[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 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 2, 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 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."
  (setq scroll-bar-mode value)

  (when scroll-bar-mode-explicit
    ;; Apply it to default-frame-alist.
    (let ((parameter (assq 'vertical-scroll-bars default-frame-alist)))
      (if (consp parameter)
	  (setcdr parameter scroll-bar-mode)
	(setq default-frame-alist
	      (cons (cons 'vertical-scroll-bars scroll-bar-mode)
		    default-frame-alist))))

    ;; Apply it to existing frames.
    (let ((frames (frame-list)))
      (while frames
	(modify-frame-parameters
	 (car frames)
	 (list (cons 'vertical-scroll-bars scroll-bar-mode)))
	(setq frames (cdr frames))))))

(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)))
			   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,
aaef169d	4	;; 2004, 2005, 2006 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
	12	;; it under the terms of the GNU General Public License as published by
	13	;; the Free Software Foundation; either version 2, or (at your option)
	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 RS	77	(defvar scroll-bar-mode)
1064fe38 RS	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 KH	83	(defun set-scroll-bar-mode-1 (ignore value)
	84	(set-scroll-bar-mode value))
	85
	86	(defun set-scroll-bar-mode (value)
04c34f2e RS	87	"Set `scroll-bar-mode' to VALUE and put the new value into effect."
	88	(setq scroll-bar-mode value)
	89
2124851f RS	90	(when scroll-bar-mode-explicit
	91	;; Apply it to default-frame-alist.
	92	(let ((parameter (assq 'vertical-scroll-bars default-frame-alist)))
	93	(if (consp parameter)
	94	(setcdr parameter scroll-bar-mode)
	95	(setq default-frame-alist
	96	(cons (cons 'vertical-scroll-bars scroll-bar-mode)
	97	default-frame-alist))))
	98
	99	;; Apply it to existing frames.
	100	(let ((frames (frame-list)))
	101	(while frames
	102	(modify-frame-parameters
	103	(car frames)
	104	(list (cons 'vertical-scroll-bars scroll-bar-mode)))
	105	(setq frames (cdr frames))))))
04c34f2e	106
61f2fe7b	107	(defcustom scroll-bar-mode default-frame-scroll-bars
04c34f2e RS	108	"*Specify whether to have vertical scroll bars, and on which side.
	109	Possible values are nil (no scroll bars), `left' (scroll bars on left)
	110	and `right' (scroll bars on right).
463deb66 RS	111	To set this variable in a Lisp program, use `set-scroll-bar-mode'
	112	to make it take real effect.
	113	Setting the variable with a customization buffer also takes effect."
64453f32	114	:type '(choice (const :tag "none (nil)" nil)
04c34f2e RS	115	(const left)
	116	(const right))
	117	:group 'frames
2669fbfb RS	118	;; The default value for :initialize would try to use :set
	119	;; when processing the file in cus-dep.el.
	120	:initialize 'custom-initialize-default
e4b201bb	121	:set 'set-scroll-bar-mode-1)
04c34f2e	122
2124851f RS	123	;; We just set scroll-bar-mode, but that was the default.
	124	;; If it is set again, that is for real.
	125	(setq scroll-bar-mode-explicit t)
	126
b1ad7c13	127	(defun scroll-bar-mode (&optional flag)
04c34f2e	128	"Toggle display of vertical scroll bars on all frames.
fe48f821 JB	129	This command applies to all frames that exist and frames to be
	130	created in the future.
	131	With a numeric argument, if the argument is negative,
	132	turn off scroll bars; otherwise, turn on scroll bars."
	133	(interactive "P")
ada464a7	134
04c34f2e	135	;; Tweedle the variable according to the argument.
61f2fe7b KS	136	(set-scroll-bar-mode (if (if (null flag)
	137	(not scroll-bar-mode)
	138	(setq flag (prefix-numeric-value flag))
	139	(or (not (numberp flag)) (>= flag 0)))
	140	default-frame-scroll-bars)))
04c34f2e RS	141
	142	(defun toggle-scroll-bar (arg)
	143	"Toggle whether or not the selected frame has vertical scroll bars.
	144	With arg, turn vertical scroll bars on if and only if arg is positive.
	145	The variable `scroll-bar-mode' controls which side the scroll bars are on
	146	when they are turned on; if it is nil, they go on the left."
	147	(interactive "P")
	148	(if (null arg)
	149	(setq arg
	150	(if (cdr (assq 'vertical-scroll-bars
	151	(frame-parameters (selected-frame))))
19c6feac KH	152	-1 1))
19c6feac KH	153	(setq arg (prefix-numeric-value arg)))
1032e793 GV	154	(modify-frame-parameters
	155	(selected-frame)
	156	(list (cons 'vertical-scroll-bars
	157	(if (> arg 0)
61f2fe7b	158	(or scroll-bar-mode default-frame-scroll-bars))))))
04c34f2e RS	159
	160	(defun toggle-horizontal-scroll-bar (arg)
	161	"Toggle whether or not the selected frame has horizontal scroll bars.
	162	With arg, turn horizontal scroll bars on if and only if arg is positive.
	163	Horizontal scroll bars aren't implemented yet."
	164	(interactive "P")
	165	(error "Horizontal scroll bars aren't implemented yet"))
fe48f821	166	\f
bf3c8a70	167	;;;; Buffer navigation using the scroll bar.
6d62a90e	168
e532b016	169	;;; This was used for up-events on button 2, but no longer.
bf3c8a70 JB	170	(defun scroll-bar-set-window-start (event)
	171	"Set the window start according to where the scroll bar is dragged.
	172	EVENT should be a scroll bar click or drag event."
6d62a90e	173	(interactive "e")
dbc4e1c1	174	(let* ((end-position (event-end event))
6d62a90e JB	175	(window (nth 0 end-position))
	176	(portion-whole (nth 2 end-position)))
	177	(save-excursion
	178	(set-buffer (window-buffer window))
	179	(save-excursion
4cad38d5 JB	180	(goto-char (+ (point-min)
	181	(scroll-bar-scale portion-whole
	182	(- (point-max) (point-min)))))
6d62a90e JB	183	(beginning-of-line)
	184	(set-window-start window (point))))))
	185
aeee66be RS	186	(defun scroll-bar-drag-position (portion-whole)
	187	"Calculate new window start for drag event."
	188	(save-excursion
	189	(goto-char (+ (point-min)
	190	(scroll-bar-scale portion-whole
	191	(- (point-max) (point-min)))))
	192	(beginning-of-line)
	193	(point)))
	194
	195	(defun scroll-bar-maybe-set-window-start (event)
	196	"Set the window start according to where the scroll bar is dragged.
	197	Only change window start if the new start is substantially different.
	198	EVENT should be a scroll bar click or drag event."
	199	(interactive "e")
	200	(let* ((end-position (event-end event))
	201	(window (nth 0 end-position))
	202	(portion-whole (nth 2 end-position))
	203	(next-portion-whole (cons (1+ (car portion-whole))
	204	(cdr portion-whole)))
	205	portion-start
	206	next-portion-start
	207	(current-start (window-start window)))
	208	(save-excursion
	209	(set-buffer (window-buffer window))
	210	(setq portion-start (scroll-bar-drag-position portion-whole))
	211	(setq next-portion-start (max
	212	(scroll-bar-drag-position next-portion-whole)
	213	(1+ portion-start)))
15655694	214	(if (or (>= current-start next-portion-start)
aeee66be	215	(< current-start portion-start))
9c005c65 KH	216	(set-window-start window portion-start)
	217	;; Always set window start, to ensure scroll bar position is updated.
	218	(set-window-start window current-start)))))
aeee66be	219
e532b016 RS	220	;; Scroll the window to the proper position for EVENT.
	221	(defun scroll-bar-drag-1 (event)
	222	(let* ((start-position (event-start event))
	223	(window (nth 0 start-position))
	224	(portion-whole (nth 2 start-position)))
	225	(save-excursion
	226	(set-buffer (window-buffer window))
d2ae6f7e RS	227	;; Calculate position relative to the accessible part of the buffer.
	228	(goto-char (+ (point-min)
	229	(scroll-bar-scale portion-whole
	230	(- (point-max) (point-min)))))
9d7ab3f0	231	(vertical-motion 0 window)
e532b016 RS	232	(set-window-start window (point)))))
	233
	234	(defun scroll-bar-drag (event)
	235	"Scroll the window by dragging the scroll bar slider.
	236	If you click outside the slider, the window scrolls to bring the slider there."
	237	(interactive "e")
c782bea5	238	(let* (done
cb183ca0 RS	239	(echo-keystrokes 0)
	240	(end-position (event-end event))
	241	(window (nth 0 end-position))
	242	(before-scroll))
	243	(with-current-buffer (window-buffer window)
	244	(setq before-scroll point-before-scroll))
	245	(save-selected-window
	246	(select-window window)
	247	(setq before-scroll
	248	(or before-scroll (point))))
	249	(scroll-bar-drag-1 event)
	250	(track-mouse
	251	(while (not done)
	252	(setq event (read-event))
	253	(if (eq (car-safe event) 'mouse-movement)
	254	(setq event (read-event)))
	255	(cond ((eq (car-safe event) 'scroll-bar-movement)
	256	(scroll-bar-drag-1 event))
	257	(t
	258	;; Exit when we get the drag event; ignore that event.
	259	(setq done t)))))
	260	(sit-for 0)
	261	(with-current-buffer (window-buffer window)
	262	(setq point-before-scroll before-scroll))))
e532b016	263
bf3c8a70 JB	264	(defun scroll-bar-scroll-down (event)
	265	"Scroll the window's top line down to the location of the scroll bar click.
	266	EVENT should be a scroll bar click."
6d62a90e	267	(interactive "e")
cb183ca0 RS	268	(let* ((end-position (event-end event))
	269	(window (nth 0 end-position))
	270	(before-scroll))
	271	(with-current-buffer (window-buffer window)
	272	(setq before-scroll point-before-scroll))
def7db1d KH	273	(unwind-protect
	274	(save-selected-window
	275	(let ((portion-whole (nth 2 end-position)))
	276	(select-window window)
	277	(setq before-scroll
	278	(or before-scroll (point)))
	279	(scroll-down
	280	(scroll-bar-scale portion-whole (1- (window-height)))))
	281	(sit-for 0))
	282	(with-current-buffer (window-buffer window)
	283	(setq point-before-scroll before-scroll)))))
6d62a90e	284
bf3c8a70 JB	285	(defun scroll-bar-scroll-up (event)
	286	"Scroll the line next to the scroll bar click to the top of the window.
	287	EVENT should be a scroll bar click."
6d62a90e	288	(interactive "e")
cb183ca0 RS	289	(let* ((end-position (event-end event))
	290	(window (nth 0 end-position))
	291	(before-scroll))
	292	(with-current-buffer (window-buffer window)
	293	(setq before-scroll point-before-scroll))
def7db1d KH	294	(unwind-protect
	295	(save-selected-window
	296	(let ((portion-whole (nth 2 end-position)))
	297	(select-window window)
	298	(setq before-scroll
	299	(or before-scroll (point)))
	300	(scroll-up
	301	(scroll-bar-scale portion-whole (1- (window-height)))))
	302	(sit-for 0))
	303	(with-current-buffer (window-buffer window)
	304	(setq point-before-scroll before-scroll)))))
6d62a90e JB	305
6d62a90e JB	306	\f
cf4eb316	307	;;; Tookit scroll bars.
6d62a90e	308
cf4eb316 GM	309	(defun scroll-bar-toolkit-scroll (event)
	310	(interactive "e")
	311	(let* ((end-position (event-end event))
	312	(window (nth 0 end-position))
	313	(part (nth 4 end-position))
	314	before-scroll)
2088cd64	315	(cond ((eq part 'end-scroll))
cf4eb316 GM	316	(t
	317	(with-current-buffer (window-buffer window)
	318	(setq before-scroll point-before-scroll))
	319	(save-selected-window
	320	(select-window window)
	321	(setq before-scroll (or before-scroll (point)))
	322	(cond ((eq part 'above-handle)
	323	(scroll-up '-))
	324	((eq part 'below-handle)
	325	(scroll-up nil))
d294c01f SM	326	((eq part 'ratio)
	327	(let* ((portion-whole (nth 2 end-position))
	328	(lines (scroll-bar-scale portion-whole
	329	(1- (window-height)))))
	330	(scroll-up (cond ((not (zerop lines)) lines)
	331	((< (car portion-whole) 0) -1)
	332	(t 1)))))
cf4eb316 GM	333	((eq part 'up)
	334	(scroll-up -1))
	335	((eq part 'down)
	336	(scroll-up 1))
	337	((eq part 'top)
	338	(set-window-start window (point-min)))
	339	((eq part 'bottom)
	340	(goto-char (point-max))
	341	(recenter))
	342	((eq part 'handle)
	343	(scroll-bar-drag-1 event))))
	344	(sit-for 0)
cf4eb316 GM	345	(with-current-buffer (window-buffer window)
cf4eb316 GM	346	(setq point-before-scroll before-scroll))))))
e532b016	347
cf4eb316 GM	348
	349	\f
	350	;;;; Bindings.
	351
	352	;;; For now, we'll set things up to work like xterm.
d08947c5	353	(cond ((and (boundp 'x-toolkit-scroll-bars) x-toolkit-scroll-bars)
cf4eb316 GM	354	(global-set-key [vertical-scroll-bar mouse-1]
	355	'scroll-bar-toolkit-scroll))
	356	(t
	357	(global-set-key [vertical-scroll-bar mouse-1]
	358	'scroll-bar-scroll-up)
	359	(global-set-key [vertical-scroll-bar drag-mouse-1]
	360	'scroll-bar-scroll-up)
	361	(global-set-key [vertical-scroll-bar down-mouse-2]
	362	'scroll-bar-drag)
	363	(global-set-key [vertical-scroll-bar mouse-3]
	364	'scroll-bar-scroll-down)
	365	(global-set-key [vertical-scroll-bar drag-mouse-3]
	366	'scroll-bar-scroll-down)))
6d62a90e JB	367
6d62a90e JB	368	\f
dc14eed2	369	(provide 'scroll-bar)
6d62a90e	370
ab5796a9	371	;;; arch-tag: 6f1d01d0-0b1e-4bf8-86db-d491e0f399f3
bf3c8a70	372	;;; scroll-bar.el ends here