bug#58101: 28.2; image-size nonsensical

bug#58101: 28.2; image-size nonsensical

[Thomas Hühn]

* Download image https://imgs.xkcd.com/comics/two_key_system_2x.png to
   disk

* Run (create-image "two_key_system_2x.png") --> (image :type png :file
   "two_key_system_2x.png" :scale 1.2038461538461538 :transform-smoothing
   t)

* Run (image-size (create-image "two_key_system_2x.png") :pixels) -->
   (30 . 30)

Expected result: (1291 . 632)


In GNU Emacs 28.2 (build 2, x86_64-w64-mingw32)
  of 2022-09-13 built on fv-az448-195
Repository revision: ea87108e99fb3243a44af1a09a1a0c8f29a2ab37
Repository branch: master
Windowing system distributor 'Microsoft Corp.', version 10.0.22621
System Description: Microsoft Windows 10 Pro (v10.0.2009.22621.521)

Configured using:
  'configure --prefix=/mingw64 --build=x86_64-w64-mingw32 --with-modules
  --without-dbus --without-compress-install --with-native-compilation
  'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe'
  CPPFLAGS=-D__USE_MINGW_ANSI_STDIO=1 LDFLAGS=-pipe'

Configured features:
ACL GIF GMP GNUTLS HARFBUZZ JPEG JSON LIBXML2 MODULES NATIVE_COMP NOTIFY
W32NOTIFY PDUMPER PNG RSVG SOUND THREADS TIFF TOOLKIT_SCROLL_BARS XPM
ZLIB

Important settings:
   value of $LC_ALL: C.UTF8
   value of $LANG: en
   locale-coding-system: cp1252

Major mode: Lisp Interaction

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   file-name-shadow-mode: t
   global-font-lock-mode: t
   font-lock-mode: t
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Load-path shadows:
c:/Users/redacted/AppData/Roaming/.emacs.d/elpa/transient-20220918.2101/transient 
hides c:/msys64/mingw64/share/emacs/28.2/lisp/transient
c:/redacted/Emacs/prolog hides 
c:/msys64/mingw64/share/emacs/28.2/lisp/progmodes/prolog

Features:
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Memory information:
((conses 16 699091 31870)
  (symbols 48 27290 1)
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-- 
Wunderschön illustrierte Kinderbücher:
https://www.schoene-kinderbuecher.de
Weblog:
https://www.thomas-huehn.de

bug#58101: 28.2; image-size nonsensical

[Eli Zaretskii]

> Date: Mon, 26 Sep 2022 20:41:45 +0200
> From: Thomas Hühn <t@2uo.de>
> 
> * Download image https://imgs.xkcd.com/comics/two_key_system_2x.png to
>    disk
> 
> * Run (create-image "two_key_system_2x.png") --> (image :type png :file
>    "two_key_system_2x.png" :scale 1.2038461538461538 :transform-smoothing
>    t)
> 
> * Run (image-size (create-image "two_key_system_2x.png") :pixels) -->
>    (30 . 30)
> 
> Expected result: (1291 . 632)

I cannot reproduce this here.  I get the expected result.  I also get
this result from create-image:

 (image :type png :file "two_key_system_2x.png" :scale 1 :transform-smoothing t)


Is this in "emacs -Q"?  If so, what version of libpng do you have
installed there?  And what happens if you start Emacs like this:

  emacs -Q --eval "(setq w32-use-native-image-API t)"

Thanks.

bug#58101: 28.2; image-size nonsensical

[Thomas Hühn]

Hi,

first of all, I think this bug could be merged with #52931, I found that 
only afterwards.

On 27.09.2022 08:05, Eli Zaretskii wrote:
>> Date: Mon, 26 Sep 2022 20:41:45 +0200
>> From: Thomas Hühn <t@2uo.de>
>>
>> * Download image https://imgs.xkcd.com/comics/two_key_system_2x.png to
>>     disk
>>
>> * Run (create-image "two_key_system_2x.png") --> (image :type png :file
>>     "two_key_system_2x.png" :scale 1.2038461538461538 :transform-smoothing
>>     t)
>>
>> * Run (image-size (create-image "two_key_system_2x.png") :pixels) -->
>>     (30 . 30)
>>
>> Expected result: (1291 . 632)
> 
> I cannot reproduce this here.  I get the expected result.  I also get

Now it seems like it's an intermittent problem.

Until yesterday (for several weaks where I've tried it every now and 
then) it resulted in what I wrote in this bug.

Then I found #52931 and tried Markus' lines.

In my opinion,

(image-size (create-image "two_key_system_2x.png") :pixels)

and

(let ((img (create-image "two_key_system_2x.png")))
   (image-size img t))

should give the same result, but it didn't! Markus' line gave 1554 . 
760, mine gave 30 . 30.

Later yesterday evening both gave 1554 . 760.

After some googling I found image-scaling-factor, and after setting that 
to 1, I always get the expected 1291 . 632 now.

(By the way, I think image-size should ignore that variable – I'm not 
displaying the image anywhere, so any display scaling shouldn't 
interfere – my use case would be inserting width and height attributes 
in HTML where I certainly want the original image dimensions)

> this result from create-image:
> 
>   (image :type png :file "two_key_system_2x.png" :scale 1 :transform-smoothing t)

With emacs -Q:

(image :type png :file "two_key_system_2x.png" :scale 1.2 
:transform-smoothing t)

That scaling factor is different now. I'll continue with emacs -Q from 
now on.

> Is this in "emacs -Q"?  If so, what version of libpng do you have

mingw64/mingw-w64-x86_64-libpng 1.6.38-1 [installed]

> installed there?  And what happens if you start Emacs like this:
> 
>    emacs -Q --eval "(setq w32-use-native-image-API t)"

(image-size (create-image "two_key_system_2x.png") :pixels)
--> (1549 . 758)

(let ((img (create-image "two_key_system_2x.png")))
   (image-size img t))
--> (1549 . 758)

Have a nice day!
Thomas
-- 
Wunderschön illustrierte Kinderbücher:
https://www.schoene-kinderbuecher.de
Weblog:
https://www.thomas-huehn.de

bug#58101: 28.2; image-size nonsensical

[Eli Zaretskii]

> Date: Tue, 27 Sep 2022 11:00:22 +0200
> From: Thomas Hühn <t@2uo.de>
> Cc: Eli Zaretskii <eliz@gnu.org>
> 
> After some googling I found image-scaling-factor, and after setting that 
> to 1, I always get the expected 1291 . 632 now.

So the issue happens because image-scaling-factor is different from 1?
If so, this doesn't seem to be a bug, does it?

bug#58101: 28.2; image-size nonsensical

[Thomas Hühn]

On 27.09.2022 11:19, Eli Zaretskii wrote:
>> Date: Tue, 27 Sep 2022 11:00:22 +0200
>> From: Thomas Hühn <t@2uo.de>
>> Cc: Eli Zaretskii <eliz@gnu.org>
>>
>> After some googling I found image-scaling-factor, and after setting that
>> to 1, I always get the expected 1291 . 632 now.
> 
> So the issue happens because image-scaling-factor is different from 1?
> If so, this doesn't seem to be a bug, does it?

I cannot reproduce the bug today, but the result until yesterday (as 
written in the bug report) was wrong, even taking image-scaling-factor 
into account (30 . 30).
-- 
Wunderschön illustrierte Kinderbücher:
https://www.schoene-kinderbuecher.de
Weblog:
https://www.thomas-huehn.de

bug#58101: 28.2; image-size nonsensical

[Eli Zaretskii]

> Date: Tue, 27 Sep 2022 11:21:46 +0200
> Cc: 58101@debbugs.gnu.org
> From: Thomas Hühn <t@2uo.de>
> 
> On 27.09.2022 11:19, Eli Zaretskii wrote:
> >> Date: Tue, 27 Sep 2022 11:00:22 +0200
> >> From: Thomas Hühn <t@2uo.de>
> >> Cc: Eli Zaretskii <eliz@gnu.org>
> >>
> >> After some googling I found image-scaling-factor, and after setting that
> >> to 1, I always get the expected 1291 . 632 now.
> > 
> > So the issue happens because image-scaling-factor is different from 1?
> > If so, this doesn't seem to be a bug, does it?
> 
> I cannot reproduce the bug today, but the result until yesterday (as 
> written in the bug report) was wrong, even taking image-scaling-factor 
> into account (30 . 30).

Well, we need a reproducible recipe to investigate, I think.

bug#58101: 28.2; image-size nonsensical

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

>> >> After some googling I found image-scaling-factor, and after setting that
>> >> to 1, I always get the expected 1291 . 632 now.
>> > 
>> > So the issue happens because image-scaling-factor is different from 1?
>> > If so, this doesn't seem to be a bug, does it?
>> 
>> I cannot reproduce the bug today, but the result until yesterday (as 
>> written in the bug report) was wrong, even taking image-scaling-factor 
>> into account (30 . 30).
>
> Well, we need a reproducible recipe to investigate, I think.

Can you try

(image-size (create-image "/tmp/two_key_system_2x.png" nil nil :scale 1.4) :pixels)

It rather sounds like `image-size' on Windows doesn't work when there's
scaling involved and then reports the size in character units instead.

bug#58101: 28.2; image-size nonsensical

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: Thomas Hühn <t@2uo.de>,  58101@debbugs.gnu.org
> Date: Tue, 27 Sep 2022 13:57:16 +0200
> 
> Can you try
> 
> (image-size (create-image "/tmp/two_key_system_2x.png" nil nil :scale 1.4) :pixels)

I get (1808 . 885).

> It rather sounds like `image-size' on Windows doesn't work when there's
> scaling involved and then reports the size in character units instead.

I don't see it here.

bug#58101: 28.2; image-size nonsensical

[Thomas Hühn]

On 27.09.2022 13:57, Lars Ingebrigtsen wrote:
> Can you try
> 
> (image-size (create-image "/tmp/two_key_system_2x.png" nil nil :scale 1.4) :pixels)
> 
> It rather sounds like `image-size' on Windows doesn't work when there's
> scaling involved and then reports the size in character units instead.


With emacs -Q:

(image-size (create-image "two_key_system_2x.png") :pixels)

--> (1549 . 758)


(let ((img (create-image "two_key_system_2x.png")))
   (image-size img t))

--> (1549 . 758)

(image-size (create-image "/tmp/two_key_system_2x.png" nil nil :scale 
1.4) :pixels)

--> (1807 . 884)

Thanks!
Thomas
-- 
Wunderschön illustrierte Kinderbücher:
https://www.schoene-kinderbuecher.de
Weblog:
https://www.thomas-huehn.de

bug#58101: 28.2; image-size nonsensical

[Lars Ingebrigtsen]

Thomas Hühn <t@2uo.de> writes:

> With emacs -Q:
>
> (image-size (create-image "two_key_system_2x.png") :pixels)
>
> --> (1549 . 758)

You previously said:

* Run (image-size (create-image "two_key_system_2x.png") :pixels) -->
  (30 . 30)

So has this bug gone away?  Or didn't you use "-Q" before?

bug#58101: 28.2; image-size nonsensical

[Thomas Hühn]

Yes, I couldn't reproduce my bug today at all. It occurred until yesterday (and several times in the weeks before that).

Is 30 . 30 a special value? It seems strange that Markus Triska got the same value on Mac years ago.

Thomas
-- 
Wunderschön illustrierte Kinderbücher:
https://www.schoene-kinderbuecher.de
Weblog:
https://www.thomas-huehn.de

> Am 27.09.2022 um 14:28 schrieb Lars Ingebrigtsen <larsi@gnus.org>:
> 
> Thomas Hühn <t@2uo.de> writes:
> 
>> With emacs -Q:
>> 
>> (image-size (create-image "two_key_system_2x.png") :pixels)
>> 
>> --> (1549 . 758)
> 
> You previously said:
> 
> * Run (image-size (create-image "two_key_system_2x.png") :pixels) -->
>  (30 . 30)
> 
> So has this bug gone away?  Or didn't you use "-Q" before?

bug#58101: 28.2; image-size nonsensical

[Lars Ingebrigtsen]

Thomas Hühn <t@2uo.de> writes:

> Yes, I couldn't reproduce my bug today at all. It occurred until
> yesterday (and several times in the weeks before that).
>
> Is 30 . 30 a special value? It seems strange that Markus Triska got
> the same value on Mac years ago.

30x30 is the default size for images that can't be displayed.  For
instance, 

(image-size (create-image "/tmp/DOES-NOT-EXIST.png" nil nil :scale 1.0) t)
=> (30 . 30)

So I think perhaps you just didn't have the image in the current
directory when you did the create-image.

bug#58101: 28.2; image-size nonsensical

[Thomas Hühn]

> 
> 30x30 is the default size for images that can't be displayed.  For
> instance, 
> 
> (image-size (create-image "/tmp/DOES-NOT-EXIST.png" nil nil :scale 1.0) t)
> => (30 . 30)
> 
> So I think perhaps you just didn't have the image in the current
> directory when you did the create-image.

Thanks!

Thomas

bug#58101: 28.2; image-size nonsensical

[Lars Ingebrigtsen]

Thomas Hühn <t@2uo.de> writes:

>> 30x30 is the default size for images that can't be displayed.  For
>> instance, 
>> 
>> (image-size (create-image "/tmp/DOES-NOT-EXIST.png" nil nil :scale 1.0) t)
>> => (30 . 30)
>> 
>> So I think perhaps you just didn't have the image in the current
>> directory when you did the create-image.
>
> Thanks!

OK; I'm closing this bug report, then.

bug#58101: 28.2; image-size nonsensical

[Stefan Kangas]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> (image-size (create-image "/tmp/two_key_system_2x.png" nil nil :scale 1.4) :pixels)

Hmm, that evaluates to "(30 . 30)" here, even though I don't even have a
file named "/tmp/two_key_system_2x.png".

Isn't that a bug?  I'd expect it to signal an error.

bug#58101: 28.2; image-size nonsensical

[Lars Ingebrigtsen]

Stefan Kangas <stefankangas@gmail.com> writes:

> Hmm, that evaluates to "(30 . 30)" here, even though I don't even have a
> file named "/tmp/two_key_system_2x.png".
>
> Isn't that a bug?  I'd expect it to signal an error.

It doesn't check whether the image exists until doing redisplay
normally (and then logs the problem in *Messages*)...  But `image-size'
could certainly signal an error in these cases, I guess.

bug#58101: 28.2; image-size nonsensical

[Eli Zaretskii]

> From: Stefan Kangas <stefankangas@gmail.com>
> Date: Tue, 27 Sep 2022 10:28:44 -0400
> Cc: Thomas Hühn <t@2uo.de>, 58101@debbugs.gnu.org
> 
> Lars Ingebrigtsen <larsi@gnus.org> writes:
> 
> > (image-size (create-image "/tmp/two_key_system_2x.png" nil nil :scale 1.4) :pixels)
> 
> Hmm, that evaluates to "(30 . 30)" here, even though I don't even have a
> file named "/tmp/two_key_system_2x.png".
> 
> Isn't that a bug?  I'd expect it to signal an error.

No, that's the normal reaction in case of failure to create an image.
I think it will signal an error if you try to display it or something.