From: David Ponce via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
To: Eli Zaretskii <eliz@gnu.org>
Cc: 73129@debbugs.gnu.org
Subject: bug#73129: 31.0.50; buffer-text-pixel-size vs. newlines
Date: Mon, 9 Sep 2024 14:56:22 +0200 [thread overview]
Message-ID: <20985fc8-7b1f-409e-9f89-3b976a6f5150@orange.fr> (raw)
In-Reply-To: <868qw1vz5d.fsf@gnu.org>
On 09/09/2024 1:34 PM, Eli Zaretskii wrote:
>> Date: Mon, 9 Sep 2024 00:22:11 +0200
>> From: David Ponce via "Bug reports for GNU Emacs,
>> the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
>>
>> Its seems that the function `buffer-text-pixel-size' is not working
>> as described when there are newlines in the buffer. Here is a quick
>> illustration (on my laptop (frame-char-width) returns 12 pixels):
>>
>> ;; As expected.
>> (with-temp-buffer
>> (insert "abcdef")
>> (car (buffer-text-pixel-size nil nil t)))
>> 72
>>
>> ;; I suppose it is as expected because newline is not displayed.
>> (with-temp-buffer
>> (insert "\n")
>> (car (buffer-text-pixel-size nil nil t)))
>> 0
>>
>> ;; ?
>> (with-temp-buffer
>> (insert "abcd\nef")
>> (car (buffer-text-pixel-size nil nil t)))
>> 48
>
> The above is the intended behavior, assuming that the default width of
> the frame's characters is 12 in your case. The maximum width of the
> text "abcd\nef" is 4 characters ("abcd"), which are 12*4 = 48 pixels.
> The part after the newline is only 2 characters, so it is narrower,
> and does not affect the result.
>
> IOW, buffer-text-pixel-size measures the 2D _dimensions_ of the text,
> not is total width.
Thanks for clarifying.
>
>> The doc string of `buffer-text-pixel-size' mentions:
>>
>> "Return size of whole text of BUFFER-OR-NAME in WINDOW."
>
> It also says:
>
> The return value is a cons of the maximum pixel-width of any text
> line and the pixel-height of all the text lines of the buffer
> specified by BUFFER-OR-NAME.
>
> Does the above explain the behavior you see?
Yes
>
> This is not a bug.
>
>> So ,I expect that the last example will return 72px (6 x 12px) + 0px
>> for the newline. But the result is 48px, which means that all the
>> text after the first newline is not counted.
>
> Your expectations are incorrect, see above.
>
>> This also impacts "string-pixel-width" which is supposed to return
>> the pixel size of the passed string, not part of it:
>>
>> (string-pixel-width "abcdef") => 72
>> (string-pixel-width "\n") => 0
>> (string-pixel-width "abcd\nef") => 48
>> (string-pixel-width "abcd\nef\ngh") => 48
>
> Yes. If you want the _total_ width of a string, remove the newlines
> from it.
>
> I think I understand the source of your confusion, so I have now
> clarified these subtle points in the doc strings of
> window-text-pixel-size, buffer-text-pixel-size, and
> string-pixel-width.
Thanks you very much!
>
>> At least this limitation should be mentioned in the doc string?
>
> I've now done so (and they are not limitations, but conscious design
> decisions which have good reasons).
>
>> A possible fix for `string-pixel-width' could be to remove all
>> the newlines from the passed string before to call
>> `buffer-text-pixel-size'? Something like this:
>
> Thanks, but that would be the wrong thing. If the caller wants a
> total width, the caller should remover the newlines or measure each
> substring separately and add the results.
I agree now that you clarified the behavior of `string-pixel-width' when
it is passed a string with embedded newlines.
> May I ask where and for what purpose did you need to measure pixel
> width of a string that included newlines?
Actually, the current behavior doesn't really impact my current work. I
just noticed it while experimenting, having passed to `string-pixel-width'
a buffer substring that spanned multiple lines. And I thought it would be
good to, at least, clarify the behavior I observed ;-)
You can close this bug.
Many thanks again for your time and assistance!
next prev parent reply other threads:[~2024-09-09 12:56 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-08 22:22 bug#73129: 31.0.50; buffer-text-pixel-size vs. newlines David Ponce via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-09-09 11:34 ` Eli Zaretskii
2024-09-09 12:56 ` David Ponce via Bug reports for GNU Emacs, the Swiss army knife of text editors [this message]
2024-09-09 13:25 ` Eli Zaretskii
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