How much is one em (image size unit)?

How much is one em (image size unit)?

[Akib Azmain Turja]

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I'm trying to show an image such that it has same height as the text and
resizes relatively with text scale.  I've achieved this with the 'em'
unit as described in (elisp)Image Descriptors.  But 1 em seems to be
pretty smaller than the font size.  How to figure out correct value in
em unit such that image and the text has correct height?

So far I've reached till this:

--8<---------------cut here---------------start------------->8---
(insert (propertize "f" 'display '(image :type xpm :height (1 . em) :ascent center :data "/* XPM */
static char * blarg_xpm[] = {
\"16 7 2 1\",
\"* c #000000\",
\". c #ffffff\",
\"**..*...........\",
\"*.*.*...........\",
\"**..*..**.**..**\",
\"*.*.*.*.*.*..*.*\",
\"**..*..**.*...**\",
\"...............*\",
\".............**.\"
};")))
--8<---------------cut here---------------end--------------->8---

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Re: How much is one em (image size unit)?

[Manuel Giraud via Users list for the GNU Emacs text editor]

Akib Azmain Turja <akib@disroot.org> writes:

> I'm trying to show an image such that it has same height as the text and
> resizes relatively with text scale.  I've achieved this with the 'em'
> unit as described in (elisp)Image Descriptors.  But 1 em seems to be
> pretty smaller than the font size.  How to figure out correct value in
> em unit such that image and the text has correct height?

Hi,

FWIW, your example works for me and scales accordingly when I zoom.
-- 
Manuel Giraud

Re: How much is one em (image size unit)?

[Akib Azmain Turja]

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Manuel Giraud via Users list for the GNU Emacs text editor
<help-gnu-emacs@gnu.org> writes:

> Akib Azmain Turja <akib@disroot.org> writes:
>
>> I'm trying to show an image such that it has same height as the text and
>> resizes relatively with text scale.  I've achieved this with the 'em'
>> unit as described in (elisp)Image Descriptors.  But 1 em seems to be
>> pretty smaller than the font size.  How to figure out correct value in
>> em unit such that image and the text has correct height?
>
> Hi,
>
> FWIW, your example works for me and scales accordingly when I zoom.

But 1 em is pretty smaller than the default font size.  I want to make
the image height and the text height same.

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Akib Azmain Turja, GPG key: 70018CE5819F17A3BBA666AFE74F0EFA922AE7F5
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Codeberg: akib
emailselfdefense.fsf.org | "Nothing can be secure without encryption."

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Re: How much is one em (image size unit)?

[Manuel Giraud via Users list for the GNU Emacs text editor]

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Akib Azmain Turja <akib@disroot.org> writes:

[...]

> But 1 em is pretty smaller than the default font size.  I want to make
> the image height and the text height same.

Here is how it look on my Emacs:

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-- 
Manuel Giraud

Re: How much is one em (image size unit)?

[Eli Zaretskii]

> From: Akib Azmain Turja <akib@disroot.org>
> Cc: Manuel Giraud <manuel@ledu-giraud.fr>
> Date: Fri, 31 Mar 2023 22:32:49 +0600
> 
> > Akib Azmain Turja <akib@disroot.org> writes:
> >
> >> I'm trying to show an image such that it has same height as the text and
> >> resizes relatively with text scale.  I've achieved this with the 'em'
> >> unit as described in (elisp)Image Descriptors.  But 1 em seems to be
> >> pretty smaller than the font size.  How to figure out correct value in
> >> em unit such that image and the text has correct height?
> >
> > Hi,
> >
> > FWIW, your example works for me and scales accordingly when I zoom.
> 
> But 1 em is pretty smaller than the default font size.  I want to make
> the image height and the text height same.

Maybe this page will help you:

  https://learn.microsoft.com/en-us/typography/opentype/spec/ttch01

Re: How much is one em (image size unit)?

[Akib Azmain Turja]

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Eli Zaretskii <eliz@gnu.org> writes:

>> From: Akib Azmain Turja <akib@disroot.org>
>> Cc: Manuel Giraud <manuel@ledu-giraud.fr>
>> Date: Fri, 31 Mar 2023 22:32:49 +0600
>> 
>> > Akib Azmain Turja <akib@disroot.org> writes:
>> >
>> >> I'm trying to show an image such that it has same height as the text and
>> >> resizes relatively with text scale.  I've achieved this with the 'em'
>> >> unit as described in (elisp)Image Descriptors.  But 1 em seems to be
>> >> pretty smaller than the font size.  How to figure out correct value in
>> >> em unit such that image and the text has correct height?
>> >
>> > Hi,
>> >
>> > FWIW, your example works for me and scales accordingly when I zoom.
>> 
>> But 1 em is pretty smaller than the default font size.  I want to make
>> the image height and the text height same.
>
> Maybe this page will help you:
>
>   https://learn.microsoft.com/en-us/typography/opentype/spec/ttch01
>

Thanks, but I couldn't understand much.  Say the line height is X em,
then how can I figure out that X?

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Re: How much is one em (image size unit)?

[Eli Zaretskii]

> From: Akib Azmain Turja <akib@disroot.org>
> Cc: help-gnu-emacs@gnu.org
> Date: Sat, 01 Apr 2023 00:15:06 +0600
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Maybe this page will help you:
> >
> >   https://learn.microsoft.com/en-us/typography/opentype/spec/ttch01
> >
> 
> Thanks, but I couldn't understand much.  Say the line height is X em,
> then how can I figure out that X?

I don't understand your problem well enough, so I cannot answer that,
sorry.

Re: How much is one em (image size unit)?

[Fu Yuan]

> 在 2023年4月1日，上午5:35，Akib Azmain Turja <akib@disroot.org> 写道：
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
>>> From: Akib Azmain Turja <akib@disroot.org>
>>> Cc: Manuel Giraud <manuel@ledu-giraud.fr>
>>> Date: Fri, 31 Mar 2023 22:32:49 +0600
>>> 
>>>> Akib Azmain Turja <akib@disroot.org> writes:
>>>> 
>>>>> I'm trying to show an image such that it has same height as the text and
>>>>> resizes relatively with text scale.  I've achieved this with the 'em'
>>>>> unit as described in (elisp)Image Descriptors.  But 1 em seems to be
>>>>> pretty smaller than the font size.  How to figure out correct value in
>>>>> em unit such that image and the text has correct height?
>>>> 
>>>> Hi,
>>>> 
>>>> FWIW, your example works for me and scales accordingly when I zoom.
>>> 
>>> But 1 em is pretty smaller than the default font size.  I want to make
>>> the image height and the text height same.
>> 
>> Maybe this page will help you:
>> 
>>  https://learn.microsoft.com/en-us/typography/opentype/spec/ttch01
>> 
> 
> Thanks, but I couldn't understand much.  Say the line height is X em,
> then how can I figure out that X?

1 em equals to the text height. If your 1 em looks smaller than the text height, something might be wrong. Perhaps post a screenshot of what you get?

Yuan 

Re: How much is one em (image size unit)?

[Akib Azmain Turja]

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Fu Yuan <casouri@gmail.com> writes:

>> 在 2023年4月1日，上午5:35，Akib Azmain Turja <akib@disroot.org> 写道：
>> 
>> Eli Zaretskii <eliz@gnu.org> writes:
>> 
>>>> From: Akib Azmain Turja <akib@disroot.org>
>>>> Cc: Manuel Giraud <manuel@ledu-giraud.fr>
>>>> Date: Fri, 31 Mar 2023 22:32:49 +0600
>>>> 
>>>>> Akib Azmain Turja <akib@disroot.org> writes:
>>>>> 
>>>>>> I'm trying to show an image such that it has same height as the text and
>>>>>> resizes relatively with text scale.  I've achieved this with the 'em'
>>>>>> unit as described in (elisp)Image Descriptors.  But 1 em seems to be
>>>>>> pretty smaller than the font size.  How to figure out correct value in
>>>>>> em unit such that image and the text has correct height?
>>>>> 
>>>>> Hi,
>>>>> 
>>>>> FWIW, your example works for me and scales accordingly when I zoom.
>>>> 
>>>> But 1 em is pretty smaller than the default font size.  I want to make
>>>> the image height and the text height same.
>>> 
>>> Maybe this page will help you:
>>> 
>>>  https://learn.microsoft.com/en-us/typography/opentype/spec/ttch01
>>> 
>> 
>> Thanks, but I couldn't understand much.  Say the line height is X em,
>> then how can I figure out that X?
>
> 1 em equals to the text height. If your 1 em looks smaller than the text height, something might be wrong. Perhaps post a screenshot of what you get?
>
> Yuan 

I have found the size of em unit, it's actually the font size (as in the
the SIZE argument of font-spec).  So, line height in em is:

#+begin_src emacs-lisp
(/ (float (default-font-height)) (font-get (font-spec :name (face-font 'default)) :size))
#+end_src

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Akib Azmain Turja, GPG key: 70018CE5819F17A3BBA666AFE74F0EFA922AE7F5
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RE: [External] : Re: How much is one em (image size unit)?

[Drew Adams]

half an M&M?

Re: [External] : Re: How much is one em (image size unit)?

[Akib Azmain Turja]

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Drew Adams <drew.adams@oracle.com> writes:

> half an M&M?

What?

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Akib Azmain Turja, GPG key: 70018CE5819F17A3BBA666AFE74F0EFA922AE7F5
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Codeberg: akib
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RE: [External] : Re: How much is one em (image size unit)?

[Drew Adams]

> > half an M&M?
> 
> What?

Sorry; I couldn't resist.

https://en.wikipedia.org/wiki/M%26M%27s

Re: [External] : Re: How much is one em (image size unit)?

[Michael Heerdegen]

Drew Adams <drew.adams@oracle.com> writes:

> half an M&M?

That was a really really good one.

Michael.