#+TITLE: Theming layer

* Table of Contents                                         :TOC_4_gh:noexport:
- [[#description][Description]]
  - [[#features][Features:]]
- [[#install][Install]]
- [[#usage][Usage]]
  - [[#example][Example]]
- [[#attributes][Attributes]]
- [[#faces][Faces]]
- [[#headers][Headers]]
- [[#example-1][Example]]

* Description
This layer allows for a simple way of modifying themes.

** Features:
  - Modify themes from your =.spacemacs=.
  - Tweak face attributes and other aspects of themes.
  - Includes three additional layer variables for tweaking headings.

* Install
To use this configuration layer, add it to your =~/.spacemacs=. You will need to
add =theming= to the existing =dotspacemacs-configuration-layers= list in this
file.

* Usage
To use this layer, set the value of =theming-modifications= (a good place is
inside your =.spacemacs= in =dotspacemacs/user-init()=).
It should be a list of the following form:

#+begin_src emacs-lisp
  ((theme1 (face1 attributes...)
           (face2 attributes...)
           ...)
   (theme2 (face1 attributes...)
           (face2 attributes...)
           ...)
   ...)
#+end_src

** Example
#+begin_src lisp
  (defun dotspacemacs/user-init ()
    (setq theming-modifications
          '((monokai
             ;; Font locking
             (font-lock-comment-face :slant italic)
             (web-mode-html-attr-name-face :inherit font-lock-variable-name-face
                                           :foreground nil)
             ;; Modeline
             (powerline-active1 :box (:color "#999999"
                                      :line-width 1
                                      :style released-button)
                                :background "#5a5a5a")))))
#+end_src
Source: [[https://gist.github.com/TheBB/f25a607b9bda4d5861f2#file-init-el-L274][gist]]

This will apply the given attributes to the relevant faces whenever the
appropriate theme is loaded. To update without changing the theme, use ~SPC SPC
spacemacs/update-theme~.

* Attributes
See [[http://www.gnu.org/software/emacs/manual/html_node/elisp/Face-Attributes.html#Face-Attributes][face attributes]] in the Emacs manual for more information. Some of the more
common attributes you might want to tweak are the following:

- =:inherit= :: the name of a face to inherit attributes from
- =:foreground= and =:background= :: Hexadecimal color strings
- =:height= :: typically a floating point number (1.0 gives the same height as
     the underlying face)
- =:weight= :: typically =bold= or =normal=
- =:underline= :: typically =nil= or =t=
- =:slant= :: typically =oblique=, =italic= or =normal=
- =:box= :: set to =t= to draw a box around characters in the foreground

* Faces
To see a list over all loaded faces and what they look like, use ~SPC SPC
list-faces-display~. You can also use ~SPC h d c~ (describe character) on a
character to see its face.

Some of the most common faces to modify are the syntactical elements:
- =font-lock-builtin-face=
- =font-lock-comment-delimiter-face=
- =font-lock-comment-face=
- =font-lock-constant-face=
- =font-lock-doc-face=
- =font-lock-function-name-face=
- =font-lock-keyword-face=
- =font-lock-preprocessor-face=
- =font-lock-string-face=
- =font-lock-type-face=
- =font-lock-variable-name-face=
- =font-lock-warning-face=

As well as the mode-line faces for the active and inactive windows:
- =powerline-active1=
- =powerline-active2=
- =powerline-inactive1=
- =powerline-inactive2=
- =mode-line=
- =mode-line-inactive=

* Headers
This layer includes three additional layer variables for tweaking headings.
Allowed values are a list of themes in which the given effect should happen, or
the symbol =all= to apply it on all themes.

- =theming-headings-inherit-from-default= :: inherits all headings from the
     default face to avoid non-monospaced fonts
- =theming-headings-same-size= :: sets the =:height= attribute to one on all
     headings to give them the same size as the rest of the text
- =theming-headings-bold= :: sets the =:weight= attribute to bold on all
     headings

* Example
An example of how to set the default font colour to be black in a custom theme leuven:

#+begin_src emacs-lisp
(defun dotspacemacs/user-init ()

  ; custom theme modification - overriding default font colour
  (setq-default
    theming-modifications
      '((leuven
          (default :foreground "#000000")
       ))
  )

)
#+end_src