Commit 0c26f463 authored by Miles Bader's avatar Miles Bader
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Initial checkin.

parent a4a74e8c
;;; button.el --- Clickable buttons
;;
;; Copyright (C) 2001 Free Software Foundation, Inc.
;;
;; Author: Miles Bader <miles@gnu.org>
;; Keywords: extensions
;;
;; 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., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
;;; Commentary:
;;
;; This package defines functions for inserting and manipulating
;; clickable buttons in Emacs buffers, such as might be used for help
;; hyperlinks, etc.
;;
;; In some ways it duplicates functionality also offered by the
;; `widget' package, but the button package has the advantage that it
;; is (1) much faster, (2) much smaller, and (3) much, much, simpler
;; (the code, that is, not the interface).
;;
;; Buttons can either use overlays, in which case the button is
;; represented by the overlay itself, or text-properties, in which case
;; the button is represented by a marker or buffer-position pointing
;; somewhere in the button. In the latter case, no markers into the
;; buffer are retained, which is important for speed if there are are
;; extremely large numbers of buttons.
;;
;; Using `define-button-type' to define default properties for buttons
;; is not necessary, but it is is encouraged, since doing so makes the
;; resulting code clearer and more efficient.
;;
;;; Code:
;; Globals
(defface button '((t :underline t))
"Default face used for buttons.")
;;;###autoload
(defvar button-map
(let ((map (make-sparse-keymap)))
(define-key map "\r" 'push-button)
(define-key map [mouse-2] 'push-button)
map)
"Keymap used by buttons.")
;;;###autoload
(defvar button-buffer-map
(let ((map (make-sparse-keymap)))
(define-key map [?\t] 'forward-button)
(define-key map [backtab] 'backward-button)
map)
"Keymap useful for buffers containing buttons.
Mode-specific keymaps may want to use this as their parent keymap.")
;; Default properties for buttons
(put 'default-button 'face 'button)
(put 'default-button 'mouse-face 'highlight)
(put 'default-button 'keymap button-map)
(put 'default-button 'type 'button)
(put 'default-button 'action 'button-nop)
(put 'default-button 'help-echo "mouse-2, RET: Push this button")
;; Make overlay buttons go away if their underlying text is deleted.
(put 'default-button 'evaporate t)
;; Prevent insertions adjacent to the text-property buttons from
;; inheriting its properties.
(put 'default-button 'rear-nonsticky t)
;; Text property buttons don't have a `button' property of their own, so
;; they inherit this.
(put 'default-button 'button t)
;; This is the default button action.
(defun button-nop (button)
"Do nothing to BUTTON."
nil)
;; Button types (which can be used to hold default properties for buttons)
;;;###autoload
(defun define-button-type (name &rest properties)
"Define a `button type' called NAME.
The remaining arguments form a sequence of PROPERTY VALUE pairs,
specifying properties to use as defaults for buttons with this type
\(a button's type may be set by giving it a `type' property when
creating the button)."
;; We use a different symbol than NAME (with `-button' appended, and
;; uninterned) to store the properties. This is to avoid name
;; clashes, since many very general properties may be include in
;; PROPERTIES.
(let ((catsym (make-symbol (concat (symbol-name name) "-button"))))
;; Provide a link so that it's easy to find the real symbol.
(put name 'button-category-symbol catsym)
;; Initialize NAME's properties using the global defaults.
(let ((default-props (symbol-plist 'default-button)))
(while default-props
(put catsym (pop default-props) (pop default-props))))
;; Add NAME as the `type' property, which will then be returned as
;; the type property of individual buttons.
(put catsym 'type name)
;; Add the properties in PROPERTIES to the real symbol.
(while properties
(put catsym (pop properties) (pop properties)))
name))
;; [this is an internal function]
(defsubst button-category-symbol (type)
"Return the symbol used by button-type TYPE to store properties.
Buttons inherit them by setting their `category' property to that symbol."
(or (get type 'button-category-symbol)
(error "Unknown button type `%s'" type)))
(defun button-type-put (type prop val)
"Set the button-type TYPE's PROP property to VAL."
(put (button-category-symbol type) prop val))
(defun button-type-get (type prop)
"Get the property of button-type TYPE named PROP."
(get (button-category-symbol type) prop))
;; Button properties and other attributes
(defun button-start (button)
"Return the position at which BUTTON starts."
(if (overlayp button)
(overlay-start button)
;; Must be a text-property button.
(or (previous-single-property-change (1+ button) 'button)
(point-min))))
(defun button-end (button)
"Return the position at which BUTTON ends."
(if (overlayp button)
(overlay-end button)
;; Must be a text-property button.
(or (next-single-property-change button 'button)
(point-max))))
(defun button-get (button prop)
"Get the property of button BUTTON named PROP."
(if (overlayp button)
(overlay-get button prop)
;; Must be a text-property button.
(get-text-property button prop)))
(defun button-put (button prop val)
"Set BUTTON's PROP property to VAL."
;; Treat some properties specially.
(cond ((eq prop 'type)
;; We translate a `type' property a `category' property, since
;; that's what's actually used by overlays/text-properties for
;; inheriting properties.
(setq prop 'category)
(setq val (button-category-symbol val)))
((eq prop 'category)
;; Disallow updating the `category' property directly.
(error "Button `category' property may not be set directly")))
;; Add the property.
(if (overlayp button)
(overlay-put button prop val)
;; Must be a text-property button.
(put-text-property
(or (previous-single-property-change (1+ button) 'button)
(point-min))
(or (next-single-property-change button 'button)
(point-max))
prop val)))
(defsubst button-activate (button)
"Call BUTTON's action property."
(funcall (button-get button 'action) button))
(defun button-label (button)
"Return BUTTON's text label."
(buffer-substring-no-properties (button-start button) (button-end button)))
;; Creating overlay buttons
;;;###autoload
(defun make-button (beg end &rest properties)
"Make a button from BEG to END in the current buffer.
The remaining arguments form a sequence of PROPERTY VALUE pairs,
specifying properties to add to the button. In particular, the `type'
property may be used to specify a button-type from which to inherit
other properties; see `define-button-type'.
Also see `make-text-button', `insert-button'."
(let ((overlay (make-overlay beg end nil t nil)))
(while properties
(button-put overlay (pop properties) (pop properties)))
;; Put a pointer to the button in the overlay, so it's easy to get
;; when we don't actually have a reference to the overlay.
(overlay-put overlay 'button overlay)
;; If the user didn't specify a type, use the default.
(unless (overlay-get overlay 'category)
(overlay-put overlay 'category 'default-button))
;; OVERLAY is the button, so return it
overlay))
;;;###autoload
(defun insert-button (label &rest properties)
"Insert a button with the label LABEL.
The remaining arguments form a sequence of PROPERTY VALUE pairs,
specifying properties to add to the button. In particular, the `type'
property may be used to specify a button-type from which to inherit
other properties; see `define-button-type'.
Also see `insert-text-button', `make-button'."
(apply #'make-button
(prog1 (point) (insert label))
(point)
properties))
;; Creating text-property buttons
;;;###autoload
(defun make-text-button (beg end &rest properties)
"Make a button from BEG to END in the current buffer.
The remaining arguments form a sequence of PROPERTY VALUE pairs,
specifying properties to add to the button. In particular, the `type'
property may be used to specify a button-type from which to inherit
other properties; see `define-button-type'.
This function is like `make-button', except that the button is actually
part of the text instead of being a property of the buffer. Creating
large numbers of buttons can also be somewhat faster using
`make-text-button'.
Also see `insert-text-button'."
(let (prop val)
(while properties
(setq prop (pop properties))
(setq val (pop properties))
;; Note that all the following code is basically equivalent to
;; `button-put', but we can do it much more efficiently since we
;; already have BEG and END.
(cond ((eq prop 'type)
;; We translate a `type' property into a `category'
;; property, since that's what's actually used by
;; text-properties for inheritance.
(setq prop 'category)
(setq val (button-category-symbol val)))
((eq prop 'category)
;; Disallow setting the `category' property directly.
(error "Button `category' property may not be set directly")))
;; Add the property.
(put-text-property beg end prop val)))
;; Return something that can be used to get at the button.
beg)
;;;###autoload
(defun insert-text-button (label &rest properties)
"Insert a button with the label LABEL.
The remaining arguments form a sequence of PROPERTY VALUE pairs,
specifying properties to add to the button. In particular, the `type'
property may be used to specify a button-type from which to inherit
other properties; see `define-button-type'.
This function is like `insert-button', except that the button is
actually part of the text instead of being a property of the buffer.
Creating large numbers of buttons can also be somewhat faster using
`insert-text-button'.
Also see `make-text-button'."
(apply #'make-text-button
(prog1 (point) (insert label))
(point)
properties))
;; Finding buttons in a buffer
(defun button-at (pos)
"Return the button at position POS in the current buffer, or nil."
(let ((button (get-char-property pos 'button)))
(if (or (overlayp button) (null button))
button
;; Must be a text-property button; return a marker pointing to it.
(copy-marker pos t))))
(defun next-button (pos &optional n wrap count-current)
"Return the Nth button after position POS in the current buffer.
If N is negative, return the Nth button before POS.
If no Nth button is found, return nil.
If WRAP is non-nil, the search wraps around at the end of the buffer.
If COUNT-CURRENT is non-nil, count any button at POS in the search,
instead of starting at the next button."
(when (null n)
(setq n 1))
(if (< n 0)
;; reverse direction
(previous-button pos (- n) wrap)
(unless count-current
;; Search for the next button boundary.
(setq pos (next-single-char-property-change pos 'button)))
(let ((button (button-at pos)))
(cond ((and button (>= n 2))
;; Found a button, but we want a different one; recurse.
(next-button (button-start button) (1- n) wrap))
(button
;; This is the button we want.
button)
((= pos (point-max))
;; Failed to find a button going forwards, either wrap or
;; return failure.
(and wrap (next-button (point-min) n nil t)))
(t
;; We must have originally been on a button, and are now in
;; the inter-button space. Recurse to find a button.
(next-button pos n wrap))))))
(defun previous-button (pos &optional n wrap count-current)
"Return the Nth button before position POS in the current buffer.
If N is negative, return the Nth button after POS.
If no Nth button is found, return nil.
If WRAP is non-nil, the search wraps around at the beginning of the buffer.
If COUNT-CURRENT is non-nil, count any button at POS in the search,
instead of starting at the next button."
(when (null n)
(setq n 1))
(if (< n 0)
;; reverse direction
(next-button pos (- n) wrap)
(unless count-current
(setq pos (previous-single-char-property-change pos 'button)))
(let ((button (and (> pos (point-min)) (button-at (1- pos)))))
(cond ((and button (>= n 2))
;; Found a button, but we want a different one; recurse.
(previous-button (button-start button) (1- n) wrap))
(button
;; This is the button we want.
button)
((= pos (point-min))
;; Failed to find a button going backwards, either wrap
;; or return failure.
(and wrap (previous-button (point-max) n nil t)))
(t
;; We must have originally been on a button, and are now in
;; the inter-button space. Recurse to find a button.
(previous-button pos (max n 1) wrap))))))
;; User commands
(defun push-button (&optional pos)
"Perform the action specified by a button at location POS.
POS may be either a buffer position or a mouse-event.
POS defaults to point, except when `push-button' is invoked
interactively as the result of a mouse-event, in which case, the
mouse event is used.
If there's no button at POS, do nothing and return nil, otherwise
return t."
(interactive
(list (if (integerp last-command-event) (point) last-command-event)))
(if (and (not (integerp pos)) (eventp pos))
;; POS is a mouse event; switch to the proper window/buffer
(let ((posn (event-start pos)))
(with-current-buffer (window-buffer (posn-window posn))
(push-button (posn-point posn))))
;; POS is just normal position
(let ((button (button-at (or pos (point)))))
(if (not button)
nil
(button-activate button)
t))))
(defun forward-button (n &optional wrap display-message)
"Move to the Nth next button, or Nth previous button if N is negative.
If WRAP is non-nil, moving past either end of the buffer continues from the
other end.
If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed.
Returns the button found."
(interactive "p\nd\nd")
(let ((button (next-button (point) n wrap)))
(if (null button)
(error (if wrap "No buttons!" "No more buttons"))
(goto-char (button-start button))
(let ((msg (and display-message (button-get button 'help-echo))))
(when msg
(message "%s" msg)))
button)))
(defun backward-button (n &optional wrap display-message)
"Move to the Nth previous button, or Nth next button if N is negative.
If WRAP is non-nil, moving past either end of the buffer continues from the
other end.
If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed.
Returns the button found."
(interactive "p\nd\nd")
(forward-button (- n) wrap display-message))
(provide 'button)
;;; button.el ends here
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