;;; acdw-fonts.el -- font setup -*- lexical-binding: t; coding: utf-8-unix -*-

;; Author: Case Duckworth <acdw@acdw.net>
;; Created: Sometime during Covid-19, 2020
;; Keywords: configuration
;; URL: https://tildegit.org/acdw/emacs

;; This file is NOT part of GNU Emacs.

;; Everyone is permitted to do whatever with this software, without
;; limitation.  This software comes without any warranty whatsoever,
;; but with two pieces of advice:
;; - Don't hurt yourself.
;; - Make good choices.

;;; Commentary:
;; This code is based heavily on (and in fact, until I am able to tweak it,
;; will be a copy of) Oliver Taylor's code, available here:
;; https://github.com/olivertaylor/olivertaylor.github.io
;; /blob/master/notes/20210324_emacs-optical-font-adjustment.org

;;; Code:


;; Variables

(defvar acdw-fonts/monospace nil
  "Monospace font to be used for `default' and `fixed-pitch' faces.")

(defvar acdw-fonts/variable nil
  "Variable font to be used for the `variable-pitch' face.")

(defvar acdw-fonts/monospace-size 11
  "Font size, an integer, to be used for the `default' and `fixed-pitch' faces.

This value is multiplied by 10, so 12 becomes 120, in order to
comply with Emacs's `set-face-attribute' requirements.")

(defvar acdw-fonts/variable-size 12
  "Font size, an integer, to be used for the `variable-pitch' face.

This value will be used to determine a relative (float) size
based on the default size.  So if your default size is 12 and
your variable size is 14, the computed relative size will be
1.16.")


;; Functions

(defun acdw-fonts/set ()
  "Set fonts according to `acdw-fonts' variables."
  (interactive)
  (set-face-attribute 'default nil
                      :family acdw-fonts/monospace
                      :height (* acdw-fonts/monospace-size 10))
  (set-face-attribute 'fixed-pitch nil
                      :family acdw-fonts/monospace
                      :height 1.0)
  (set-face-attribute 'variable-pitch nil
                      :family acdw-fonts/variable
                      :height 1.0))


;;; Larger Variable Pitch Mode


;; A minor mode to scale the variable-pitch face up to the height defined in
;; `acdw-fonts/variable-size' and the fixed-pitch face down to the height
;; defined in `acdw-fonts/monospace-size', buffer locally. This mode should
;; be enabled wherever you want to adjust face sizes, perhaps with a hook.

(make-variable-buffer-local
 (defvar larger-variable-pitch-mode-status nil
   "Status of the larger-variable-pitch-mode"))

(make-variable-buffer-local
 (defvar variable-pitch-remapping nil
   "variable-pitch remapping cookie for larger-variable-pitch-mode."))

(make-variable-buffer-local
 (defvar fixed-pitch-remapping nil
   "fixed-pitch remapping cookie for larger-variable-pitch-mode"))

(defun larger-variable-pitch-mode-toggle ()
  (setq larger-variable-pitch-mode-status
        (not larger-variable-pitch-mode-status))
  (if larger-variable-pitch-mode-status
      (progn
        (setq variable-pitch-remapping
              (face-remap-add-relative
               'variable-pitch :height (/ (float acdw-fonts/variable-size)
                                          (float acdw-fonts/monospace-size))))
        (setq fixed-pitch-remapping
              (face-remap-add-relative
               'fixed-pitch :height (/ (float acdw-fonts/monospace-size)
                                       (float acdw-fonts/variable-size))))
        (force-window-update (current-buffer)))
    (progn
      (face-remap-remove-relative variable-pitch-remapping)
      (face-remap-remove-relative fixed-pitch-remapping))))

(define-minor-mode larger-variable-pitch-mode
  "Minor mode to scale the variable- and fixed-pitch faces up and down."
  :init-value nil
  :lighter " V+"
  (larger-variable-pitch-mode-toggle))

(defun acdw-fonts/buffer-face-hook ()
  "Activate and deactivate larger-variable-pitch-mode minor mode."
  (if buffer-face-mode
      (larger-variable-pitch-mode 1)
    (larger-variable-pitch-mode -1)))

(add-hook 'buffer-face-mode-hook #'acdw-fonts/buffer-face-hook)

(provide 'acdw-fonts)
;;; acdw-fonts.el ends here