[bpt/emacs.git] / lisp / scroll-bar.el

;;; scroll-bar.el --- window system-independent scroll bar support

;; Copyright (C) 1993, 1994, 1995, 1999, 2000, 2001, 2002, 2003,
;;   2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.

;; Maintainer: FSF
;; Keywords: hardware

;; This file is part of GNU Emacs.

;; GNU Emacs 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 3, or (at your option)
;; any later version.

;; GNU Emacs 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 GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Commentary:

;; Window-system-independent bindings of mouse clicks on the scroll bar.
;; Presently emulates the scroll-bar behavior of xterm.

;;; Code:

(require 'mouse)

\f
;;;; Utilities.

(defun scroll-bar-event-ratio (event)
  "Given a scroll bar event EVENT, return the scroll bar position as a ratio.
The value is a cons cell (PORTION . WHOLE) containing two integers
whose ratio gives the event's vertical position in the scroll bar, with 0
referring to the top and 1 to the bottom."
  (nth 2 event))

(defun scroll-bar-scale (num-denom whole)
  "Given a pair (NUM . DENOM) and WHOLE, return (/ (* NUM WHOLE) DENOM).
This is handy for scaling a position on a scroll bar into real units,
like buffer positions.  If SCROLL-BAR-POS is the (PORTION . WHOLE) pair
from a scroll bar event, then (scroll-bar-scale SCROLL-BAR-POS
\(buffer-size)) is the position in the current buffer corresponding to
that scroll bar position."
  ;; We multiply before we divide to maintain precision.
  ;; We use floating point because the product of a large buffer size
  ;; with a large scroll bar portion can easily overflow a lisp int.
  (truncate (/ (* (float (car num-denom)) whole) (cdr num-denom))))

(defun scroll-bar-columns (side)
  "Return the width, measured in columns, of the vertical scrollbar on SIDE.
SIDE must be the symbol `left' or `right'."
  (let* ((wsb   (window-scroll-bars))
         (vtype (nth 2 wsb))
         (cols  (nth 1 wsb)))
    (cond
     ((not (memq side '(left right)))
      (error "`left' or `right' expected instead of %S" side))
     ((and (eq vtype side) cols))
     ((eq (frame-parameter nil 'vertical-scroll-bars) side)
      ;; nil means it's a non-toolkit scroll bar, and its width in
      ;; columns is 14 pixels rounded up.
      (ceiling (or (frame-parameter nil 'scroll-bar-width) 14)
               (frame-char-width)))
     (0))))

\f
;;;; Helpful functions for enabling and disabling scroll bars.

(defvar scroll-bar-mode)
(defvar previous-scroll-bar-mode nil)

(defvar scroll-bar-mode-explicit nil
  "Non-nil means `set-scroll-bar-mode' should really do something.
This is nil while loading `scroll-bar.el', and t afterward.")

(defun set-scroll-bar-mode-1 (ignore value)
  (set-scroll-bar-mode value))

(defun set-scroll-bar-mode (value)
  "Set `scroll-bar-mode' to VALUE and put the new value into effect."
  (if scroll-bar-mode
      (setq previous-scroll-bar-mode scroll-bar-mode))

  (setq scroll-bar-mode value)

  (when scroll-bar-mode-explicit
    (modify-all-frames-parameters (list (cons 'vertical-scroll-bars
					      scroll-bar-mode)))))

(defcustom scroll-bar-mode default-frame-scroll-bars
  "*Specify whether to have vertical scroll bars, and on which side.
Possible values are nil (no scroll bars), `left' (scroll bars on left)
and `right' (scroll bars on right).
To set this variable in a Lisp program, use `set-scroll-bar-mode'
to make it take real effect.
Setting the variable with a customization buffer also takes effect."
  :type '(choice (const :tag "none (nil)" nil)
		 (const left)
		 (const right))
  :group 'frames
  ;; The default value for :initialize would try to use :set
  ;; when processing the file in cus-dep.el.
  :initialize 'custom-initialize-default
  :set 'set-scroll-bar-mode-1)

;; We just set scroll-bar-mode, but that was the default.
;; If it is set again, that is for real.
(setq scroll-bar-mode-explicit t)

(defun scroll-bar-mode (&optional flag)
  "Toggle display of vertical scroll bars on all frames.
This command applies to all frames that exist and frames to be
created in the future.
With a numeric argument, if the argument is negative,
turn off scroll bars; otherwise, turn on scroll bars."
  (interactive "P")

  ;; Tweedle the variable according to the argument.
  (set-scroll-bar-mode (if (if (null flag) 
			       (not scroll-bar-mode)
			     (setq flag (prefix-numeric-value flag))
			     (or (not (numberp flag)) (>= flag 0)))
			   (or previous-scroll-bar-mode
			       default-frame-scroll-bars))))

(defun toggle-scroll-bar (arg)
  "Toggle whether or not the selected frame has vertical scroll bars.
With arg, turn vertical scroll bars on if and only if arg is positive.
The variable `scroll-bar-mode' controls which side the scroll bars are on
when they are turned on; if it is nil, they go on the left."
  (interactive "P")
  (if (null arg)
      (setq arg
	    (if (cdr (assq 'vertical-scroll-bars
			   (frame-parameters (selected-frame))))
		-1 1))
    (setq arg (prefix-numeric-value arg)))
  (modify-frame-parameters
   (selected-frame)
   (list (cons 'vertical-scroll-bars
	       (if (> arg 0)
		   (or scroll-bar-mode default-frame-scroll-bars))))))

(defun toggle-horizontal-scroll-bar (arg)
  "Toggle whether or not the selected frame has horizontal scroll bars.
With arg, turn horizontal scroll bars on if and only if arg is positive.
Horizontal scroll bars aren't implemented yet."
  (interactive "P")
  (error "Horizontal scroll bars aren't implemented yet"))
\f
;;;; Buffer navigation using the scroll bar.

;;; This was used for up-events on button 2, but no longer.
(defun scroll-bar-set-window-start (event)
  "Set the window start according to where the scroll bar is dragged.
EVENT should be a scroll bar click or drag event."
  (interactive "e")
  (let* ((end-position (event-end event))
	 (window (nth 0 end-position))
	 (portion-whole (nth 2 end-position)))
    (save-excursion
      (set-buffer (window-buffer window))
      (save-excursion
	(goto-char (+ (point-min)
		      (scroll-bar-scale portion-whole
					(- (point-max) (point-min)))))
	(beginning-of-line)
	(set-window-start window (point))))))

(defun scroll-bar-drag-position (portion-whole)
  "Calculate new window start for drag event."
  (save-excursion
    (goto-char (+ (point-min)
		  (scroll-bar-scale portion-whole
				    (- (point-max) (point-min)))))
    (beginning-of-line)
    (point)))

(defun scroll-bar-maybe-set-window-start (event)
  "Set the window start according to where the scroll bar is dragged.
Only change window start if the new start is substantially different.
EVENT should be a scroll bar click or drag event."
  (interactive "e")
  (let* ((end-position (event-end event))
	 (window (nth 0 end-position))
	 (portion-whole (nth 2 end-position))
	 (next-portion-whole (cons (1+ (car portion-whole))
				   (cdr portion-whole)))
	 portion-start
	 next-portion-start
	 (current-start (window-start window)))
    (save-excursion
      (set-buffer (window-buffer window))
      (setq portion-start (scroll-bar-drag-position portion-whole))
      (setq next-portion-start (max
				(scroll-bar-drag-position next-portion-whole)
				(1+ portion-start)))
      (if (or (>= current-start next-portion-start)
	      (< current-start portion-start))
	  (set-window-start window portion-start)
	;; Always set window start, to ensure scroll bar position is updated.
	(set-window-start window current-start)))))

;; Scroll the window to the proper position for EVENT.
(defun scroll-bar-drag-1 (event)
  (let* ((start-position (event-start event))
	 (window (nth 0 start-position))
	 (portion-whole (nth 2 start-position)))
    (save-excursion
      (set-buffer (window-buffer window))
      ;; Calculate position relative to the accessible part of the buffer.
      (goto-char (+ (point-min)
		    (scroll-bar-scale portion-whole
				      (- (point-max) (point-min)))))
      (vertical-motion 0 window)
      (set-window-start window (point)))))

(defun scroll-bar-drag (event)
  "Scroll the window by dragging the scroll bar slider.
If you click outside the slider, the window scrolls to bring the slider there."
  (interactive "e")
  (let* (done
	 (echo-keystrokes 0)
	 (end-position (event-end event))
	 (window (nth 0 end-position))
	 (before-scroll))
    (with-current-buffer (window-buffer window)
      (setq before-scroll point-before-scroll))
    (save-selected-window
      (select-window window)
      (setq before-scroll
	    (or before-scroll (point))))
    (scroll-bar-drag-1 event)
    (track-mouse
      (while (not done)
	(setq event (read-event))
	(if (eq (car-safe event) 'mouse-movement)
	    (setq event (read-event)))
	(cond ((eq (car-safe event) 'scroll-bar-movement)
	       (scroll-bar-drag-1 event))
	      (t
	       ;; Exit when we get the drag event; ignore that event.
	       (setq done t)))))
    (sit-for 0)
    (with-current-buffer (window-buffer window)
      (setq point-before-scroll before-scroll))))

(defun scroll-bar-scroll-down (event)
  "Scroll the window's top line down to the location of the scroll bar click.
EVENT should be a scroll bar click."
  (interactive "e")
  (let* ((end-position (event-end event))
	 (window (nth 0 end-position))
	 (before-scroll))
    (with-current-buffer (window-buffer window)
      (setq before-scroll point-before-scroll))
    (unwind-protect
	(save-selected-window
	  (let ((portion-whole (nth 2 end-position)))
	    (select-window window)
	    (setq before-scroll
		  (or before-scroll (point)))
	    (scroll-down
	     (scroll-bar-scale portion-whole (1- (window-height)))))
	  (sit-for 0))
      (with-current-buffer (window-buffer window)
	(setq point-before-scroll before-scroll)))))

(defun scroll-bar-scroll-up (event)
  "Scroll the line next to the scroll bar click to the top of the window.
EVENT should be a scroll bar click."
  (interactive "e")
  (let* ((end-position (event-end event))
	 (window (nth 0 end-position))
	 (before-scroll))
    (with-current-buffer (window-buffer window)
      (setq before-scroll point-before-scroll))
    (unwind-protect
	(save-selected-window
	  (let ((portion-whole (nth 2 end-position)))
	    (select-window window)
	    (setq before-scroll
		  (or before-scroll (point)))
	    (scroll-up
	     (scroll-bar-scale portion-whole (1- (window-height)))))
	  (sit-for 0))
      (with-current-buffer (window-buffer window)
	(setq point-before-scroll before-scroll)))))

\f
;;; Tookit scroll bars.

(defun scroll-bar-toolkit-scroll (event)
  (interactive "e")
  (let* ((end-position (event-end event))
	 (window (nth 0 end-position))
	 (part (nth 4 end-position))
	 before-scroll)
    (cond ((eq part 'end-scroll))
	  (t
	   (with-current-buffer (window-buffer window)
	     (setq before-scroll point-before-scroll))
	   (save-selected-window
	     (select-window window)
	     (setq before-scroll (or before-scroll (point)))
	     (cond ((eq part 'above-handle)
		    (scroll-up '-))
		   ((eq part 'below-handle)
		    (scroll-up nil))
		   ((eq part 'ratio)
		    (let* ((portion-whole (nth 2 end-position))
			   (lines (scroll-bar-scale portion-whole
						    (1- (window-height)))))
		      (scroll-up (cond ((not (zerop lines)) lines)
				       ((< (car portion-whole) 0) -1)
				       (t 1)))))
		   ((eq part 'up)
		    (scroll-up -1))
		   ((eq part 'down)
		    (scroll-up 1))
		   ((eq part 'top)
		    (set-window-start window (point-min)))
		   ((eq part 'bottom)
		    (goto-char (point-max))
		    (recenter))
		   ((eq part 'handle)
		    (scroll-bar-drag-1 event))))
	   (sit-for 0)
	   (with-current-buffer (window-buffer window)
	     (setq point-before-scroll before-scroll))))))


\f
;;;; Bindings.

;;; For now, we'll set things up to work like xterm.
(cond ((and (boundp 'x-toolkit-scroll-bars) x-toolkit-scroll-bars)
       (global-set-key [vertical-scroll-bar mouse-1]
		       'scroll-bar-toolkit-scroll))
      (t
       (global-set-key [vertical-scroll-bar mouse-1]
		       'scroll-bar-scroll-up)
       (global-set-key [vertical-scroll-bar drag-mouse-1]
		       'scroll-bar-scroll-up)
       (global-set-key [vertical-scroll-bar down-mouse-2]
		       'scroll-bar-drag)
       (global-set-key [vertical-scroll-bar mouse-3]
		       'scroll-bar-scroll-down)
       (global-set-key [vertical-scroll-bar drag-mouse-3]
		       'scroll-bar-scroll-down)))

\f
(provide 'scroll-bar)

;; arch-tag: 6f1d01d0-0b1e-4bf8-86db-d491e0f399f3
;;; scroll-bar.el ends here
Commit	Line	Data
55535639	1	;;; scroll-bar.el --- window system-independent scroll bar support
6d62a90e	2
0d30b337	3	;; Copyright (C) 1993, 1994, 1995, 1999, 2000, 2001, 2002, 2003,
409cc4a3	4	;; 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
6d62a90e JB	5
	6	;; Maintainer: FSF
	7	;; Keywords: hardware
	8
b578f267	9	;; This file is part of GNU Emacs.
6d62a90e	10
b578f267 EN	11	;; GNU Emacs is free software; you can redistribute it and/or modify
b578f267 EN	12	;; it under the terms of the GNU General Public License as published by
b4aa6026	13	;; the Free Software Foundation; either version 3, or (at your option)
b578f267	14	;; any later version.
6d62a90e	15
b578f267 EN	16	;; GNU Emacs is distributed in the hope that it will be useful,
	17	;; but WITHOUT ANY WARRANTY; without even the implied warranty of
	18	;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	19	;; GNU General Public License for more details.
6d62a90e	20
b578f267 EN	21	;; You should have received a copy of the GNU General Public License
b578f267 EN	22	;; along with GNU Emacs; see the file COPYING. If not, write to the
086add15 LK	23	;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
086add15 LK	24	;; Boston, MA 02110-1301, USA.
76550a57	25
d9ecc911 ER	26	;;; Commentary:
	27
	28	;; Window-system-independent bindings of mouse clicks on the scroll bar.
	29	;; Presently emulates the scroll-bar behavior of xterm.
b578f267	30
d9ecc911 ER	31	;;; Code:
d9ecc911 ER	32
dbc4e1c1 JB	33	(require 'mouse)
dbc4e1c1 JB	34
6d62a90e JB	35	\f
	36	;;;; Utilities.
	37
86828678 RS	38	(defun scroll-bar-event-ratio (event)
	39	"Given a scroll bar event EVENT, return the scroll bar position as a ratio.
	40	The value is a cons cell (PORTION . WHOLE) containing two integers
	41	whose ratio gives the event's vertical position in the scroll bar, with 0
	42	referring to the top and 1 to the bottom."
	43	(nth 2 event))
	44
bf3c8a70	45	(defun scroll-bar-scale (num-denom whole)
6d62a90e	46	"Given a pair (NUM . DENOM) and WHOLE, return (/ (* NUM WHOLE) DENOM).
bf3c8a70 JB	47	This is handy for scaling a position on a scroll bar into real units,
	48	like buffer positions. If SCROLL-BAR-POS is the (PORTION . WHOLE) pair
	49	from a scroll bar event, then (scroll-bar-scale SCROLL-BAR-POS
6d62a90e	50	\(buffer-size)) is the position in the current buffer corresponding to
bf3c8a70	51	that scroll bar position."
6d62a90e JB	52	;; We multiply before we divide to maintain precision.
6d62a90e JB	53	;; We use floating point because the product of a large buffer size
bf3c8a70	54	;; with a large scroll bar portion can easily overflow a lisp int.
6d62a90e JB	55	(truncate (/ (* (float (car num-denom)) whole) (cdr num-denom))))
6d62a90e JB	56
9fd76d04 MY	57	(defun scroll-bar-columns (side)
	58	"Return the width, measured in columns, of the vertical scrollbar on SIDE.
	59	SIDE must be the symbol `left' or `right'."
	60	(let* ((wsb (window-scroll-bars))
	61	(vtype (nth 2 wsb))
	62	(cols (nth 1 wsb)))
	63	(cond
	64	((not (memq side '(left right)))
	65	(error "`left' or `right' expected instead of %S" side))
	66	((and (eq vtype side) cols))
	67	((eq (frame-parameter nil 'vertical-scroll-bars) side)
	68	;; nil means it's a non-toolkit scroll bar, and its width in
	69	;; columns is 14 pixels rounded up.
	70	(ceiling (or (frame-parameter nil 'scroll-bar-width) 14)
	71	(frame-char-width)))
	72	(0))))
	73
6d62a90e	74	\f
fe48f821	75	;;;; Helpful functions for enabling and disabling scroll bars.
fe48f821	76
1064fe38	77	(defvar scroll-bar-mode)
f62c3ee2	78	(defvar previous-scroll-bar-mode nil)
1064fe38	79
2124851f RS	80	(defvar scroll-bar-mode-explicit nil
	81	"Non-nil means `set-scroll-bar-mode' should really do something.
	82	This is nil while loading `scroll-bar.el', and t afterward.")
	83
e4b201bb KH	84	(defun set-scroll-bar-mode-1 (ignore value)
	85	(set-scroll-bar-mode value))
	86
	87	(defun set-scroll-bar-mode (value)
04c34f2e	88	"Set `scroll-bar-mode' to VALUE and put the new value into effect."
f62c3ee2 JD	89	(if scroll-bar-mode
	90	(setq previous-scroll-bar-mode scroll-bar-mode))
	91
04c34f2e RS	92	(setq scroll-bar-mode value)
04c34f2e RS	93
2124851f	94	(when scroll-bar-mode-explicit
095fe281 KL	95	(modify-all-frames-parameters (list (cons 'vertical-scroll-bars
095fe281 KL	96	scroll-bar-mode)))))
04c34f2e	97
61f2fe7b	98	(defcustom scroll-bar-mode default-frame-scroll-bars
04c34f2e RS	99	"*Specify whether to have vertical scroll bars, and on which side.
	100	Possible values are nil (no scroll bars), `left' (scroll bars on left)
	101	and `right' (scroll bars on right).
463deb66 RS	102	To set this variable in a Lisp program, use `set-scroll-bar-mode'
	103	to make it take real effect.
	104	Setting the variable with a customization buffer also takes effect."
64453f32	105	:type '(choice (const :tag "none (nil)" nil)
04c34f2e RS	106	(const left)
	107	(const right))
	108	:group 'frames
2669fbfb RS	109	;; The default value for :initialize would try to use :set
	110	;; when processing the file in cus-dep.el.
	111	:initialize 'custom-initialize-default
e4b201bb	112	:set 'set-scroll-bar-mode-1)
04c34f2e	113
2124851f RS	114	;; We just set scroll-bar-mode, but that was the default.
	115	;; If it is set again, that is for real.
	116	(setq scroll-bar-mode-explicit t)
	117
b1ad7c13	118	(defun scroll-bar-mode (&optional flag)
04c34f2e	119	"Toggle display of vertical scroll bars on all frames.
fe48f821 JB	120	This command applies to all frames that exist and frames to be
	121	created in the future.
	122	With a numeric argument, if the argument is negative,
	123	turn off scroll bars; otherwise, turn on scroll bars."
	124	(interactive "P")
ada464a7	125
04c34f2e	126	;; Tweedle the variable according to the argument.
61f2fe7b KS	127	(set-scroll-bar-mode (if (if (null flag)
	128	(not scroll-bar-mode)
	129	(setq flag (prefix-numeric-value flag))
	130	(or (not (numberp flag)) (>= flag 0)))
f62c3ee2 JD	131	(or previous-scroll-bar-mode
f62c3ee2 JD	132	default-frame-scroll-bars))))
04c34f2e RS	133
	134	(defun toggle-scroll-bar (arg)
	135	"Toggle whether or not the selected frame has vertical scroll bars.
	136	With arg, turn vertical scroll bars on if and only if arg is positive.
	137	The variable `scroll-bar-mode' controls which side the scroll bars are on
	138	when they are turned on; if it is nil, they go on the left."
	139	(interactive "P")
	140	(if (null arg)
	141	(setq arg
	142	(if (cdr (assq 'vertical-scroll-bars
	143	(frame-parameters (selected-frame))))
19c6feac KH	144	-1 1))
19c6feac KH	145	(setq arg (prefix-numeric-value arg)))
1032e793 GV	146	(modify-frame-parameters
	147	(selected-frame)
	148	(list (cons 'vertical-scroll-bars
	149	(if (> arg 0)
61f2fe7b	150	(or scroll-bar-mode default-frame-scroll-bars))))))
04c34f2e RS	151
	152	(defun toggle-horizontal-scroll-bar (arg)
	153	"Toggle whether or not the selected frame has horizontal scroll bars.
	154	With arg, turn horizontal scroll bars on if and only if arg is positive.
	155	Horizontal scroll bars aren't implemented yet."
	156	(interactive "P")
	157	(error "Horizontal scroll bars aren't implemented yet"))
fe48f821	158	\f
bf3c8a70	159	;;;; Buffer navigation using the scroll bar.
6d62a90e	160
e532b016	161	;;; This was used for up-events on button 2, but no longer.
bf3c8a70 JB	162	(defun scroll-bar-set-window-start (event)
	163	"Set the window start according to where the scroll bar is dragged.
	164	EVENT should be a scroll bar click or drag event."
6d62a90e	165	(interactive "e")
dbc4e1c1	166	(let* ((end-position (event-end event))
6d62a90e JB	167	(window (nth 0 end-position))
	168	(portion-whole (nth 2 end-position)))
	169	(save-excursion
	170	(set-buffer (window-buffer window))
	171	(save-excursion
4cad38d5 JB	172	(goto-char (+ (point-min)
	173	(scroll-bar-scale portion-whole
	174	(- (point-max) (point-min)))))
6d62a90e JB	175	(beginning-of-line)
	176	(set-window-start window (point))))))
	177
aeee66be RS	178	(defun scroll-bar-drag-position (portion-whole)
	179	"Calculate new window start for drag event."
	180	(save-excursion
	181	(goto-char (+ (point-min)
	182	(scroll-bar-scale portion-whole
	183	(- (point-max) (point-min)))))
	184	(beginning-of-line)
	185	(point)))
	186
	187	(defun scroll-bar-maybe-set-window-start (event)
	188	"Set the window start according to where the scroll bar is dragged.
	189	Only change window start if the new start is substantially different.
	190	EVENT should be a scroll bar click or drag event."
	191	(interactive "e")
	192	(let* ((end-position (event-end event))
	193	(window (nth 0 end-position))
	194	(portion-whole (nth 2 end-position))
	195	(next-portion-whole (cons (1+ (car portion-whole))
	196	(cdr portion-whole)))
	197	portion-start
	198	next-portion-start
	199	(current-start (window-start window)))
	200	(save-excursion
	201	(set-buffer (window-buffer window))
	202	(setq portion-start (scroll-bar-drag-position portion-whole))
	203	(setq next-portion-start (max
	204	(scroll-bar-drag-position next-portion-whole)
	205	(1+ portion-start)))
15655694	206	(if (or (>= current-start next-portion-start)
aeee66be	207	(< current-start portion-start))
9c005c65 KH	208	(set-window-start window portion-start)
	209	;; Always set window start, to ensure scroll bar position is updated.
	210	(set-window-start window current-start)))))
aeee66be	211
e532b016 RS	212	;; Scroll the window to the proper position for EVENT.
	213	(defun scroll-bar-drag-1 (event)
	214	(let* ((start-position (event-start event))
	215	(window (nth 0 start-position))
	216	(portion-whole (nth 2 start-position)))
	217	(save-excursion
	218	(set-buffer (window-buffer window))
d2ae6f7e RS	219	;; Calculate position relative to the accessible part of the buffer.
	220	(goto-char (+ (point-min)
	221	(scroll-bar-scale portion-whole
	222	(- (point-max) (point-min)))))
9d7ab3f0	223	(vertical-motion 0 window)
e532b016 RS	224	(set-window-start window (point)))))
	225
	226	(defun scroll-bar-drag (event)
	227	"Scroll the window by dragging the scroll bar slider.
	228	If you click outside the slider, the window scrolls to bring the slider there."
	229	(interactive "e")
c782bea5	230	(let* (done
cb183ca0 RS	231	(echo-keystrokes 0)
	232	(end-position (event-end event))
	233	(window (nth 0 end-position))
	234	(before-scroll))
	235	(with-current-buffer (window-buffer window)
	236	(setq before-scroll point-before-scroll))
	237	(save-selected-window
	238	(select-window window)
	239	(setq before-scroll
	240	(or before-scroll (point))))
	241	(scroll-bar-drag-1 event)
	242	(track-mouse
	243	(while (not done)
	244	(setq event (read-event))
	245	(if (eq (car-safe event) 'mouse-movement)
	246	(setq event (read-event)))
	247	(cond ((eq (car-safe event) 'scroll-bar-movement)
	248	(scroll-bar-drag-1 event))
	249	(t
	250	;; Exit when we get the drag event; ignore that event.
	251	(setq done t)))))
	252	(sit-for 0)
	253	(with-current-buffer (window-buffer window)
	254	(setq point-before-scroll before-scroll))))
e532b016	255
bf3c8a70 JB	256	(defun scroll-bar-scroll-down (event)
	257	"Scroll the window's top line down to the location of the scroll bar click.
	258	EVENT should be a scroll bar click."
6d62a90e	259	(interactive "e")
cb183ca0 RS	260	(let* ((end-position (event-end event))
	261	(window (nth 0 end-position))
	262	(before-scroll))
	263	(with-current-buffer (window-buffer window)
	264	(setq before-scroll point-before-scroll))
def7db1d KH	265	(unwind-protect
	266	(save-selected-window
	267	(let ((portion-whole (nth 2 end-position)))
	268	(select-window window)
	269	(setq before-scroll
	270	(or before-scroll (point)))
	271	(scroll-down
	272	(scroll-bar-scale portion-whole (1- (window-height)))))
	273	(sit-for 0))
	274	(with-current-buffer (window-buffer window)
	275	(setq point-before-scroll before-scroll)))))
6d62a90e	276
bf3c8a70 JB	277	(defun scroll-bar-scroll-up (event)
	278	"Scroll the line next to the scroll bar click to the top of the window.
	279	EVENT should be a scroll bar click."
6d62a90e	280	(interactive "e")
cb183ca0 RS	281	(let* ((end-position (event-end event))
	282	(window (nth 0 end-position))
	283	(before-scroll))
	284	(with-current-buffer (window-buffer window)
	285	(setq before-scroll point-before-scroll))
def7db1d KH	286	(unwind-protect
	287	(save-selected-window
	288	(let ((portion-whole (nth 2 end-position)))
	289	(select-window window)
	290	(setq before-scroll
	291	(or before-scroll (point)))
	292	(scroll-up
	293	(scroll-bar-scale portion-whole (1- (window-height)))))
	294	(sit-for 0))
	295	(with-current-buffer (window-buffer window)
	296	(setq point-before-scroll before-scroll)))))
6d62a90e JB	297
6d62a90e JB	298	\f
cf4eb316	299	;;; Tookit scroll bars.
6d62a90e	300
cf4eb316 GM	301	(defun scroll-bar-toolkit-scroll (event)
	302	(interactive "e")
	303	(let* ((end-position (event-end event))
	304	(window (nth 0 end-position))
	305	(part (nth 4 end-position))
	306	before-scroll)
2088cd64	307	(cond ((eq part 'end-scroll))
cf4eb316 GM	308	(t
	309	(with-current-buffer (window-buffer window)
	310	(setq before-scroll point-before-scroll))
	311	(save-selected-window
	312	(select-window window)
	313	(setq before-scroll (or before-scroll (point)))
	314	(cond ((eq part 'above-handle)
	315	(scroll-up '-))
	316	((eq part 'below-handle)
	317	(scroll-up nil))
d294c01f SM	318	((eq part 'ratio)
	319	(let* ((portion-whole (nth 2 end-position))
	320	(lines (scroll-bar-scale portion-whole
	321	(1- (window-height)))))
	322	(scroll-up (cond ((not (zerop lines)) lines)
	323	((< (car portion-whole) 0) -1)
	324	(t 1)))))
cf4eb316 GM	325	((eq part 'up)
	326	(scroll-up -1))
	327	((eq part 'down)
	328	(scroll-up 1))
	329	((eq part 'top)
	330	(set-window-start window (point-min)))
	331	((eq part 'bottom)
	332	(goto-char (point-max))
	333	(recenter))
	334	((eq part 'handle)
	335	(scroll-bar-drag-1 event))))
	336	(sit-for 0)
cf4eb316 GM	337	(with-current-buffer (window-buffer window)
cf4eb316 GM	338	(setq point-before-scroll before-scroll))))))
e532b016	339
cf4eb316 GM	340
	341	\f
	342	;;;; Bindings.
	343
	344	;;; For now, we'll set things up to work like xterm.
d08947c5	345	(cond ((and (boundp 'x-toolkit-scroll-bars) x-toolkit-scroll-bars)
cf4eb316 GM	346	(global-set-key [vertical-scroll-bar mouse-1]
	347	'scroll-bar-toolkit-scroll))
	348	(t
	349	(global-set-key [vertical-scroll-bar mouse-1]
	350	'scroll-bar-scroll-up)
	351	(global-set-key [vertical-scroll-bar drag-mouse-1]
	352	'scroll-bar-scroll-up)
	353	(global-set-key [vertical-scroll-bar down-mouse-2]
	354	'scroll-bar-drag)
	355	(global-set-key [vertical-scroll-bar mouse-3]
	356	'scroll-bar-scroll-down)
	357	(global-set-key [vertical-scroll-bar drag-mouse-3]
	358	'scroll-bar-scroll-down)))
6d62a90e JB	359
6d62a90e JB	360	\f
dc14eed2	361	(provide 'scroll-bar)
6d62a90e	362
cbee283d	363	;; arch-tag: 6f1d01d0-0b1e-4bf8-86db-d491e0f399f3
bf3c8a70	364	;;; scroll-bar.el ends here