104 lines
3.7 KiB
EmacsLisp
104 lines
3.7 KiB
EmacsLisp
;;; scrollbar.el -- window system-independent scrollbar support.
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;;; Copyright (C) 1993 Free Software Foundation, Inc.
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;; Maintainer: FSF
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;; Keywords: hardware
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;;; This file is part of GNU Emacs.
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;;; GNU Emacs is free software; you can redistribute it and/or modify
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;;; it under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 2, or (at your option)
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;;; any later version.
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;;; GNU Emacs is distributed in the hope that it will be useful,
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;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Emacs; see the file COPYING. If not, write to
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;;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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(require 'mouse)
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;;;; Utilities.
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(defun scrollbar-scale (num-denom whole)
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"Given a pair (NUM . DENOM) and WHOLE, return (/ (* NUM WHOLE) DENOM).
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This is handy for scaling a position on a scrollbar into real units,
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like buffer positions. If SCROLLBAR-POS is the (PORTION . WHOLE) pair
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from a scrollbar event, then (scrollbar-scale SCROLLBAR-POS
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\(buffer-size)) is the position in the current buffer corresponding to
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that scrollbar position."
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;; We multiply before we divide to maintain precision.
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;; We use floating point because the product of a large buffer size
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;; with a large scrollbar portion can easily overflow a lisp int.
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(truncate (/ (* (float (car num-denom)) whole) (cdr num-denom))))
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;;;; Buffer navigation using the scrollbar.
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(defun scrollbar-set-window-start (event)
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"Set the window start according to where the scrollbar is dragged.
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EVENT should be a scrollbar click or drag event."
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(interactive "e")
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(let* ((end-position (event-end event))
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(window (nth 0 end-position))
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(portion-whole (nth 2 end-position)))
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(save-excursion
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(set-buffer (window-buffer window))
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(save-excursion
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(goto-char (scrollbar-scale portion-whole (buffer-size)))
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(beginning-of-line)
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(set-window-start window (point))))))
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(defun scrollbar-scroll-down (event)
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"Scroll the window's top line down to the location of the scrollbar click.
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EVENT should be a scrollbar click."
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(interactive "e")
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(let ((old-selected-window (selected-window)))
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(unwind-protect
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(progn
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(let* ((end-position (event-end event))
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(window (nth 0 end-position))
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(portion-whole (nth 2 end-position)))
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(select-window window)
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(scroll-down
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(scrollbar-scale portion-whole (1- (window-height))))))
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(select-window old-selected-window))))
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(defun scrollbar-scroll-up (event)
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"Scroll the line next to the scrollbar click to the top of the window.
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EVENT should be a scrollbar click."
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(interactive "e")
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(let ((old-selected-window (selected-window)))
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(unwind-protect
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(progn
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(let* ((end-position (event-end event))
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(window (nth 0 end-position))
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(portion-whole (nth 2 end-position)))
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(select-window window)
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(scroll-up
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(scrollbar-scale portion-whole (1- (window-height))))))
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(select-window old-selected-window))))
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;;;; Bindings.
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;;; For now, we'll set things up to work like xterm.
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(global-set-key [vertical-scrollbar mouse-1] 'scrollbar-scroll-up)
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(global-set-key [vertical-scrollbar drag-mouse-1] 'scrollbar-scroll-up)
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(global-set-key [vertical-scrollbar mouse-2] 'scrollbar-set-window-start)
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(global-set-key [vertical-scrollbar drag-mouse-2] 'scrollbar-set-window-start)
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(global-set-key [vertical-scrollbar mouse-3] 'scrollbar-scroll-down)
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(global-set-key [vertical-scrollbar drag-mouse-3] 'scrollbar-scroll-down)
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(provide 'scrollbar)
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;;; scrollbar.el ends here
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