minimap.el

;;; minimap.el --- Sidebar showing a "mini-map" of a buffer

;; Copyright (C) 2009-2011 Free Software Foundation, Inc.

;; Author: David Engster <dengste@eml.cc>
;; Keywords:
;; Version: 1.0

;; This file is part of GNU Emacs.

;; This program is free software; you can redistribute it and/or
;; modify it under the terms of the GNU General Public License
;; as published by the Free Software Foundation; either version 2
;; of the License, or (at your option) any later version.
;;
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License
;; along with this program.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; This file is an implementation of a minimap sidebar, i.e., a
;; smaller display of the current buffer on the left side.  It
;; highlights the currently shown region and updates its position
;; automatically.  You can navigate in the minibar by dragging the
;; active region with the mouse, which will scroll the corresponding
;; edit buffer.

;; To create the minimap sidebar, type M-x minimap-create.
;; To dismiss it, type M-x minimap-kill.

;; Usage:
;;  * Use 'M-x minimap-create' in a buffer you're currently editing.
;;  * Use 'M-x minimap-kill' to kill the minimap.
;;  * Use 'M-x customize-group RET minimap RET' to adapt minimap to your needs.

;;; KNOWN BUGS:

;; * Currently cannot deal with images.
;; * Display/movement can be a bit erratic at times.

;;; TODO:

;; * Fix known bugs.
;; * Make sidebar permanently visible. This requires something like a
;;   'window group' feature in Emacs, which is currently being worked on.
;; * Moving the active region with the keyboard / mouse-wheel ?


;;; Customizable variables:

(defgroup minimap nil
  "A minimap sidebar for Emacs."
  :group 'convenience)

(defface minimap-font-face
  '((default :family "DejaVu Sans Mono" :height 30))
  "Face used for text in minimap buffer, notably the font family and height.
This height should be really small.  You probably want to use a
TrueType font for this.  After changing this, you should
recreate the minimap to avoid problems with recentering."
  :group 'minimap)

(defface minimap-active-region-background
  '((((background dark)) (:background "#4517305D0000"))
    (t (:background "#C847D8FEFFFF")))
  "Face for the active region in the minimap.
By default, this is only a different background color."
  :group 'minimap)

(defface minimap-semantic-function-face
  '((((background dark))
     (:box (:line-width 1 :color "white")
	   :inherit (font-lock-function-name-face minimap-font-face)
	   :height 2.5 :background "gray10"))
    (t (:box (:line-width 1 :color "black")
	     :inherit (font-lock-function-name-face minimap-font-face)
	     :height 2.5 :background "gray90")))
  "Face used for functions in the semantic overlay.")

(defface minimap-semantic-variable-face
  '((((background dark))
     (:box (:line-width 1 :color "white")
	   :inherit (font-lock-variable-name-face minimap-font-face)
	    :height 2.5 :background "gray10"))
    (t (:box (:line-width 1 :color "black")
	     :inherit (font-lock-function-name-face minimap-font-face)
	     :height 2.5 :background "gray90")))
  "Face used for variables in the semantic overlay.")

(defface minimap-semantic-type-face
  '((((background dark))
     (:box (:line-width 1 :color "white")
	   :inherit (font-lock-type-face minimap-font-face)
	   :height 2.5 :background "gray10"))
    (t (:box (:line-width 1 :color "black")
	     :inherit (font-lock-function-name-face minimap-font-face)
	     :height 2.5 :background "gray90")))
  "Face used for types in the semantic overlay.")

(defcustom minimap-width-fraction 0.2
  "Fraction of width which should be used for minimap sidebar."
  :type 'number
  :group 'minimap)

(defcustom minimap-window-location 'left
  "Location of the minimap window.
Can be either the symbol `left' or `right'."
  :type '(choice (const :tag "Left" left)
		 (const :tag "Right" right))
  :group 'minimap)

(defcustom minimap-buffer-name-prefix "*MINIMAP* "
  "Prefix for buffer names of minimap sidebar."
  :type 'string
  :group 'minimap)

(defcustom minimap-update-delay 0.2
  "Delay in seconds after which sidebar gets updated.
Setting this to 0 will let the minimap react immediately, but
this will slow down scrolling."
  :type 'number
  :set (lambda (sym value)
	 (set sym value)
	 (when (and (boundp 'minimap-timer-object)
		    minimap-timer-object)
	   (cancel-timer minimap-timer-object)
	   (setq minimap-timer-object
		 (run-with-idle-timer
		  minimap-update-delay t 'minimap-update))))
  :group 'minimap)

(defcustom minimap-always-recenter nil
  "Whether minimap sidebar should be recentered after every point movement."
  :type 'boolean
  :group 'minimap)

(defcustom minimap-recenter-type 'relative
  "Specifies the type of recentering the minimap should use.
The minimap can use different types of recentering, i.e., how the
minimap should behave when you scroll in the main window or when
you drag the active region with the mouse.  The following
explanations will probably not help much, so simply try them and
choose the one which suits you best.

`relative' -- The position of the active region in the minimap
corresponds with the relative position of this region in the
buffer.  This the default.

`middle' -- The active region will stay fixed in the middle of
the minimap.

`free' -- The position will be more or less free.  When dragging
the active region, the minimap will scroll when you reach the
bottom or top."
  :type '(choice (const :tag "Relative" relative)
		 (const :tag "Middle" middle)
		 (const :tag "Free" free))
  :group 'minimap)

(defcustom minimap-hide-scroll-bar t
  "Whether the minimap should hide the vertical scrollbar."
  :type 'boolean
  :group 'minimap)

(defcustom minimap-hide-fringes t
  "Whether the minimap should hide the fringes."
  :type 'boolean
  :group 'minimap)

(defcustom minimap-dedicated-window nil
  "Whether the minimap should create a dedicated window."
  :type 'boolean
  :group 'minimap)

(defcustom minimap-display-semantic-overlays t
  "Display overlays from CEDET's semantic analyzer.
If you use CEDET and the buffer's major-mode is supported, the
minimap can display overlays generated by the semantic analyzer.
By default, it will apply the faces `minimap-semantic-<X>-face',
with <X> being \"function\", \"variable\" and \"type\".  Also, it
will display the name of the tag in the middle of the overlay in
the corresponding font-lock face.

See also `minimap-enlarge-certain-faces', which can be used as
fallback."
  :type 'boolean
  :group 'minimap)

(defcustom minimap-enlarge-certain-faces 'as-fallback
  "Whether certain faces should be enlarged in the minimap.
All faces listed in `minimap-normal-height-faces' will be
displayed using the default font height, allowing you to still
read text using those faces.  By default, this should enlarge all
function names in the minimap, given you have font locking
enabled.  This variable can have the following values:

'as-fallback (the default) -- The feature will only be activated
  if information from CEDET's semantic analyzer isn't available
  (see: `minimap-display-semantic-overlays').
'always -- Always active.
nil -- Inactive."
  :type '(choice (const :tag "Fallback if CEDET unavailable." 'as-fallback)
		 (const :tag "Always active." 'always)
		 (const :tag "Inactive." nil))
  :group 'minimap)

(defcustom minimap-normal-height-faces '(font-lock-function-name-face)
  "List of faces which should be displayed with normal height.
When `minimap-enlarge-certain-faces' is non-nil, all faces in
this list will be displayed using the default font height.  By
default, this list contains `font-lock-function-name-face', so
you can still read function names in the minimap."
  :type '(repeat face)
  :group 'minimap)

(defcustom minimap-sync-overlay-properties '(face invisible)
  "Specifies which overlay properties should be synced.
Unlike text properties, overlays are not applied automatically to
the minimap and must be explicitly synced.  This variable
specifies which overlay properties should be synced by
`minimap-sync-overlays'.  Most importantly, this variable should
include 'invisible', so that hidden text does not appear in the
minimap buffer."
  :type '(repeat symbol)
  :group 'minimap)

;;; Internal variables

(defvar minimap-start nil)
(defvar minimap-end nil)
(defvar minimap-active-overlay nil)
(defvar minimap-bufname nil)
(defvar minimap-timer-object nil)
(defvar minimap-active-minimaps 0)
(defvar minimap-base-overlay nil)
(defvar minimap-numlines nil)
(defvar minimap-pointmin-overlay nil)

(make-variable-buffer-local 'minimap-start)
(make-variable-buffer-local 'minimap-end)
(make-variable-buffer-local 'minimap-active-overlay)
(make-variable-buffer-local 'minimap-bufname)
(make-variable-buffer-local 'minimap-base-overlay)
(make-variable-buffer-local 'minimap-numlines)
(make-variable-buffer-local 'minimap-pointmin-overlay)

;;; Minimap creation / killing

;;;###autoload
(defun minimap-create ()
  "Create a minimap sidebar for the current window."
  (interactive)
  ;; If minimap is visible, do nothing.
  (unless (and minimap-bufname
	       (get-buffer minimap-bufname)
	       (get-buffer-window (get-buffer minimap-bufname)))
    (let ((bufname (concat minimap-buffer-name-prefix
			   (buffer-name (current-buffer))))
	  (new-win (if (eq minimap-window-location 'left)
		       (split-window-horizontally
			(round (* (window-width)
				  minimap-width-fraction)))
		     (split-window-horizontally
		      (round (* (window-width)
				(- 1 minimap-width-fraction))))
		     (other-window 1))))
      ;; If minimap exists but isn't visible, reuse it.
      (if (and minimap-bufname
	       (get-buffer minimap-bufname))
	  (switch-to-buffer minimap-bufname t)
	;; Otherwise create new minimap
	(minimap-new-minimap bufname)
	;; If this is the first minimap, create the idle timer.
	(when (zerop minimap-active-minimaps)
	  (setq minimap-timer-object
		(run-with-idle-timer minimap-update-delay t 'minimap-update)))
	(setq minimap-active-minimaps
	      (1+ minimap-active-minimaps))))
    (other-window 1)
    (minimap-sync-overlays)))

(defun minimap-new-minimap (bufname)
  "Create new minimap BUFNAME for current buffer and window."
  (let ((indbuf (make-indirect-buffer (current-buffer) bufname t))
	(edges (window-pixel-edges)))
    (setq minimap-bufname bufname)
    (set-buffer indbuf)
    (when minimap-hide-scroll-bar
      (setq vertical-scroll-bar nil))
    (switch-to-buffer indbuf)
    (setq minimap-base-overlay (make-overlay (point-min) (point-max) nil t t))
    (overlay-put minimap-base-overlay 'face 'minimap-font-face)
    (overlay-put minimap-base-overlay 'priority 1)
    (setq minimap-pointmin-overlay (make-overlay (point-min) (1+ (point-min))))
    (setq minimap-start (window-start)
	  minimap-end (window-end)
	  minimap-active-overlay (make-overlay minimap-start minimap-end)
	  line-spacing 0)
    (overlay-put minimap-active-overlay 'face
		 'minimap-active-region-background)
    (overlay-put minimap-active-overlay 'priority 5)
    (minimap-mode 1)
    (when (and (boundp 'linum-mode)
	       linum-mode)
      (linum-mode 0))
    (when minimap-hide-fringes
      (set-window-fringes nil 0 0))
    (when minimap-dedicated-window
      (set-window-dedicated-p nil t))
    (setq buffer-read-only t)
    ;; Calculate the actual number of lines displayable with the minimap face.
    (setq minimap-numlines
	  (floor
	   (/
	    (- (nth 3 edges) (nth 1 edges))
	    (car (progn (redisplay) (window-line-height))))))))

;;;###autoload
(defun minimap-kill ()
  "Kill minimap for current buffer.
Cancel the idle timer if no more minimaps are active."
  (interactive)
  (if (null minimap-bufname)
      (message "No minimap associated with %s." (buffer-name (current-buffer)))
    (let ((curname (buffer-name (current-buffer)))
	  (buf (get-buffer minimap-bufname))
	  (win (get-buffer-window minimap-bufname)))
      (setq minimap-bufname nil)
      (if (null buf)
	  (message "No minimap associated with %s." curname)
	(when win
	  (delete-window win))
	(kill-buffer buf)
	(when (zerop
	       (setq minimap-active-minimaps
		     (1- minimap-active-minimaps)))
	  (cancel-timer minimap-timer-object)
	  (setq minimap-timer-object nil))
	(message "Minimap for %s killed." curname)))))

;;; Minimap update

(defun minimap-update (&optional force)
  "Update minimap sidebar if necessary.
This is meant to be called from the idle-timer or the post command hook.
When FORCE, enforce update of the active region."
  (when minimap-bufname
    (let ((win (get-buffer-window minimap-bufname))
	  start end pt ov)
      (when win
	(setq start (window-start)
	      end (window-end)
	      pt (point)
	      ov)
	(with-selected-window win
	  (unless (and (not force)
		       (= minimap-start start)
		       (= minimap-end end))
	    (move-overlay minimap-active-overlay start end)
	    (setq minimap-start start
		  minimap-end end)
	    (minimap-recenter (line-number-at-pos (/ (+ end start) 2))
			      (/ (- (line-number-at-pos end)
				    (line-number-at-pos start))
				 2)))
	  (goto-char pt)
	  (when minimap-always-recenter
	    (recenter (round (/ (window-height) 2)))))))))

;;; Overlay movement

(defun minimap-move-overlay-mouse (start-event)
  "Move overlay by tracking mouse movement."
  (interactive "e")
  (mouse-set-point start-event)
  (when (get-buffer-window (buffer-base-buffer (current-buffer)))
    (let* ((echo-keystrokes 0)
	   (end-posn (event-end start-event))
	   (start-point (posn-point end-posn))
	   (make-cursor-line-fully-visible nil)
	   (cursor-type nil)
	   (pcselmode (when (boundp 'pc-selection-mode)
			pc-selection-mode))
           pt ev)
      (when (and pcselmode (fboundp 'pc-selection-mode))
	(pc-selection-mode -1))
      (move-overlay minimap-active-overlay start-point minimap-end)
      (track-mouse
	(minimap-set-overlay start-point)
	(while (and
		(consp (setq ev (read-event)))
		(eq (car ev) 'mouse-movement))
	  (setq pt (posn-point (event-start ev)))
	  (when (numberp pt)
	    (minimap-set-overlay pt))))
      (select-window (get-buffer-window (buffer-base-buffer)))
      (minimap-update)
      (when (and pcselmode (fboundp 'pc-selection-mode))
	(pc-selection-mode 1)))))

(defun minimap-set-overlay (pt)
  "Set overlay position, with PT being the middle."
  (goto-char pt)
  (let* ((ovstartline (line-number-at-pos minimap-start))
	 (ovendline (line-number-at-pos minimap-end))
	 (ovheight (round (/ (- ovendline ovstartline) 2)))
	 (line (line-number-at-pos))
	 (winstart (window-start))
	 (winend (window-end))
	 newstart newend)
    (setq pt (point-at-bol))
    (setq newstart (minimap-line-to-pos (- line ovheight)))
    ;; Perform recentering
    (minimap-recenter line ovheight)
    ;; Set new position in main buffer and redisplay
    (with-selected-window (get-buffer-window (buffer-base-buffer))
      (goto-char pt)
      (set-window-start nil newstart)
      (redisplay t)
      (setq newend (window-end)))
    (when (eq minimap-recenter-type 'free)
      (while (> newend winend)
	(scroll-up 5)
	(redisplay t)
	(setq winend (window-end))))
    (move-overlay minimap-active-overlay newstart newend)))

(defun minimap-line-to-pos (line)
  "Return point position of line number LINE."
  (save-excursion
    (goto-char 1)
    (if (eq selective-display t)
	(re-search-forward "[\n\C-m]" nil 'end (1- line))
      (forward-line (1- line)))
    (point)))

(defun minimap-recenter (middle height)
  "Recenter the minimap according to `minimap-recenter-type'.
MIDDLE is the line number in the middle of the active region.
HEIGHT is the number of lines from MIDDLE to begin/end of the
active region."
  (cond
   ;; Relative recentering
   ((eq minimap-recenter-type 'relative)
    (let* ((maxlines (line-number-at-pos (point-max)))
	   percentage relpos newline start numlines)
      (setq numlines (count-lines (window-start) (window-end)))
      (setq percentage (/ (float middle) (float maxlines)))
      (setq newline (ceiling (* percentage numlines)))
      (setq start (minimap-line-to-pos
		   (- middle height
		      (floor (* percentage
				(- numlines height height))))))
      (or (> start (point-min))
	  (setq start (point-min)))
      ;; If (point-max) already visible, don't go further
      (if (and (> start (window-start))
	       (with-selected-window (get-buffer-window (buffer-base-buffer))
		 (= (point-max) (window-end))))
	  (save-excursion
	    (goto-char (point-max))
	    (recenter -1))
	(unless (and (> start (window-start))
		     (= (point-max) (window-end)))
	  (set-window-start nil start)))))
   ;; Middle recentering
    ((eq minimap-recenter-type 'middle)
     (let ((start (- middle height
		     (floor (* 0.5
			       (- minimap-numlines height height))))))
       (if (< start 1)
	   (progn
	     ;; Hack: Emacs cannot scroll down any further, so we fake
	     ;; it using an overlay.  Otherwise, the active region
	     ;; would move to the top.
	     (overlay-put minimap-pointmin-overlay
			  'display (concat
				    (make-string (abs start) 10)
				    (buffer-substring (point-min) (1+ (point-min)))))
	     (overlay-put minimap-pointmin-overlay
			  'face `(:background ,(face-background 'default)))
	     (overlay-put minimap-pointmin-overlay
			  'priority 10)
	     (setq start 1))
	 (overlay-put minimap-pointmin-overlay 'display "")
	 (overlay-put minimap-pointmin-overlay 'face nil))
       (set-window-start nil (minimap-line-to-pos start))))
    ;; Free recentering
    ((eq minimap-recenter-type 'free)
     (let ((newstart (minimap-line-to-pos (- middle height)))
	   (winstart (window-start)))
       (while (< newstart winstart)
	 (scroll-down 5)
	 (redisplay t)
	 (setq winstart (window-start)))))))

;;; Minimap minor mode

(defvar minimap-mode-map (make-sparse-keymap)
  "Keymap used by `minimap-mode'.")

(define-key minimap-mode-map [down-mouse-1] 'minimap-move-overlay-mouse)
(define-key minimap-mode-map [down-mouse-2] 'minimap-move-overlay-mouse)
(define-key minimap-mode-map [down-mouse-3] 'minimap-move-overlay-mouse)

(define-minor-mode minimap-mode
  "Minor mode for minimap sidebar."
  nil "minimap" minimap-mode-map)

;;; Sync minimap with modes which create/delete overlays.

(defun minimap-sync-overlays ()
  "Synchronize overlays between base and minimap buffer.
Apply semantic overlays or face enlargement if necessary."
  (interactive)
  (when minimap-bufname
    (let ((baseov (overlays-in (point-min) (point-max)))
	  (semantic (and (boundp 'semantic-version)
			 (semantic-active-p)))
	  ov props p)
      (with-current-buffer minimap-bufname
	(remove-overlays)
	(while baseov
	  (when (setq props (minimap-get-sync-properties (car baseov)))
	    (setq ov (make-overlay (overlay-start (car baseov))
				   (overlay-end (car baseov))))
	    (while (setq p (car props))
	      (overlay-put ov (car p) (cadr p))
	      (setq props (cdr props))))
	  (setq baseov (cdr baseov)))
	(move-overlay minimap-pointmin-overlay (point-min) (1+ (point-min)))
	;; Re-apply font overlay
	(move-overlay minimap-base-overlay (point-min) (point-max)))
      ;; Face enlargement
      (when (and font-lock-mode
		 (or (eq minimap-enlarge-certain-faces 'always)
		     (and (eq minimap-enlarge-certain-faces 'as-fallback)
			  (or (not minimap-display-semantic-overlays)
			      (not semantic)))))
	(when (eq font-lock-support-mode 'jit-lock-mode)
	  (jit-lock-fontify-now))
	(with-current-buffer minimap-bufname
	  (minimap-enlarge-faces)))
      ;; Semantic overlays
      (when (and semantic
		 minimap-display-semantic-overlays)
	  (minimap-apply-semantic-overlays)))
    (minimap-update t)))

(defun minimap-get-sync-properties (ov)
  "Get properties from overlay OV which should be synced.
You can specify those properties with
`minimap-sync-overlay-properties'."
  (delq nil
	(mapcar
	 (lambda (p)
	   (let ((val (overlay-get ov p)))
	     (if val
		 (list p val)
	       nil)))
	 minimap-sync-overlay-properties)))

(defun minimap-enlarge-faces ()
  "Apply default font to all faces in `minimap-normal-height-faces'.
This has to be called in the minimap buffer."
  (let ((pos (next-single-property-change (point-min) 'face))
	next ov face)
    (while pos
      (setq face (get-text-property pos 'face))
      (when (delq nil (mapcar (lambda (x) (equal x face))
			      minimap-normal-height-faces))
	(setq ov
	      (make-overlay pos
			    (setq pos (next-single-property-change pos 'face))))
	(overlay-put ov 'face `(:family ,(face-font 'default)))
	(overlay-put ov 'priority 5))
      (setq pos (next-single-property-change pos 'face)))))

(defun minimap-apply-semantic-overlays ()
  "Apply semantic overlays to the minimap.
This has to be called from the base buffer."
    (let ((tags (semantic-fetch-tags))
	  tag class ov ovnew)
      (while tags
	(setq tag (car tags))
	(setq class (semantic-tag-class tag))
	(setq ov (semantic-tag-overlay tag))
	(when (and (overlayp ov)
		   (or (eq class 'function)
		       (eq class 'type)
		       (eq class 'variable)))
	  (with-current-buffer minimap-bufname
	    (let ((start (overlay-start ov))
		  (end (overlay-end ov))
		  (name (semantic-tag-name tag)))
	      (overlay-put
	       (setq ovnew (make-overlay start end))
	       'face `(:background ,(face-background
				     (intern (format "minimap-semantic-%s-face"
						     (symbol-name class))))))
	      (overlay-put ovnew 'priority 1)
	      (setq start
		    (minimap-line-to-pos (/ (+ (line-number-at-pos start)
					       (line-number-at-pos end)) 2)))
	      (setq end (progn (goto-char start) (point-at-eol)))
	      (setq ovnew (make-overlay start end))
	      (overlay-put ovnew 'face (format "minimap-semantic-%s-face"
					       (symbol-name class)))
	      (overlay-put ovnew 'display (concat "  " name "  "))
	      (overlay-put ovnew 'priority 6))))
	(setq tags (cdr tags)))))

;; outline-(minor-)mode
(add-hook 'outline-view-change-hook 'minimap-sync-overlays)

;; hideshow
(add-hook 'hs-hide-hook 'minimap-sync-overlays)
(add-hook 'hs-show-hook 'minimap-sync-overlays)

(provide 'minimap)

;;; minimap.el ends here