On 9/30/24 13:52, Leif Halvard Silli wrote:
Just a short reply, to admit an error of terminology, however my point
remains:
I should not have said "style rule". I should have said (property)
declaration, or something like that.
Declaration is vague. Let's call this
---
color: red
---
a property, and this
---
h1 { color: red }
---
a rule.
Of course the entire set of property rules - aka style rule - for the
detail element you showcased in your reply, should not be ignored. Doing
that, would be counter to the CSS specs.
But the very property
margin: 1rem 0;
should be ignored by XXE if it does not understand it.
Quoting CSS 2.1 <https://www.w3.org/TR/CSS2/syndata.html#parsing-errors
<https://www.w3.org/TR/CSS2/syndata.html#parsing-errors>> (which is not
up to date, but I think this remains):
]]
Unknown properties. User agents must ignore a declaration with an
unknown property. For example, if the style sheet is:
h1 { color: red; rotation: 70minutes }
the user agent will treat this as if the style sheet had been
h1 { color: red }
[[
Does this make my RFC more doable for you?
Yes. We'll review our current implementation of the CSS engine and we'll
do our best to make it more consistent when an unknown property or
unknown property value is parsed.
Leif Halvard Silli
Den 30. september 2024 12:42:31 CEST, skrev Hussein Shafie
<huss...@xmlmind.com>:
On 9/30/24 10:49, Leif Halvard Silli wrote:
This relates to how XXE itself treats CSS values that it does
not support, and it in particular relates to the Emulate Browser
view for XHTML documents (though in principle and perhaps also
in practise, it does also relate to the Semantic View, when one
alter the way XXE displays elements).
Theory:
When a CSS parser discovers a value that it does not
support, it should ignore the entire style rule.
This behavior is totally counter-intuitive and would make developing
CSS stylesheets specifically for XXE (an important goal for us) more
difficult.
Let's explain this.
You want to style an XML document. For that, you write a number of
CSS rules using your CSS knowledge. For example, something as simple as:
detail {
display: block;
color: navy;
margin: 1rem 0;
}
According to the behavior you describe, <detail> would not be styled
at all just because the CSS author used the very common "rem" length
unit (currently not supported by XXE).
The behavior you describe makes it very difficult for a CSS author
to pinpoint XXE limitations in terms of CSS support and work around
them.
Example:
blockquote{margin-left:1mm}
blockquote{margin-left:1km}
In the above example, because 'km' (as much as I know) is an
unsupported unit value in CSS, the second style rule should be
completely ignored, and the first style rule should be used and
applied.
XXE does not follow this rule, it seems. In addition, XXE has
many limitations with regard to the degree to which it supports CSS.
Indeed.
Good, conforming, CSS support has never been a design goal of XXE.
XXE supports just enough CSS to make an XML document look decent on
screen and that's it.
So for instance, the Emulate Browser View supports the
'margin-left' property, as long as one uses the units that XXE
supports. Thus it supports
margin-left:200px;
But it does not support
margin-left:55%;
(If we use the built in style editor to add margin-left:55%; for
a particular element, we are told that this value unit is not
supported.)
For that reason, if, inside a <style> element, one does this:
margin-left:200px;
margin-left:55%;
Then, for instance, Firefox would use the last style rule, since
it knows about both units and thus supports both rules – but the
last rule should override the first rule. Whereas the Emulate
View should ignore the last rule and apply the first rule, since
it does not know about the percentage unit it margin styles.
Currently, howver, this does not happen. What happens instead,
is that both rules are ignored by XXE.
This looks like a bug. We'll investigate this and if possible, try
to fix this bug.
With XXE:
------------------------------------------------------------------------
margin-left:200px;
margin-left:55%;
------------------------------------------------------------------------
should be equivalent to:
------------------------------------------------------------------------
margin-left:200px;
------------------------------------------------------------------------
and not to:
------------------------------------------------------------------------
margin-left:0;
------------------------------------------------------------------------
This has several effects. The most important thing being that i
makes it difficult to work around the limitations of XXE’s
Emulate Browser view.
It also makes Emulate Browser kind of useless, since one way to
work around this limitation, is to make XXE spesific CSS styles
that goes into
'xhtml-config:css/xhtml_user_styles.css' (for the Emulate
Browser view) or
'xhtml-config:css/xhtml5.css' (for the semantic view).
The "Emulate Web Browser" CSS stylesheet has its uses, which are
explained here:
https://www.xmlmind.com/xmleditor/_distrib/doc/xhtml/view.html
<https://www.xmlmind.com/xmleditor/_distrib/doc/xhtml/view.html>
Some users like it for very modest reasons, for example, simply
because they are used to see lists rendered by default in a compact
way (just like in web browsers).
But if you add the margin-left:200px; to xhtml_user_styles.css,
and you also add marign-left:55% to the <style> element of the
document you are editing, then XXE will in fact ignore both
stylel rules and default to margin-left:0;
So please make life simpler for us and make XXE ignore style
rules entirely when it does not understand/support the unit
value that is used inside the style rule!
Sorry but we will not implement your RFC.
--
Hussein SHAFIE, Product Manager, huss...@xmlmind.com
XMLmind Software, 35 rue Louis Leblanc, 78120 Rambouillet, France
Phone: +33 (0)9 52 80 80 37, Fax: +33 (0)9 57 80 80 37, www.xmlmind.com
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