Info-history-forward

Info-history-forward

[Juri Linkov]

I'd like to provide an enhancement that people have requested for
a long time.

Info has the `l' command which moves one step back through the history.
But there is no symmetric command to move forward.  Here is a simple
implementation.  It works like `Forward' button in web browsers.

There is a free key binding "r" in Info-mode-map suitable for
`Info-history-forward'.  It has several mnemonics like "return",
or even "right" whereas opposite "l" would mean "left" representing
imaginable direction of moving through the Info history.

Index: lisp/info.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/info.el,v
retrieving revision 1.413
diff -u -r1.413 info.el
--- lisp/info.el	13 Dec 2004 19:31:32 -0000	1.413
+++ lisp/info.el	28 Dec 2004 02:17:19 -0000
@@ -47,6 +47,10 @@
   "Stack of info nodes user has visited.
 Each element of list is a list (FILENAME NODENAME BUFFERPOS).")
 
+(defvar Info-history-forward nil
+  "Stack of info nodes user has visited with `Info-last' command.
+Each element of list is a list (FILENAME NODENAME BUFFERPOS).")
+
 (defvar Info-history-list nil
   "List of all info nodes user has visited.
 Each element of list is a list (FILENAME NODENAME).")
@@ -1295,7 +1308,8 @@
 	;; Add a new unique history item to full history list
 	(let ((new-history (list Info-current-file Info-current-node)))
 	  (setq Info-history-list
-		(cons new-history (delete new-history Info-history-list))))
+		(cons new-history (delete new-history Info-history-list)))
+	  (setq Info-history-forward nil))
 	(if (not (eq Info-fontify-maximum-menu-size nil))
             (Info-fontify-node))
 	(Info-display-images-node)
@@ -1736,13 +1751,31 @@
   (interactive)
   (or Info-history
       (error "This is the first Info node you looked at"))
-  (let (filename nodename opoint)
+  (let ((history-forward
+	 (cons (list Info-current-file Info-current-node (point))
+	       Info-history-forward))
+	filename nodename opoint)
     (setq filename (car (car Info-history)))
     (setq nodename (car (cdr (car Info-history))))
     (setq opoint (car (cdr (cdr (car Info-history)))))
     (setq Info-history (cdr Info-history))
     (Info-find-node filename nodename)
     (setq Info-history (cdr Info-history))
+    (setq Info-history-forward history-forward)
+    (goto-char opoint)))
+
+(defun Info-history-forward ()
+  "Go forward in the history of visited nodes."
+  (interactive)
+  (or Info-history-forward
+      (error "This is the last Info node you looked at"))
+  (let ((history-forward (cdr Info-history-forward))
+	filename nodename opoint)
+    (setq filename (car (car Info-history-forward)))
+    (setq nodename (car (cdr (car Info-history-forward))))
+    (setq opoint (car (cdr (cdr (car Info-history-forward)))))
+    (Info-find-node filename nodename)
+    (setq Info-history-forward history-forward)
     (goto-char opoint)))
 
 ;;;###autoload
@@ -2900,6 +2933,7 @@
   (define-key Info-mode-map "n" 'Info-next)
   (define-key Info-mode-map "p" 'Info-prev)
   (define-key Info-mode-map "q" 'Info-exit)
+  (define-key Info-mode-map "r" 'Info-history-forward)
   (define-key Info-mode-map "s" 'Info-search)
   (define-key Info-mode-map "S" 'Info-search-case-sensitively)
   ;; For consistency with Rmail.
@@ -2951,8 +2985,10 @@
     :help "Search for another occurrence of regular expression"]
    ["Go to Node..." Info-goto-node
     :help "Go to a named node"]
-   ["Last" Info-last :active Info-history
+   ["Back history (last)" Info-last :active Info-history
     :help "Go to the last node you were at"]
+   ["Forward history" Info-history-forward :active Info-history-forward
+    :help "Go to the previous node left with Info-last"]
    ["History" Info-history :active Info-history-list
     :help "Go to menu of visited nodes"]
    ["Table of Contents" Info-toc
@@ -3101,6 +3137,7 @@
 \\[Info-directory]	Go to the Info directory node.
 \\[Info-follow-reference]	Follow a cross reference.  Reads name of reference.
 \\[Info-last]	Move to the last node you were at.
+\\[Info-history-forward]	Move to the previous node left with Info-last.
 \\[Info-history]	Go to menu of visited nodes.
 \\[Info-toc]	Go to table of contents of the current Info file.
 \\[Info-top-node]	Go to the Top node of this file.
@@ -3157,6 +3194,7 @@
   (make-local-variable 'Info-tag-table-buffer)
   (setq Info-tag-table-buffer nil)
   (make-local-variable 'Info-history)
+  (make-local-variable 'Info-history-forward)
   (make-local-variable 'Info-index-alternatives)
   (setq header-line-format
 	(if Info-use-header-line

-- 
Juri Linkov
http://www.jurta.org/emacs/

RE: Info-history-forward

[Drew Adams]

    I'd like to provide an enhancement that people have requested...
    Info has the `l' command which moves one step back through the history.
    But there is no symmetric command to move forward... It works like
    `Forward' button in web browsers.

Great! (I was one of those who requested this - thanks.)

Five-button mice often have mouse-5 and mouse-4 bound by default to forward
and back for Web browsing etc. I'd suggest these bindings in `info' for
Emacs too, by default. Currently, I bind mouse-4 to `Info-last' on
`Info-mode-map' - it's quite convenient.

It would be good to change the name of `Info-last' to `Info-back' (or
`Info-history-back').

 - Drew

Re: Info-history-forward

[Miles Bader]

> Five-button mice often have mouse-5 and mouse-4 bound by default to forward
> and back for Web browsing etc. I'd suggest these bindings in `info' for
> Emacs too, by default.

At the least I think it would have to be a system-specific binding --
mouse-4 and mouse-5 represent the scroll-wheel on X systems, and it
would definitely be bad to bind the scroll-wheel to
backward/forward-history!

In general it seems as if anything except buttons 1-3 may be too
inconsistently defined to have a very useful default binding.  [a
shame, because some mice seem to have about 20 "buttons" of one sort
or another!]

-Miles

RE: Info-history-forward

[Drew Adams]

    > Five-button mice often have mouse-5 and mouse-4 bound by
    > default to forward and back for Web browsing etc.
    > I'd suggest these bindings in `info' for
    > Emacs too, by default.

    At the least I think it would have to be a system-specific binding --
    mouse-4 and mouse-5 represent the scroll-wheel on X systems, and it
    would definitely be bad to bind the scroll-wheel to
    backward/forward-history!

    In general it seems as if anything except buttons 1-3 may be too
    inconsistently defined to have a very useful default binding.  [a
    shame, because some mice seem to have about 20 "buttons" of one sort
    or another!]

Yes, a shame (although I'll no doubt steer clear of *20*-button mice -
sounds diabolically teratological, and they likely just return "42", which
is not the answer I'm looking for).

Depending on how similar the various platforms behave in this regard,
perhaps it could be the default value for those platforms for which it
works?

The thing about "X systems" is not clear to me. I use this on both Windows
(21.3.50) and Linux (21.3.1) - I use the mouse wheel (e.g. for scrolling)
and I still have `mouse-4' bound to `Info-last'. On Linux I have the
impression that I'm using X Window :-). Just what is the platform-specific
caveat? What am I blissfully missing?

Thanks,

  Drew

Re: Info-history-forward

[Juri Linkov]

"Drew Adams" <drew.adams@oracle.com> writes:
> It would be good to change the name of `Info-last' to `Info-back' (or
> `Info-history-back').

Yes.  The name `Info-last' is misleading.  That's why in the patch
I changed the text of the menu item from "Last" to "Back history (last)".

Maybe the change should be more radical and all mentions of the "last"
be replaced with a "back in history" everywhere, leaving only

(defalias 'Info-last 'Info-history-back)

for backward compatibility.

-- 
Juri Linkov
http://www.jurta.org/emacs/

Re: Info-history-forward

[Eli Zaretskii]

> From: Juri Linkov <juri@jurta.org>
> Date: Wed, 29 Dec 2004 04:11:02 +0200
> Cc: emacs-devel@gnu.org
> 
> Maybe the change should be more radical and all mentions of the "last"
> be replaced with a "back in history" everywhere, leaving only
> 
> (defalias 'Info-last 'Info-history-back)
> 
> for backward compatibility.

If this new command is installed, please don't forget to add an
appropriate menu item and tool-bar button, similar to the ones defined
now for Info-last.

Re: Info-history-forward

[Juri Linkov]

"Eli Zaretskii" <eliz@gnu.org> writes:
> If this new command is installed, please don't forget to add an
> appropriate menu item and tool-bar button, similar to the ones defined
> now for Info-last.

You can see the menu item in the patch I sent.

As for the tool-bar button, this is an interesting question.

Info-last reuses the icon created for undo command.  Its file has the
name "undo.xpm" and contains the image of an arrow pointing to the left.
Naturally, we could create a mirrored image, but how to name a new file?
"redo.xpm"?  But there is no concept of redo in Emacs.  Isn't such file
name misleading?

-- 
Juri Linkov
http://www.jurta.org/emacs/

Re: Info-history-forward

[Robert J. Chassell]

   Info-last reuses the icon created for undo command.  Its file has the
   name "undo.xpm" ...

which is a poor choice for an Info command since it is not an undo.

Please change the name to one that makes more sense for Info, such as
Info-previous-node.xpm.  If you use the same icon, you can make a
link, which does not take much space on a system.

    how to name a new file?

Info-previous-node.xpm or whatever.

Re: Info-history-forward

[Eli Zaretskii]

> Cc: emacs-devel@gnu.org
> From: Juri Linkov <juri@jurta.org>
> Date: Wed, 29 Dec 2004 08:33:59 +0200
> 
> Naturally, we could create a mirrored image, but how to name a new file?

info-fwd.xpm or some such.  (The icon should be a mirrored image of
what undo.xpm displays, but there's no reason to make the name be a
mirrored image as well.)

Re: Info-history-forward

[Eli Zaretskii]

> Date: Wed, 29 Dec 2004 13:06:27 +0000 (UTC)
> From: "Robert J. Chassell" <bob@rattlesnake.com>
> 
>    Info-last reuses the icon created for undo command.  Its file has the
>    name "undo.xpm" ...
> 
> which is a poor choice for an Info command since it is not an undo.

undo.xpm is used by the `undo' command; Info-last just reuses the
image.  I'm not sure it's such a bad thing, but if people think such
reuse is confusing, we could make a copy of the undo icon under the
name info-last or some such.

Re: Info-history-forward

[Juri Linkov]

"Eli Zaretskii" <eliz@gnu.org> writes:
>> From: Juri Linkov <juri@jurta.org>
>> Naturally, we could create a mirrored image, but how to name a new file?
>
> info-fwd.xpm or some such.

Then a better file name that describes the image instead of its use is
fwd_arrow.xpm (there is already right_arrow.xpm).  And maybe to rename
undo.xpm to back_arrow.xpm if this is necessary.

-- 
Juri Linkov
http://www.jurta.org/emacs/

Re: Info-history-forward

[Jan D.]

> "Eli Zaretskii" <eliz@gnu.org> writes:
>>> From: Juri Linkov <juri@jurta.org>
>>> Naturally, we could create a mirrored image, but how to name a new 
>>> file?
>>
>> info-fwd.xpm or some such.
>
> Then a better file name that describes the image instead of its use is
> fwd_arrow.xpm (there is already right_arrow.xpm).  And maybe to rename
> undo.xpm to back_arrow.xpm if this is necessary.

If you do decide to rename the image file, please make a note in README 
in lisp/toolbar so we don't forget that the original icon file in GTK 
is named undo.xpm.

Thanks,

	Jan D.

Re: Info-history-forward

[Eli Zaretskii]

> Cc: emacs-devel@gnu.org, Eli Zaretskii <eliz@gnu.org>
> From: "Jan D." <jan.h.d@swipnet.se>
> Date: Thu, 30 Dec 2004 09:16:28 +0100
> 
> >> info-fwd.xpm or some such.
> >
> > Then a better file name that describes the image instead of its use is
> > fwd_arrow.xpm (there is already right_arrow.xpm).  And maybe to rename
> > undo.xpm to back_arrow.xpm if this is necessary.
> 
> If you do decide to rename the image file, please make a note in README 
> in lisp/toolbar so we don't forget that the original icon file in GTK 
> is named undo.xpm.

In that case, it's probably better not to rename undo.xpm at all.

Re: Info-history-forward

[Richard Stallman]

    undo.xpm is used by the `undo' command; Info-last just reuses the
    image.  I'm not sure it's such a bad thing, but if people think such
    reuse is confusing, we could make a copy of the undo icon under the
    name info-last or some such.

It is confusing to use the same icon for "move back" and "undo".
We need two different icons, not just two different file names.

Re: Info-history-forward

[Juri Linkov]

Richard Stallman <rms@gnu.org> writes:
> It is confusing to use the same icon for "move back" and "undo".
> We need two different icons, not just two different file names.

Yes, different icons and files is a better solution.  The file names
would be the following:

back_arrow.xpm (+ lc-back_arrow.xpm, back_arrow.pbm)
fwd_arrow.xpm (+ lc-fwd_arrow.xpm, fwd_arrow.pbm)

As for icon images, I propose the image from undo.xpm (i.e. an arrow
with curly tail, and its mirrored image) with colors changed to
colors in up_arrow.xpm, right_arrow.xpm and left_arrow.xpm.

Another alternative would be standard images used for back/forward buttons
in Mozilla Firefox, but these images might be confused for left/right
arrows in right_arrow.xpm and left_arrow.xpm bound to Info-prev and Info-next.

-- 
Juri Linkov
http://www.jurta.org/emacs/

Re: Info-history-forward

[Chong Yidong]

> As for icon images, I propose the image from undo.xpm (i.e. an arrow
> with curly tail, and its mirrored image) with colors changed to
> colors in up_arrow.xpm, right_arrow.xpm and left_arrow.xpm.
>
> Another alternative would be standard images used for back/forward buttons
> in Mozilla Firefox, but these images might be confused for left/right
> arrows in right_arrow.xpm and left_arrow.xpm bound to Info-prev and
> Info-next.

We probably want to get the icon from GTK rather than Firefox. After all,
Emacs already uses several GTK "stock" icons. The icons can be found in
the gtk sources, or at

http://art.gnome.org/art-icons/gtk-stock/index.php

In particular, GTK's "undo" icon is probably what we want:

http://art.gnome.org/images/icons/gtk-stock/stock_undo_24.png

Re: Info-history-forward

[Richard Stallman]

    As for icon images, I propose the image from undo.xpm (i.e. an arrow
    with curly tail, and its mirrored image) with colors changed to
    colors in up_arrow.xpm, right_arrow.xpm and left_arrow.xpm.

    Another alternative would be standard images used for back/forward buttons
    in Mozilla Firefox, but these images might be confused for left/right
    arrows in right_arrow.xpm and left_arrow.xpm bound to Info-prev and Info-next.

I am not an icon connoisseur, so I will leave this up to others.

Re: Info-history-forward

[Juri Linkov]

"Chong Yidong" <cyd@stupidchicken.com> writes:
> We probably want to get the icon from GTK rather than Firefox. After all,
> Emacs already uses several GTK "stock" icons. The icons can be found in
> the gtk sources, or at
>
> http://art.gnome.org/art-icons/gtk-stock/index.php

Before making the proposal I already looked at all GTK stock icons
at http://cvs.gnome.org/viewcvs/gtk%2B/gtk/stock-icons/ and found
no more suitable icons than GTK "undo" icon with different colors.

> In particular, GTK's "undo" icon is probably what we want:
>
> http://art.gnome.org/images/icons/gtk-stock/stock_undo_24.png

As Richard already pointed out it is confusing to use "undo" icon for
"move back".

Could you find and suggest GTK icons for Info-history-back/forward
better than "undo" icon?

-- 
Juri Linkov
http://www.jurta.org/emacs/

Re: Info-history-forward

[Chong Yidong]

> As Richard already pointed out it is confusing to use "undo" icon for
> "move back".
>
> Could you find and suggest GTK icons for Info-history-back/forward
> better than "undo" icon?

The obvious choice would be the left-arrow and right-arrow icons, no?

http://art.gnome.org/images/icons/gtk-stock/stock_left_arrow_24.png
http://art.gnome.org/images/icons/gtk-stock/stock_right_arrow_24.png

Re: Info-history-forward

[Juri Linkov]

"Chong Yidong" <cyd@stupidchicken.com> writes:
>> Could you find and suggest GTK icons for Info-history-back/forward
>> better than "undo" icon?
>
> The obvious choice would be the left-arrow and right-arrow icons, no?
>
> http://art.gnome.org/images/icons/gtk-stock/stock_left_arrow_24.png
> http://art.gnome.org/images/icons/gtk-stock/stock_right_arrow_24.png

Exactly the same GTK icons are already used in Info for `Info-prev' and
`Info-next' commands.

There is a need for additional icons for `Info-history-back' and
`Info-history-forward'.

-- 
Juri Linkov
http://www.jurta.org/emacs/