;;; help.el --- help commands for Emacs
;; Copyright (C) 1985, 1986, 1993, 1994, 1998, 1999, 2000, 2001, 2002,
-;; 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
+;; 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
;; Maintainer: FSF
;; Keywords: help, internal
;; 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)
+;; the Free Software Foundation; either version 3, or (at your option)
;; any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
(add-hook 'temp-buffer-setup-hook 'help-mode-setup)
(add-hook 'temp-buffer-show-hook 'help-mode-finish)
+;; The variable `help-window' below is used by `help-mode-finish' to
+;; communicate the window displaying help (the "help window") to the
+;; macro `with-help-window'. The latter sets `help-window' to t before
+;; invoking `with-output-to-temp-buffer'. If and only if `help-window'
+;; is eq to t, `help-mode-finish' (called by `temp-buffer-setup-hook')
+;; sets `help-window' to the window selected by `display-buffer'.
+;; Exiting `with-help-window' and calling `print-help-return-message'
+;; reset `help-window' to nil.
+(defvar help-window nil
+ "Window chosen for displaying help.")
+
+;; `help-window-point-marker' is a marker you can move to a valid
+;; position of the buffer shown in the help window in order to override
+;; the standard positioning mechanism (`point-min') chosen by
+;; `with-output-to-temp-buffer'. `with-help-window' has this point
+;; nowhere before exiting. Currently used by `view-lossage' to assert
+;; that the last keystrokes are always visible.
+(defvar help-window-point-marker (make-marker)
+ "Marker to override default `window-point' of `help-window'.")
+
(defvar help-map
(let ((map (make-sparse-keymap)))
(define-key map (char-to-string help-char) 'help-for-help)
(define-key map "." 'display-local-help)
(define-key map "?" 'help-for-help)
+ (define-key map "\C-a" 'about-emacs)
(define-key map "\C-c" 'describe-copying)
(define-key map "\C-d" 'describe-distribution)
(define-key map "\C-e" 'view-emacs-problems)
If FUNCTION is nil, it applies `message', thus displaying the message.
In addition, this function sets up `help-return-method', which see, that
specifies what to do when the user exits the help buffer."
+ ;; Reset `help-window' here to avoid confusing `help-mode-finish'.
+ (setq help-window nil)
(and (not (get-buffer-window standard-output))
(let ((first-message
(cond ((or
. display-local-help. Display any available local help at point
in the echo area.
+C-a Display information about Emacs.
C-c Display Emacs copying permission (GNU General Public License).
C-d Display Emacs ordering information.
C-e Display info about Emacs problems.
The prefix described consists of all but the last event
of the key sequence that ran this command."
(interactive)
- (let* ((key (this-command-keys)))
+ (let ((key (this-command-keys)))
(describe-bindings
(if (stringp key)
(substring key 0 (1- (length key)))
(when (consp version)
(let* ((all-versions
(let (res)
- (mapcar
+ (mapc
(lambda (file)
(with-temp-buffer
(insert-file-contents
((<= version 18)
(setq version (format "%d" version)))
((> version emacs-major-version)
- (error "No news about emacs %d (yet)" version))))
+ (error "No news about Emacs %d (yet)" version))))
(let* ((vn (if (stringp version)
(string-to-number version)
version))
To record all your input on a file, use `open-dribble-file'."
(interactive)
(help-setup-xref (list #'view-lossage) (interactive-p))
- (with-output-to-temp-buffer (help-buffer)
+ (with-help-window (help-buffer)
(princ (mapconcat (lambda (key)
(if (or (integerp key) (symbolp key) (listp key))
(single-key-description key)
(while (progn (move-to-column 50) (not (eobp)))
(when (search-forward " " nil t)
(delete-char -1))
- (insert "\n")))
- (print-help-return-message)))
+ (insert "\n"))
+ ;; jidanni wants to see the last keystrokes immediately.
+ (set-marker help-window-point-marker (point)))))
\f
;; Key bindings
then we display only bindings that start with that prefix."
(interactive)
(let ((buf (current-buffer)))
- (with-output-to-temp-buffer "*Help*"
+ (with-help-window "*Help*"
(with-current-buffer standard-output
(describe-buffer-bindings buf prefix menus)))))
"Where is command: ")
obarray 'commandp t))
(list (if (equal val "") fn (intern val)) current-prefix-arg)))
+ (unless definition (error "No command"))
(let ((func (indirect-function definition))
(defs nil)
(standard-output (if insert (current-buffer) t)))
(princ string)))))
nil)
-(defun string-key-binding (key)
- "Value is the binding of KEY in a string.
-If KEY is an event on a string, and that string has a `local-map'
-or `keymap' property, return the binding of KEY in the string's keymap."
- (let* ((defn nil)
- (start (when (vectorp key)
- (if (memq (aref key 0)
- '(mode-line header-line left-margin right-margin))
- (event-start (aref key 1))
- (and (consp (aref key 0))
- (event-start (aref key 0))))))
- (string-info (and (consp start) (nth 4 start))))
- (when string-info
- (let* ((string (car string-info))
- (pos (cdr string-info))
- (local-map (and (>= pos 0)
- (< pos (length string))
- (or (get-text-property pos 'local-map string)
- (get-text-property pos 'keymap string)))))
- (setq defn (and local-map (lookup-key local-map key)))))
- defn))
-
(defun help-key-description (key untranslated)
(let ((string (key-description key)))
(if (or (not untranslated)
(menu-bar-update-yank-menu "(any string)" nil))
(setq key (read-key-sequence "Describe key (or click or menu item): "))
;; If KEY is a down-event, read and discard the
- ;; corresponding up-event.
- (if (and (vectorp key)
- (eventp (elt key 0))
- (memq 'down (event-modifiers (elt key 0))))
- (read-event))
+ ;; corresponding up-event. Note that there are also
+ ;; down-events on scroll bars and mode lines: the actual
+ ;; event then is in the second element of the vector.
+ (and (vectorp key)
+ (let ((last-idx (1- (length key))))
+ (and (eventp (aref key last-idx))
+ (memq 'down (event-modifiers (aref key last-idx)))))
+ (read-event))
(list
key
(if current-prefix-arg (prefix-numeric-value current-prefix-arg))
(fset 'yank-menu (cons 'keymap yank-menu))))))
(if (numberp untranslated)
(setq untranslated (this-single-command-raw-keys)))
- (save-excursion
- (let ((modifiers (event-modifiers (aref key 0)))
- (standard-output (if insert (current-buffer) t))
- window position)
- ;; For a mouse button event, go to the button it applies to
- ;; to get the right key bindings. And go to the right place
- ;; in case the keymap depends on where you clicked.
- (if (or (memq 'click modifiers) (memq 'down modifiers)
- (memq 'drag modifiers))
- (setq window (posn-window (event-start (aref key 0)))
- position (posn-point (event-start (aref key 0)))))
- (if (windowp window)
- (progn
- (set-buffer (window-buffer window))
- (goto-char position)))
- ;; Ok, now look up the key and name the command.
- (let ((defn (or (string-key-binding key)
- (key-binding key t)))
- key-desc)
- ;; Handle the case where we faked an entry in "Select and Paste" menu.
- (if (and (eq defn nil)
- (stringp (aref key (1- (length key))))
- (eq (key-binding (substring key 0 -1)) 'yank-menu))
- (setq defn 'menu-bar-select-yank))
- ;; Don't bother user with strings from (e.g.) the select-paste menu.
- (if (stringp (aref key (1- (length key))))
- (aset key (1- (length key)) "(any string)"))
- (if (and (> (length untranslated) 0)
- (stringp (aref untranslated (1- (length untranslated)))))
- (aset untranslated (1- (length untranslated))
- "(any string)"))
- ;; Now describe the key, perhaps as changed.
- (setq key-desc (help-key-description key untranslated))
- (if (or (null defn) (integerp defn) (equal defn 'undefined))
- (princ (format "%s is undefined" key-desc))
- (princ (format (if (windowp window)
- "%s at that spot runs the command %s"
- "%s runs the command %s")
- key-desc
- (if (symbolp defn) defn (prin1-to-string defn)))))))))
+ (let* ((event (if (and (symbolp (aref key 0))
+ (> (length key) 1)
+ (consp (aref key 1)))
+ (aref key 1)
+ (aref key 0)))
+ (modifiers (event-modifiers event))
+ (standard-output (if insert (current-buffer) t))
+ (mouse-msg (if (or (memq 'click modifiers) (memq 'down modifiers)
+ (memq 'drag modifiers)) " at that spot" ""))
+ (defn (key-binding key t))
+ key-desc)
+ ;; Handle the case where we faked an entry in "Select and Paste" menu.
+ (if (and (eq defn nil)
+ (stringp (aref key (1- (length key))))
+ (eq (key-binding (substring key 0 -1)) 'yank-menu))
+ (setq defn 'menu-bar-select-yank))
+ ;; Don't bother user with strings from (e.g.) the select-paste menu.
+ (if (stringp (aref key (1- (length key))))
+ (aset key (1- (length key)) "(any string)"))
+ (if (and (> (length untranslated) 0)
+ (stringp (aref untranslated (1- (length untranslated)))))
+ (aset untranslated (1- (length untranslated)) "(any string)"))
+ ;; Now describe the key, perhaps as changed.
+ (setq key-desc (help-key-description key untranslated))
+ (if (or (null defn) (integerp defn) (equal defn 'undefined))
+ (princ (format "%s%s is undefined" key-desc mouse-msg))
+ (princ (format "%s%s runs the command %S" key-desc mouse-msg defn)))))
(defun describe-key (&optional key untranslated up-event)
"Display documentation of the function invoked by KEY.
(list
key
(prefix-numeric-value current-prefix-arg)
- ;; If KEY is a down-event, read the corresponding up-event
- ;; and use it as the third argument.
- (if (and (vectorp key)
- (eventp (elt key 0))
- (memq 'down (event-modifiers (elt key 0))))
- (read-event))))
+ ;; If KEY is a down-event, read and include the
+ ;; corresponding up-event. Note that there are also
+ ;; down-events on scroll bars and mode lines: the actual
+ ;; event then is in the second element of the vector.
+ (and (vectorp key)
+ (let ((last-idx (1- (length key))))
+ (and (eventp (aref key last-idx))
+ (memq 'down (event-modifiers (aref key last-idx)))))
+ (or (and (eventp (aref key 0))
+ (memq 'down (event-modifiers (aref key 0)))
+ ;; However, for the C-down-mouse-2 popup
+ ;; menu, there is no subsequent up-event. In
+ ;; this case, the up-event is the next
+ ;; element in the supplied vector.
+ (= (length key) 1))
+ (and (> (length key) 1)
+ (eventp (aref key 1))
+ (memq 'down (event-modifiers (aref key 1)))))
+ (read-event))))
;; Put yank-menu back as it was, if we changed it.
(when saved-yank-menu
(setq yank-menu (copy-sequence saved-yank-menu))
(fset 'yank-menu (cons 'keymap yank-menu))))))
(if (numberp untranslated)
(setq untranslated (this-single-command-raw-keys)))
- (save-excursion
- (let ((modifiers (event-modifiers (aref key 0)))
- window position)
- ;; For a mouse button event, go to the button it applies to
- ;; to get the right key bindings. And go to the right place
- ;; in case the keymap depends on where you clicked.
- (if (or (memq 'click modifiers) (memq 'down modifiers)
- (memq 'drag modifiers))
- (setq window (posn-window (event-start (aref key 0)))
- position (posn-point (event-start (aref key 0)))))
- (when (windowp window)
- (set-buffer (window-buffer window))
- (goto-char position))
- (let ((defn (or (string-key-binding key) (key-binding key t))))
- ;; Handle the case where we faked an entry in "Select and Paste" menu.
- (if (and (eq defn nil)
- (stringp (aref key (1- (length key))))
- (eq (key-binding (substring key 0 -1)) 'yank-menu))
- (setq defn 'menu-bar-select-yank))
- (if (or (null defn) (integerp defn) (equal defn 'undefined))
- (message "%s is undefined" (help-key-description key untranslated))
- (help-setup-xref (list #'describe-function defn) (interactive-p))
- ;; Don't bother user with strings from (e.g.) the select-paste menu.
- (if (stringp (aref key (1- (length key))))
- (aset key (1- (length key)) "(any string)"))
- (if (and untranslated
- (stringp (aref untranslated (1- (length untranslated)))))
- (aset untranslated (1- (length untranslated))
- "(any string)"))
- (with-output-to-temp-buffer (help-buffer)
- (princ (help-key-description key untranslated))
- (if (windowp window)
- (princ " at that spot"))
- (princ " runs the command ")
- (prin1 defn)
- (princ "\n which is ")
- (describe-function-1 defn)
- (when up-event
- (let ((type (event-basic-type up-event))
- (hdr "\n\n-------------- up event ---------------\n\n")
- defn sequence
- mouse-1-tricky mouse-1-remapped)
- (setq sequence (vector up-event))
- (when (and (eq type 'mouse-1)
- (windowp window)
+ (let* ((event (aref key (if (and (symbolp (aref key 0))
+ (> (length key) 1)
+ (consp (aref key 1)))
+ 1
+ 0)))
+ (modifiers (event-modifiers event))
+ (mouse-msg (if (or (memq 'click modifiers) (memq 'down modifiers)
+ (memq 'drag modifiers)) " at that spot" ""))
+ (defn (key-binding key t))
+ defn-up defn-up-tricky ev-type
+ mouse-1-remapped mouse-1-tricky)
+
+ ;; Handle the case where we faked an entry in "Select and Paste" menu.
+ (when (and (eq defn nil)
+ (stringp (aref key (1- (length key))))
+ (eq (key-binding (substring key 0 -1)) 'yank-menu))
+ (setq defn 'menu-bar-select-yank))
+ (if (or (null defn) (integerp defn) (equal defn 'undefined))
+ (message "%s%s is undefined"
+ (help-key-description key untranslated) mouse-msg)
+ (help-setup-xref (list #'describe-function defn) (interactive-p))
+ ;; Don't bother user with strings from (e.g.) the select-paste menu.
+ (when (stringp (aref key (1- (length key))))
+ (aset key (1- (length key)) "(any string)"))
+ (when (and untranslated
+ (stringp (aref untranslated (1- (length untranslated)))))
+ (aset untranslated (1- (length untranslated))
+ "(any string)"))
+ ;; Need to do this before erasing *Help* buffer in case event
+ ;; is a mouse click in an existing *Help* buffer.
+ (when up-event
+ (setq ev-type (event-basic-type up-event))
+ (let ((sequence (vector up-event)))
+ (when (and (eq ev-type 'mouse-1)
+ mouse-1-click-follows-link
+ (not (eq mouse-1-click-follows-link 'double))
+ (setq mouse-1-remapped
+ (mouse-on-link-p (event-start up-event))))
+ (setq mouse-1-tricky (and (integerp mouse-1-click-follows-link)
+ (> mouse-1-click-follows-link 0)))
+ (cond ((stringp mouse-1-remapped)
+ (setq sequence mouse-1-remapped))
+ ((vectorp mouse-1-remapped)
+ (setcar up-event (elt mouse-1-remapped 0)))
+ (t (setcar up-event 'mouse-2))))
+ (setq defn-up (key-binding sequence nil nil (event-start up-event)))
+ (when mouse-1-tricky
+ (setq sequence (vector up-event))
+ (aset sequence 0 'mouse-1)
+ (setq defn-up-tricky (key-binding sequence nil nil (event-start up-event))))))
+ (with-help-window (help-buffer)
+ (princ (help-key-description key untranslated))
+ (princ (format "\
+%s runs the command %S
+ which is "
+ mouse-msg defn))
+ (describe-function-1 defn)
+ (when up-event
+ (unless (or (null defn-up)
+ (integerp defn-up)
+ (equal defn-up 'undefined))
+ (princ (format "
+
+----------------- up-event %s----------------
+
+<%S>%s%s runs the command %S
+ which is "
+ (if mouse-1-tricky "(short click) " "")
+ ev-type mouse-msg
+ (if mouse-1-remapped
+ " is remapped to <mouse-2>\nwhich" "")
+ defn-up))
+ (describe-function-1 defn-up))
+ (unless (or (null defn-up-tricky)
+ (integerp defn-up-tricky)
+ (eq defn-up-tricky 'undefined))
+ (princ (format "
+
+----------------- up-event (long click) ----------------
+
+Pressing <%S>%s for longer than %d milli-seconds
+runs the command %S
+ which is "
+ ev-type mouse-msg
mouse-1-click-follows-link
- (not (eq mouse-1-click-follows-link 'double))
- (setq mouse-1-remapped
- (with-current-buffer (window-buffer window)
- (mouse-on-link-p (posn-point
- (event-start up-event))))))
- (setq mouse-1-tricky (and (integerp mouse-1-click-follows-link)
- (> mouse-1-click-follows-link 0)))
- (cond ((stringp mouse-1-remapped)
- (setq sequence mouse-1-remapped))
- ((vectorp mouse-1-remapped)
- (setcar up-event (elt mouse-1-remapped 0)))
- (t (setcar up-event 'mouse-2))))
- (setq defn (or (string-key-binding sequence)
- (key-binding sequence)))
- (unless (or (null defn) (integerp defn) (equal defn 'undefined))
- (princ (if mouse-1-tricky
- "\n\n----------------- up-event (short click) ----------------\n\n"
- hdr))
- (setq hdr nil)
- (princ (symbol-name type))
- (if (windowp window)
- (princ " at that spot"))
- (if mouse-1-remapped
- (princ " is remapped to <mouse-2>\n which" ))
- (princ " runs the command ")
- (prin1 defn)
- (princ "\n which is ")
- (describe-function-1 defn))
- (when mouse-1-tricky
- (setcar up-event 'mouse-1)
- (setq defn (or (string-key-binding (vector up-event))
- (key-binding (vector up-event))))
- (unless (or (null defn) (integerp defn) (eq defn 'undefined))
- (princ (or hdr
- "\n\n----------------- up-event (long click) ----------------\n\n"))
- (princ "Pressing mouse-1")
- (if (windowp window)
- (princ " at that spot"))
- (princ (format " for longer than %d milli-seconds\n"
- mouse-1-click-follows-link))
- (princ " runs the command ")
- (prin1 defn)
- (princ "\n which is ")
- (describe-function-1 defn)))))
- (print-help-return-message)))))))
+ defn-up-tricky))
+ (describe-function-1 defn-up-tricky)))))))
\f
(defun describe-mode (&optional buffer)
"Display documentation of current major mode and minor modes.
For this to work correctly for a minor mode, the mode's indicator
variable \(listed in `minor-mode-alist') must also be a function
whose documentation describes the minor mode."
- (interactive)
+ (interactive "@")
(unless buffer (setq buffer (current-buffer)))
(help-setup-xref (list #'describe-mode buffer)
(interactive-p))
;; For the sake of help-do-xref and help-xref-go-back,
;; don't switch buffers before calling `help-buffer'.
- (with-output-to-temp-buffer (help-buffer)
+ (with-help-window (help-buffer)
(with-current-buffer buffer
(let (minor-modes)
;; Older packages do not register in minor-mode-list but only in
(let ((mode mode-name))
(with-current-buffer standard-output
(let ((start (point)))
- (insert (format-mode-line mode))
+ (insert (format-mode-line mode nil nil buffer))
(add-text-properties start (point) '(face bold)))))
(princ " mode:\n")
- (princ (documentation major-mode)))
- (print-help-return-message))))
+ (princ (documentation major-mode))))))
(defun describe-minor-mode (minor-mode)
(cond
((= 0 (length i))
nil)
- ((eq (aref i 0) ?\ )
+ ((eq (aref i 0) ?\s)
(substring i 1))
(t
i))))
"Return a minor mode symbol from its indicator on the modeline."
;; remove first space if existed
(if (and (< 0 (length indicator))
- (eq (aref indicator 0) ?\ ))
+ (eq (aref indicator 0) ?\s))
(setq indicator (substring indicator 1)))
(let ((minor-modes minor-mode-alist)
result)
;; remove first space if existed
(if (and (stringp anindicator)
(> (length anindicator) 0)
- (eq (aref anindicator 0) ?\ ))
+ (eq (aref anindicator 0) ?\s))
(setq anindicator (substring anindicator 1)))
(if (equal indicator anindicator)
(setq result minor-mode
(remove-hook 'temp-buffer-show-hook 'resize-temp-buffer-window)))
(defun resize-temp-buffer-window ()
- "Resize the current window to fit its contents.
+ "Resize the selected window to fit its contents.
Will not make it higher than `temp-buffer-max-height' nor smaller than
`window-min-height'. Do nothing if it is the only window on its frame, if it
is not as wide as the frame or if some of the window's contents are scrolled
out of view."
(unless (or (one-window-p 'nomini)
(not (pos-visible-in-window-p (point-min)))
- (/= (frame-width) (window-width)))
+ (not (window-full-width-p)))
(fit-window-to-buffer
(selected-window)
(if (functionp temp-buffer-max-height)
temp-buffer-max-height))))
\f
+;;; help-window
+
+(defcustom help-window-select 'other
+ "Non-nil means select help window for viewing.
+Choices are:
+ never (nil) Select help window only if there is no other window
+ on its frame.
+ other Select help window unless the selected window is the
+ only other window on its frame.
+ always (t) Always select the help window.
+
+This option has effect if and only if the help window was created
+by `with-help-window'"
+ :type '(choice (const :tag "never (nil)" nil)
+ (const :tag "other" other)
+ (const :tag "always (t)" t))
+ :group 'help
+ :version "23.1")
+
+(defun help-window-display-message (quit-part window &optional other)
+ "Display message telling how to quit and scroll help window.
+QUIT-PART is a string telling how to quit the help window WINDOW.
+Optional argument OTHER non-nil means return text telling how to
+scroll the \"other\" window."
+ (let ((scroll-part
+ (cond
+ ((pos-visible-in-window-p
+ (with-current-buffer (window-buffer window)
+ (point-max)) window)
+ ;; Buffer end is visible.
+ ".")
+ (other ", \\[scroll-other-window] to scroll help.")
+ (t ", \\[scroll-up] to scroll help."))))
+ (message "%s"
+ (substitute-command-keys (concat quit-part scroll-part)))))
+
+(defun help-window-setup-finish (window &optional reuse keep-frame)
+ "Finish setting up help window WINDOW.
+Select WINDOW according to the value of `help-window-select'.
+Display message telling how to scroll and eventually quit WINDOW.
+
+Optional argument REUSE non-nil means WINDOW has been reused \(by
+`display-buffer'\) for displaying help. Optional argument
+KEEP-FRAME non-nil means that quitting must no delete the frame
+of WINDOW."
+ (let ((number-of-windows
+ (length (window-list (window-frame window) 'no-mini window))))
+ (cond
+ ((eq window (selected-window))
+ ;; The help window is the selected window, probably the
+ ;; `pop-up-windows' nil case.
+ (help-window-display-message
+ (if reuse
+ "Type \"q\" to restore this window"
+ ;; This should not be taken.
+ "Type \"q\" to quit") window))
+ ((= number-of-windows 1)
+ ;; The help window is alone on a frame and not the selected
+ ;; window, could be the `pop-up-frames' t case.
+ (help-window-display-message
+ (cond
+ (keep-frame "Type \"q\" to delete this window")
+ (reuse "Type \"q\" to restore this window")
+ (view-remove-frame-by-deleting "Type \"q\" to delete this frame")
+ (t "Type \"q\" to iconify this frame"))
+ window))
+ ((and (= number-of-windows 2)
+ (eq (window-frame window) (window-frame (selected-window))))
+ ;; There are two windows on the help window's frame and the other
+ ;; window is the selected one.
+ (if (memq help-window-select '(nil other))
+ ;; Do not select the help window.
+ (help-window-display-message
+ (if reuse
+ ;; Offer `display-buffer' for consistency with
+ ;; `print-help-return-message'. This is hardly TRT when
+ ;; the other window and the selected window display the
+ ;; same buffer but has been handled this way ever since.
+ "Type \\[display-buffer] RET to restore the other window"
+ ;; The classic "two windows" configuration.
+ "Type \\[delete-other-windows] to delete the help window")
+ window t)
+ ;; Select help window and tell how to quit.
+ (select-window window)
+ (help-window-display-message
+ (if reuse
+ "Type \"q\" to restore this window"
+ "Type \"q\" to delete this window") window)))
+ (help-window-select
+ ;; Issuing a message with 3 or more windows on the same frame
+ ;; without selecting the help window doesn't make any sense.
+ (select-window window)
+ (help-window-display-message
+ (if reuse
+ "Type \"q\" to restore this window"
+ "Type \"q\" to delete this window") window)))))
+
+(defun help-window-setup (list-of-frames list-of-window-tuples)
+ "Set up help window.
+LIST-OF-FRAMES and LIST-OF-WINDOW-TUPLES are the lists of frames
+and window quadruples built by `with-help-window'. The help
+window itself is specified by the variable `help-window'."
+ (let* ((help-buffer (window-buffer help-window))
+ ;; `help-buffer' now denotes the help window's buffer.
+ (view-entry
+ (assq help-window
+ (buffer-local-value 'view-return-to-alist help-buffer)))
+ (help-entry (assq help-window list-of-window-tuples)))
+
+ ;; Handle `help-window-point-marker'.
+ (when (eq (marker-buffer help-window-point-marker) help-buffer)
+ (set-window-point help-window help-window-point-marker)
+ ;; Reset `help-window-point-marker'.
+ (set-marker help-window-point-marker nil))
+
+ (cond
+ (view-entry
+ ;; `view-return-to-alist' has an entry for the help window.
+ (cond
+ ((eq help-window (selected-window))
+ ;; The help window is the selected window, probably because the
+ ;; user followed a backward/forward button or a cross reference.
+ ;; In this case just purge stale entries from
+ ;; `view-return-to-alist' but leave the entry alone and don't
+ ;; display a message.
+ (view-return-to-alist-update help-buffer))
+ ((and help-entry (eq (cadr help-entry) help-buffer))
+ ;; The help window was not selected but displayed the help
+ ;; buffer. In this case reuse existing exit information but try
+ ;; to get back to the selected window when quitting. Don't
+ ;; display a message since the user must have seen one before.
+ (view-return-to-alist-update
+ help-buffer (cons help-window
+ (cons (selected-window) (cddr view-entry)))))
+ (help-entry
+ ;; The help window was not selected, did display the help buffer
+ ;; earlier, but displayed another buffer when help was invoked.
+ ;; Set up things so that quitting will show that buffer again.
+ (view-return-to-alist-update
+ help-buffer (cons help-window
+ (cons (selected-window) (cdr help-entry))))
+ (help-window-setup-finish help-window t))
+ (t
+ ;; The help window is new but `view-return-to-alist' had an
+ ;; entry for it. This should never happen.
+ (view-return-to-alist-update
+ help-buffer (cons help-window
+ (cons (selected-window) 'quit-window)))
+ (help-window-setup-finish help-window t))))
+ (help-entry
+ ;; `view-return-to-alist' does not have an entry for help window
+ ;; but `list-of-window-tuples' does. Hence `display-buffer' must
+ ;; have reused an existing window.
+ (if (eq (cadr help-entry) help-buffer)
+ ;; The help window displayed `help-buffer' before but no
+ ;; `view-return-to-alist' entry was found probably because the
+ ;; user manually switched to the help buffer. Set up things
+ ;; for `quit-window' although `view-exit-action' should be
+ ;; able to handle this case all by itself.
+ (progn
+ (view-return-to-alist-update
+ help-buffer (cons help-window
+ (cons (selected-window) 'quit-window)))
+ (help-window-setup-finish help-window t))
+ ;; The help window displayed another buffer before. Set up
+ ;; things in a way that quitting can orderly show that buffer
+ ;; again. The window-start and window-point information from
+ ;; `list-of-window-tuples' provide the necessary information.
+ (view-return-to-alist-update
+ help-buffer (cons help-window
+ (cons (selected-window) (cdr help-entry))))
+ (help-window-setup-finish help-window t)))
+ ((memq (window-frame help-window) list-of-frames)
+ ;; The help window is a new window on an existing frame. This
+ ;; case must be handled specially by `help-window-setup-finish'
+ ;; and `view-mode-exit' to ascertain that quitting does _not_
+ ;; inadvertently delete the frame.
+ (view-return-to-alist-update
+ help-buffer (cons help-window
+ (cons (selected-window) 'keep-frame)))
+ (help-window-setup-finish help-window nil t))
+ (t
+ ;; The help window is shown on a new frame. In this case quitting
+ ;; shall handle both, the help window _and_ its frame. We changed
+ ;; the default of `view-remove-frame-by-deleting' to t in order to
+ ;; intuitively DTRT here.
+ (view-return-to-alist-update
+ help-buffer (cons help-window (cons (selected-window) t)))
+ (help-window-setup-finish help-window)))))
+
+;; `with-help-window' is a wrapper for `with-output-to-temp-buffer'
+;; providing the following additional twists:
+
+;; (1) Issue more accurate messages telling how to scroll and quit the
+;; help window.
+
+;; (2) Make `view-mode-exit' DTRT in more cases.
+
+;; (3) An option (customizable via `help-window-select') to select the
+;; help window automatically.
+
+;; (4) A marker (`help-window-point-marker') to move point in the help
+;; window to an arbitrary buffer position.
+
+;; Note: It's usually always wrong to use `print-help-return-message' in
+;; the body of `with-help-window'.
+(defmacro with-help-window (buffer-name &rest body)
+ "Display buffer BUFFER-NAME in a help window evaluating BODY.
+Select help window if the actual value of the user option
+`help-window-select' says so."
+ (declare (indent 1) (debug t))
+ ;; Bind list-of-frames to `frame-list' and list-of-window-tuples to a
+ ;; list of one <window window-buffer window-start window-point> tuple
+ ;; for each live window.
+ `(let ((list-of-frames (frame-list))
+ (list-of-window-tuples
+ (let (list)
+ (walk-windows
+ (lambda (window)
+ (push (list window (window-buffer window)
+ (window-start window) (window-point window))
+ list))
+ 'no-mini t)
+ list)))
+ ;; We set `help-window' to t in order to trigger `help-mode-finish'
+ ;; to set `help-window' to the actual help window.
+ (setq help-window t)
+ ;; Make `help-window-point-marker' point nowhere (the only place
+ ;; where this should be set to a buffer position is within BODY).
+ (set-marker help-window-point-marker nil)
+
+ (with-output-to-temp-buffer ,buffer-name
+ (progn ,@body))
+
+ (when (windowp help-window)
+ ;; Set up help window.
+ (help-window-setup list-of-frames list-of-window-tuples))
+
+ ;; Reset `help-window' to nil to avoid confusing future calls of
+ ;; `help-mode-finish' by "plain" `with-output-to-temp-buffer'.
+ (setq help-window nil)))
+\f
(provide 'help)
;; arch-tag: cf427352-27e9-49b7-9a6f-741ebab02423
HCoop / bpt / emacs.git / blobdiff