From: Manuel Giraud via "Emacs development discussions." <emacs-devel@gnu.org>
To: Alan Third <alan@idiocy.org>
Cc: emacs-devel <emacs-devel@gnu.org>
Subject: Re: Images :scale and :width/:height relation
Date: Sun, 03 Sep 2023 15:37:11 +0200 [thread overview]
Message-ID: <8734zvcr94.fsf@ledu-giraud.fr> (raw)
In-Reply-To: <ZPJQQjwe8fhY2QEf@idiocy.org> (Alan Third's message of "Fri, 1 Sep 2023 21:57:38 +0100")
Alan Third <alan@idiocy.org> writes:
> On Fri, Sep 01, 2023 at 12:46:11PM +0200, Manuel Giraud via Emacs development discussions. wrote:
>> Hi,
>>
>> For the need of bug#65581, I'd like to have access to the current scale
>> of an image. But it seems that this one does not always reflect
>> reality. For instance, you can have a image with an original width of
>> 500 scaled down to a width of 100 (by mean of the :width keyword) and
>> its :scale keyword will still be 1.
>>
>> In "(elisp) Image Descriptors", it is said that:
>>
>> If both ‘:scale’ and ‘:height’/‘:width’ are specified, the
>> height/width will be adjusted by the specified scaling factor.
>>
>> But it does not seems to work the other way around.
>
> I think you've maybe misunderstood. If you set :width 100, and :scale
> 2, then the actual image will have a width of 200. The image spec will
> still say :width 100 :scale 2.
Ok. So with both a :width and a :scale, each does its scaling. From
the info, I thought that a :scale set would then modify :width
accordingly.
>> Wouldn't it be a good thing if 'create-image' return a
>> « normalized » image spec where the :width, :height and :scale are
>> filled and kept in sync?
>
> It would probably be nice, but it's not that easy as you can't work
> out the scale, given a desired width or height, without loading the
> image first to get the real width, and Emacs only loads the image at
> display time.
Hum, I see.
> IIRC the likes of eww will actively load an image and then get the
> size and set the scale accordingly. Perhaps that sort of behaviour
> should be made available generally.
I should have a look their then. But Emacs does not have a way of
asking "what are the dimensions of this image" without loading it into
its cache?
--
Manuel Giraud
next prev parent reply other threads:[~2023-09-03 13:37 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-01 10:46 Images :scale and :width/:height relation Manuel Giraud via Emacs development discussions.
2023-09-01 20:57 ` Alan Third
2023-09-03 13:37 ` Manuel Giraud via Emacs development discussions. [this message]
2023-09-03 16:40 ` Alan Third
-- strict thread matches above, loose matches on Subject: below --
2023-09-01 9:54 Manuel Giraud
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