-;;; scrollbar.el -- window system-independent scrollbar support.
+;;; scroll-bar.el --- window system-independent scroll bar support.
-;;; Copyright (C) 1993 Free Software Foundation, Inc.
+;;; Copyright (C) 1993, 1994, 1995 Free Software Foundation, Inc.
;; Maintainer: FSF
;; Keywords: hardware
;;; along with GNU Emacs; see the file COPYING. If not, write to
;;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+;;; Code:
+
+;;; 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 scrollbar-scale (num-denom whole)
+(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 scrollbar into real units,
-like buffer positions. If SCROLLBAR-POS is the (PORTION . WHOLE) pair
-from a scrollbar event, then (scrollbar-scale SCROLLBAR-POS
+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 scrollbar position."
+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 scrollbar portion can easily overflow a lisp int.
+ ;; with a large scroll bar portion can easily overflow a lisp int.
(truncate (/ (* (float (car num-denom)) whole) (cdr num-denom))))
\f
;;;; Helpful functions for enabling and disabling scroll bars.
-(defvar scroll-bar-mode nil)
(defun scroll-bar-mode (flag)
"Toggle display of vertical scroll bars on each frame.
With a numeric argument, if the argument is negative,
turn off scroll bars; otherwise, turn on scroll bars."
(interactive "P")
- (setq scroll-bar-mode (if (null flag) (not scroll-bar-mode)
- (or (not (numberp flag)) (>= flag 0))))
- (mapcar
- (function
- (lambda (param-name)
- (let ((parameter (assq param-name default-frame-alist)))
- (if (consp parameter)
- (setcdr parameter scroll-bar-mode)
- (setq default-frame-alist
- (cons (cons param-name scroll-bar-mode)
- default-frame-alist))))))
- '(vertical-scrollbars horizontal-scrollbars))
- (let ((frames (frame-list)))
- (while frames
- (modify-frame-parameters
- (car frames)
- (list (cons 'vertical-scrollbars scroll-bar-mode)
- (cons 'horizontal-scrollbars scroll-bar-mode)))
- (setq frames (cdr frames)))))
+ (if flag (setq flag (prefix-numeric-value flag)))
+
+ ;; Obtain the current setting by looking at default-frame-alist.
+ (let ((scroll-bar-mode
+ (let ((assq (assq 'vertical-scroll-bars default-frame-alist)))
+ (if assq (cdr assq) t))))
+
+ ;; Tweedle it according to the argument.
+ (setq scroll-bar-mode (if (null flag) (not scroll-bar-mode)
+ (or (not (numberp flag)) (>= flag 0))))
+
+ ;; Apply it to default-frame-alist.
+ (mapcar
+ (function
+ (lambda (param-name)
+ (let ((parameter (assq param-name default-frame-alist)))
+ (if (consp parameter)
+ (setcdr parameter scroll-bar-mode)
+ (setq default-frame-alist
+ (cons (cons param-name scroll-bar-mode)
+ default-frame-alist))))))
+ '(vertical-scroll-bars horizontal-scroll-bars))
+
+ ;; Apply it to existing frames.
+ (let ((frames (frame-list)))
+ (while frames
+ (modify-frame-parameters
+ (car frames)
+ (list (cons 'vertical-scroll-bars scroll-bar-mode)
+ (cons 'horizontal-scroll-bars scroll-bar-mode)))
+ (setq frames (cdr frames))))))
\f
-;;;; Buffer navigation using the scrollbar.
+;;;; Buffer navigation using the scroll bar.
-(defun scrollbar-set-window-start (event)
- "Set the window start according to where the scrollbar is dragged.
-EVENT should be a scrollbar click or drag event."
+;;; 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))
(save-excursion
(set-buffer (window-buffer window))
(save-excursion
- (goto-char (scrollbar-scale portion-whole (buffer-size)))
+ (goto-char (+ (point-min)
+ (scroll-bar-scale portion-whole
+ (- (point-max) (point-min)))))
(beginning-of-line)
(set-window-start window (point))))))
-(defun scrollbar-scroll-down (event)
- "Scroll the window's top line down to the location of the scrollbar click.
-EVENT should be a scrollbar click."
+;; 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)))))
+ (beginning-of-line)
+ (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))
+ (or point-before-scroll
+ (setq point-before-scroll (point)))
+ ;; Our scrolling can move point; don't let that clear point-before-scroll.
+ (let (point-before-scroll)
+ (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))))
+
+(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 ((old-selected-window (selected-window)))
(unwind-protect
(let* ((end-position (event-end event))
(window (nth 0 end-position))
(portion-whole (nth 2 end-position)))
- (select-window window)
- (scroll-down
- (scrollbar-scale portion-whole (1- (window-height))))))
+ (let (point-before-scroll)
+ (select-window window))
+ (or point-before-scroll
+ (setq point-before-scroll (point)))
+ (let (point-before-scroll)
+ (scroll-down
+ (scroll-bar-scale portion-whole (1- (window-height)))))))
(select-window old-selected-window))))
-(defun scrollbar-scroll-up (event)
- "Scroll the line next to the scrollbar click to the top of the window.
-EVENT should be a scrollbar click."
+(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 ((old-selected-window (selected-window)))
(unwind-protect
(let* ((end-position (event-end event))
(window (nth 0 end-position))
(portion-whole (nth 2 end-position)))
- (select-window window)
- (scroll-up
- (scrollbar-scale portion-whole (1- (window-height))))))
+ (let (point-before-scroll)
+ (select-window window))
+ (or point-before-scroll
+ (setq point-before-scroll (point)))
+ (let (point-before-scroll)
+ (scroll-up
+ (scroll-bar-scale portion-whole (1- (window-height)))))))
(select-window old-selected-window))))
\f
;;;; Bindings.
;;; For now, we'll set things up to work like xterm.
-(global-set-key [vertical-scrollbar mouse-1] 'scrollbar-scroll-up)
-(global-set-key [vertical-scrollbar drag-mouse-1] 'scrollbar-scroll-up)
+(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-scrollbar mouse-2] 'scrollbar-set-window-start)
-(global-set-key [vertical-scrollbar drag-mouse-2] 'scrollbar-set-window-start)
-
-(global-set-key [vertical-scrollbar mouse-3] 'scrollbar-scroll-down)
-(global-set-key [vertical-scrollbar drag-mouse-3] 'scrollbar-scroll-down)
+(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 'scrollbar)
+(provide 'scroll-bar)
-;;; scrollbar.el ends here
+;;; scroll-bar.el ends here