Configuration

onon needs no configuration. When you want different defaults or keys, write them in Lua, in a config.lua holding only what you change. :config (Settings… or Cmd-, on macOS) opens the file in your text editor, creating it if there is none. :reload-config applies your edits without restarting.

onon.options.dual_page = true
onon.options.fit_mode = "width"
onon.theme.font = { family = "Iosevka", size = 15 }

onon.bind("<C-d>", onon.next_page)
onon.bind("<C-u>", onon.prev_page)

The example configuration lists every option and default binding, generated from the same registry the app uses.

Where it lives

onon loads the first of these that exists:

Platform	Location
Any	The path given with --config
Linux	~/.config/onon/config.lua
Linux	$XDG_CONFIG_HOME/onon/config.lua
Linux	Each $XDG_CONFIG_DIRS/onon/config.lua
Linux	/etc/xdg/onon/config.lua
macOS	~/Library/Application Support/onon/config.lua
macOS	~/.config/onon/config.lua
Windows	%APPDATA%\onon\config.lua

--no-config starts from the built-in defaults, ignoring every file.

Options

Options are fields of onon.options, or onon.o for short:

onon.o.scroll_off = 8
onon.o.smooth_scroll_dampening = 0.3

At runtime, :set inspects and changes them: :set scroll_step? shows a value, :set dual_page! toggles a boolean, and :set scroll_step=80 sets one. The reference lists every option with its type and default.

Key and mouse bindings

onon.bind takes a key or sequence and an action, or a Lua function:

onon.bind("H", onon.prev_page)
onon.bind("gg", onon.first_page)
onon.bind("<C-o>", onon.jump_backward)
onon.bind("r", function() onon.rotation(onon.rotation() + 90) end)

onon.bind_mouse("middle_down", onon.pan)
onon.bind_mouse("<C-wheel-up>", onon.zoom_in)

Keys in angle brackets use the names in the reference: <CR>, <Esc>, <Space>, <PgDn>, <F1>, <C-a> for Control, <A-x> for Alt, <D-s> for Cmd on macOS and <S-Tab> for Shift. onon.unbind and onon.unbind_mouse remove a binding. Sequences that start with a digit, ' or " are taken by counts and marks.

:keybinds edits bindings inside onon. Bindings changed there are kept in the session database and applied before config.lua, so where the two disagree, config.lua wins.

Commands

: opens the command prompt. Tab completes commands, options and paths:

:page iv           go to the page labelled iv
:search \Cmoss     search, matching case
:fit width
:open chapter2.pdf
:theme birch
:w                 save annotations

Status bar

The status bar is two templates, left and right:

onon.o.status_bar_left = "{message}"
onon.o.status_bar_right = "{document}  {label}/{total}  {zoom}"
onon.o.status_bar_visible = false -- hide it

The placeholders include {page}, {label}, {total}, {zoom}, {search} and {modified}. The reference has the full list. How the bar looks comes from the theme.

Session data

Each document’s place, marks and zoom, recent files, prompt history, the chosen theme and keybindings changed in onon are kept in session.sqlite:

Platform	Directory
Linux	$XDG_DATA_HOME/onon or ~/.local/share/onon
macOS	~/Library/Application Support/onon
Windows	%APPDATA%\onon

Set onon.o.session_database = false to keep nothing.