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456 lines
17 KiB
EmacsLisp
456 lines
17 KiB
EmacsLisp
;;; button.el --- clickable buttons
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;;
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;; Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
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;;
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;; Author: Miles Bader <miles@gnu.org>
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;; Keywords: extensions
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;;
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;; This file is part of GNU Emacs.
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;;
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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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;;
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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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;;
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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 the
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;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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;; Boston, MA 02110-1301, USA.
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;;; Commentary:
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;;
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;; This package defines functions for inserting and manipulating
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;; clickable buttons in Emacs buffers, such as might be used for help
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;; hyperlinks, etc.
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;;
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;; In some ways it duplicates functionality also offered by the
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;; `widget' package, but the button package has the advantage that it
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;; is (1) much faster, (2) much smaller, and (3) much, much, simpler
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;; (the code, that is, not the interface).
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;;
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;; Buttons can either use overlays, in which case the button is
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;; represented by the overlay itself, or text-properties, in which case
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;; the button is represented by a marker or buffer-position pointing
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;; somewhere in the button. In the latter case, no markers into the
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;; buffer are retained, which is important for speed if there are are
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;; extremely large numbers of buttons.
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;;
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;; Using `define-button-type' to define default properties for buttons
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;; is not necessary, but it is is encouraged, since doing so makes the
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;; resulting code clearer and more efficient.
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;;
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;;; Code:
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;; Globals
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;; Use color for the MS-DOS port because it doesn't support underline.
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(defface button '((((type pc) (class color))
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(:foreground "lightblue"))
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(t :underline t))
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"Default face used for buttons."
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:group 'faces)
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;;;###autoload
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(defvar button-map
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(let ((map (make-sparse-keymap)))
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(define-key map "\r" 'push-button)
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(define-key map [mouse-2] 'push-button)
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map)
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"Keymap used by buttons.")
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;;;###autoload
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(defvar button-buffer-map
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(let ((map (make-sparse-keymap)))
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(define-key map [?\t] 'forward-button)
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(define-key map [backtab] 'backward-button)
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map)
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"Keymap useful for buffers containing buttons.
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Mode-specific keymaps may want to use this as their parent keymap.")
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;; Default properties for buttons
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(put 'default-button 'face 'button)
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(put 'default-button 'mouse-face 'highlight)
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(put 'default-button 'keymap button-map)
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(put 'default-button 'type 'button)
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;; action may be either a function to call, or a marker to go to
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(put 'default-button 'action 'ignore)
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(put 'default-button 'help-echo "mouse-2, RET: Push this button")
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;; Make overlay buttons go away if their underlying text is deleted.
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(put 'default-button 'evaporate t)
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;; Prevent insertions adjacent to the text-property buttons from
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;; inheriting its properties.
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(put 'default-button 'rear-nonsticky t)
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;; Text property buttons don't have a `button' property of their own, so
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;; they inherit this.
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(put 'default-button 'button t)
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;; A `category-symbol' property for the default button type
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(put 'button 'button-category-symbol 'default-button)
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;; Button types (which can be used to hold default properties for buttons)
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;; Because button-type properties are inherited by buttons using the
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;; special `category' property (implemented by both overlays and
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;; text-properties), we need to store them on a symbol to which the
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;; `category' properties can point. Instead of using the symbol that's
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;; the name of each button-type, however, we use a separate symbol (with
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;; `-button' appended, and uninterned) to store the properties. This is
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;; to avoid name clashes.
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;; [this is an internal function]
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(defsubst button-category-symbol (type)
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"Return the symbol used by button-type TYPE to store properties.
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Buttons inherit them by setting their `category' property to that symbol."
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(or (get type 'button-category-symbol)
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(error "Unknown button type `%s'" type)))
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;;;###autoload
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(defun define-button-type (name &rest properties)
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"Define a `button type' called NAME.
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The remaining arguments form a sequence of PROPERTY VALUE pairs,
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specifying properties to use as defaults for buttons with this type
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\(a button's type may be set by giving it a `type' property when
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creating the button, using the :type keyword argument).
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In addition, the keyword argument :supertype may be used to specify a
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button-type from which NAME inherits its default property values
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\(however, the inheritance happens only when NAME is defined; subsequent
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changes to a supertype are not reflected in its subtypes)."
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(let ((catsym (make-symbol (concat (symbol-name name) "-button")))
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(super-catsym
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(button-category-symbol
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(or (plist-get properties 'supertype)
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(plist-get properties :supertype)
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'button))))
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;; Provide a link so that it's easy to find the real symbol.
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(put name 'button-category-symbol catsym)
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;; Initialize NAME's properties using the global defaults.
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(let ((default-props (symbol-plist super-catsym)))
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(while default-props
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(put catsym (pop default-props) (pop default-props))))
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;; Add NAME as the `type' property, which will then be returned as
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;; the type property of individual buttons.
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(put catsym 'type name)
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;; Add the properties in PROPERTIES to the real symbol.
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(while properties
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(let ((prop (pop properties)))
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(when (eq prop :supertype)
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(setq prop 'supertype))
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(put catsym prop (pop properties))))
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;; Make sure there's a `supertype' property
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(unless (get catsym 'supertype)
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(put catsym 'supertype 'button))
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name))
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(defun button-type-put (type prop val)
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"Set the button-type TYPE's PROP property to VAL."
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(put (button-category-symbol type) prop val))
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(defun button-type-get (type prop)
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"Get the property of button-type TYPE named PROP."
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(get (button-category-symbol type) prop))
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(defun button-type-subtype-p (type supertype)
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"Return t if button-type TYPE is a subtype of SUPERTYPE."
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(or (eq type supertype)
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(and type
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(button-type-subtype-p (button-type-get type 'supertype)
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supertype))))
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;; Button properties and other attributes
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(defun button-start (button)
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"Return the position at which BUTTON starts."
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(if (overlayp button)
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(overlay-start button)
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;; Must be a text-property button.
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(or (previous-single-property-change (1+ button) 'button)
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(point-min))))
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(defun button-end (button)
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"Return the position at which BUTTON ends."
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(if (overlayp button)
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(overlay-end button)
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;; Must be a text-property button.
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(or (next-single-property-change button 'button)
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(point-max))))
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(defun button-get (button prop)
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"Get the property of button BUTTON named PROP."
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(if (overlayp button)
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(overlay-get button prop)
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;; Must be a text-property button.
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(get-text-property button prop)))
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(defun button-put (button prop val)
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"Set BUTTON's PROP property to VAL."
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;; Treat some properties specially.
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(cond ((memq prop '(type :type))
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;; We translate a `type' property a `category' property, since
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;; that's what's actually used by overlays/text-properties for
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;; inheriting properties.
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(setq prop 'category)
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(setq val (button-category-symbol val)))
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((eq prop 'category)
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;; Disallow updating the `category' property directly.
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(error "Button `category' property may not be set directly")))
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;; Add the property.
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(if (overlayp button)
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(overlay-put button prop val)
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;; Must be a text-property button.
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(put-text-property
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(or (previous-single-property-change (1+ button) 'button)
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(point-min))
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(or (next-single-property-change button 'button)
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(point-max))
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prop val)))
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(defsubst button-activate (button &optional use-mouse-action)
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"Call BUTTON's action property.
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If USE-MOUSE-ACTION is non-nil, invoke the button's mouse-action
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instead of its normal action; if the button has no mouse-action,
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the normal action is used instead."
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(let ((action (or (and use-mouse-action (button-get button 'mouse-action))
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(button-get button 'action))))
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(if (markerp action)
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(save-selected-window
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(select-window (display-buffer (marker-buffer action)))
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(goto-char action)
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(recenter 0))
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(funcall action button))))
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(defun button-label (button)
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"Return BUTTON's text label."
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(buffer-substring-no-properties (button-start button) (button-end button)))
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(defsubst button-type (button)
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"Return BUTTON's button-type."
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(button-get button 'type))
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(defun button-has-type-p (button type)
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"Return t if BUTTON has button-type TYPE, or one of TYPE's subtypes."
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(button-type-subtype-p (button-get button 'type) type))
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;; Creating overlay buttons
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;;;###autoload
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(defun make-button (beg end &rest properties)
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"Make a button from BEG to END in the current buffer.
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The remaining arguments form a sequence of PROPERTY VALUE pairs,
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specifying properties to add to the button.
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In addition, the keyword argument :type may be used to specify a
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button-type from which to inherit other properties; see
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`define-button-type'.
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Also see `make-text-button', `insert-button'."
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(let ((overlay (make-overlay beg end nil t nil)))
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(while properties
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(button-put overlay (pop properties) (pop properties)))
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;; Put a pointer to the button in the overlay, so it's easy to get
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;; when we don't actually have a reference to the overlay.
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(overlay-put overlay 'button overlay)
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;; If the user didn't specify a type, use the default.
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(unless (overlay-get overlay 'category)
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(overlay-put overlay 'category 'default-button))
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;; OVERLAY is the button, so return it
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overlay))
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;;;###autoload
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(defun insert-button (label &rest properties)
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"Insert a button with the label LABEL.
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The remaining arguments form a sequence of PROPERTY VALUE pairs,
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specifying properties to add to the button.
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In addition, the keyword argument :type may be used to specify a
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button-type from which to inherit other properties; see
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`define-button-type'.
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Also see `insert-text-button', `make-button'."
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(apply #'make-button
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(prog1 (point) (insert label))
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(point)
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properties))
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;; Creating text-property buttons
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;;;###autoload
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(defun make-text-button (beg end &rest properties)
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"Make a button from BEG to END in the current buffer.
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The remaining arguments form a sequence of PROPERTY VALUE pairs,
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specifying properties to add to the button.
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In addition, the keyword argument :type may be used to specify a
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button-type from which to inherit other properties; see
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`define-button-type'.
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This function is like `make-button', except that the button is actually
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part of the text instead of being a property of the buffer. Creating
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large numbers of buttons can also be somewhat faster using
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`make-text-button'.
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Also see `insert-text-button'."
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(let ((type-entry
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(or (plist-member properties 'type)
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(plist-member properties :type))))
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;; Disallow setting the `category' property directly.
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(when (plist-get properties 'category)
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(error "Button `category' property may not be set directly"))
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(if (null type-entry)
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;; The user didn't specify a `type' property, use the default.
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(setq properties (cons 'category (cons 'default-button properties)))
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;; The user did specify a `type' property. Translate it into a
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;; `category' property, which is what's actually used by
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;; text-properties for inheritance.
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(setcar type-entry 'category)
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(setcar (cdr type-entry)
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(button-category-symbol (car (cdr type-entry))))))
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;; Now add all the text properties at once
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(add-text-properties beg end properties)
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;; Return something that can be used to get at the button.
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beg)
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;;;###autoload
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(defun insert-text-button (label &rest properties)
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"Insert a button with the label LABEL.
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The remaining arguments form a sequence of PROPERTY VALUE pairs,
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specifying properties to add to the button.
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In addition, the keyword argument :type may be used to specify a
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button-type from which to inherit other properties; see
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`define-button-type'.
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This function is like `insert-button', except that the button is
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actually part of the text instead of being a property of the buffer.
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Creating large numbers of buttons can also be somewhat faster using
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`insert-text-button'.
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Also see `make-text-button'."
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(apply #'make-text-button
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(prog1 (point) (insert label))
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(point)
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properties))
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;; Finding buttons in a buffer
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(defun button-at (pos)
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"Return the button at position POS in the current buffer, or nil."
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(let ((button (get-char-property pos 'button)))
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(if (or (overlayp button) (null button))
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button
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;; Must be a text-property button; return a marker pointing to it.
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(copy-marker pos t))))
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(defun next-button (pos &optional count-current)
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"Return the next button after position POS in the current buffer.
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If COUNT-CURRENT is non-nil, count any button at POS in the search,
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instead of starting at the next button."
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(unless count-current
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;; Search for the next button boundary.
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(setq pos (next-single-char-property-change pos 'button)))
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(and (< pos (point-max))
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(or (button-at pos)
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;; We must have originally been on a button, and are now in
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;; the inter-button space. Recurse to find a button.
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(next-button pos))))
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(defun previous-button (pos &optional count-current)
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"Return the Nth button before position POS in the current buffer.
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If COUNT-CURRENT is non-nil, count any button at POS in the search,
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instead of starting at the next button."
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(unless count-current
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(setq pos (previous-single-char-property-change pos 'button)))
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(and (> pos (point-min))
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(or (button-at (1- pos))
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;; We must have originally been on a button, and are now in
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;; the inter-button space. Recurse to find a button.
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(previous-button pos))))
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;; User commands
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(defun push-button (&optional pos use-mouse-action)
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"Perform the action specified by a button at location POS.
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POS may be either a buffer position or a mouse-event. If
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USE-MOUSE-ACTION is non-nil, invoke the button's mouse-action
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instead of its normal action; if the button has no mouse-action,
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the normal action is used instead. The action may be either a
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function to call or a marker to display.
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POS defaults to point, except when `push-button' is invoked
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interactively as the result of a mouse-event, in which case, the
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mouse event is used.
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If there's no button at POS, do nothing and return nil, otherwise
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return t."
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(interactive
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(list (if (integerp last-command-event) (point) last-command-event)))
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(if (and (not (integerp pos)) (eventp pos))
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;; POS is a mouse event; switch to the proper window/buffer
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(let ((posn (event-start pos)))
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(with-current-buffer (window-buffer (posn-window posn))
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(push-button (posn-point posn) t)))
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;; POS is just normal position
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(let ((button (button-at (or pos (point)))))
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(if (not button)
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nil
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(button-activate button use-mouse-action)
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t))))
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(defun forward-button (n &optional wrap display-message)
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"Move to the Nth next button, or Nth previous button if N is negative.
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If N is 0, move to the start of any button at point.
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If WRAP is non-nil, moving past either end of the buffer continues from the
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other end.
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If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed.
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Any button with a non-nil `skip' property is skipped over.
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Returns the button found."
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(interactive "p\nd\nd")
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(let (button)
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(if (zerop n)
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;; Move to start of current button
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(if (setq button (button-at (point)))
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(goto-char (button-start button)))
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;; Move to Nth next button
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(let ((iterator (if (> n 0) #'next-button #'previous-button))
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(wrap-start (if (> n 0) (point-min) (point-max))))
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(setq n (abs n))
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(setq button t) ; just to start the loop
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(while (and (> n 0) button)
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(setq button (funcall iterator (point)))
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(when (and (not button) wrap)
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(setq button (funcall iterator wrap-start t)))
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(when button
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(goto-char (button-start button))
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(unless (button-get button 'skip)
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(setq n (1- n)))))))
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(if (null button)
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(error (if wrap "No buttons!" "No more buttons"))
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(let ((msg (and display-message (button-get button 'help-echo))))
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(when msg
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(message "%s" msg)))
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button)))
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(defun backward-button (n &optional wrap display-message)
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"Move to the Nth previous button, or Nth next button if N is negative.
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If N is 0, move to the start of any button at point.
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If WRAP is non-nil, moving past either end of the buffer continues from the
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other end.
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If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed.
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Any button with a non-nil `skip' property is skipped over.
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Returns the button found."
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(interactive "p\nd\nd")
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(forward-button (- n) wrap display-message))
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(provide 'button)
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;;; arch-tag: 5f2c7627-413b-4097-b282-630f89d9c5e9
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;;; button.el ends here
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