count: make value buffer-local, font-changing commands.

* count.el (count-mode-value): Make this variable buffer-local, so
  that we can have different buffers count different values.

  (counting-font-step): Add a variable that controls the font-size
  scaling factor within the counting buffers.  I shall consider if I
  need to make this variable buffer-local as well.

  (count-mode, count-refresh): Refactor some logic into the function
  `count-refresh`.

  (count-mode-map): Add bindings for font-size changing commands.

  (count-make-pad-string): Account for the font-size scaling variable
  in the calculation of the size of the numbers to be centered.

  (count-enlarge, count-shrink): Commands for changing the
  font-scaling variable, so as to achieve the effect of enlarging and
  shrinking the texts within the counting buffers.

1 files changed, 34 insertions, 8 deletions

diff --git a/count.el b/count.el
index 0b20005..4b2e25d 100644
--- a/count.el
+++ b/count.el
@@ -27,20 +27,26 @@
 (defvar counting-buffer-name "*Count*"
   "The name of the buffer within which to count.")
 
-(defvar count-mode-value 0
+(defvar counting-font-step 10
+  "The proportion by which the counting value font size is
+increased.")
+
+(defvar-local count-mode-value 0
   "The value of the current count.")
 
 (define-derived-mode count-mode special-mode "Count"
   "Major mode for counting."
-  (setq text-scale-mode-amount 10)
-  (text-scale-mode 1)
   (count-refresh)
   (set 'cursor-type nil))
 
-(define-key count-mode-map (vector 'up) #'count-up)
-(define-key count-mode-map (vector 'down) #'count-down)
-(define-key count-mode-map (vector ?r) #'count-refresh)
-(define-key count-mode-map (vector ?o) #'count-reset)
+(let ((map count-mode-map))
+  (define-key map (vector 'up) #'count-up)
+  (define-key map (vector 'down) #'count-down)
+  (define-key map (vector ?r) #'count-refresh)
+  (define-key map (vector ?o) #'count-reset)
+  (define-key map (vector ?=) #'count-enlarge)
+  (define-key map (vector ?-) #'count-shrink))
+
 
 (defun count-start-or-switch ()
   "Start counting in an old buffer if possible."
@@ -65,7 +71,9 @@
   (let* ((number-str (format "%d" number))
          (number-str-width (* (string-pixel-width number-str)
                               ;; account for the remapping
-                              (expt 1.2 10)))
+                              (expt
+                               text-scale-mode-step
+                               counting-font-step)))
          (space-width (string-pixel-width (string #x20)))
          (padding (/ (- (window-pixel-width) (* 2 space-width)
                         number-str-width)
@@ -85,6 +93,8 @@
   (cond
    ((derived-mode-p 'count-mode)
     (let ((inhibit-read-only t))
+      (setq text-scale-mode-amount counting-font-step)
+      (text-scale-mode 1)
       (delete-region (point-min) (point-max))
       (insert (count-make-pad-string count-mode-value))))
    ((user-error
@@ -110,5 +120,21 @@
   (setq count-mode-value 0)
   (count-refresh))
 
+(defun count-enlarge (&optional arg)
+  "Increase the font size by ARG steps.
+The size of one step is defined by `text-scale-mode-step'."
+  (interactive "p")
+  (setq arg (cond ((null arg) 1) ((prefix-numeric-value arg))))
+  (setq counting-font-step (+ counting-font-step arg))
+  (count-refresh))
+
+(defun count-shrink (&optional arg)
+  "Decrease the font size by ARG steps.
+The size of one step is defined by `text-scale-mode-step'."
+  (interactive "p")
+  (setq arg (cond ((null arg) 1) ((prefix-numeric-value arg))))
+  (setq counting-font-step (- counting-font-step arg))
+  (count-refresh))
+
 (provide 'count)
 ;;; count.el ends here