Why is `(1 . width)` zero?

Why is `(1 . width)` zero?

[Jörg Sommer]

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Hi,

I'm using GNU Emacs 27.1¹ with X and the font DejaVu Sans Mono. I would like
to align a text on the right side and thought I can use this:

```lisp
(let* ((text " abcd")
       (len (length text))
       )
  (add-text-properties 0 1 `(display (space :align-to (- text (,len . width)))) text)
  (insert "\n" (format "%S" text) "\n" text "\n"))
```

but it doesn't work. The text is outside the visible space. Similar with a
text that should be indented:

```lisp
(let ((text " abcd"))
  (add-text-properties 0 1 `(display (space :width (10 . width))) text)
  (insert "\n" (format "%S" text) "\n" text "\n"))
```

It shows up in the first column. But in the TUI it works. So, what's wrong
with `width` in GUI?

My main goal is to place a text on the right side that the user might scale
down with face attributes:

```lisp
(set-face-attribute 'lsp-ui-sideline-global nil :height 0.5)

(let* ((text " abcd")
       (len (length text))
       )
  (add-text-properties 0 len '(font-lock-face (error lsp-ui-sideline-global)) text)
  (add-text-properties 0 1 `(display (space :align-to (- text (,len . width)))) text)
  (insert "\n" (format "%S" text) "\n" text "\n"))
```

Are there any other ways to get this?


Kind regards

Jörg


¹ build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.23, cairo version 1.16.0
  of 2020-11-08, modified by Debian

-- 
> Definiere ‚Demokratie‘ …
… eine Mehrheit beweist einer Minderheit, dass Widerstand zwecklos ist.

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Re: Why is `(1 . width)` zero?

[Robert Pluim]

>>>>> On Mon, 18 Jan 2021 09:51:13 +0100, Jörg Sommer <joerg@jo-so.de> said:

    Jörg> Hi,
    Jörg> I'm using GNU Emacs 27.1¹ with X and the font DejaVu Sans Mono. I would like
    Jörg> to align a text on the right side and thought I can use this:

    Jörg> ```lisp
    Jörg> (let* ((text " abcd")
    Jörg>        (len (length text))
    Jörg>        )
    Jörg>   (add-text-properties 0 1 `(display (space :align-to (- text (,len . width)))) text)
    Jörg>   (insert "\n" (format "%S" text) "\n" text "\n"))
    Jörg> ```

    Jörg> but it doesn't work. The text is outside the visible space. Similar with a
    Jörg> text that should be indented:

    Jörg> ```lisp
    Jörg> (let ((text " abcd"))
    Jörg>   (add-text-properties 0 1 `(display (space :width (10 . width))) text)
    Jörg>   (insert "\n" (format "%S" text) "\n" text "\n"))
    Jörg> ```

    Jörg> It shows up in the first column. But in the TUI it works. So, what's wrong
    Jörg> with `width` in GUI?

Both of those work fine for me in emacs-27 under X (using DejaVu Sans
Mono Book). Does it do the same in 'emacs -Q' and in emacs compiled
from the latest emacs-27 sources?

    Jörg> Are there any other ways to get this?

:align-to is the way to do it.

Robert

Re: Why is `(1 . width)` zero?

[Michael Heerdegen]

Robert Pluim <rpluim@gmail.com> writes:

> Both of those work fine for me in emacs-27 under X (using DejaVu Sans
> Mono Book). Does it do the same in 'emacs -Q' and in emacs compiled
> from the latest emacs-27 sources?

Works for me as well (master built).  But I also have the Debian version
installed, the same as Jörg's, and there it doesn't work indeed, I see
the same as Jörg there.

Michael.

Re: Why is `(1 . width)` zero?

[Jörg Sommer]

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Robert Pluim schrieb am Mo 18. Jan, 16:06 (+0100):
> >>>>> On Mon, 18 Jan 2021 09:51:13 +0100, Jörg Sommer <joerg@jo-so.de> said:
> 
>     Jörg> Hi,
>     Jörg> I'm using GNU Emacs 27.1¹ with X and the font DejaVu Sans Mono. I would like
>     Jörg> to align a text on the right side and thought I can use this:
> 
>     Jörg> ```lisp
>     Jörg> (let* ((text " abcd")
>     Jörg>        (len (length text))
>     Jörg>        )
>     Jörg>   (add-text-properties 0 1 `(display (space :align-to (- text (,len . width)))) text)
>     Jörg>   (insert "\n" (format "%S" text) "\n" text "\n"))
>     Jörg> ```
> 
>     Jörg> but it doesn't work. The text is outside the visible space. Similar with a
>     Jörg> text that should be indented:
> 
>     Jörg> ```lisp
>     Jörg> (let ((text " abcd"))
>     Jörg>   (add-text-properties 0 1 `(display (space :width (10 . width))) text)
>     Jörg>   (insert "\n" (format "%S" text) "\n" text "\n"))
>     Jörg> ```
> 
>     Jörg> It shows up in the first column. But in the TUI it works. So, what's wrong
>     Jörg> with `width` in GUI?
> 
> Both of those work fine for me in emacs-27 under X (using DejaVu Sans
> Mono Book). Does it do the same in 'emacs -Q' and in emacs compiled
> from the latest emacs-27 sources?

Thank you Robert for your feedback. I've tried the latest master and it
works fine. Hence, there was something between 27.1 and 8f4b3b812aa. I've
bisect this range and found this commit:

commit d340a979dbbd6150a3af4783cf8b3b65368bbdad (HEAD)
Author: Stefan Monnier <monnier@iro.umontreal.ca>
Date:   Wed Oct 7 10:51:35 2020 -0400

    * lisp/doc-view.el: Fix "can't resize root window" error

    (doc-view-fit-window-to-page): Change approach to detect when the
    frame needs to be resized.

I don't see why, but it fixes the problem of width being zero when Emacs is
built with `--with-cairo`. Hence, an update of the Debian package should
bring a working version.


Kind regards Jörg

PS: Please Cc me. I'm not subscribed to the list.


-- 
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schon flüchtiger Lektüre man all die Bäume um Vergebung bitten möchte,
die für den Schund ihr Leben lassen mussten.“ (Michael Jürgs,
                      Seichtgebiete – Warum wir hemmungslos verblöden)

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Re: Why is `(1 . width)` zero?

[Robert Thorpe]

Jörg Sommer <joerg@jo-so.de> writes:

> [1:text/plain Hide]
>
> Hi,
>
> I'm using GNU Emacs 27.1¹ with X and the font DejaVu Sans Mono. I would like
> to align a text on the right side and thought I can use this:
>
> ```lisp
> (let* ((text " abcd")
>        (len (length text))
>        )
>   (add-text-properties 0 1 `(display (space :align-to (- text (,len . width)))) text)
>   (insert "\n" (format "%S" text) "\n" text "\n"))
> ```

I don't understand your problem.  But I this snippet looks wrong:

>   (- text (,len . width))

You can't do arithmetic on a pair.

BR,
Robert Thorpe

Re: Why is `(1 . width)` zero?

[tomas]

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On Tue, Jan 19, 2021 at 06:53:57AM +0000, Robert Thorpe wrote:
> Jörg Sommer <joerg@jo-so.de> writes:
> 
> > [1:text/plain Hide]
> >
> > Hi,
> >
> > I'm using GNU Emacs 27.1¹ with X and the font DejaVu Sans Mono. I would like
> > to align a text on the right side and thought I can use this:
> >
> > ```lisp
> > (let* ((text " abcd")
> >        (len (length text))
> >        )
> >   (add-text-properties 0 1 `(display (space :align-to (- text (,len . width)))) text)
> >   (insert "\n" (format "%S" text) "\n" text "\n"))
> > ```
> 
> I don't understand your problem.  But I this snippet looks wrong:
> 
> >   (- text (,len . width))
> 
> You can't do arithmetic on a pair.

I think this is misleading. The :align-to takes its own mini-language [1],
where this (num . unit) has its own meaning (behind the scenes, unit is
just "how many pixels per unit, in good old TeX tradition, as far as my
yet-coffeine-depleted status allows me to see).

Cheers

[1] 39.16.3 Pixel Specification for Spaces
    https://www.gnu.org/software/emacs/manual/html_node/elisp/Pixel-Specification.html

 - t

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Re: Why is `(1 . width)` zero?

[Jörg Sommer]

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Jörg Sommer schrieb am Mo 18. Jan, 23:23 (+0100):
> Robert Pluim schrieb am Mo 18. Jan, 16:06 (+0100):
> > >>>>> On Mon, 18 Jan 2021 09:51:13 +0100, Jörg Sommer <joerg@jo-so.de> said:
> > 
> >     Jörg> Hi,
> >     Jörg> I'm using GNU Emacs 27.1¹ with X and the font DejaVu Sans Mono. I would like
> >     Jörg> to align a text on the right side and thought I can use this:
> > 
> >     Jörg> ```lisp
> >     Jörg> (let* ((text " abcd")
> >     Jörg>        (len (length text))
> >     Jörg>        )
> >     Jörg>   (add-text-properties 0 1 `(display (space :align-to (- text (,len . width)))) text)
> >     Jörg>   (insert "\n" (format "%S" text) "\n" text "\n"))
> >     Jörg> ```
> > 
> >     Jörg> but it doesn't work. The text is outside the visible space. Similar with a
> >     Jörg> text that should be indented:
> > 
> >     Jörg> ```lisp
> >     Jörg> (let ((text " abcd"))
> >     Jörg>   (add-text-properties 0 1 `(display (space :width (10 . width))) text)
> >     Jörg>   (insert "\n" (format "%S" text) "\n" text "\n"))
> >     Jörg> ```
> > 
> >     Jörg> It shows up in the first column. But in the TUI it works. So, what's wrong
> >     Jörg> with `width` in GUI?
> > 
> > Both of those work fine for me in emacs-27 under X (using DejaVu Sans
> > Mono Book). Does it do the same in 'emacs -Q' and in emacs compiled
> > from the latest emacs-27 sources?
> 
> Thank you Robert for your feedback. I've tried the latest master and it
> works fine. Hence, there was something between 27.1 and 8f4b3b812aa. I've
> bisect this range and found this commit:
> 

Sorry, I've picked the wrong commit. This one fixes the problem and a
backport to 27.1 fixes it there, too.

commit c7804ac4018fb03787f291d7ef1739b34914d930 (HEAD, refs/bisect/with-space)
Author: Stefan Monnier <monnier@iro.umontreal.ca>
Date:   Thu Oct 8 09:49:20 2020 -0400

    * src/ftcrfont.c (ftcrfont_open): Initialize the `max_width` field
    
    On a 32bit build, Emacs can otherwise crash with a !FIXNUM_OVERFLOW_P
    assertion in `Ffont_info` by simply doing `emacs -Q` and then `C-s`.
    
    * src/font.c: Try and detect uninitialized `max_width` fields.
    (font_make_object): Set max_width to a silly value.
    (Ffont_info): Check the value is not silly any more.

-- 
$ cat /dev/random
#!/usr/bin/perl -WT
print "hello world\n";

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Re: Why is `(1 . width)` zero?

[Robert Thorpe]

<tomas@tuxteam.de> writes:

>> You can't do arithmetic on a pair.
>
> I think this is misleading. The :align-to takes its own mini-language [1],
> where this (num . unit) has its own meaning (behind the scenes, unit is
> just "how many pixels per unit, in good old TeX tradition, as far as my
> yet-coffeine-depleted status allows me to see).
>
> Cheers
>
> [1] 39.16.3 Pixel Specification for Spaces
>     https://www.gnu.org/software/emacs/manual/html_node/elisp/Pixel-Specification.html

I see, that's clever.  Jorg, ignore my previous mail.

BR,
Robert Thorpe

Re: Why is `(1 . width)` zero?

[Robert Pluim]

>>>>> On Tue, 19 Jan 2021 10:37:24 +0100, Jörg Sommer <joerg@jo-so.de> said:

    Jörg> Jörg Sommer schrieb am Mo 18. Jan, 23:23 (+0100):
    >> Robert Pluim schrieb am Mo 18. Jan, 16:06 (+0100):
    >> > Both of those work fine for me in emacs-27 under X (using DejaVu Sans
    >> > Mono Book). Does it do the same in 'emacs -Q' and in emacs compiled
    >> > from the latest emacs-27 sources?
    >> 
    >> Thank you Robert for your feedback. I've tried the latest master and it
    >> works fine. Hence, there was something between 27.1 and 8f4b3b812aa. I've
    >> bisect this range and found this commit:
    >> 

Ah, my emacs-27 build wasn't using Cairo, which is why I thought it
worked there.

    Jörg> Sorry, I've picked the wrong commit. This one fixes the problem and a
    Jörg> backport to 27.1 fixes it there, too.

Yes, the other one looked somewhat unlikely. This one fixes things for
me as well on emacs-27 with Cairo.

Robert

Re: Why is `(1 . width)` zero?

[Robert Pluim]

>>>>> On Tue, 19 Jan 2021 10:37:24 +0100, Jörg Sommer <joerg@jo-so.de> said:
    Jörg> Sorry, I've picked the wrong commit. This one fixes the problem and a
    Jörg> backport to 27.1 fixes it there, too.

    Jörg> commit c7804ac4018fb03787f291d7ef1739b34914d930 (HEAD, refs/bisect/with-space)
    Jörg> Author: Stefan Monnier <monnier@iro.umontreal.ca>
    Jörg> Date:   Thu Oct 8 09:49:20 2020 -0400

    Jörg>     * src/ftcrfont.c (ftcrfont_open): Initialize the `max_width` field
    
    Jörg>     On a 32bit build, Emacs can otherwise crash with a !FIXNUM_OVERFLOW_P
    Jörg>     assertion in `Ffont_info` by simply doing `emacs -Q` and then `C-s`.
    
    Jörg>     * src/font.c: Try and detect uninitialized `max_width` fields.
    Jörg>     (font_make_object): Set max_width to a silly value.
    Jörg>     (Ffont_info): Check the value is not silly any more.

Eli, is this ok to backport to emacs-27?

Thanks

Robert

Re: Why is `(1 . width)` zero?

[Eli Zaretskii]

> From: Robert Pluim <rpluim@gmail.com>
> Cc: help-gnu-emacs@gnu.org, eliz@gnu.org
> Date: Sun, 24 Jan 2021 11:45:15 +0100
> 
>     Jörg> Author: Stefan Monnier <monnier@iro.umontreal.ca>
>     Jörg> Date:   Thu Oct 8 09:49:20 2020 -0400
> 
>     Jörg>     * src/ftcrfont.c (ftcrfont_open): Initialize the `max_width` field
>     
>     Jörg>     On a 32bit build, Emacs can otherwise crash with a !FIXNUM_OVERFLOW_P
>     Jörg>     assertion in `Ffont_info` by simply doing `emacs -Q` and then `C-s`.
>     
>     Jörg>     * src/font.c: Try and detect uninitialized `max_width` fields.
>     Jörg>     (font_make_object): Set max_width to a silly value.
>     Jörg>     (Ffont_info): Check the value is not silly any more.
> 
> Eli, is this ok to backport to emacs-27?

Hmm... I'm not sure I understand how this solves the issue.
Everything that's in eassert will compile to nothing in a production
build, and the rest doesn't really ensure max_width is initialized to
a reasonable value (zero is as unreasonable as a large value)?

Isn't there a better fix for this?