bug#48307: Feature request: provide default keybindings to change the font size in all windows

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Clément Pit-Claudel]

Hi all,

Emacs has keybindings to change the font size in the current buffer (C-x C-=, etc which use text-scale-adjust).  We don't have keybindings for commands to change the font size globally, and in fact we don't have commands for that purpose at all, AFAICT.

My students keep running into this issue, and it seems pretty common online, too:
- https://stackoverflow.com/questions/18783227/emacs-zoom-in-out-globally
- https://stackoverflow.com/questions/24705984/increase-decrease-font-size-in-an-emacs-frame-not-just-buffer
- https://www.reddit.com/r/emacs/comments/dip6e6/zoom_in_zoom_out/

… and there are many libraries that reimplement solutions to this issue:
- https://www.emacswiki.org/emacs/download/zoom-frm.el
- https://practicalli.github.io/spacemacs/install-spacemacs/change-font.html
- https://github.com/purcell/default-text-scale
- https://www.emacswiki.org/emacs/GlobalTextScaleMode
- https://www.emacswiki.org/emacs/SetFonts#ZoomFrame

I'm sure many more people have custom code for this (I do).  Not all the implementations are good, and it would be very nice if such a feature were available out of the box.

Currently mouse-wheel-text-scale is bound to C-<mouse-5> and C-<mouse-4>; could we have an equivalent command for all buffers, maybe on C-S-<mouse-5> and C-S-<mouse-4>?

Clément.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Eli Zaretskii]

> From: Clément Pit-Claudel <cpitclaudel@gmail.com>
> Date: Sun, 9 May 2021 03:09:45 -0400
> 
> Emacs has keybindings to change the font size in the current buffer (C-x C-=, etc which use text-scale-adjust).  We don't have keybindings for commands to change the font size globally, and in fact we don't have commands for that purpose at all, AFAICT.
> 
> My students keep running into this issue, and it seems pretty common online, too:

It is not clear what should the requested feature do, and the links
you provided each talk about different aspects of the problem without
actually completely defining the requested functionality.

So: what should be the effect of this "global" change of the "font
size"?  Some thought-provoking questions:

 . should this affect only the faces whose fonts don't define their
   own size, or should it affect _all_ fonts?
 . should this really affect _all_ the buffers? e.g., what about the
   minibuffer and the echo-area buffers?
 . should this affect all the frames or just the currently selected
   frame? what about future frames?
 . should this affect the mode line?
 . should this affect tooltips?
 . should this affect the fringes and their bitmaps?
 . should this affect the menu bar, the drop-down menus, and the GUI
   dialogs?

We need a clear understanding of the feature before we implement it,
IMO.

Thanks.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[martin rudalics]

 > Currently mouse-wheel-text-scale is bound to C-<mouse-5> and
 > C-<mouse-4>; could we have an equivalent command for all buffers,
 > maybe on C-S-<mouse-5> and C-S-<mouse-4>?

I suppose you mean a command for all _frames_.  Any buffer-local text
scaling would still override that.

martin

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Clément Pit-Claudel]

On 5/9/21 4:43 AM, martin rudalics wrote:
>> Currently mouse-wheel-text-scale is bound to C-<mouse-5> and
>> C-<mouse-4>; could we have an equivalent command for all buffers,
>> maybe on C-S-<mouse-5> and C-S-<mouse-4>?
> 
> I suppose you mean a command for all _frames_.  Any buffer-local text
> scaling would still override that.

Sure: I meant something that scales the font in every window (and possibly in every frame, too, indeed)

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Clément Pit-Claudel]

On 5/9/21 4:23 AM, Eli Zaretskii wrote:
> So: what should be the effect of this "global" change of the "font
> size"?  Some thought-provoking questions:

Thanks.  Some wild guesses:

>  . should this affect only the faces whose fonts don't define their
>    own size, or should it affect _all_ fonts?

Probably all of them except the ones that specify an absolute height?

>  . should this really affect _all_ the buffers? e.g., what about the
>    minibuffer and the echo-area buffers?

Yes, certainly.

>  . should this affect all the frames or just the currently selected
>    frame? what about future frames?

I'm guessing all frames.

>  . should this affect the mode line?

Absolutely.

>  . should this affect tooltips?

Yes, to the extent that we have control over that.

>  . should this affect the fringes and their bitmaps?

That would be nice.

>  . should this affect the menu bar, the drop-down menus, and the GUI
>    dialogs?

That's extra credit; I guess it could be nice?

> We need a clear understanding of the feature before we implement it,
> IMO.

Indeed, although starting with an implementation and refining it over time could be good, too (to some extent I think the specifics matter less than having something available).  For example, just including any one of the short implementations into Emacs by default would work to solve the concrete issue that I'm talking about (with the pandemic we do screen-sharing all the time, and I hear "how do I resize the font in Emacs again?" more than once a week these days ^^).

A good approximation of what I would like that command to do is what menu-set-font does if you ignore the part about changing the face and only change the size part.  Something similar to doing text-scale-adjust in every buffer would also work, too (I've noticed that changing the :height attribute of the default face is slow, while text-scale-adjust is fast).  

bug#48307: [External] : bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Drew Adams]

> and there are many libraries that reimplement
> solutions to this issue:

Except for zoom-frm.el, which dates from 2005, those
all seem to date from at least 2013.

It doesn't really look like zoom-frm.el RE-implements
this.  It also looks to be the only one that lets you
use the same commands to text-scale (zoom individual
buffers - in all of their windows) or zoom frames
(zoom all windows in a frame).

As for zooming all frames together, zoom-frm.el has
commands `zoom-all-frames-(in|out)' for that.

But when it comes to zooming all frames in some way,
the questions Eli raised seem relevant, in general.

IMO, it's particularly useful to be able to optionally
(1) zoom a buffer everywhere, so all its windows show
its text at the same size _OR_ (2) show a buffer's text
at different sizes in different windows.  Text-scaling
does (only) #1.  Frame zooming allows #2.

bug#48307: [External] : bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Drew Adams]

> >> Currently mouse-wheel-text-scale is bound to C-<mouse-5> and
> >> C-<mouse-4>; could we have an equivalent command for all buffers,
> >> maybe on C-S-<mouse-5> and C-S-<mouse-4>?
> >
> > I suppose you mean a command for all _frames_.  Any buffer-local text
> > scaling would still override that.
> 
> Sure: I meant something that scales the font in every window (and possibly in
> every frame, too, indeed)

That's what frame-zooming does (in zoom-frm.el).
It just zooms in or out on a frame (or all frames).

(To be clear, zoom-frm.el doesn't zoom images etc.
It just affects font size.)

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Eli Zaretskii]

> Cc: 48307@debbugs.gnu.org
> From: Clément Pit-Claudel <cpitclaudel@gmail.com>
> Date: Sun, 9 May 2021 11:31:57 -0400
> 
> Indeed, although starting with an implementation and refining it over time could be good, too (to some extent I think the specifics matter less than having something available).  For example, just including any one of the short implementations into Emacs by default would work to solve the concrete issue that I'm talking about (with the pandemic we do screen-sharing all the time, and I hear "how do I resize the font in Emacs again?" more than once a week these days ^^).

Why not point them to Options->Set Default Font menu item?  That does
almost everything you asked for in your answer to my questions.  In
fact, given that we already have that menu item, it could be argued we
already have the feature implemented.

bug#48307: [External] : bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Drew Adams]

> >  . should this affect only the faces whose fonts don't define their
> >    own size, or should it affect _all_ fonts?
> 
> Probably all of them except the ones that specify
> an absolute height?

Frame zooming does that.

> >  . should this really affect _all_ the buffers? e.g.,
> > what about the minibuffer and the echo-area buffers?
> 
> Yes, certainly.

Frame zooming does that.

> >  . should this affect the mode line?
> 
> Absolutely.

Frame zooming does that.

> >  . should this affect tooltips?
> 
> Yes, to the extent that we have control over that.

Frame zooming does not do that.

(And I, for one, don't think I would want that.  Maybe
it could be an optional behavior, if there's really a
use case for it.)

> >  . should this affect the fringes and their bitmaps?
> 
> That would be nice.

Frame zooming does not do that.

Likewise, it doesn't zoom scroll bar width.  But it would
certainly be possible to zoom such things (and tooltips).
That should likely be optional - be able to specify for
_each_ such non-font thing whether to zoom it when zooming
a frame.

> >  . should this affect the menu bar, the drop-down menus, and the GUI
> >    dialogs?
> 
> That's extra credit; I guess it could be nice?

Frame zooming does not do that.
 
> I hear "how do I resize the font in Emacs again?"
> more than once a week these days

There are likely many things in Emacs that people
learn and forget, if they don't use them often.
And not just Emacs.  I'm sure you're used to that,
as a teacher.

> A good approximation of what I would like that
> command to do is what menu-set-font does if you
> ignore the part about changing the face and only
> change the size part.

Frame zooming does that.

> Something similar to doing text-scale-adjust in
> every buffer would also work, too

That wouldn't let you show parts of the same buffer
in different windows with text show at different
sizes.

bug#48307: [External] : bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Drew Adams]

> > I hear "how do I resize the font in Emacs again?"
> > more than once a week these days ^^).
> 
> Why not point them to Options->Set Default Font menu item?  That does
> almost everything you asked for in your answer to my questions.  In
> fact, given that we already have that menu item, it could be argued we
> already have the feature implemented.

For only that use case, that suffices, indeed.

But this enhancement request is about _incrementally_
zooming (I think); that is, the kind of thing you do
with `C-x (+|-)'.

Users of other apps, especially browsers, are used to
using, say, `C-(+-)' or `C-wheel-(up|down)' to zoom
the browser window.

(You can also a mouse wheel for frame zooming with
zoom-frm.el.  I use that most of the time, not
`C-x (+|-)'.)

bug#48307: [External] : bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Eli Zaretskii]

> From: Drew Adams <drew.adams@oracle.com>
> CC: "48307@debbugs.gnu.org" <48307@debbugs.gnu.org>
> Date: Sun, 9 May 2021 16:39:33 +0000
> 
> > > I hear "how do I resize the font in Emacs again?"
> > > more than once a week these days ^^).
> > 
> > Why not point them to Options->Set Default Font menu item?  That does
> > almost everything you asked for in your answer to my questions.  In
> > fact, given that we already have that menu item, it could be argued we
> > already have the feature implemented.
> 
> For only that use case, that suffices, indeed.
> 
> But this enhancement request is about _incrementally_
> zooming (I think); that is, the kind of thing you do
> with `C-x (+|-)'.

When you click on that menu item, Emacs pops up a GUI font selection
dialog, where you can increase or decrease the font size.  So if the
font you selected doesn't fit, you can do the same again and pick up a
different size.

IOW, no one said that this has to be done with a key sequence that has
"+" or "-" as its part.

Of course writing a wrapper for that command whcih is bound to mouse
wheel with some modifier should be trivial if that's the main issue
here; patches welcome.  I thought the request was for a non-existing
feature, so I pointed out that it already exists.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Gregory Heytings]

>
> Not all the implementations are good, and it would be very nice if such 
> a feature were available out of the box.
>

Would the following do what you want?

(defun global-text-scale-adjust-do (increment)
   (set-face-attribute 'default nil :height
 		      (+ (face-attribute 'default :height) increment))
   (message "Use + and - for further adjustment")
   (set-transient-map
    (let ((map (make-sparse-keymap)))
      (define-key map (kbd "+") 'global-text-scale-adjust-increase)
      (define-key map (kbd "-") 'global-text-scale-adjust-decrease)
      map)))
(defun global-text-scale-adjust-increase ()
   (interactive)
   (global-text-scale-adjust-do +5))
(defun global-text-scale-adjust-decrease ()
   (interactive)
   (global-text-scale-adjust-do -5))
(global-set-key (kbd "C-x M-+") 'global-text-scale-adjust-increase)
(global-set-key (kbd "C-x M--") 'global-text-scale-adjust-decrease)

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Clément Pit-Claudel]

On 5/9/21 4:16 PM, Gregory Heytings wrote:
>> Not all the implementations are good, and it would be very nice if such a feature were available out of the box.
>>
> 
> Would the following do what you want?
> 
> (defun global-text-scale-adjust-do (increment)
>   (set-face-attribute 'default nil :height
>               (+ (face-attribute 'default :height) increment))
>   (message "Use + and - for further adjustment")
>   (set-transient-map
>    (let ((map (make-sparse-keymap)))
>      (define-key map (kbd "+") 'global-text-scale-adjust-increase)
>      (define-key map (kbd "-") 'global-text-scale-adjust-decrease)
>      map)))
> (defun global-text-scale-adjust-increase ()
>   (interactive)
>   (global-text-scale-adjust-do +5))
> (defun global-text-scale-adjust-decrease ()
>   (interactive)
>   (global-text-scale-adjust-do -5))
> (global-set-key (kbd "C-x M-+") 'global-text-scale-adjust-increase)
> (global-set-key (kbd "C-x M--") 'global-text-scale-adjust-decrease)

Yup, probably.  The performance isn't great, but that's more or less what I have in my .emacs.

bug#48307: [External] : bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Clément Pit-Claudel]

On 5/9/21 11:58 AM, Drew Adams wrote:
> It doesn't really look like zoom-frm.el RE-implements this.

Sorry if the term RE-implementing ruffled feathers.  If zoom-frm works well and can be merged into Emacs, then it would fit the bill perfectly, I expect.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Gregory Heytings]

>
> Yup, probably.
>

Why "probably"?  Is something missing?

>
> The performance isn't great,
>

Of course, if you need to recalculate all fonts and redisplay all frames, 
it takes some time.  But AFAICS the performance is similar to the one of, 
say, Chromium or Visual Studio when you press C-+ and C--.  The effect is 
not immediate.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Clément Pit-Claudel]

On 5/9/21 6:03 PM, Gregory Heytings wrote:
> 
>>
>> Yup, probably.
>>
> 
> Why "probably"?  Is something missing?

I'm not sure: I don't know if this is the right implementation, or if there's something subtly wrong about it.  It looks good to me (though it's missing a command to go back to the original size), but since there are many implementations that use different strategies I had concluded that there must be some subtlety.

>> The performance isn't great,
>>
> 
> Of course, if you need to recalculate all fonts and redisplay all frames, it takes some time.  But AFAICS the performance is similar to the one of, say, Chromium or Visual Studio when you press C-+ and C--.  The effect is not immediate.

There's something more subtle happening, because using text-scale-adjust is much faster, even on a frame with a single buffer.

bug#48307: [External] : bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Clément Pit-Claudel]

On 5/9/21 12:58 PM, Eli Zaretskii wrote:
> Of course writing a wrapper for that command whcih is bound to mouse
> wheel with some modifier should be trivial if that's the main issue
> here; patches welcome.  I thought the request was for a non-existing
> feature, so I pointed out that it already exists.

Sorry, it sounds like the original request was unclear.  Drew's description is pretty good.  The request is specifically for a new keybinding; it may well be that the code that goes behind it is trivial.

I'd love to provide a patch, but I have no idea what it should say.   I've counted 5 different implementations of the functionality (6 now with Gregory's).  All are acceptable, and I don't know enough about Emacs' fonts to judge which one is best, or whether they're all equally reasonable (for example Gregory uses set-face-attribute, and Steve uses face-spec-set in default-text-scale.el).

On 5/9/21 12:08 PM, Eli Zaretskii wrote:
> In fact, given that we already have that menu item, it could be argued we
> already have the feature implemented.

Almost, yes.  What we're missing are commands for incrementing and decrementing the size interactively; we only menu-set-font.  It's indeed what I recommend that people use when they ask. It's pretty good, even though sometimes (depending on how the user configured fonts in the first place) it starts with the wrong size and font, so you have to scroll through the list.  

Sorry for not mentioning menu-set-font explicitly in the original message.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Gregory Heytings]

>
> I'm not sure: I don't know if this is the right implementation, or if 
> there's something subtly wrong about it.  It looks good to me (though 
> it's missing a command to go back to the original size), but since there 
> are many implementations that use different strategies I had concluded 
> that there must be some subtlety.
>

I don't know.  It's certainly possible to do something more complex, but 
this is equivalent to changing the size with Options -> Set Default Font.

>
> There's something more subtle happening, because using text-scale-adjust 
> is much faster, even on a frame with a single buffer.
>

Again I don't know, but I don't think so.  AFAICS it's faster because 
redisplaying a single buffer without changing the window and frame size is 
faster than redisplaying all buffers in a frame and resizing the frame 
itself.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[martin rudalics]

 >> I suppose you mean a command for all _frames_.  Any buffer-local text
 >> scaling would still override that.
 >
 > Sure: I meant something that scales the font in every window (and
 > possibly in every frame, too, indeed)

There is one subtle difference you should be aware of:

(1) If you change the size of the default font of a live frame, that
     frame's size may change unless you rule out implied resizing for it.

(2) If you change the font in all windows showing a buffer by adjusting
     that buffer's text scaling, frame sizes will stay the same.

So you have to be precise about the "something that scales" you want.

martin

bug#48307: [External] : bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Drew Adams]

> There is one subtle difference you should be aware of:
> 
> (1) If you change the size of the default font of a live frame, that
>      frame's size may change unless you rule out implied resizing for
>      it.
> 
> (2) If you change the font in all windows showing a buffer by adjusting
>      that buffer's text scaling, frame sizes will stay the same.
> 
> So you have to be precise about the "something that scales" you want.

Indeed.  Zooming (text scaling or frame zooming) and
fitting windows or frames to buffer text are different
things.  There should be ways to get different
combinations (e.g. autofit window/frame or not).

To enable windows to show the same text (e.g. without
wrapping or introducing extra blank space at the
right), I introduced option `text-scale-resize-window'.

It lets you automatically resize the selected window
(horizontally, vertically, or both) when text is
resized, so that the way the window fits the buffer
text remains relatively constant.

Shrinking the text in one window shrinks that window,
giving more space to adjacent windows.

If you also use library `fit-frame.el', then 1-window
frames also respond to text resizing by scaling.  If
not, then the text-scale commands have no effect on
frame size for one-window frames.

(I tried to get Emacs to add such an option, but had
no luck with that.)

https://www.emacswiki.org/emacs/download/face-remap%2b.el

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Gregory Heytings]

[-- Attachment #1: Type: text/plain, Size: 269 bytes --]


Thanks for mentioning frame-inhibit-implied-resize, I did not know it 
exists.

I attach a patch that does, I believe, what Clément has in mind. 
Comments and feedback welcome.

Note that this patch can't be applied yet, my paperwork is still not 
finished :(

[-- Attachment #2: Type: text/x-diff, Size: 7718 bytes --]

From d0316d6264ab0ccbfe7fcb77aae8549a25fc14ff Mon Sep 17 00:00:00 2001
From: Gregory Heytings <gregory@heytings.org>
Date: Mon, 10 May 2021 14:06:37 +0000
Subject: [PATCH] Global adjustments to the default face

* lisp/face-remap.el (global-text-scale-adjust): New command.
(text-scale-adjust): Refer to the new related command.

* lisp/mwheel.el (mouse-wheel-scroll-amount): Add the new command
to the mouse wheel scrolling events.
(mouse-wheel-global-text-scale): New function.
(mouse-wheel-mode): Use	the new function with mouse-wheel-mode.

* doc/emacs/display.texi (Text Scale): Document the new command.

* etc/NEWS: Mention the new command and its bindings.
---
 doc/emacs/display.texi | 11 +++++++++
 etc/NEWS               | 10 ++++++++
 lisp/face-remap.el     | 56 +++++++++++++++++++++++++++++++++++++++++-
 lisp/mwheel.el         | 19 +++++++++++++-
 4 files changed, 94 insertions(+), 2 deletions(-)

diff --git a/doc/emacs/display.texi b/doc/emacs/display.texi
index 58d08b43c0..1e499f247c 100644
--- a/doc/emacs/display.texi
+++ b/doc/emacs/display.texi
@@ -837,6 +837,17 @@ Text Scale
 to the @code{text-scale-adjust} command restores the default height,
 the same as typing @kbd{C-x C-0}.
 
+@cindex ajust global face height
+@findex global-text-scale-adjust
+@kindex C-x C-M-+
+@kindex C-x C-M--
+@kindex C-x C-M-0
+@kindex C-M-wheel-down
+@kindex C-M-wheel-up
+  Similarly, to change the height of the default face globally, type
+@kbd{C-x C-M-+}, @kbd{C-x C-M--} or @kbd{C-x C-M-0}, or scroll the
+mouse wheel with the @kbd{Ctrl} and @kbd{Meta} modifiers pressed.
+
 @cindex increase buffer face height
 @findex text-scale-increase
 @cindex decrease buffer face height
diff --git a/etc/NEWS b/etc/NEWS
index c759b333b6..2a1161b75f 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -399,6 +399,16 @@ When this option is set, direction changes in Isearch move to another
 search match, if there is one, instead of moving point to the other
 end of the current match.
 
++++
+** New command to change the default face height globally.
+To increase it, type 'C-x C-M-+'; to decrease it, type 'C-x C-M--';
+to restore the default face height, type 'C-x C-M-0'.  The final key
+in these commands may be repeated without the leading 'C-x' and without
+the modifier, e.g. 'C-x C-M-+ C-M-+ C-M-+' and 'C-x C-M-+ + +' increase
+the default face height by three steps.  When mouse-wheel-mode is
+enabled, 'C-M-wheel-up' and 'C-M-wheel-down' also increase and decrease
+the default face height globally.
+
 ** Outline
 
 +++
diff --git a/lisp/face-remap.el b/lisp/face-remap.el
index 5914ee4a20..f4a52dfb54 100644
--- a/lisp/face-remap.el
+++ b/lisp/face-remap.el
@@ -371,7 +371,9 @@ text-scale-adjust
 `text-scale-increase' command which makes repetition convenient
 even when it is bound in a non-top-level keymap.  For binding in
 a top-level keymap, `text-scale-increase' or
-`text-scale-decrease' may be more appropriate."
+`text-scale-decrease' may be more appropriate.
+
+See also the related command `global-text-scale-adjust'."
   (interactive "p")
   (let ((ev last-command-event)
 	(echo-keystrokes nil))
@@ -393,6 +395,58 @@ text-scale-adjust
                (lambda () (interactive) (text-scale-adjust (abs inc))))))
          map))))) ;; )
 
+(defvar global-text-scale-adjust--default-height nil)
+
+;;;###autoload (define-key ctl-x-map [(control meta ?+)] 'global-text-scale-adjust)
+;;;###autoload (define-key ctl-x-map [(control meta ?-)] 'global-text-scale-adjust)
+;;;###autoload (define-key ctl-x-map [(control meta ?0)] 'global-text-scale-adjust)
+;;;###autoload
+(defun global-text-scale-adjust (increment)
+  "Globally adjust the height of the default face by INCREMENT.
+
+INCREMENT may be passed as a numeric prefix argument.
+
+The adjustment made depends on the final component of the key binding
+used to invoke the command, with all modifiers removed:
+
+   +   Globally increase the height of the default face
+   -   Globally decrease the height of the default face
+   0   Globally reset the height of the default face
+
+After adjusting, further adjust the default face height as long as the
+key, with all modifiers removed, is one of the above characters.
+
+Buffer-local face adjustements remain in effect when global face
+adjustments are made.
+
+See also the related command `text-scale-adjust'."
+  (interactive "p")
+  (when (display-graphic-p)
+    (unless global-text-scale-adjust--default-height
+      (setq global-text-scale-adjust--default-height
+            (face-attribute 'default :height)))
+    (let ((event last-command-event)
+          (echo-keystrokes nil))
+      (let* ((key (event-basic-type event))
+             (inc
+              (pcase key
+                (?+ (* increment 5))
+                (?- (* (- increment) 5))
+                (?0 (- global-text-scale-adjust--default-height
+                       (face-attribute 'default :height)))
+                (_ (* increment 5)))))
+        (let ((frame-inhibit-implied-resize t))
+          (set-face-attribute 'default nil :height
+                              (+ (face-attribute 'default :height) inc)))
+        (message "Use +,-,0 for further adjustment")
+        (set-transient-map
+         (let ((map (make-sparse-keymap)))
+           (dolist (mod '(() (control meta)))
+             (dolist (key '(?+ ?- ?0))
+               (define-key map (vector (append mod (list key)))
+                 'global-text-scale-adjust)))
+           map))))))
+
 \f
 ;; ----------------------------------------------------------------
 ;; buffer-face-mode
diff --git a/lisp/mwheel.el b/lisp/mwheel.el
index 048f50c772..d5944fef7e 100644
--- a/lisp/mwheel.el
+++ b/lisp/mwheel.el
@@ -84,7 +84,10 @@ mouse-wheel-inhibit-click-time
   :type 'number)
 
 (defcustom mouse-wheel-scroll-amount
-  '(1 ((shift) . hscroll) ((meta) . nil) ((control) . text-scale))
+  '(1 ((shift) . hscroll)
+      ((meta) . nil)
+      ((control meta) . global-text-scale)
+      ((control) . text-scale))
   "Amount to scroll windows by when spinning the mouse wheel.
 This is an alist mapping the modifier key to the amount to scroll when
 the wheel is moved with the modifier key depressed.
@@ -377,6 +380,16 @@ mouse-wheel-text-scale
                (text-scale-decrease 1)))
       (select-window selected-window))))
 
+(defun mouse-wheel-global-text-scale (event)
+  "Increase or decrease the global height of the default face according to the EVENT."
+  (interactive (list last-input-event))
+  (let ((button (mwheel-event-button event)))
+    (unwind-protect
+        (cond ((eq button mouse-wheel-down-event)
+               (global-text-scale-adjust 1))
+              ((eq button mouse-wheel-up-event)
+               (global-text-scale-adjust -1))))))
+
 (defvar mouse-wheel--installed-bindings-alist nil
   "Alist of all installed mouse wheel key bindings.")
 
@@ -433,6 +446,10 @@ mouse-wheel-mode
         (dolist (event (list mouse-wheel-down-event mouse-wheel-up-event))
           (mouse-wheel--add-binding `[,(list (caar binding) event)]
                                     'mouse-wheel-text-scale)))
+       ((and (consp binding) (eq (cdr binding) 'global-text-scale))
+        (dolist (event (list mouse-wheel-down-event mouse-wheel-up-event))
+          (mouse-wheel--add-binding `[,(append (car binding) (list event))]
+                                    'mouse-wheel-global-text-scale)))
        ;; Bindings for scrolling.
        (t
         (dolist (event (list mouse-wheel-down-event mouse-wheel-up-event
-- 
2.30.2

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Eli Zaretskii]

> Date: Sun, 09 May 2021 22:56:34 +0000
> From: Gregory Heytings <gregory@heytings.org>
> Cc: 48307@debbugs.gnu.org
> 
> > There's something more subtle happening, because using text-scale-adjust 
> > is much faster, even on a frame with a single buffer.
> 
> Again I don't know, but I don't think so.  AFAICS it's faster because 
> redisplaying a single buffer without changing the window and frame size is 
> faster than redisplaying all buffers in a frame and resizing the frame 
> itself.

Enlarging the frame means we also interact with the WM and await its
response, no?

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Gregory Heytings]

>>> There's something more subtle happening, because using 
>>> text-scale-adjust is much faster, even on a frame with a single 
>>> buffer.
>>
>> Again I don't know, but I don't think so.  AFAICS it's faster because 
>> redisplaying a single buffer without changing the window and frame size 
>> is faster than redisplaying all buffers in a frame and resizing the 
>> frame itself.
>
> Enlarging the frame means we also interact with the WM and await its 
> response, no?
>

The patch I just sent avoids that problem, and does what other programs do 
when the user zooms: their frames are not resized.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Eli Zaretskii]

> Date: Mon, 10 May 2021 14:17:55 +0000
> From: Gregory Heytings <gregory@heytings.org>
> Cc: Clément Pit-Claudel <cpitclaudel@gmail.com>,
>  48307@debbugs.gnu.org
> 
> +        (let ((frame-inhibit-implied-resize t))
> +          (set-face-attribute 'default nil :height
> +                              (+ (face-attribute 'default :height) inc)))

Why does it make sense to inhibit frame resizing in this case?  I
think it will make an ugly display: mode-line text will spill over,
lines will become wrapped, etc.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Eli Zaretskii]

> Date: Mon, 10 May 2021 14:24:35 +0000
> From: Gregory Heytings <gregory@heytings.org>
> cc: cpitclaudel@gmail.com, 48307@debbugs.gnu.org
> 
> The patch I just sent avoids that problem, and does what other programs do 
> when the user zooms: their frames are not resized.

I think it's a mistake.  Other programs don't change all the fonts on
display, only the one in the main window, which is more similar to
text-scale-adjust.  This feature was supposed to change _everything_,
which is why it modifies the default face.

bug#48307: [External] : bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Drew Adams]

> The patch I just sent avoids that problem, and does what other
> programs do when the user zooms: their frames are not resized.

Doing just what other programs do can be good or bad -
a blessing or a curse.  It's often better to be able to
do so, but not be limited to doing so.

Not resizing the frame to continue to show the buffer
in the same way within it (e.g. perhaps no wrapping
and no wasted blank space at the right) is not
necessarily what a given user wants in a given context.

I use automatic fitting of frames to the (single) buffer
shown in them, by default.  Zooming a frame, and having
it continue to fit the text the same way, is a feature,
not a bug.  Like most features, it should of course be
optional.

As I mentioned in a earlier mail in this thread today,
I provided similar optional behavior for text scaling.

Zooming out by text scaling shouldn't necessarily add,
in effect, a lot of blank space at the right.  (I like
to avoid such wasted space, whether it's for windows
or frames, in general.)

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Gregory Heytings]

>> +        (let ((frame-inhibit-implied-resize t))
>> +          (set-face-attribute 'default nil :height
>> +                              (+ (face-attribute 'default :height) inc)))
>
> Why does it make sense to inhibit frame resizing in this case?  I think 
> it will make an ugly display: mode-line text will spill over, lines will 
> become wrapped, etc.
>

Because (1) it's what other programs do, (2) it's also what 
text-scale-adjust does, (3) it's much faster, (4) if you do not inhibit 
frame resizing the frame can easily become larger than your screen.  Note 
that global-text-scale-adjust uses smaller steps than text-scale-adjust, 
so the user can more easily control the potential undesirable effects.

bug#48307: [External] : bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Drew Adams]

> > Why does it make sense to inhibit frame resizing in this case?  I
> > think it will make an ugly display: mode-line text will spill over,
> > lines will become wrapped, etc.
> >
> 
> Because (1) it's what other programs do,

See what I wrote.  That can be good and bad.
Why limit Emacs to what other programs do?

> (2) it's also what text-scale-adjust does,

See what I wrote.  Text scaling too can benefit from
being able to fit window size to text, to keep what
you see pretty much the same regardless of zoom 
factor.

> (3) it's much faster, (4) if you do not inhibit
> frame resizing the frame can easily become larger
> than your screen.

Depends on what the code resizing the frame does.
Nothing requires frame resizing not to respect
screen boundaries.  (But yes, usually it's a
_feature_ that you can have part of a window-mgr
window (frame) off-screen.)

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Clément Pit-Claudel]

On 5/10/21 10:26 AM, Eli Zaretskii wrote:
>> Date: Mon, 10 May 2021 14:17:55 +0000
>> From: Gregory Heytings <gregory@heytings.org>
>> Cc: Clément Pit-Claudel <cpitclaudel@gmail.com>,
>>  48307@debbugs.gnu.org
>>
>> +        (let ((frame-inhibit-implied-resize t))
>> +          (set-face-attribute 'default nil :height
>> +                              (+ (face-attribute 'default :height) inc)))
> 
> Why does it make sense to inhibit frame resizing in this case?  I
> think it will make an ugly display: mode-line text will spill over,
> lines will become wrapped, etc.

I think preventing frame resizing is the right move, at least in the context that I had in mind (screen sharing): if you scale the frame and the font at once, then nothing changes on the recipient's screen (since the videoconferencing software scales the frame to a constant size).

(Besides, that's what menu-set-font does; and it's easy to resize the frame after scaling the font, no?)

bug#48307: [External] : bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Gregory Heytings]

[-- Attachment #1: Type: text/plain, Size: 731 bytes --]


>>> Why does it make sense to inhibit frame resizing in this case?  I 
>>> think it will make an ugly display: mode-line text will spill over, 
>>> lines will become wrapped, etc.
>>
>> Because (1) it's what other programs do,
>
> See what I wrote.  That can be good and bad. Why limit Emacs to what 
> other programs do?
>

I don't want to limit Emacs to anything... but not everything can be bound 
to a key or a mouse event.  Perhaps this could become a defcustom, 
defaulting to t?  I tried to understand what Clément had in mind, and IIUC 
my understanding was right.

I will not use that feature, but I tried both frame-inhibit-implied-resize 
nil and t, and I'd guess that t is what most users would want.

bug#48307: [External] : bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Drew Adams]

> > Why does it make sense to inhibit frame resizing in this case?  I
> > think it will make an ugly display: mode-line text will spill over,
> > lines will become wrapped, etc.
> 
> I think preventing frame resizing is the right move,

There's no single "right" move, here, IMO.  Which
behavior should be the _default_ one is a different
question.  But both behaviors should be possible -
each has its uses.

> at least in the context that I had in mind (screen sharing)

Exactly - see above.  That's a particular context.

> (Besides, that's what menu-set-font does;

Not very relevant, IMO, but OK.  Again, this is a
consideration, perhaps, for which behavior to choose
as default.

> and it's easy to resize the frame after scaling the font, no?)

No.  It's not so easy to get right, e.g. to keep the
same fit as before zooming (text scaling or frame
zooming).  And someone who wants that likely doesn't
want to have to do it manually each time.

bug#48307: [External] : bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Drew Adams]

> >>> Why does it make sense to inhibit frame resizing in this case?  I
> >>> think it will make an ugly display: mode-line text will spill over,
> >>> lines will become wrapped, etc.
> >>
> >> Because (1) it's what other programs do,
> >
> > See what I wrote.  That can be good and bad. Why limit Emacs to what
> > other programs do?
> 
> I don't want to limit Emacs to anything... but not everything can be
> bound to a key or a mouse event.  Perhaps this could become a defcustom,
> defaulting to t?

,----
| text-scale-resize-window is a variable defined in `face-remap+.el'.
| 
| Its value is t
| 
| Documentation:
| Non-nil means text scaling resizes the window or frame accordingly.
| For example, if you use `C-x C--' (`text-scale-decrease')' to make the
| text smaller, then the window or frame is made smaller by a similar
| factor.
| 
| If the window is not alone in its frame, then the window is resized.
| Otherwise, the frame is resized (provided you also use library
| `fit-frame.el').  The frame is always resized both horizontally and
| vertically.
| 
| You can customize this variable.
`----

bug#48307: [External] : bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Clément Pit-Claudel]

On 5/10/21 11:22 AM, Drew Adams wrote:
>>> Why does it make sense to inhibit frame resizing in this case?  I
>>> think it will make an ugly display: mode-line text will spill over,
>>> lines will become wrapped, etc.
>>
>> I think preventing frame resizing is the right move,
> 
> There's no single "right" move, here, IMO.  Which
> behavior should be the _default_ one is a different
> question.  But both behaviors should be possible -
> each has its uses.

Well, there's a concrete request that stems from a concrete need — my students and colleagues running into trouble when sharing their screen.  Of course, I don't have objections to including other features.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Eli Zaretskii]

> Cc: rudalics@gmx.at, 48307@debbugs.gnu.org
> From: Clément Pit-Claudel <cpitclaudel@gmail.com>
> Date: Mon, 10 May 2021 10:53:57 -0400
> 
> (Besides, that's what menu-set-font does

No, it doesn't, at least not here.  My frame is resized when I choose
the same font of a different size.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Gregory Heytings]

[-- Attachment #1: Type: text/plain, Size: 863 bytes --]


>> The patch I just sent avoids that problem, and does what other programs 
>> do when the user zooms: their frames are not resized.
>
> I think it's a mistake.  Other programs don't change all the fonts on 
> display, only the one in the main window, which is more similar to 
> text-scale-adjust.  This feature was supposed to change _everything_, 
> which is why it modifies the default face.
>

Indeed, but that feature is already present on C-x C-{+-0}.  And I don't 
know any other program that changes its frame size when a zoom factor is 
applied.

What the existing C-x C-{+-0} does is what C-{+-0} does in Atom.  What the 
proposed C-x C-M-{+-0} does is what C-{+-0} does in Visual Studio.

As I said, I would not object to make this configurable with a defcustom, 
which would default to "do not resize".  Would you agree with that?

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Clément Pit-Claudel]

On 5/10/21 12:16 PM, Eli Zaretskii wrote:
>> Cc: rudalics@gmx.at, 48307@debbugs.gnu.org
>> From: Clément Pit-Claudel <cpitclaudel@gmail.com>
>> Date: Mon, 10 May 2021 10:53:57 -0400
>>
>> (Besides, that's what menu-set-font does
> 
> No, it doesn't, at least not here.  My frame is resized when I choose
> the same font of a different size.

Good catch.  But not past the size of the screen, it seems.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Clément Pit-Claudel]

On 5/10/21 10:17 AM, Gregory Heytings wrote:

> Thanks for mentioning frame-inhibit-implied-resize, I did not know it exists.
> 
> I attach a patch that does, I believe, what Clément has in mind. Comments and feedback welcome.
> 
> Note that this patch can't be applied yet, my paperwork is still not finished :(

The patch looks good, thanks!.  You could bind combinations with '=', too, since text-scale-adjust does that (you can press = instead of +).  

More complicated: I wonder if it'd be easy to ignore repeated delayed input. As it stands, keeping '+' pressed will zoom in continuously, and continue zooming in after '+' is released, until all buffered repeated '+' inputs are processed.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Gregory Heytings]

>
> More complicated: I wonder if it'd be easy to ignore repeated delayed 
> input. As it stands, keeping '+' pressed will zoom in continuously, and 
> continue zooming in after '+' is released, until all buffered repeated 
> '+' inputs are processed.
>

What do you mean exactly by "ignore repeated delayed input"?  Do you want 
to "throw away" the remaining "+" keys when "+" is released?  Or do you 
want to disable the zoom effect, count the "+" keypresses, and apply the 
effect of all the keys in one go?

(My computer is a bit too fast I guess, I cannot see what you see.)

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Clément Pit-Claudel]

On 5/10/21 2:16 PM, Gregory Heytings wrote:
> 
>>
>> More complicated: I wonder if it'd be easy to ignore repeated delayed input. As it stands, keeping '+' pressed will zoom in continuously, and continue zooming in after '+' is released, until all buffered repeated '+' inputs are processed.
>>
> 
> What do you mean exactly by "ignore repeated delayed input"?  Do you want to "throw away" the remaining "+" keys when "+" is released?

This one.

> (My computer is a bit too fast I guess, I cannot see what you see.)

Either that, or my keyboard is fast :)  Try adding (sleep-for 1) right before the font size adjustment, then press "+" for a second or so and release it.  Emacs will keep processing the delayed "+" input and keep zooming.

Not sure that it matters much.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Eli Zaretskii]

> From: Clément Pit-Claudel <cpitclaudel@gmail.com>
> Date: Mon, 10 May 2021 14:34:58 -0400
> Cc: 48307@debbugs.gnu.org
> 
> Either that, or my keyboard is fast :)  Try adding (sleep-for 1) right before the font size adjustment, then press "+" for a second or so and release it.  Emacs will keep processing the delayed "+" input and keep zooming.

I don't think that Emacs can know when the user stopped pressing the
keys.  Without that, how can we know when to discard keypresses still
in the queue.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Clément Pit-Claudel]

On 5/10/21 2:46 PM, Eli Zaretskii wrote:
>> From: Clément Pit-Claudel <cpitclaudel@gmail.com>
>> Date: Mon, 10 May 2021 14:34:58 -0400
>> Cc: 48307@debbugs.gnu.org
>>
>> Either that, or my keyboard is fast :)  Try adding (sleep-for 1) right before the font size adjustment, then press "+" for a second or so and release it.  Emacs will keep processing the delayed "+" input and keep zooming.
> 
> I don't think that Emacs can know when the user stopped pressing the
> keys.  Without that, how can we know when to discard keypresses still
> in the queue.

Got it, thanks.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Gregory Heytings]

[-- Attachment #1: Type: text/plain, Size: 134 bytes --]


Here is the updated patch with, as discussed, a new user option to control 
the frame resizing, and the additional C-x C-M-= binding.

[-- Attachment #2: Type: text/x-diff, Size: 8768 bytes --]

From e1d50941106519fd0b2ad97adbd66cb4ee9c621b Mon Sep 17 00:00:00 2001
From: Gregory Heytings <gregory@heytings.org>
Date: Mon, 10 May 2021 19:28:43 +0000
Subject: [PATCH] Global adjustments to the default face

* lisp/face-remap.el (global-text-scale-adjust): New command.
(text-scale-adjust): Refer to the new related command.
(global-text-scale-adjust-resizes-frames): New user option.

* lisp/mwheel.el (mouse-wheel-scroll-amount): Add the new command
to the mouse wheel scrolling events.
(mouse-wheel-global-text-scale): New function.
(mouse-wheel-mode): Use the new function with mouse-wheel-mode.

* doc/emacs/display.texi (Text Scale): Document the new command and
the new user option.

* etc/NEWS: Mention the new command and its bindings, and the new
user option.
---
 doc/emacs/display.texi | 16 ++++++++++
 etc/NEWS               | 12 ++++++++
 lisp/face-remap.el     | 68 +++++++++++++++++++++++++++++++++++++++++-
 lisp/mwheel.el         | 19 +++++++++++-
 4 files changed, 113 insertions(+), 2 deletions(-)

diff --git a/doc/emacs/display.texi b/doc/emacs/display.texi
index 58d08b43c0..44c27e7db8 100644
--- a/doc/emacs/display.texi
+++ b/doc/emacs/display.texi
@@ -837,6 +837,22 @@ Text Scale
 to the @code{text-scale-adjust} command restores the default height,
 the same as typing @kbd{C-x C-0}.
 
+@cindex ajust global face height
+@findex global-text-scale-adjust
+@kindex C-x C-M-+
+@kindex C-x C-M-=
+@kindex C-x C-M--
+@kindex C-x C-M-0
+@kindex C-M-wheel-down
+@kindex C-M-wheel-up
+  Similarly, to change the height of the default face globally, type
+@kbd{C-x C-M-+}, @kbd{C-x C-M-=}, @kbd{C-x C-M--} or @kbd{C-x C-M-0},
+or scroll the mouse wheel with both the @kbd{Ctrl} and @kbd{Meta}
+modifiers pressed.  To enable frame resizing when the height of the
+default face is changed globally, customize the variable
+@code{global-text-scale-adjust-resizes-frames} (@pxref{Easy
+Customization}).
+
 @cindex increase buffer face height
 @findex text-scale-increase
 @cindex decrease buffer face height
diff --git a/etc/NEWS b/etc/NEWS
index c759b333b6..7f7a0d8669 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -399,6 +399,18 @@ When this option is set, direction changes in Isearch move to another
 search match, if there is one, instead of moving point to the other
 end of the current match.
 
++++
+** New command to change the default face height globally.
+To increase it, type 'C-x C-M-+' or 'C-x C-M-='; to decrease it, type
+'C-x C-M--'; to restore the default face height, type 'C-x C-M-0'.
+The final key in these commands may be repeated without the leading
+'C-x' and without the modifier, e.g. 'C-x C-M-+ C-M-+ C-M-+' and 'C-x
+C-M-+ + +' increase the default face height by three steps.  When
+mouse-wheel-mode is enabled, 'C-M-wheel-up' and 'C-M-wheel-down' also
+increase and decrease the default face height globally.  Additionally,
+the variable 'global-text-scale-adjust-resizes-frames' controls
+whether the frames are resized when the default face height is changed.
+
 ** Outline
 
 +++
diff --git a/lisp/face-remap.el b/lisp/face-remap.el
index 5914ee4a20..eae2bfc3c7 100644
--- a/lisp/face-remap.el
+++ b/lisp/face-remap.el
@@ -371,7 +371,9 @@ text-scale-adjust
 `text-scale-increase' command which makes repetition convenient
 even when it is bound in a non-top-level keymap.  For binding in
 a top-level keymap, `text-scale-increase' or
-`text-scale-decrease' may be more appropriate."
+`text-scale-decrease' may be more appropriate.
+
+See also the related command `global-text-scale-adjust'."
   (interactive "p")
   (let ((ev last-command-event)
 	(echo-keystrokes nil))
@@ -393,6 +395,70 @@ text-scale-adjust
                (lambda () (interactive) (text-scale-adjust (abs inc))))))
          map))))) ;; )
 
+(defcustom global-text-scale-adjust-resizes-frames nil
+  "Whether `global-text-scale-adjust' resizes the frames."
+  :type '(choice (const :tag "Off" nil)
+                 (const :tag "On" t))
+  :group 'display
+  :version "28.1")
+
+(defvar global-text-scale-adjust--default-height nil)
+
+;;;###autoload (define-key ctl-x-map [(control meta ?+)] 'global-text-scale-adjust)
+;;;###autoload (define-key ctl-x-map [(control meta ?=)] 'global-text-scale-adjust)
+;;;###autoload (define-key ctl-x-map [(control meta ?-)] 'global-text-scale-adjust)
+;;;###autoload (define-key ctl-x-map [(control meta ?0)] 'global-text-scale-adjust)
+;;;###autoload
+(defun global-text-scale-adjust (increment)
+  "Globally adjust the height of the default face by INCREMENT.
+
+INCREMENT may be passed as a numeric prefix argument.
+
+The adjustment made depends on the final component of the key binding
+used to invoke the command, with all modifiers removed:
+
+   +, =   Globally increase the height of the default face
+   -      Globally decrease the height of the default face
+   0      Globally reset the height of the default face
+
+After adjusting, further adjust the default face height as long as the
+key, with all modifiers removed, is one of the above characters.
+
+Buffer-local face adjustements remain in effect when global face
+adjustments are made.
+
+The variable `global-text-scale-adjust-resizes-frames', which controls
+whether the frames are resized when the default face is adjusted.
+
+See also the related command `text-scale-adjust'."
+  (interactive "p")
+  (when (display-graphic-p)
+    (unless global-text-scale-adjust--default-height
+      (setq global-text-scale-adjust--default-height
+            (face-attribute 'default :height)))
+    (let* ((key (event-basic-type last-command-event))
+           (echo-keystrokes nil)
+           (inc
+            (pcase key
+              ((or ?+ ?=) (* increment 5))
+              (?- (* (- increment) 5))
+              (?0 (- global-text-scale-adjust--default-height
+                     (face-attribute 'default :height)))
+              (_ (* increment 5)))))
+      (let ((frame-inhibit-implied-resize
+             (not global-text-scale-adjust-resizes-frames)))
+        (set-face-attribute 'default nil :height
+                            (+ (face-attribute 'default :height) inc)))
+      (when (characterp key)
+        (message "Use +,-,0 for further adjustment")
+        (set-transient-map
+         (let ((map (make-sparse-keymap)))
+           (dolist (mod '(() (control meta)))
+             (dolist (key '(?+ ?= ?- ?0))
+               (define-key map (vector (append mod (list key)))
+                 'global-text-scale-adjust)))
+           map))))))
+
 \f
 ;; ----------------------------------------------------------------
 ;; buffer-face-mode
diff --git a/lisp/mwheel.el b/lisp/mwheel.el
index 048f50c772..d5944fef7e 100644
--- a/lisp/mwheel.el
+++ b/lisp/mwheel.el
@@ -84,7 +84,10 @@ mouse-wheel-inhibit-click-time
   :type 'number)
 
 (defcustom mouse-wheel-scroll-amount
-  '(1 ((shift) . hscroll) ((meta) . nil) ((control) . text-scale))
+  '(1 ((shift) . hscroll)
+      ((meta) . nil)
+      ((control meta) . global-text-scale)
+      ((control) . text-scale))
   "Amount to scroll windows by when spinning the mouse wheel.
 This is an alist mapping the modifier key to the amount to scroll when
 the wheel is moved with the modifier key depressed.
@@ -377,6 +380,16 @@ mouse-wheel-text-scale
                (text-scale-decrease 1)))
       (select-window selected-window))))
 
+(defun mouse-wheel-global-text-scale (event)
+  "Increase or decrease the global height of the default face according to the EVENT."
+  (interactive (list last-input-event))
+  (let ((button (mwheel-event-button event)))
+    (unwind-protect
+        (cond ((eq button mouse-wheel-down-event)
+               (global-text-scale-adjust 1))
+              ((eq button mouse-wheel-up-event)
+               (global-text-scale-adjust -1))))))
+
 (defvar mouse-wheel--installed-bindings-alist nil
   "Alist of all installed mouse wheel key bindings.")
 
@@ -433,6 +446,10 @@ mouse-wheel-mode
         (dolist (event (list mouse-wheel-down-event mouse-wheel-up-event))
           (mouse-wheel--add-binding `[,(list (caar binding) event)]
                                     'mouse-wheel-text-scale)))
+       ((and (consp binding) (eq (cdr binding) 'global-text-scale))
+        (dolist (event (list mouse-wheel-down-event mouse-wheel-up-event))
+          (mouse-wheel--add-binding `[,(append (car binding) (list event))]
+                                    'mouse-wheel-global-text-scale)))
        ;; Bindings for scrolling.
        (t
         (dolist (event (list mouse-wheel-down-event mouse-wheel-up-event
-- 
2.30.2

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Clément Pit-Claudel]

On 5/10/21 3:35 PM, Gregory Heytings wrote:
> Here is the updated patch with, as discussed, a new user option to control the frame resizing, and the additional C-x C-M-= binding.

Looks good!  A small stylistic comment:

+           (pcase key
+              ((or ?+ ?=) (* increment 5))
+              (?- (* (- increment) 5))
+              (?0 (- global-text-scale-adjust--default-height
+                     (face-attribute 'default :height)))
+              (_ (* increment 5)))))

Do you need the first branch?  If you remove it, those cases will be caught by the default fall-through.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Gregory Heytings]

>
> Looks good!  A small stylistic comment:
>
> +           (pcase key
> +              ((or ?+ ?=) (* increment 5))
> +              (?- (* (- increment) 5))
> +              (?0 (- global-text-scale-adjust--default-height
> +                     (face-attribute 'default :height)))
> +              (_ (* increment 5)))))
>
> Do you need the first branch?  If you remove it, those cases will be 
> caught by the default fall-through.
>

Oh yes, indeed!  Thanks :-)

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Gregory Heytings]

[-- Attachment #1: Type: text/plain, Size: 108 bytes --]


Updated patch attached.  The main added feature is that face resizing is 
now bounded (between 10 and 500).

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: Type: text/x-diff; name=Global-adjustments-to-the-default-face.patch, Size: 8716 bytes --]

From d47e46a0108aa3499cdf4ff61da5134650a96818 Mon Sep 17 00:00:00 2001
From: Gregory Heytings <gregory@heytings.org>
Date: Tue, 25 May 2021 07:56:38 +0000
Subject: [PATCH] Global adjustments to the default face

* lisp/face-remap.el (global-text-scale-adjust): New command.
(text-scale-adjust): Refer to the new related command.
(global-text-scale-adjust-resizes-frames): New user option.

* lisp/mwheel.el (mouse-wheel-scroll-amount): Add the new command
to the mouse wheel scrolling events.
(mouse-wheel-global-text-scale): New function.
(mouse-wheel-mode): Use the new function with mouse-wheel-mode.

* doc/emacs/display.texi (Text Scale): Document the new command and
the new user option.

* etc/NEWS: Mention the new command and its bindings, and the new
user option.
---
 doc/emacs/display.texi | 16 ++++++++++
 etc/NEWS               | 12 ++++++++
 lisp/face-remap.el     | 68 +++++++++++++++++++++++++++++++++++++++++-
 lisp/mwheel.el         | 19 +++++++++++-
 4 files changed, 113 insertions(+), 2 deletions(-)

diff --git a/doc/emacs/display.texi b/doc/emacs/display.texi
index 5fccdaa834..01121ffee6 100644
--- a/doc/emacs/display.texi
+++ b/doc/emacs/display.texi
@@ -837,6 +837,22 @@ Text Scale
 to the @code{text-scale-adjust} command restores the default height,
 the same as typing @kbd{C-x C-0}.
 
+@cindex ajust global face height
+@findex global-text-scale-adjust
+@kindex C-x C-M-+
+@kindex C-x C-M-=
+@kindex C-x C-M--
+@kindex C-x C-M-0
+@kindex C-M-wheel-down
+@kindex C-M-wheel-up
+  Similarly, to change the height of the default face globally, type
+@kbd{C-x C-M-+}, @kbd{C-x C-M-=}, @kbd{C-x C-M--} or @kbd{C-x C-M-0},
+or scroll the mouse wheel with both the @kbd{Ctrl} and @kbd{Meta}
+modifiers pressed.  To enable frame resizing when the height of the
+default face is changed globally, customize the variable
+@code{global-text-scale-adjust-resizes-frames} (@pxref{Easy
+Customization}).
+
 @cindex increase buffer face height
 @findex text-scale-increase
 @cindex decrease buffer face height
diff --git a/etc/NEWS b/etc/NEWS
index e11b860616..c5c4a93d90 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -416,6 +416,18 @@ When this option is set, direction changes in Isearch move to another
 search match, if there is one, instead of moving point to the other
 end of the current match.
 
++++
+** New command to change the default face height globally.
+To increase it, type 'C-x C-M-+' or 'C-x C-M-='; to decrease it, type
+'C-x C-M--'; to restore the default face height, type 'C-x C-M-0'.
+The final key in these commands may be repeated without the leading
+'C-x' and without the modifiers, e.g. 'C-x C-M-+ C-M-+ C-M-+' and 'C-x
+C-M-+ + +' increase the default face height by three steps.  When
+mouse-wheel-mode is enabled, 'C-M-wheel-up' and 'C-M-wheel-down' also
+increase and decrease the default face height globally.  Additionally,
+the variable 'global-text-scale-adjust-resizes-frames' controls
+whether the frames are resized when the default face height is changed.
+
 ** Outline
 
 +++
diff --git a/lisp/face-remap.el b/lisp/face-remap.el
index 5914ee4a20..5e136e368b 100644
--- a/lisp/face-remap.el
+++ b/lisp/face-remap.el
@@ -371,7 +371,9 @@ text-scale-adjust
 `text-scale-increase' command which makes repetition convenient
 even when it is bound in a non-top-level keymap.  For binding in
 a top-level keymap, `text-scale-increase' or
-`text-scale-decrease' may be more appropriate."
+`text-scale-decrease' may be more appropriate.
+
+See also the related command `global-text-scale-adjust'."
   (interactive "p")
   (let ((ev last-command-event)
 	(echo-keystrokes nil))
@@ -393,6 +395,70 @@ text-scale-adjust
                (lambda () (interactive) (text-scale-adjust (abs inc))))))
          map))))) ;; )
 
+(defcustom global-text-scale-adjust-resizes-frames nil
+  "Whether `global-text-scale-adjust' resizes the frames."
+  :type '(choice (const :tag "Off" nil)
+                 (const :tag "On" t))
+  :group 'display
+  :version "28.1")
+
+(defvar global-text-scale-adjust--default-height nil)
+
+;;;###autoload (define-key ctl-x-map [(control meta ?+)] 'global-text-scale-adjust)
+;;;###autoload (define-key ctl-x-map [(control meta ?=)] 'global-text-scale-adjust)
+;;;###autoload (define-key ctl-x-map [(control meta ?-)] 'global-text-scale-adjust)
+;;;###autoload (define-key ctl-x-map [(control meta ?0)] 'global-text-scale-adjust)
+;;;###autoload
+(defun global-text-scale-adjust (increment)
+  "Globally adjust the height of the default face by INCREMENT.
+
+INCREMENT may be passed as a numeric prefix argument.
+
+The adjustment made depends on the final component of the key binding
+used to invoke the command, with all modifiers removed:
+
+   +, =   Globally increase the height of the default face
+   -      Globally decrease the height of the default face
+   0      Globally reset the height of the default face
+
+After adjusting, further adjust the default face height as long as the
+key, with all modifiers removed, is one of the above characters.
+
+Buffer-local face adjustements remain in effect when global face
+adjustments are made.
+
+The variable `global-text-scale-adjust-resizes-frames' controls whether
+the frames are resized when the default face is adjusted.
+
+See also the related command `text-scale-adjust'."
+  (interactive "p")
+  (when (display-graphic-p)
+    (unless global-text-scale-adjust--default-height
+      (setq global-text-scale-adjust--default-height
+            (face-attribute 'default :height)))
+    (let* ((key (event-basic-type last-command-event))
+           (echo-keystrokes nil)
+           (cur (face-attribute 'default :height))
+           (inc
+            (pcase key
+              (?- (* (- increment) 5))
+              (?0 (- global-text-scale-adjust--default-height cur))
+              (_ (* increment 5))))
+           (new (+ cur inc)))
+      (when (< 10 new 500)
+        (let ((frame-inhibit-implied-resize
+               (not global-text-scale-adjust-resizes-frames)))
+          (set-face-attribute 'default nil :height new)))
+      (when (characterp key)
+        (message "Use +,-,0 for further adjustment")
+        (set-transient-map
+         (let ((map (make-sparse-keymap)))
+           (dolist (mod '(() (control meta)))
+             (dolist (key '(?+ ?= ?- ?0))
+               (define-key map (vector (append mod (list key)))
+                 'global-text-scale-adjust)))
+           map))))))
+
 \f
 ;; ----------------------------------------------------------------
 ;; buffer-face-mode
diff --git a/lisp/mwheel.el b/lisp/mwheel.el
index b31805a575..8fb38c3d84 100644
--- a/lisp/mwheel.el
+++ b/lisp/mwheel.el
@@ -84,7 +84,10 @@ mouse-wheel-inhibit-click-time
   :type 'number)
 
 (defcustom mouse-wheel-scroll-amount
-  '(1 ((shift) . hscroll) ((meta) . nil) ((control) . text-scale))
+  '(1 ((shift) . hscroll)
+      ((meta) . nil)
+      ((control meta) . global-text-scale)
+      ((control) . text-scale))
   "Amount to scroll windows by when spinning the mouse wheel.
 This is an alist mapping the modifier key to the amount to scroll when
 the wheel is moved with the modifier key depressed.
@@ -380,6 +383,16 @@ mouse-wheel-text-scale
                (text-scale-decrease 1)))
       (select-window selected-window))))
 
+(defun mouse-wheel-global-text-scale (event)
+  "Increase or decrease the global height of the default face according to the EVENT."
+  (interactive (list last-input-event))
+  (let ((button (mwheel-event-button event)))
+    (unwind-protect
+        (cond ((eq button mouse-wheel-down-event)
+               (global-text-scale-adjust 1))
+              ((eq button mouse-wheel-up-event)
+               (global-text-scale-adjust -1))))))
+
 (defvar mouse-wheel--installed-bindings-alist nil
   "Alist of all installed mouse wheel key bindings.")
 
@@ -436,6 +449,10 @@ mouse-wheel-mode
         (dolist (event (list mouse-wheel-down-event mouse-wheel-up-event))
           (mouse-wheel--add-binding `[,(list (caar binding) event)]
                                     'mouse-wheel-text-scale)))
+       ((and (consp binding) (eq (cdr binding) 'global-text-scale))
+        (dolist (event (list mouse-wheel-down-event mouse-wheel-up-event))
+          (mouse-wheel--add-binding `[,(append (car binding) (list event))]
+                                    'mouse-wheel-global-text-scale)))
        ;; Bindings for scrolling.
        (t
         (dolist (event (list mouse-wheel-down-event mouse-wheel-up-event
-- 
2.30.2

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Eli Zaretskii]

> Date: Tue, 25 May 2021 07:58:42 +0000
> From: Gregory Heytings <gregory@heytings.org>
> Cc: 48307@debbugs.gnu.org
> 
> Updated patch attached.

Thanks.

> The main added feature is that face resizing is now bounded (between
> 10 and 500).

Hmm, the GCS frowns on arbitrary limits, so perhaps we should have a
defcustom to control the limits?

> +@kindex C-M-wheel-up
> +  Similarly, to change the height of the default face globally, type
> +@kbd{C-x C-M-+}, @kbd{C-x C-M-=}, @kbd{C-x C-M--} or @kbd{C-x C-M-0},
> +or scroll the mouse wheel with both the @kbd{Ctrl} and @kbd{Meta}
> +modifiers pressed.  To enable frame resizing when the height of the
> +default face is changed globally, customize the variable
> +@code{global-text-scale-adjust-resizes-frames} (@pxref{Easy
> +Customization}).

The last part should explain why frame resizing is related to font
size changes, it isn't obvious.

Also, I wonder whether we should say "height of the default face's
font", because this is what this actually does.  I'm not sure every
user will understand the notion of the height of a face.

And finally, "height" or "size"?

> +(defun global-text-scale-adjust (increment)
> +  "Globally adjust the height of the default face by INCREMENT.
> +
> +INCREMENT may be passed as a numeric prefix argument.

The last sentence should start with "Interactively, ".  Also, the doc
string should tell what are the units of INCREMENT.

> +The adjustment made depends on the final component of the key binding
> +used to invoke the command, with all modifiers removed:

I wonder if we could rephrase this to be less awkward and more clear.

> +After adjusting, further adjust the default face height as long as the
> +key, with all modifiers removed, is one of the above characters.

And this.

> +Buffer-local face adjustements remain in effect when global face
> +adjustments are made.

I don't think I understand what this means, so it would be good to
clarify that.

> +The variable `global-text-scale-adjust-resizes-frames' controls whether
> +the frames are resized when the default face is adjusted.

Suggest to say "... resized to keep the same number of lines and
characters per line ...".

> +           (inc
> +            (pcase key
> +              (?- (* (- increment) 5))
> +              (?0 (- global-text-scale-adjust--default-height cur))
> +              (_ (* increment 5))))

Do we really need pcase here?

> +(defun mouse-wheel-global-text-scale (event)
> +  "Increase or decrease the global height of the default face according to the EVENT."

This sentence is too long to fit on a single line.  Suggest to make it
shorter:

  "Increase or decrease the height of the default face according to EVENT."

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Gregory Heytings]

Thanks for your feedback, a few comments before updating the patch:

>> The main added feature is that face resizing is now bounded (between 10 
>> and 500).
>
> Hmm, the GCS frowns on arbitrary limits,
>

What is "the GCS"?

>
> so perhaps we should have a defcustom to control the limits?
>

I'd rather wait for a feature request to add a defcustom for this.  IMO 
10-500 is a reasonable range for that feature, 10 is really small and 500 
is really huge.

>
> Also, I wonder whether we should say "height of the default face's 
> font", because this is what this actually does.  I'm not sure every user 
> will understand the notion of the height of a face.
>

I used "height" because it's what text-scale-{adjust,increase,decrease} 
use.  Otherwise I would have used the word "size" indeed.  WDYT?

>> +Buffer-local face adjustements remain in effect when global face 
>> +adjustments are made.
>
> I don't think I understand what this means, so it would be good to 
> clarify that.
>

It means that if you C-x C-+ in a buffer B (buffer-local face adjustment), 
and then C-x C-M-+, the buffer-local adjustment in B remains in effect, or 
IOW that after C-x C-M-+ the buffer B will still have a larger font than 
the other buffers.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Eli Zaretskii]

> Date: Tue, 25 May 2021 12:58:59 +0000
> From: Gregory Heytings <gregory@heytings.org>
> cc: cpitclaudel@gmail.com, 48307@debbugs.gnu.org
> 
> Thanks for your feedback, a few comments before updating the patch:
> 
> >> The main added feature is that face resizing is now bounded (between 10 
> >> and 500).
> >
> > Hmm, the GCS frowns on arbitrary limits,
> >
> 
> What is "the GCS"?

GNU Coding Standards.

> > so perhaps we should have a defcustom to control the limits?
> >
> 
> I'd rather wait for a feature request to add a defcustom for this.  IMO 
> 10-500 is a reasonable range for that feature, 10 is really small and 500 
> is really huge.

We could avoid arguing about what's reasonable by providing an option.

Lars, WDYT?

> > Also, I wonder whether we should say "height of the default face's 
> > font", because this is what this actually does.  I'm not sure every user 
> > will understand the notion of the height of a face.
> >
> 
> I used "height" because it's what text-scale-{adjust,increase,decrease} 
> use.  Otherwise I would have used the word "size" indeed.  WDYT?

I prefer "size".

> >> +Buffer-local face adjustements remain in effect when global face 
> >> +adjustments are made.
> >
> > I don't think I understand what this means, so it would be good to 
> > clarify that.
> >
> 
> It means that if you C-x C-+ in a buffer B (buffer-local face adjustment), 
> and then C-x C-M-+, the buffer-local adjustment in B remains in effect, or 
> IOW that after C-x C-M-+ the buffer B will still have a larger font than 
> the other buffers.

I think what's missing is the last part you wrote, or some variant
thereof.  "Remains in effect" is ambiguous because it isn't clear
whether the absolute size remains in effect or the relative size does.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Gregory Heytings]

>>> Also, I wonder whether we should say "height of the default face's 
>>> font", because this is what this actually does.  I'm not sure every 
>>> user will understand the notion of the height of a face.
>>
>> I used "height" because it's what text-scale-{adjust,increase,decrease} 
>> use.  Otherwise I would have used the word "size" indeed.  WDYT?
>
> I prefer "size".
>

Okay, so should I also replace the word "height" by "size" in 
text-scale-{adjust,increase,decrease}?

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Eli Zaretskii]

> Date: Tue, 25 May 2021 13:16:42 +0000
> From: Gregory Heytings <gregory@heytings.org>
> cc: cpitclaudel@gmail.com, 48307@debbugs.gnu.org
> 
> 
> >>> Also, I wonder whether we should say "height of the default face's 
> >>> font", because this is what this actually does.  I'm not sure every 
> >>> user will understand the notion of the height of a face.
> >>
> >> I used "height" because it's what text-scale-{adjust,increase,decrease} 
> >> use.  Otherwise I would have used the word "size" indeed.  WDYT?
> >
> > I prefer "size".
> 
> Okay, so should I also replace the word "height" by "size" in 
> text-scale-{adjust,increase,decrease}?

I guess so, yes.

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

>> >> The main added feature is that face resizing is now bounded (between 10 
>> >> and 500).

[...]

>> I'd rather wait for a feature request to add a defcustom for this.  IMO 
>> 10-500 is a reasonable range for that feature, 10 is really small and 500 
>> is really huge.
>
> We could avoid arguing about what's reasonable by providing an option.

I can definitely see people wanting to go below 10, so I think a user
option here would be nice.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#48307: Feature request: provide default keybindings to change the font size in all windows

[Lars Ingebrigtsen]

Gregory Heytings <gregory@heytings.org> writes:

> From d47e46a0108aa3499cdf4ff61da5134650a96818 Mon Sep 17 00:00:00 2001
> From: Gregory Heytings <gregory@heytings.org>
> Date: Tue, 25 May 2021 07:56:38 +0000
> Subject: [PATCH] Global adjustments to the default face
>
> * lisp/face-remap.el (global-text-scale-adjust): New command.
> (text-scale-adjust): Refer to the new related command.
> (global-text-scale-adjust-resizes-frames): New user option.

I've now respun the patch for Emacs 29, and it seems to work well, so
I've now pushed, adjusting for the comments that arrived after the
patch, and general changes in the terminology in this area that have
been done lately.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no