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

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

;; Copyright (C) 1993-1995, 1999-2011 Free Software Foundation, Inc.

;; Maintainer: FSF
;; Keywords: hardware
;; Package: emacs

;; 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 of the License, 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.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

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

;;; Code:

(require 'mouse)
(eval-when-compile (require 'cl))

\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 (value)
  "Set the scroll bar mode to VALUE and put the new value into effect.
See the `scroll-bar-mode' variable for possible values to use."
  (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 (lambda (_sym val) (set-scroll-bar-mode val)))

;; 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 get-scroll-bar-mode () scroll-bar-mode)
(defsetf get-scroll-bar-mode set-scroll-bar-mode)

(define-minor-mode scroll-bar-mode
  "Toggle vertical scroll bars on all frames (Scroll Bar mode).
With a prefix argument ARG, enable Scroll Bar mode if ARG is
positive, and disable it otherwise.  If called from Lisp, enable
the mode if ARG is omitted or nil.

This command applies to all frames that exist and frames to be
created in the future."
  :variable (eq (get-scroll-bar-mode)
                (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)))
    (with-current-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)))
    (with-current-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
      (with-current-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)

;;; scroll-bar.el ends here
Commit	Line	Data
55535639	1	;;; scroll-bar.el --- window system-independent scroll bar support
6d62a90e	2
73b0cd50	3	;; Copyright (C) 1993-1995, 1999-2011 Free Software Foundation, Inc.
6d62a90e JB	4
	5	;; Maintainer: FSF
	6	;; Keywords: hardware
bd78fa1d	7	;; Package: emacs
6d62a90e	8
b578f267	9	;; This file is part of GNU Emacs.
6d62a90e	10
eb3fa2cf	11	;; GNU Emacs is free software: you can redistribute it and/or modify
b578f267	12	;; it under the terms of the GNU General Public License as published by
eb3fa2cf GM	13	;; the Free Software Foundation, either version 3 of the License, or
eb3fa2cf GM	14	;; (at your option) 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	21	;; You should have received a copy of the GNU General Public License
eb3fa2cf	22	;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
76550a57	23
d9ecc911 ER	24	;;; Commentary:
	25
	26	;; Window-system-independent bindings of mouse clicks on the scroll bar.
	27	;; Presently emulates the scroll-bar behavior of xterm.
b578f267	28
d9ecc911 ER	29	;;; Code:
d9ecc911 ER	30
dbc4e1c1	31	(require 'mouse)
80ac5d4d	32	(eval-when-compile (require 'cl))
dbc4e1c1	33
6d62a90e JB	34	\f
	35	;;;; Utilities.
	36
86828678 RS	37	(defun scroll-bar-event-ratio (event)
	38	"Given a scroll bar event EVENT, return the scroll bar position as a ratio.
	39	The value is a cons cell (PORTION . WHOLE) containing two integers
	40	whose ratio gives the event's vertical position in the scroll bar, with 0
	41	referring to the top and 1 to the bottom."
	42	(nth 2 event))
	43
bf3c8a70	44	(defun scroll-bar-scale (num-denom whole)
6d62a90e	45	"Given a pair (NUM . DENOM) and WHOLE, return (/ (* NUM WHOLE) DENOM).
bf3c8a70 JB	46	This is handy for scaling a position on a scroll bar into real units,
	47	like buffer positions. If SCROLL-BAR-POS is the (PORTION . WHOLE) pair
	48	from a scroll bar event, then (scroll-bar-scale SCROLL-BAR-POS
6d62a90e	49	\(buffer-size)) is the position in the current buffer corresponding to
bf3c8a70	50	that scroll bar position."
6d62a90e JB	51	;; We multiply before we divide to maintain precision.
6d62a90e JB	52	;; We use floating point because the product of a large buffer size
bf3c8a70	53	;; with a large scroll bar portion can easily overflow a lisp int.
6d62a90e JB	54	(truncate (/ (* (float (car num-denom)) whole) (cdr num-denom))))
6d62a90e JB	55
9fd76d04 MY	56	(defun scroll-bar-columns (side)
	57	"Return the width, measured in columns, of the vertical scrollbar on SIDE.
	58	SIDE must be the symbol `left' or `right'."
	59	(let* ((wsb (window-scroll-bars))
	60	(vtype (nth 2 wsb))
	61	(cols (nth 1 wsb)))
	62	(cond
	63	((not (memq side '(left right)))
	64	(error "`left' or `right' expected instead of %S" side))
	65	((and (eq vtype side) cols))
	66	((eq (frame-parameter nil 'vertical-scroll-bars) side)
	67	;; nil means it's a non-toolkit scroll bar, and its width in
	68	;; columns is 14 pixels rounded up.
	69	(ceiling (or (frame-parameter nil 'scroll-bar-width) 14)
	70	(frame-char-width)))
	71	(0))))
	72
6d62a90e	73	\f
fe48f821	74	;;;; Helpful functions for enabling and disabling scroll bars.
fe48f821	75
1064fe38	76	(defvar scroll-bar-mode)
f62c3ee2	77	(defvar previous-scroll-bar-mode nil)
1064fe38	78
2124851f RS	79	(defvar scroll-bar-mode-explicit nil
	80	"Non-nil means `set-scroll-bar-mode' should really do something.
	81	This is nil while loading `scroll-bar.el', and t afterward.")
	82
e4b201bb	83	(defun set-scroll-bar-mode (value)
d7956b14 LMI	84	"Set the scroll bar mode to VALUE and put the new value into effect.
d7956b14 LMI	85	See the `scroll-bar-mode' variable for possible values to use."
f62c3ee2 JD	86	(if scroll-bar-mode
	87	(setq previous-scroll-bar-mode scroll-bar-mode))
	88
04c34f2e RS	89	(setq scroll-bar-mode value)
04c34f2e RS	90
2124851f	91	(when scroll-bar-mode-explicit
095fe281 KL	92	(modify-all-frames-parameters (list (cons 'vertical-scroll-bars
095fe281 KL	93	scroll-bar-mode)))))
04c34f2e	94
61f2fe7b	95	(defcustom scroll-bar-mode default-frame-scroll-bars
9201cc28	96	"Specify whether to have vertical scroll bars, and on which side.
04c34f2e RS	97	Possible values are nil (no scroll bars), `left' (scroll bars on left)
04c34f2e RS	98	and `right' (scroll bars on right).
463deb66 RS	99	To set this variable in a Lisp program, use `set-scroll-bar-mode'
	100	to make it take real effect.
	101	Setting the variable with a customization buffer also takes effect."
64453f32	102	:type '(choice (const :tag "none (nil)" nil)
04c34f2e RS	103	(const left)
	104	(const right))
	105	:group 'frames
2669fbfb RS	106	;; The default value for :initialize would try to use :set
	107	;; when processing the file in cus-dep.el.
	108	:initialize 'custom-initialize-default
06b60517	109	:set (lambda (_sym val) (set-scroll-bar-mode val)))
04c34f2e	110
2124851f RS	111	;; We just set scroll-bar-mode, but that was the default.
	112	;; If it is set again, that is for real.
	113	(setq scroll-bar-mode-explicit t)
	114
80ac5d4d SM	115	(defun get-scroll-bar-mode () scroll-bar-mode)
80ac5d4d SM	116	(defsetf get-scroll-bar-mode set-scroll-bar-mode)
06e21633	117
80ac5d4d	118	(define-minor-mode scroll-bar-mode
06e21633 CY	119	"Toggle vertical scroll bars on all frames (Scroll Bar mode).
	120	With a prefix argument ARG, enable Scroll Bar mode if ARG is
	121	positive, and disable it otherwise. If called from Lisp, enable
	122	the mode if ARG is omitted or nil.
	123
fe48f821	124	This command applies to all frames that exist and frames to be
06e21633	125	created in the future."
80ac5d4d SM	126	:variable (eq (get-scroll-bar-mode)
	127	(or previous-scroll-bar-mode
	128	default-frame-scroll-bars)))
04c34f2e RS	129
	130	(defun toggle-scroll-bar (arg)
	131	"Toggle whether or not the selected frame has vertical scroll bars.
	132	With arg, turn vertical scroll bars on if and only if arg is positive.
	133	The variable `scroll-bar-mode' controls which side the scroll bars are on
	134	when they are turned on; if it is nil, they go on the left."
	135	(interactive "P")
	136	(if (null arg)
	137	(setq arg
	138	(if (cdr (assq 'vertical-scroll-bars
	139	(frame-parameters (selected-frame))))
19c6feac KH	140	-1 1))
19c6feac KH	141	(setq arg (prefix-numeric-value arg)))
1032e793 GV	142	(modify-frame-parameters
	143	(selected-frame)
	144	(list (cons 'vertical-scroll-bars
	145	(if (> arg 0)
61f2fe7b	146	(or scroll-bar-mode default-frame-scroll-bars))))))
04c34f2e	147
06b60517	148	(defun toggle-horizontal-scroll-bar (_arg)
04c34f2e RS	149	"Toggle whether or not the selected frame has horizontal scroll bars.
	150	With arg, turn horizontal scroll bars on if and only if arg is positive.
	151	Horizontal scroll bars aren't implemented yet."
	152	(interactive "P")
	153	(error "Horizontal scroll bars aren't implemented yet"))
fe48f821	154	\f
bf3c8a70	155	;;;; Buffer navigation using the scroll bar.
6d62a90e	156
7fdbcd83	157	;; This was used for up-events on button 2, but no longer.
bf3c8a70 JB	158	(defun scroll-bar-set-window-start (event)
	159	"Set the window start according to where the scroll bar is dragged.
	160	EVENT should be a scroll bar click or drag event."
6d62a90e	161	(interactive "e")
dbc4e1c1	162	(let* ((end-position (event-end event))
6d62a90e JB	163	(window (nth 0 end-position))
6d62a90e JB	164	(portion-whole (nth 2 end-position)))
7fdbcd83	165	(with-current-buffer (window-buffer window)
6d62a90e	166	(save-excursion
4cad38d5 JB	167	(goto-char (+ (point-min)
	168	(scroll-bar-scale portion-whole
	169	(- (point-max) (point-min)))))
6d62a90e JB	170	(beginning-of-line)
	171	(set-window-start window (point))))))
	172
aeee66be RS	173	(defun scroll-bar-drag-position (portion-whole)
	174	"Calculate new window start for drag event."
	175	(save-excursion
	176	(goto-char (+ (point-min)
	177	(scroll-bar-scale portion-whole
	178	(- (point-max) (point-min)))))
	179	(beginning-of-line)
	180	(point)))
	181
	182	(defun scroll-bar-maybe-set-window-start (event)
	183	"Set the window start according to where the scroll bar is dragged.
	184	Only change window start if the new start is substantially different.
	185	EVENT should be a scroll bar click or drag event."
	186	(interactive "e")
	187	(let* ((end-position (event-end event))
	188	(window (nth 0 end-position))
	189	(portion-whole (nth 2 end-position))
	190	(next-portion-whole (cons (1+ (car portion-whole))
	191	(cdr portion-whole)))
	192	portion-start
	193	next-portion-start
	194	(current-start (window-start window)))
7fdbcd83	195	(with-current-buffer (window-buffer window)
aeee66be RS	196	(setq portion-start (scroll-bar-drag-position portion-whole))
	197	(setq next-portion-start (max
	198	(scroll-bar-drag-position next-portion-whole)
	199	(1+ portion-start)))
15655694	200	(if (or (>= current-start next-portion-start)
aeee66be	201	(< current-start portion-start))
9c005c65 KH	202	(set-window-start window portion-start)
	203	;; Always set window start, to ensure scroll bar position is updated.
	204	(set-window-start window current-start)))))
aeee66be	205
e532b016 RS	206	;; Scroll the window to the proper position for EVENT.
	207	(defun scroll-bar-drag-1 (event)
	208	(let* ((start-position (event-start event))
	209	(window (nth 0 start-position))
	210	(portion-whole (nth 2 start-position)))
06b60517	211	(save-excursion
71572c03 JD	212	(with-current-buffer (window-buffer window)
	213	;; Calculate position relative to the accessible part of the buffer.
	214	(goto-char (+ (point-min)
	215	(scroll-bar-scale portion-whole
	216	(- (point-max) (point-min)))))
	217	(vertical-motion 0 window)
	218	(set-window-start window (point))))))
e532b016 RS	219
	220	(defun scroll-bar-drag (event)
	221	"Scroll the window by dragging the scroll bar slider.
	222	If you click outside the slider, the window scrolls to bring the slider there."
	223	(interactive "e")
c782bea5	224	(let* (done
cb183ca0 RS	225	(echo-keystrokes 0)
	226	(end-position (event-end event))
	227	(window (nth 0 end-position))
	228	(before-scroll))
	229	(with-current-buffer (window-buffer window)
	230	(setq before-scroll point-before-scroll))
	231	(save-selected-window
	232	(select-window window)
	233	(setq before-scroll
	234	(or before-scroll (point))))
	235	(scroll-bar-drag-1 event)
	236	(track-mouse
	237	(while (not done)
	238	(setq event (read-event))
	239	(if (eq (car-safe event) 'mouse-movement)
	240	(setq event (read-event)))
	241	(cond ((eq (car-safe event) 'scroll-bar-movement)
	242	(scroll-bar-drag-1 event))
	243	(t
	244	;; Exit when we get the drag event; ignore that event.
	245	(setq done t)))))
	246	(sit-for 0)
	247	(with-current-buffer (window-buffer window)
	248	(setq point-before-scroll before-scroll))))
e532b016	249
bf3c8a70 JB	250	(defun scroll-bar-scroll-down (event)
	251	"Scroll the window's top line down to the location of the scroll bar click.
	252	EVENT should be a scroll bar click."
6d62a90e	253	(interactive "e")
cb183ca0 RS	254	(let* ((end-position (event-end event))
	255	(window (nth 0 end-position))
	256	(before-scroll))
	257	(with-current-buffer (window-buffer window)
	258	(setq before-scroll point-before-scroll))
def7db1d KH	259	(unwind-protect
	260	(save-selected-window
	261	(let ((portion-whole (nth 2 end-position)))
	262	(select-window window)
	263	(setq before-scroll
	264	(or before-scroll (point)))
	265	(scroll-down
	266	(scroll-bar-scale portion-whole (1- (window-height)))))
	267	(sit-for 0))
	268	(with-current-buffer (window-buffer window)
	269	(setq point-before-scroll before-scroll)))))
6d62a90e	270
bf3c8a70 JB	271	(defun scroll-bar-scroll-up (event)
	272	"Scroll the line next to the scroll bar click to the top of the window.
	273	EVENT should be a scroll bar click."
6d62a90e	274	(interactive "e")
cb183ca0 RS	275	(let* ((end-position (event-end event))
	276	(window (nth 0 end-position))
	277	(before-scroll))
	278	(with-current-buffer (window-buffer window)
	279	(setq before-scroll point-before-scroll))
def7db1d KH	280	(unwind-protect
	281	(save-selected-window
	282	(let ((portion-whole (nth 2 end-position)))
	283	(select-window window)
	284	(setq before-scroll
	285	(or before-scroll (point)))
	286	(scroll-up
	287	(scroll-bar-scale portion-whole (1- (window-height)))))
	288	(sit-for 0))
	289	(with-current-buffer (window-buffer window)
	290	(setq point-before-scroll before-scroll)))))
6d62a90e JB	291
6d62a90e JB	292	\f
cf4eb316	293	;;; Tookit scroll bars.
6d62a90e	294
cf4eb316 GM	295	(defun scroll-bar-toolkit-scroll (event)
	296	(interactive "e")
	297	(let* ((end-position (event-end event))
	298	(window (nth 0 end-position))
	299	(part (nth 4 end-position))
	300	before-scroll)
2088cd64	301	(cond ((eq part 'end-scroll))
cf4eb316 GM	302	(t
	303	(with-current-buffer (window-buffer window)
	304	(setq before-scroll point-before-scroll))
	305	(save-selected-window
	306	(select-window window)
	307	(setq before-scroll (or before-scroll (point)))
	308	(cond ((eq part 'above-handle)
	309	(scroll-up '-))
	310	((eq part 'below-handle)
	311	(scroll-up nil))
d294c01f SM	312	((eq part 'ratio)
	313	(let* ((portion-whole (nth 2 end-position))
	314	(lines (scroll-bar-scale portion-whole
	315	(1- (window-height)))))
	316	(scroll-up (cond ((not (zerop lines)) lines)
	317	((< (car portion-whole) 0) -1)
	318	(t 1)))))
cf4eb316 GM	319	((eq part 'up)
	320	(scroll-up -1))
	321	((eq part 'down)
	322	(scroll-up 1))
	323	((eq part 'top)
	324	(set-window-start window (point-min)))
	325	((eq part 'bottom)
	326	(goto-char (point-max))
	327	(recenter))
	328	((eq part 'handle)
	329	(scroll-bar-drag-1 event))))
	330	(sit-for 0)
cf4eb316 GM	331	(with-current-buffer (window-buffer window)
cf4eb316 GM	332	(setq point-before-scroll before-scroll))))))
e532b016	333
cf4eb316 GM	334
	335	\f
	336	;;;; Bindings.
	337
7fdbcd83	338	;; For now, we'll set things up to work like xterm.
d08947c5	339	(cond ((and (boundp 'x-toolkit-scroll-bars) x-toolkit-scroll-bars)
cf4eb316 GM	340	(global-set-key [vertical-scroll-bar mouse-1]
	341	'scroll-bar-toolkit-scroll))
	342	(t
	343	(global-set-key [vertical-scroll-bar mouse-1]
	344	'scroll-bar-scroll-up)
	345	(global-set-key [vertical-scroll-bar drag-mouse-1]
	346	'scroll-bar-scroll-up)
	347	(global-set-key [vertical-scroll-bar down-mouse-2]
	348	'scroll-bar-drag)
	349	(global-set-key [vertical-scroll-bar mouse-3]
	350	'scroll-bar-scroll-down)
	351	(global-set-key [vertical-scroll-bar drag-mouse-3]
	352	'scroll-bar-scroll-down)))
6d62a90e JB	353
6d62a90e JB	354	\f
dc14eed2	355	(provide 'scroll-bar)
6d62a90e	356
bf3c8a70	357	;;; scroll-bar.el ends here