Emacs calendar: show more than 3 months?

Question

In Emacs, when you display the calendar with M-x calendar, you get a three-month display – last month, this month, and next month – in a new window that\'s just 8 l

Answer 1

I modified "12-MONTH CALENDAR -- SCROLLS BY MONTH (FORWARDS / BACKWARDS)" answer and adapted it to Emacs post 23.3 version - no calendar-for-loop macro - and changed scroll from by one month to by one year. This version show entire calendar for current year. Going backwards which < and forwards > by one year. It doesn't show on full screen, but half screen, which make it easy to use when working which vertical splits and it's more like extended version of build in calendar.

;; https://stackoverflow.com/questions/9547912/emacs-calendar-show-more-than-3-months
(defun farynaio/year-calendar (&optional year)
  "Generate a one year calendar that can be scrolled by year in each direction.
This is a modification of:  http://homepage3.nifty.com/oatu/emacs/calendar.html
See also: https://stackoverflow.com/questions/9547912/emacs-calendar-show-more-than-3-months"
  (interactive)
  (require 'calendar)
  (let* (
      (current-year (number-to-string (nth 5 (decode-time (current-time)))))
      (month 0)
      (year (if year year (string-to-number (format-time-string "%Y" (current-time))))))
    (switch-to-buffer (get-buffer-create calendar-buffer))
    (when (not (eq major-mode 'calendar-mode))
      (calendar-mode))
    (setq displayed-month month)
    (setq displayed-year year)
    (setq buffer-read-only nil)
    (erase-buffer)
    ;; horizontal rows
    (dotimes (j 4)
      ;; vertical columns
      (dotimes (i 3)
        (calendar-generate-month
          (setq month (+ month 1))
          year
          ;; indentation / spacing between months
          (+ 5 (* 25 i))))
      (goto-char (point-max))
      (insert (make-string (- 10 (count-lines (point-min) (point-max))) ?\n))
      (widen)
      (goto-char (point-max))
      (narrow-to-region (point-max) (point-max)))
    (widen)
    (goto-char (point-min))
    (setq buffer-read-only t)))

(defun farynaio/scroll-year-calendar-forward (&optional arg event)
  "Scroll the yearly calendar by year in a forward direction."
  (interactive (list (prefix-numeric-value current-prefix-arg)
                     last-nonmenu-event))
  (unless arg (setq arg 0))
  (save-selected-window
    (if (setq event (event-start event)) (select-window (posn-window event)))
    (unless (zerop arg)
      (let* (
              (year (+ displayed-year arg)))
        (jarfar/year-calendar year)))
    (goto-char (point-min))
    (run-hooks 'calendar-move-hook)))

(defun farynaio/scroll-year-calendar-backward (&optional arg event)
  "Scroll the yearly calendar by year in a backward direction."
  (interactive (list (prefix-numeric-value current-prefix-arg)
                     last-nonmenu-event))
  (farynaio/scroll-year-calendar-forward (- (or arg 1)) event))

(define-key calendar-mode-map "<" 'farynaio/scroll-year-calendar-backward)
(define-key calendar-mode-map ">" 'farynaio/scroll-year-calendar-forward)

(defalias 'year-calendar 'farynaio/year-calendar)

Answer 2

There doesn't seem to be an easy way to do this. I was able to knock up the following code, which will show all twelve months, in a row, in a separate frame.

(require 'cl)
(require 'calendar)

(defun twelve-month-calendar ()
  (interactive)
  (let ((calendar-buffer (get-buffer-create "12-month calendar"))
        (month 12)
        (year 2012))
    (set-buffer calendar-buffer)
    (setq calendar-frame (make-frame))
    (make-variable-buffer-local 'font-lock-face)
    (set-face-attribute 'default calendar-frame :height 70)
    (set-frame-width calendar-frame 300)
    (erase-buffer)
    (dotimes (i 12)
      (calendar-generate-month month year 0)
      (calendar-increment-month month year -1))
    (calendar-mode)))

You might need to tweak it a bit, depending on your screen/font size.

Answer 3

12-MONTH CALENDAR -- SCROLLS BY MONTH (FORWARDS / BACKWARDS)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;                                                                            ;;;
;;; Scroll a yearly calendar by month -- in a forwards or backwards direction. ;;;
;;;                                                                            ;;;
;;; To try out this example, evaluate the entire code snippet and type:        ;;;
;;;                                                                            ;;;
;;;     M-x year-calendar                                                      ;;;
;;;                                                                            ;;;
;;; To scroll forward by month, type the key:  >                               ;;;
;;;                                                                            ;;;
;;; To scroll backward by month, type the key:  <                              ;;;
;;;                                                                            ;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(eval-after-load "calendar" '(progn
  (define-key calendar-mode-map "<" 'lawlist-scroll-year-calendar-backward)
  (define-key calendar-mode-map ">" 'lawlist-scroll-year-calendar-forward) ))

(defmacro lawlist-calendar-for-loop (var from init to final do &rest body)
  "Execute a for loop.
Evaluate BODY with VAR bound to successive integers from INIT to FINAL,
inclusive.  The standard macro `dotimes' is preferable in most cases."
  `(let ((,var (1- ,init)))
    (while (>= ,final (setq ,var (1+ ,var)))
      ,@body)))

(defun year-calendar (&optional month year)
  "Generate a one (1) year calendar that can be scrolled by month in each direction.
This is a modification of:  http://homepage3.nifty.com/oatu/emacs/calendar.html
See also:  http://ivan.kanis.fr/caly.el"
(interactive)
  (require 'calendar)
  (let* ((current-year (number-to-string (nth 5 (decode-time (current-time)))))
         (month (if month month
           (string-to-number
             (read-string "Please enter a month number (e.g., 1):  " nil nil "1"))))
         (year (if year year
           (string-to-number
             (read-string "Please enter a year (e.g., 2014):  "
               nil nil current-year)))))
    (switch-to-buffer (get-buffer-create calendar-buffer))
    (when (not (eq major-mode 'calendar-mode))
      (calendar-mode))
    (setq displayed-month month)
    (setq displayed-year year)
    (setq buffer-read-only nil)
    (erase-buffer)
    ;; horizontal rows
    (lawlist-calendar-for-loop j from 0 to 3 do
      ;; vertical columns
      (lawlist-calendar-for-loop i from 0 to 2 do
        (calendar-generate-month
          ;; month
          (cond
            ((> (+ (* j 3) i month) 12)
              (- (+ (* j 3) i month) 12))
            (t
              (+ (* j 3) i month)))
          ;; year
          (cond
            ((> (+ (* j 3) i month) 12)
             (+ year 1))
            (t
              year))
          ;; indentation / spacing between months
          (+ 5 (* 25 i))))
      (goto-char (point-max))
      (insert (make-string (- 10 (count-lines (point-min) (point-max))) ?\n))
      (widen)
      (goto-char (point-max))
      (narrow-to-region (point-max) (point-max)))
    (widen)
    (goto-char (point-min))
    (setq buffer-read-only t)))

(defun lawlist-scroll-year-calendar-forward (&optional arg event)
  "Scroll the yearly calendar by month in a forward direction."
  (interactive (list (prefix-numeric-value current-prefix-arg)
                     last-nonmenu-event))
  (unless arg (setq arg 1))
  (save-selected-window
    (if (setq event (event-start event)) (select-window (posn-window event)))
    (unless (zerop arg)
      (let ((month displayed-month)
            (year displayed-year))
        (calendar-increment-month month year arg)
        (year-calendar month year)))
    (goto-char (point-min))
    (run-hooks 'calendar-move-hook)))

(defun lawlist-scroll-year-calendar-backward (&optional arg event)
  "Scroll the yearly calendar by month in a backward direction."
  (interactive (list (prefix-numeric-value current-prefix-arg)
                     last-nonmenu-event))
  (lawlist-scroll-year-calendar-forward (- (or arg 1)) event))

---

Answer 4

It's not easy to do this, the code to generate calendar is:

(defun calendar-generate (month year)
  "Generate a three-month Gregorian calendar centered around MONTH, YEAR."
  ;; A negative YEAR is interpreted as BC; -1 being 1 BC, and so on.
  ;; Note that while calendars for years BC could be displayed as it
  ;; stands, almost all other calendar functions (eg holidays) would
  ;; at best have unpredictable results for such dates.
  (if (< (+ month (* 12 (1- year))) 2)
      (error "Months before January, 1 AD cannot be displayed"))
  (setq displayed-month month
        displayed-year year)
  (erase-buffer)
  (calendar-increment-month month year -1)
  (dotimes (i 3)
    (calendar-generate-month month year
                             (+ calendar-left-margin
                                (* calendar-month-width i)))
    (calendar-increment-month month year 1)))

Here, (dotimes (i 3) ...) generate 3 months in a row.

So if you want to generate more than 3 months in more than 1 row, you must override calendar-generate function by yourself, same as @Luke said.