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;;; link.el --- Hypertext links in text buffers
;; Author: Torsten Hilbrich <torsten.hilbrich@gmx.net>
;; Keywords: interface, hypermedia
;; Version: 1.10
;; This file 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.
;; This file 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., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
;;; Commentary:
;; This file contains functions for using links in buffers. A link is
;; a part of the buffer marked with a special face, beeing
;; hightlighted while the mouse points to it and beeing activated when
;; pressing return or clicking the button2.
;; Which each link a function and some data are associated. Upon
;; clicking the function is called with the data as only
;; argument. Both the function and the data are stored in text
;; properties.
;;
;; link-create-link - insert a new link for the text in the given range
;; link-initialize-keymap - install the keybinding for selecting links
;;; Code:
(eval-when-compile
(require 'cl))
(defun link-create-link (start end face function &optional data help)
"Create a link in the current buffer starting from `start' going to `end'.
The `face' is used for displaying, the `data' are stored together with the
link. Upon clicking the `function' is called with `data' as argument."
(let ((properties `(face ,face
mouse-face highlight
link t
link-data ,data
help-echo ,help
link-function ,function)))
(remove-text-properties start end properties)
(add-text-properties start end properties)))
(defun link-insert-link (text face function &optional data help)
"Insert the `text' at point to be formatted as link.
The `face' is used for displaying, the `data' are stored together with the
link. Upon clicking the `function' is called with `data' as argument."
(let ((start (point)))
(insert text)
(link-create-link start (point) face function data help)))
(defun link-selected (&optional all)
"Is called upon clicking or otherwise visiting the link."
(interactive)
(let* ((properties (text-properties-at (point)))
(function (plist-get properties 'link-function))
(data (plist-get properties 'link-data)))
(if function
(funcall function data all))))
(defun link-selected-all ()
"Called for meta clicking the link"
(interactive)
(link-selected 'all))
(defun link-mouse-click (event &optional all)
"Is called upon clicking the link."
(interactive "@e")
(mouse-set-point event)
(link-selected))
(defun link-mouse-click-all (event)
"Is called upon meta clicking the link."
(interactive "@e")
(mouse-set-point event)
(link-selected-all))
(defun link-next-link ()
"Return the position of the next link or nil if there is none"
(let* ((pos (point))
(pos (next-single-property-change pos 'link)))
(if pos
(if (text-property-any pos (min (1+ pos) (point-max)) 'link t)
pos
(next-single-property-change pos 'link))
nil)))
(defun link-prev-link ()
"Return the position of the previous link or nil if there is none"
(let* ((pos (point))
(pos (previous-single-property-change pos 'link)))
(if pos
(if (text-property-any pos (1+ pos) 'link t)
pos
(let ((val (previous-single-property-change pos 'link)))
(if val
val
(text-property-any (point-min) (1+ (point-min)) 'link t))))
nil)))
(defun link-initialize-keymap (keymap)
"Defines the necessary bindings inside keymap"
(if (and (boundp 'running-xemacs) running-xemacs)
(progn
(define-key keymap [button2] 'link-mouse-click)
(define-key keymap [(meta button2)] 'link-mouse-click-all))
(define-key keymap [mouse-2] 'link-mouse-click)
(define-key keymap [M-mouse-2] 'link-mouse-click-all))
(define-key keymap "\r" 'link-selected)
(define-key keymap "\M-\r" 'link-selected-all))
(provide 'link)
;;; link.el ends here
|
