for Gnome 3)gconftool-2(for Gnome 2)
Of course, a particular system will probably only need one of these. In practice, the relevant binaries are usually part of the desktop environment, and you shouldn't need to install anything extra.
Assuming that the compile-time dependencies are available, it's just a matter of:
$ make
$ sudo make install
Note that I wrote LBC specifically for Linux, and intend it to be
compiled using gcc. It uses gcc-specific C library extensions.
To compile on NetBSD, you'll need to invoke gmake specifically,
rather than make, as the Makefile uses GNU templates. Of course,
this means you'll need to install gmake (e.g., pkgin -y install gmake).
-a,--aspect={landscape|portrait|any}
Include images with the specified aspect ratio. The default is 'any'. Note that any image whose width is greater than its height, even by one pixels, is "landscape".
-d,--dirs={dir1:dir2...}
A colon-separated list of directories to include. This option is an alternative to listing directories or files as plain arguments to the program. The result is the same, but this option can be used in a configuration file.
The list can, in fact, include individual files if necessary.
--dual
Enable different images on dual monitors, if the desktop supports it.
lbc shows a warning if this feature is enabled with a background
change method that does not support it. At present, I believe Xfce4 is
the only supported desktop that has this feature.
-f,--foreground
Run LBC in the foreground, attached to console. This feature is for debugging -- when run in the background, no logging is produced after all the initial checks are made. In normal circumstances, LBC detaches from the terminal after ensuring that image files are available, and no further logging is produced.
-h,--height={pixels}
Include only images of at least the specified height (see Limitations section below).
-i,--interval={seconds}
Sets the time interval between background changes. The default is 120 seconds.
--log-level={0..4}
Sets the amount of logging from fatal errors only (0), to a huge amount
of trace logging (4). The default level is 1. Note that most logging will
only be seen with the --foreground option. Log levels 2 or higher
will probably not be comprehensible except when examined along side the
program's source code.
--max-files=N
Limit the number of files stored by the program. If this limit is reached, LBC will show a warning message. The default value is 1000; this can safely be increased by a factor of 10-100 on most systems, should the need arise.
-m,--method={name}
Sets the background changing method. See the section 'Background change
methods' for more information. The default is gnome-shell.
-n,--next
Signals a running instance of LBC switch to the next background image.
-p,--prev
Signals a running instance of LBC to switch to the previous background image.
-s,--stop
Shut down an instance of the program running in the background.
-v,--version
Show version number, and exit
-w,--width={pixels}
Include only images of at least the specified width (see Limitations section below).
This is the default. With this method, the program uses the command
gsettings set org.gnome.desktop.background picture-uri to change
the background. This should work on any Gnome 3 system using gnome-shell as
the desktop manager, including Wayland-based systems.
This method uses the command gconftool-2 --set /desktop/gnome/background/picture_filename This should work on Gnome 2
and systems derived from it.
This method uses the command xview --onroot. Naturally, it will only
work if xview is installed, and if the X root window is visible. The
root window is not normally visible on Gnome and similar desktop setups,
because
the desktop draws over it. However, it can sometimes be made visible
by disabling desktop painting. This method is mostly suitable for very
minimal X set-ups using old-fashioned window managers.
This method uses xfconf-query to set the backgrounds on up to two
monitors. In principle, Xfce4 allows different backgrounds on each virtual
desktop,
but this program does not make use of that feature. However, it can
put different images on dual monitors.
This method executes a user-supplied command, provided by the --cmd
argument. The command will be executed with either one or two arguments;
if --dual is set, there will be two arguments, one for each
image filename. Otherwise, there will be one argument. The command can carry out
any operation. Anything it produces to standard out or standard error will be
visible in foreground mode, otherwise the output is lost.
LBC reads /etc/lbc.rc and $HOME/.lbc.rc, with the latter taking
precedence. Any of the long-form command-line options can be used
in the configuration file, in the form
option=value
A sample configuration file is in the samples/ directory but, of course,
this will need to be adjusted to suit a particular installation.
Because there are so many different desktop configurations in use, it's
impossible to give specific details for configuring LBC to
auto-start. In many systems, a program can be started along with the
desktop by creating a .desktop file in $HOME/.config/autostart.
The samples/ directory has an example desktop file for this purpose,
but it will need
to be adjusted to suit the installation.
lbc traps SIGUSR1 and SIGUSR2 signals. These move to the next and
previous images, respectively. SIGINT causes lbc to shut down cleanly.
lbc will take will take up to a second to respond to these signals.
lbc writes its process ID into a file $HOME/.lbc.lck. So long
as it's running, lbc will hold an advisory lock on this file.
This prevents multiple LBC processes being created for the same user,
and also allows one instance to signal another (e.g., when using
the --next option). If LBC is killed without being shut down cleanly,
or the system crashes, the lock file might be left behind, and have to
be deleted manually.
LBC displays images in random order. However, images are randomized at start time, so moving forward or backward through the list of images will produce consistent results.
LBC is happy to be given a specific list of files, rather than directories. There's no limit (other than the shell) on the number of files, or the number of directories they come from.
There is thus a difference between:
lbc $HOME/Pictures
and
lbc $HOME/Pictures/*.jpg
-- the first example will recursively descend the Pictures/
directory, and include all images it finds. The second will only
include images in the top level of the Pictures/ directory, because
only these will match the *.jpg pattern.
Which method is preferable depends on the organization of the images.
LBC stores the complete list of image filenames in memory. Worse,
it stores those filenames with wide-character representation.
A list of a thousand files could consume about half a megabyte of
memory.
This is a nugatory sum in a modern desktop system, or even a Raspberry Pi.
However, there is a --max-files option to limit the memory
usage if necessary -- or to increase it if the circumstances
allow.
An image is taken to be in "landscape" orientation if its aspect ratio is larger than 1.5, and portrait if it is less than 0.67. These numbers are intended to include most images that can reasonably be displayed on a screen of the appropriate orientation.
As of June 2022, this utility does not work with the latest gnome-shell versions that have a "Dark" mode. The command that sets the background appears to work, but it has no effect. I presume that this is a bug in gnome-shell but, since the maintainers have never documented a way to change the background other than using the settings GUI, I guess it could be argued that it isn't a bug. Whatever the position, it doesn't work. It seems to work fine in "Light" mode.
At present image size/aspect checks only work on JPEG files. It would be easy enough to extend it to cover other image types -- at the cost of increasing the number of dependencies the program has -- but I don't have enough images of any other type to test it works properly.
If a directory to be included is actually a symbolic link to a directory, its name must be followed by a forward-slash ('/'). The reason is rather technical, and too boring to explain in detail.
LBC may well conflict with whatever background changer is built into the desktop environment, unless it's disabled. Whatever facility the desktop provides to select images will, of course, not work with LBC.
Version 2.0 expands directories recursively by default. Previous versions required recursion to be enabled explicitly.
Because recursive expansion is the default, Version 2.0 has a configurable file limit.
Version 2.0 has facilities to examine certain image files, and only include those that match certain criteria. It is possible, for example, to include only landscape-orientation images for a landscape screen.
Version 2.0 supports a configuration file, as well as explicit configuration using the command line.
Version 0.0.1, October 2013
First release
Version 0.0.2, April 2014
Added dual-monitor support
Version 0.0.3, November 2016
Re-badged from "gnome-background-changer" and generally tidied up
Version 0.0.4, June 2020
Made Xfce4 support more robust, by searching for specific last-image
configuration settings, rather than assuming them. These settings seem
surprisingly variable between Xfce4 releases.
Version 2.0a, July 2020
Complete reimplementation. Introduced size/aspect ratio filters.
Version 2.0b, April 2021
Tightened up the requirements for "portrait" and "landscape" orientation.
Version 2.0c, December 2023
Changed the gnome-shell method to set both dark and light themes.