Re: SVGTextContentElement interface broken

Hi Domenico,

If you appended a test case, it would be much easier to reproduce your
problem. Though as it works in Firefox, as you say, I think the issues you
mention are rather related to implementations, not the specification itself.

For the specification it is fine to declare xml:space as deprecated because
its features are covered by the white-space property's values.

And looking at the example at
https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/xml:space, it
seems that current versions of Chrome and Edge do still support the
xml:space attribute.
And support for the white-space property in SVG is tracked in
https://crbug.com/366558 for Chromium based browsers.

Sebastian

On Thu, 18 Mar 2021 at 13:16, Domenico Strazzullo <
strazzullo.domenico@gmail.com> wrote:

> While wondering if the statements at developer.mozilla [1] were 100%
> dependable, I got the expected confirmation that SVG2 [2] specifies that xml:space
> is “retained for backwards compatibility”, proving that the warning in
> [1] makes false statements, in particular “Be aware that this feature may
> cease to work at any time.”, while, as per the specification, it must not
> cease to work. Unfortunately, as arbitrary as it may be, that statement
> proves to be true.
>
> Difficult now to guess if anyone can, or is willing to do something about
> it.
>
> Domenico
>
> On Thu, Mar 11, 2021 at 2:38 PM Domenico Strazzullo <
> strazzullo.domenico@gmail.com> wrote:
>
>> Hi,
>>
>> The concerned methods are: getComputedTextLength(),
>> getSubStringLength(), getStartPositionOfChar(), and getEndPositionOfChar().
>>
>> The task is to get the advance values in a string of rendered and
>> formatted text.
>>
>> getStartPositionOfChar() and getEndPositionOfChar() are obviously the
>> most appropriate for that task. But they fail. Then
>> getComputedTextLength() and getSubStringLength(), which can both do the job (programmatically
>> rebuilding the string one character at a time), were tested, and also
>> failed. This is true for Chrome and Edge, while Firefox executes the
>> task flawlessly using any of those four methods.
>>
>> I repeat, Firefox executes the task flawlessly using any of those four
>> methods.
>>
>> What’s causing the failure (errors thrown on wrong “charnum” and/or
>> “nchars” parameters -> freeze of the concerned text element) is the
>> charCode 32 (space bar) – which, incidentally, can be replaced
>> programmatically by charCode 160 (non breaking space) during after-input
>> processing, and before using any of the aforementioned methods (but
>> still… this would be just a cheap workaround).
>>
>> More precisely, double spaces and trailing spaces cause the errors, but
>> also a single inner space depending on the method used and the proceedings.
>>
>> After puzzlement and then investigation, you learn that the "xml:space"
>> attribute is deprecated in SVG2, and at
>>
>> https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/xml:space
>>
>> you read "Instead of using the xml:space attribute, use the white-space
>> CSS property". But... in the Browser compatibility section you can see that
>> only Firefox has full support, all the others showing the "Compatibility
>> unknown" sign – at my expense I found out that Chrome and Edge obviously
>> decided to break the support, even though it's nothing like common practice
>> to break backward compatibility, quite the contrary.
>>
>> But that is nothing, when visiting the white-space CSS property page,
>> Browser compatibility section, you learn that only Firefox – and defunct
>> Internet Explorer – has full "Support in SVG"! All the others show a
>> merciless "No". And not only that, the white-space CSS property is just a
>> candidate recommendation in CSS Text Module Level 3. It seems then that
>> somebody decided to take something fundamental out of SVG with the
>> intention to replace it with an extraneous feature that is not quite there
>> yet, and in any case not implemented. Did that/those persons even consider
>> that SVG does not have the same text module as the markup language that is
>> the natural target for CSS?
>>
>> Please, cancel the deprecation of "xml:space" in SVG.
>>
>> Regards,
>> Domenico
>>
>