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https://github.com/hugo-heagren/svg-battery-indicator

Simple battery indicator
https://github.com/hugo-heagren/svg-battery-indicator

battery emacs svg

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Simple battery indicator

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README 

        
#+title: svg-battery-indicator.el



This is a simple package for generating an SVG battery indicator for

us in the mode-line or tab-bar. It's not on MELPA or Gnu Elpa, so

you'll have to install it manually, or using a GitHub helper like

straight. See the top right of the screen-shot below:



[[./svg-battery-indicator.jpg]]



This package requires Emacs to be built with SVG support. You can test

this by running ~(image-type-available-p 'svg)~. If you get ~t~, you

have SVG support.



* Usage

The indicator takes advantage of ~display-battery-mode~ (and the

~battery.el~ library generally). Primarily, this package provides a

function (~svg-battery-indicator~) which takes a charge level and

returns an SVG. You then need to setup battery.el to use this

function. You need to have ~battery-status-function~ (whatever it is)

include the generated SVG and a letter (which will be used as an

expando) in its return value.



There are two ways to do this. One way is to set

~battery-status-function~ to your own function, with the right kind of

return value. I did this by writing a simple wrapper over the function

I was using otherwise. You might have something like this in your

~init.el~ (you needn't use '?i' -- that's just what I used):



#+begin_src elisp

(defun my/battery-upower-with-svg ()

  "Wrapper over `battery-upower' which adds an SVG for \"i\"."

  (let* ((data (battery-upower))

	 (percentage (car (read-from-string (cdr (assq ?p data)))))

	 (charging (string= (alist-get ?b data) "+"))

	 (svg (svg-battery-indicator percentage charging))

	 ;; NOTE This string has to be non-empty

	 (str (propertize " " 'display svg)))

    `(,@data (?i . ,str))))



(display-battery-mode)



(setq battery-mode-line-format "%p%% %i")



;; To display in the mode-line

(add-to-list 'mode-line-format

	     'battery-mode-line-string)



;; To display in the tab-bar

(add-to-list 'tab-bar-format

	     'battery-mode-line-string)



#+end_src



The second way is to advice your existing ~battery-status-function~.

This package provides a function designed for doing this. To use, add

~svg-battery-indicator-status-advice~ as ~:filter-return~ advice to

~battery-status-function~ (whatever ~battery-status-function~ is on

your machine). The expando ~%i~ will then be available in

~battery-mode-line-format~, and expands to a battery SVG.



You might have something like this in your ~init.el~:



#+begin_src elisp

  (advice-add

   ;; NOTE that `battery-status-function' is UNQUOTED. It's a variable,

   ;; which battery.el requires to point at a function, with a return

   ;; value which `svg-battery-indicator-status-advice' can handle.

   battery-status-function

   :filter-return

   #'svg-battery-indicator-status-advice)



  (display-battery-mode)



  (setq battery-mode-line-format "%p%% %i")



  ;; To display in the mode-line

  (add-to-list 'mode-line-format

	       'battery-mode-line-string)



  ;; To display in the tab-bar

  (add-to-list 'tab-bar-format

	       'battery-mode-line-string)

#+end_src



* Customization

The variable ~svg-battery-indicator-length~ sets the length of the

indicator. Otherwise all customization is through ~battery.el~. The

indicator uses the threshholds set in ~battery-load-low~ and

~battery-load-critical~, and represents them with the foreground

colours from the faces ~battery-load-low~ and ~battery-load-critical~.