Spaceline

Introduction
The default themes
- Optional dependencies
- Troubleshooting
Moderate configuration
Deep configuration
Tweaking or defining your own mode-line

Introduction

This is the package that provides Spacemacs with its famous mode-line theme. It has been extracted as an independent package for general fun and profit.

This package provides features for three kinds of users.

You just want to use the Spacemacs mode-line theme and forget about it.
You want to use something similar to the Spacemacs mode-line theme, but with a handful of easy tweaks.
You want an easy-to-use library for building your own mode-line from scratch, and you think the Spacemacs theme looks good.

The functionality for each are described in the following sections.

The files in this package are organized as follows. Choose which you want to load based on what you want to do.

spaceline.el: Contains the core library used to define segments and render the modeline. It defines no segments by itself except the global segment. (See below.)
spaceline-segments.el: Defines all the segments used by the default Spacemacs theme, but doesn’t do anything with them.
spaceline-config.el: Defines the default themes.

The default themes

To install it, just load spaceline-config and call the theme function you want. E.g.

(require 'spaceline-config)
(spaceline-spacemacs-theme)

The package comes bundled with two themes:

spaceline-spacemacs-theme: The theme used by Spacemacs
spaceline-emacs-theme: A theme which is similar to the one used by Spacemacs, but which has been designed to look good without the dependencies that the Spacemacs theme needs.

In addition, Spaceline supports custom themes for Info+ and Helm. These can be enabled through global minor modes:

spaceline-helm-mode
spaceline-info-mode (requires the info+ package)

These are also defined in spaceline-config.el.

Optional dependencies

These themes include several segments that depend on third-party packages. If these packages are not installed, these segments will be invisible and not show any output. As such, they can be considered optional dependencies.

Here follows a brief list of these dependencies. For more information consult the upstream sources.

Persp-mode

Persp-mode is a powerful workspace-like package. Spaceline shows the current workspace name.

Eyebrowse

Eyebrowse is a simpler workspace-like package. If it is installed, The Spacemacs theme will show the current workspace number. The Emacs theme uses the workspace number as a fallback for the perspective name: thus if persp-mode is installed, the Eyebrowse workspace will not be shown.

Winum

Winum shows a number for each window, and it works with both themes.

To prevent winum from inserting its own number in the mode-line, you have to set winum-auto-setup-mode-line to nil before activating winum-mode:

(setq winum-auto-setup-mode-line nil)
(winum-mode)

Auto-compile

Auto-compile automatically compiles Emacs Lisp files on save if there is an older byte-compiled file. Spaceline shows warnings when they occur.

Anzu

Anzu shows the current match and the total number of matches while searching.

Note that Anzu inserts itself in the modeline, to let spaceline handle the modeline, make sure to (setq anzu-cons-mode-line-p nil) or customize it.

Flycheck

Flycheck is a powerful syntax-checking package. Spaceline shows errors, warnings and notifications from it.

ERC

ERC is an IRC client built in to Emacs. Spaceline shows channels with new messages if you have erc-track turned on.

Org

Spaceline shows the currently clocking org-mode task.

Org-pomodoro

Spaceline integrates with org-pomodoro by showing its clocks.

Python virtual environments

The currently active environments as reported by pyenv-mode or pyvenv are shown in Spaceline.

Nyan cat

Nyan-mode shows the current position in the buffer with kittens and rainbows.

Fancy battery

Fancy-battery shows battery information in the modeline.

Evil

Evil makes Emacs behave like Vim. The first segment in the Spacemacs theme shows the current Evil state if all the other dependencies do not report information (i.e. no perspective, workspace or window number). The Emacs theme does not include any information from Evil.

You can color the modeline according to the current Evil state by setting spaceline-highlight-face-func to spaceline-highlight-face-evil-state.

Troubleshooting

There are a number of reasons why Spaceline might look different on your setup compared to Spacemacs proper. Some of the most important ones are addressed here.

You’re missing an optional dependency. Spacemacs includes packages that display information in the mode-line. The leftmost segment is invisible if eyebrowse-mode, persp-mode, window-numbering-mode and evil are all not present. If you don’t wish to use these packages, consider using the Emacs theme.
Consider setting or increasing the value of powerline-height to give your mode-line some room to breathe.
The default powerline separator is arrow, but Spacemacs uses wave. You should try out various settings of powerline-default-separator to find the one that works for you. Note that you need to recompile the modeline with M-x spaceline-compile after setting this variable.
If you’re using eyebrowse-mode or window-numbering-mode, consider setting spaceline-workspace-numbers-unicode and spaceline-window-numbers-unicode to t to get the nice-looking unicode numbers seen in the screenshot.
Use Diminish to tweak the output of the minor modes segment.
To get the mode-line highlight to change color depending on the evil state, set spaceline-highlight-face-func to spaceline-highlight-face-evil-state.

Moderate configuration

Turning segments on and off

Each segment has a variable spaceline-NAME-p that can switch the segment off by setting it to nil. There are also three convenient interactive functions for toggling:

spaceline-toggle-<name>
spaceline-toggle-<name>-on
spaceline-toggle-<name>-off

These can be bound to whichever keys you like.

Here is a complete list of segments bundled with Spacemacs.

persp-name: integrates with persp-mode.
workspace-number: integrates with eyebrowse.
window-number: integrates with window-numbering.
evil-state: shows the current evil state, integrates with evil.
anzu: integrates with anzu.
auto-compile: integrates with auto-compile.
buffer-modified: the standard marker denoting whether the buffer is modified or not.
buffer-size: the size of the buffer.
buffer-id: the name of the buffer.
remote-host: the host for remote buffers.
major-mode: the current major mode.
flycheck-error: number of flycheck errors, integrates with flycheck.
flycheck-warning: number of flycheck warnings, integrates with flycheck.
flycheck-info: number of flycheck notifications, integrates with flycheck.
minor-modes: the currently enabled minor modes. The output of this segment can be tweaked with Diminish.
process: the background process associated with the buffer, if any.
erc-track: IRC channels with new messages, integrates with erc.
version-control: version control information.
org-pomodoro: integrates with org-pomodoro.
org-clock: the current org clock, integrates with org.
nyan-cat: integrates with nyan-mode.
battery: integrates with fancy-battery-mode.
which-function: integrates with which-function-mode.
python-pyvenv: integrates with pyvenv.
python-pyenv: integrates with pyenv.
paradox-menu: integrates with paradox.
selection-info: information about the currently active selection, if any.
input-method: shows the current active input method, if any.
buffer-encoding-abbrev: the line ending convention used in the current buffer (unix, dos or mac).
point-position: the value of point (disabled by default).
line-column: current line and column.
global: meta-segment used by third-party packages.
buffer-position: shows the current position in the buffer as a percentage.
hud: shows the currently visible part of the buffer.

In addition, the following segments are defined, but are not used in the default themes.

line: current line.
column: current column.
projectile-root: root of current projectile project, integrates with projectile.
buffer-encoding: like buffer-encoding-abbrev, but not abbreviated.

For the custom helm modeline, the following segments are used.

helm-buffer-id: the name of the current helm session.
helm-number: number of helm candidates.
helm-help: a brief help string.
helm-prefix-argument: shows the prefix argument, if any.
helm-follow: shows whether helm-follow is turned on.

For the custom info modeline, the following segments are used.

info-topic: the current topic.
info-nodes: breadcrumbs.

The highlight face

The highlight face is the face that (by default) is a sharp orange, used e.g. by the HUD segment on the far right, and the first segment on the left (note that it may be invisible if you are using the Spacemacs theme but not some of its optional dependencies). The actual face used as a highlight face is determined by a function, which can be configured by setting the value of spaceline-highlight-face-func. Spaceline comes with three choices, but of course you can write your own:

spaceline-highlight-face-default: Uses the orange, all the time. This is the default.
spaceline-highlight-face-evil-state: Chooses a face determined by the current evil state. The face corresponding to each state is determined by the association list spaceline-evil-state-faces, which contains default values for the standard evil states. (Spacemacs has a few more.)
spaceline-highlight-face-modified: Chooses a face determined by the status of the current buffer (modified, unmodified or read-only).

Note that the highlight face is only used in the active window.

Other faces

In the active window, the mode-line will use these faces:

powerline-active1
powerline-active2
mode-line

And in inactive windows:

powerline-inactive1
powerline-inactive2
mode-line-inactive

To override this, you can set the variable spaceline-face-func. This should be a function that accepts two arguments and returns a face symbol. The arguments are:

face: either of face1, face2, line and highlight.
active: a boolean determining whether the window is active or not.

If this function is not set, Spaceline delegates the highlight face to spaceline-highlight-face-func (see above), and picks the others according to the above scheme.

Powerline separators

Set powerline-default-separator to configure this. The docstring for that variable enumerates the choices.

Each separator comes in two directions: left and right. The variables spaceline-separator-dir-left and spaceline-separator-dir-right specify which directions to alternate between on the left and right side, respectively.

By default these variables are set to nil, which means Spaceline will choose the directions that look best for your chosen separator style. However, you can set to override this, for example:

(setq spaceline-separator-dir-left '(left . left))
(setq spaceline-separator-dir-right '(right . right))

Note that you must recompile the modelines after changing the separators, by calling M-x spaceline-compile.

Hooks

The hook spaceline-pre-hook is executed before rendering the modeline. Don’t put any performance-intensive functions here!

Unicode numbers

By default, Spacemacs displays window numbers and workspace numbers in nice unicode symbols. To do this in Spaceline, set spaceline-window-numbers-unicode or spaceline-workspace-numbers-unicode to true, respectively.

Spacemacs also does this with most minor modes. This is a feature that has not been ported to Spaceline. To do this, use Diminish.

Minor modes separator

To configure the separator between the minor modes, use spaceline-minor-modes-separator.

Org clock

The displayed value of the org-clock segment is determined by the function org-clock-get-clock-string by default. To configure another function, use spaceline-org-clock-format-function.

Deep configuration

To understand how to do this, we must first understand how Spaceline constructs a mode-line.

Segments

A segment is any part of the mode-line that produces some kind of visible output. Typically, segments have been defined ahead of time using spaceline-define-segment, in which case the segment is referred to by a symbol, but segments may also be literals (strings or numbers, say) or lists of other segments.

These are all valid segments, provided my-segment has been defined:

my-segment
"alfa"
(my-segment 89)

Segments may also have properties associated with them. Spaceline supports a variety of properties. They can be applied as follows, for a ‘singleton’ segment:

(my-segment :prop-a value-a :prop-b value-b)

Or for a list of segments:

((my-segment 89)
 :prop-a value-a
 :prop-b value-b)

Defining a segment

Use spaceline-define-segment to define a segment and associate it to a symbol.

(spaceline-define-segment name
  "Docstring"
  ;; A single form whose value is the value of the segment.
  ;; It may return a string, an image or a list of such.
  (when condition
     output)

  ;; Additional keyword properties go here
  :prop-a value-a
  :prop-b value-b)

In addition to storing the segment, this macro produces a variable called spaceline-NAME-p whose value may be set to switch the segment off or on manually. Three interactive functions are also defined:

spaceline-toggle-NAME
spaceline-toggle-NAME-on
spaceline-toggle-NAME-off

These are convenient to bind to keys, and they do what it says on the tin.

Note that if you redefine a segment, you more than likely have to recompile the modelines with M-x spaceline-compile for the changes to take effect.

Properties

The valid properties are

:priority: arbitrary number to prioritize which segments are hidden first when the window shrinks. The higher the number, the higher the priority.
:when: A form that, if it evaluates to nil, will prevent the segment from showing. Note that in spaceline-define-segment you might just as well use an ordinary when form. Therefore this only makes sense to use in a segment spec.
:separator: A separator inserted between each element of the value of the given segment. This makes most sense for lists of segments, or segments whose values are typically lists (such as minor-modes).
:fallback: A segment which will be displayed in place of the current segment if it should produce no output (either due to a nil :when condition or because the return value of the segment itself is nil or the empty string).
:face: The face in which to render the segment. It may be better to use this than (or in addition) to propertizing the output directly, since Spaceline needs to know the faces to propertize the separators correctly. This may be either default-face, other-face or highlight-face, or a form evaluating to a face. Thus any face symbol which is not either of the above three must be quoted.
:tight: Set to t to tell Spaceline that the segment should not have any padding on the right or left. Use :tight-left and :tight-right for even finer control.
:skip-alternate: Set to t to skip the regular alternating faces for this segment.

All of these are valid both in spaceline-define-segment as well as directly in the segment spec, with the excption of :when.

Additionally, spaceline-define-segment allows two additional properties.

:enabled: Sets the initial value of the toggle variable.
:global-override: Many third-party packages provide mode-line information by inserting a segment in the list global-mode-string. Sometimes you might like to write your own segment for this, in which case you have to prevent the package from using global-mode-string, or you will end up with duplicate information and a crowded mode-line. To do this, set :global-override to the symbol (or list of symbols) which you want to exclude from global-mode-string. This setting will be honored by the global segment, which is defined by Spaceline core in spaceline.el.

The properties which take effect for any given segment are, in order of priority:

the properties specified in the segment specification
the properties given in the call to spaceline-define-segment
the properties of the parent segment

The exceptions are :when, which must be true on all levels for a segment to be displayed, and :fallback which does not pass through from the parent segment.

Bindings

When evaluating a segment, its :when condition or its :face property, the following bindings are available for convenience.

active: Whether the current window is active or not. Many segments use :when active to only show in the current window.
default-face: The face with which the current segment should be rendered. If you don’t define a :face, this is what you get. For best results, stick to the default face as often as you can.
other-face: The alternating default face. Spaceline switches default-face and other-face for each top-level segment.
highlight-face: The face used to highlight ‘important’ parts, whatever that may be. This may be customized.
line-face: The face with which the empty part in the middle of the mode-line will be rendered.

Note that the segment code runs in an environment with many local variables, therefore it’s a good idea to write segments as pure functions that do not change state.

Compiling a mode-line

Finally, call the function spaceline-compile. It accepts three arguments: a modeline name, and two lists of segments, for the left and right sides.

This produces a function spaceline-ml-NAME that evaluates the mode-line. To use it, set mode-line-format to

("%e" (:eval (spaceline-ml-NAME)))

If you do not specify a name, the modeline will be installed as main.

If you do not specify segment lists, it will either recompile the given modeline with the segments specified last time, or recompile all modelines if the name is not specified.

When called interactively, the latter behaviour takes effect, that is, all modelines are recompiled.

The variable spaceline-byte-compile decides whether the resulting function will be byte-compiled. This is recommended for regular usage, as it involves potentially significant performance benefits.

Tweaking or defining your own mode-line

To tweak the properties such as :when or :priority of specific segments, or having your own selection of segments and order of appearance, you have to define your own mode-line and spaceline-compile it.

For instance, to use Spacemac’s mode-line definition as a starting point to your own, add this to your .emacs or .spacemacs and tweak it:

(spaceline-compile
  ; left side
  '(((persp-name
      workspace-number
      window-number)
     :fallback evil-state
     :face highlight-face
     :priority 100)
    (anzu :priority 95)
    auto-compile
    ((buffer-modified buffer-size buffer-id remote-host)
     :priority 98)
    (major-mode :priority 79)
    (process :when active)
    ((flycheck-error flycheck-warning flycheck-info)
     :when active
     :priority 89)
    (minor-modes :when active
                 :priority 9)
    (mu4e-alert-segment :when active)
    (erc-track :when active)
    (version-control :when active
                     :priority 78)
    (org-pomodoro :when active)
    (org-clock :when active)
    nyan-cat)
  ; right side
  '(which-function
    (python-pyvenv :fallback python-pyenv)
    (purpose :priority 94)
    (battery :when active)
    (selection-info :priority 95)
    input-method
    ((buffer-encoding-abbrev
      point-position
      line-column)
     :separator " | "
     :priority 96)
    (global :when active)
    (buffer-position :priority 99)
    (hud :priority 99)))

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