This is just a quick-and-dirty fork of Bert Muennich's sxiv, which adds the ability to invert colors.

The code to invert colors is taken directly from Julien Danjou's telak.

For now it will just invert the colors if launched with the -V flag. Eventually I'd like to add the ability to toggle the inverted state.

sxiv: Simple (or small or suckless) X Image Viewer

sxiv is an alternative to feh and qiv. Its only dependency besides xlib is imlib2. The primary goal for writing sxiv is to create an image viewer, which only has the most basic features required for fast image viewing (the ones I want). It has vi key bindings and works nicely with tiling window managers. Its code base should be kept small and clean to make it easy for you to dig into it and customize it for your needs.

• Basic image operations, e.g. zooming, panning, rotating
• Customizable key and mouse button mappings (in config.h)
• Thumbnail mode: grid of selectable previews of all images
• Ability to cache thumbnails for fast re-loading
• Basic support for multi-frame images
• Display image information in window title

Additional features, that need to be enabled at compile-time (in config.h), because they depend on additional libraries:

• Load all frames from GIF files and play GIF animations (requires giflib)
• Auto-orientate JPEG images according to their EXIF tags (requires libexif)

Image mode:

Thumbnail mode:

sxiv is built using the commands:

$ make
# make install

Please note, that the latter one requires root privileges. By default, sxiv is installed using the prefix "/usr/local", so the full path of the executable will be "/usr/local/bin/sxiv".

You can install sxiv into a directory of your choice by changing the second command to:

# make PREFIX="/your/dir" install

The build-time specific settings of sxiv can be found in the file config.h. Please check and change them, so that they fit your needs. If the file config.h does not already exist, then you have to create it with the following command:

$ make config.h

sxiv has two modes of operation: image and thumbnail mode. The default is image mode, in which only the current image is shown. In thumbnail mode a grid of small previews is displayed, making it easy to choose an image to open.

sxiv supports the following command-line options:

-c           Remove all orphaned cache files from thumbnail cache and exit
-d           Scale all images to 100%, but fit large images into window
-F           Use size-hints to make the window fixed/floating
-f           Start in fullscreen mode
-g GEOMETRY  Set window position and size
             (see section GEOMETRY SPECIFICATIONS of X(7))
-n NUM       Start at picture NUM
-p           Pixelize, i.e. turn off image anti-aliasing
-q           Be quiet, disable warnings
-r           Search given directories recursively for images
-s           Scale all images to fit into window
-t           Start in thumbnail mode
-v           Print version information and exit
-Z           Same as `-z 100'
-z ZOOM      Scale all images to current zoom level, use ZOOM at startup

The following key mappings are available; differences between image view and thumbnail mode are denoted via brackets:

q            Quit sxiv
Return       Switch to thumbnail mode [open selected image]

n,Space      Go to the next image
p,Backspace  Go to the previous image
g,G          Go to [select] first/last image
[,]          Go 10 images backward/forward

Ctrl-n,p     Go to the next/previous frame of a multi-frame image
Ctrl-Space   Play/pause animation of a multi-frame image

+,=          Zoom in
-            Zoom out
0            Set zoom level to 100%
w            Fit image into window

h,j,k,l      Pan image [move selection] left/down/up/right
             (also with arrow keys)
H,J,K,L      Pan to left/bottom/top/right image edge
Ctrl-h,j,k,l Pan image one window width/height left/down/up/right
             (also with Ctrl-arrow keys)

<,>          Rotate image (counter-)clockwise by 90 degrees

W            Resize window to fit image
f            Toggle fullscreen mode (requires an EWMH/NetWM compliant
             window manager)

a            Toggle anti-aliasing
A            Toggle visibility of alpha-channel, i.e. transparency
D            Remove image from file list and go to [select] next image
r            Reload image

Additionally, the following mouse mappings are available:

Button1      Go to the next image
             [select image/open image if it is already selected]
Button2      Drag image with mouse while keeping it pressed
Button3      Go to the previous image
Scroll       Pan image up/down [scroll up/down one thumbnail row]
Shift+Scroll Pan image left/right
Ctrl+Scroll  Zoom in/out