i3-layout-manager

Saving, loading and managing layouts for i3wm.

Preamble - dont worry, I solved all of this

i3 window manager supports saving and loading of window layouts, however, the features are bare-bone and partially missing. According to the manual, the layout tree can be exported into a json file. The file contains a description of the containers of a workspace with prefilled (and commented) potential matching rules for the windows. User is supposed to uncomment the desierd one (and/or modify them) and delete the unsused ones. Moreover, user should add a surrouding root container which is missing in the file (this baffles me, why cant they save it too?).

So doing it manually (which I dont want) consists of following steps, as described at i3wm.org:

1. export the workspace into jason using i3-save-tree --workspace ...
2. edit the json to match your desired matching rules for the windows
3. wrap the file in a root node, which defines the root split.
4. when needed, load the layout using i3-append ...

However, this plan has flaws. Its not scalable, its not automated and loading a layout does not work when windows are already present in the current workspace. To fix it, I built this i3-layout-manager. Currently, its a hacky-type of a shell script, but feel free to contribute :-).

How does it work?

1. The workspace tree is exported usin i3-save-tree --workspace ...
2. The tree for all workspaces on the currently focused monitor exported using i3-save-tree --output ...
3. The location of the current workspace in the all-tree is found by matching the workspace-tree file on the monitor-tree file.
4. The parameters of the root split are extracted and the workspace tree is wrapped in a new split.
5. User is then asked about how should the windows be matched. The options are:

• All by instance (instance will be uncommented for all windows)
• Match any window to any placeholder
• Choose an option for each window. The user will be asked to choose between the class, instance and title for each window. The tree file will be modified according to the selected options automatically.

6. After that the tree is save and ready to be loaded.
7. User can load the layout either before opening windows, which creates placeholders, or after windows have been already created in a workspace. The second part normally does not work.
8. To apply a layout, we first move all windows containing a process from the workspace using xdotool, which leaves only placeholders. Then we kill all the old placeholders, before we apply the layout, which spawns new placeholders in the correct places. Lastly we move the windows back, which triggers the swallow mechanicm in the same way, as newly create windows do.

How to use it?

• By directly running the script

./layout_manager.sh

It uses rofi to interact with the user, no file editing or coding is required. You can bind the script to an i3 key kombination.

• The layout manager can load a layout by running

./layout_manager.sh <layout_name>

which is useful for automation.

Dependencies

• vim/nvim
• jq
• i3
• rofi
• xdotool
• x11-xserver-utils

sudo apt-install jq vim rofi xdotool x11-xserver-utils

FAQ

• Why do you use vim for the automated file editing?

Vim is great for this kind of work. A simple oneliner can do complex edits which would be difficult to program even using, e.g., python. Thanks to this, the layout manager was hacked up in single day.