Add "line-height"

[federicomenaquintero]

This is in CSS3, which is kind of required for SVG2, which I'm slowly getting at in librsvg 😃

[jdm]

@bors-servo r+

[bors-servo]

📌 Commit d086eef has been approved by jdm

[bors-servo]

⌛ Testing commit d086eef with merge 0e6b972...

[bors-servo]

☀️ Test successful - checks-travis
Approved by: jdm
Pushing 0e6b972 to master...

[federicomenaquintero]

That was fast, thank you!

[SimonSapin]

I don’t find line-height in https://svgwg.org/svg2-draft/eltindex.html or https://svgwg.org/svg2-draft/attindex.html, so it doesn’t like it’s an element name or attribute name which is what html5ever uses the LocalName type for. Servo uses https://docs.rs/string_cache/0.8.0/string_cache/#with-compile-time-atoms to define a separate Atom type for CSS property names, with the names of all supported properties as static atoms. I recommend librsvg does the same, so a PR like this one isn’t needed every time you add support for a new property.

[federicomenaquintero]

Oh, line-height is indeed a property name, not an attribute name, from https://www.w3.org/TR/CSS22/visudet.html#propdef-line-height

It wasn't clear to me if the names in markup5ever are in fact attribute names that happen to correspond to properties.

Am I doing something wrong here:

• Librsvg stores all attribute names and CSS property names as QualName, because the code more or less evolved to that, and because I thought that attributes which have the same name as properties may as well use the same representation for their name. Should property names live elsewhere / am I wrongly using QualName because it seemed like a convenient way to have a namespace/name?
• (Note that librsvg does not implement CSS namespaces yet...)
• If I define my own string cache for CSS property names, won't there be awkward conversions between QualName, which expects type LocalName = Atom<LocalNameStaticSet>, and my own string cache? (If the answer above was "QualName is not meant for CSS property names", then I guess this question is moot :)

[SimonSapin]

CSS properties do not have namespaces. CSS @namespace rules affect selectors, not properties, and is relevant to the namespace of element types and attributes names being matched.

SVG has a number of presentation attributes that map to CSS properties of corresponding names, but not all SVG attributes are "presentation" and not all CSS properties relevant to SVG have a corresponding attribute. (Parsing the value of those attributes is also slightly different from parsing the value of the corresponding property in a stylesheet or style attribute context.)