Re: [eclipse-incubator-e4-dev] CSS namespaces

[Ralf Sternberg <rsternberg@xxxxxxxxxxxxxx>]

Hi Kevin,

see my comment below:

Kevin McGuire wrote:
>  > Hi,
>  >
>  > Angelo brought up CSS namespaces, I think this is an important topic
>  > that hasn't been discussed here yet.
>
> Sigh... yes.
>
>  > The question is how to specify
>  > custom widget types in CSS. With SWT, the widget names are unambiguous,
>  > but custom widgets can involve name collisions.
>  >
>  > Using CSS namespaces would be an option, although I would then opt for
>  > using a default namespace for SWT to avoid clutter. The CSS could look
>  > like this:
>  >
>  >    @namespace "org.eclipse.swt.widgets";
>  >    @namespace my "my.name.space";
>  >
>  >    Label {
>  >      color;red;
>  >    }
>  >
>  >    my|Label {
>  >      color;red;
>  >    }
>  >
>  > On the other hand, some frequently used SWT widgets live in
>  > "org.eclipse.swt.custom" (CLabel, CCombo, CTabFolder, ...), so those
>  > would have to be prefixed as well (which I somehow dislike):
>  >
>  >    swtcustom|CLabel {
>  >      color: blue;
>  >    }
>
> Agree, I dislike it too. It's annoying to clutter the typical case (SWT 
> widgets, regardless of whether they are custom or not).
>
>  > Moreover, CSS 3 is not yet widely adopted and the available parsers do
>  > not support it out-of-the-box.
>
> Good point.
>  
>  > An alternative to CSS namespaces could be some kind of mapping between
>  > widget classes and CSS element names.
>
> I think this is a reasonable approach. Extended widgets outside of SWT 
> would need some form of qualified name, not so much to prevent clashing 
> with SWT since presumably everyone avoids that, but to prevent clashing 
> with each other.  The element names can be whatever we want them to be, 
> since its our code that'll do the mapping from CSS to widget method 
> calls.  So we could solve it without resorting to CSS name spaces, for 
> example by requiring that extended widgets register their names with us 
> in some qualified fashion (e.g. NebulaGallery).  Kinda hacky but would 
> work.

Yes, that's also our preferred approach. In RAP we have an extension 
point for themeable widgets anyway (the RAP theming has to know about 
themeable widgets to keep styling and layout in sync between client and 
server). This is also a suitable place to register such an element name. 
I'm not sure whether such an extension point would also be appropriate 
for Eclipse in general. Who would have to register with such an 
extension point? The component provider, e.g. Nebula?

Ralf

> Kevin
>
>
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