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+;;; 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