ikiwiki/doc/todo/CSS_classes_for_links.mdwn

Hi Joey,

What do you think about CSS classes for links to display link with icon?
You probably know that there are wikis with that feature, for example
Moin Moin.

Here is a piece of `common.css` file grabbed from <http://wiki.openwrt.org>
site which is powered by Moin Moin wiki:

    a.www:before {content: url(../img/moin-www.png); margin: 0 0.2em;}
    a.http:before {content: url(../img/moin-www.png); margin: 0 0.2em;}
    a.https:before {content: url(../img/moin-www.png); margin: 0 0.2em;}
    a.file:before {content: url(../img/moin-ftp.png); margin: 0 0.2em;}
    a.ftp:before {content: url(../img/moin-ftp.png); margin: 0 0.2em;}
    a.nntp:before {content: url(../img/moin-news.png); margin: 0 0.2em;}
    a.news:before {content: url(../img/moin-news.png); margin: 0 0.2em;}
    a.telnet:before {content: url(../img/moin-telnet.png); margin: 0 0.2em;}
    a.irc:before {content: url(../img/moin-telnet.png); margin: 0 0.2em;}
    a.mailto:before {content: url(../img/moin-email.png); margin: 0 0.2em;}
    a.attachment:before {content: url(../img/moin-attach.png); margin: 0 0.2em;}
    a.badinterwiki:before {content: url(../img/moin-inter.png); margin: 0 0.2em;}
    a.interwiki:before {content: url(../img/moin-inter.png); margin: 0 0.2em;}

You can see that they use a lot of CSS classes for links, but only one CSS class
for external links is enough for me :) Please look at my example:

    \[[Foo]]                    -> <a href="http://www.mywiki.org/foo.html">Foo</a>
    \[[Bar|foo/bar]]            -> <a href="http://www.mywiki.org/foo/bar.html">Bar</a>
    <http://www.gnu.org/>      -> <a class="external" href="http://www.gnu.org/">http://www.gnu.org/</a>
    [GNU](http://www.gnu.org/) -> <a class="external" href="http://www.gnu.org/">GNU</a>
    [RMS](mailto:rms@gnu.org)  -> <a href="mailto:rms@gnu.org">RMS</a>

My best regards,

--[[Paweł|ptecza]]

> If you did not already know, you can achieve similar results using CSS3
> selectors.  Eg: `a[href="http://www.foobar.com/"] { foobar: css }` or
> `a[title~="Mail"] {text-decoration: none; }`.  See
> <http://www.w3.org/TR/2001/CR-css3-selectors-20011113/> for a complete list.

>> Hi Charles,
>>
>> Thanks for the hint! I don't know CSS3 yet :) What modern and popular
>> WWW browsers do support it now?
>>
>>> Safari supports it. Firefoz&Co support most of it. IE6 did not, but IE7
>>> supports a fair part of CSS3, ans is said to support selectors.
>>>
>>> Example on how to use selectors here: http://www.kryogenix.org/days/2002/08/30/external
>>>
>>> I also think this should be in an external plugin, not in ikiwiki.
>>>

I find CSS3 support still spotty...  Here are some notes on how to do this in IkiWiki with jQuery: <http://iki.u32.net/setup/External_Links> --[[sabr]]

> If you need to achieve this in IkiWiki itself, I imagine you could create a
> plugin which runs in the `format` phase of rendering and search/replaces
> specific link patterns.  This should be a fairly simple exercise in regular
> expressions.
>
> --CharlesMauch

>> I've never written plugin for ikiwiki, but I can try if it's simple job :)
>>
>> --[[Paweł|ptecza]]

> I wouldn't mind adding a _single_ css class to ikiwiki links, but it
> would have to be a class added to all internal, not all external, links.
> Reason is that there are many ways for external links to get into an
> ikiwiki page, including being entered as raw html. The only time ikiwiki
> controls a link is when an internal link is added using a WikiLink.
>
> (Note that tags get their own special
> [[rel_attribute|rel_attribute_for_links]] now that CSS can use.)
> 
> --[[Joey]]

>> I had a little look at this, last weekend. I added a class definition to
>> the `htmllink` call in `linkify` in `link.pm`. It works pretty well, but
>> I'd also need to adjust other `htmllink` calls (map, inline, etc.). I found
>> other methods (CSS3 selectors, etc.) to be unreliable.
>> 
>> Would you potentially accept a patch that added `class="internal"` to
>> various `htmllink` calls in ikiwiki?
>> 
>> How configurable do you think this behaviour should be? I'm considering a
>> config switch to enable or disable this behaviour, or possibly a
>> configurable list of class names to append for internal links (defaulting
>> to an empty list for backwards compatibility)>
>> 
>> As an alternative to patching the uses of `htmllink`, what do you think
>> about patching `htmllink` itself? Are there circumstances where it might be
>> used to generate a non-internal link? -- [[Jon]]

>>> I think that the minimum configurability to get something that
>>> can be used by CSS to style the links however the end user wants
>>> is the best thing to shoot for. Ideally, no configurability. And
>>> a tip or something documenting how to use the classes in your CSS
>>> to style links so that eg, external links have a warning icon.
>>> 
>>> `htmllink` can never be used to generate an external link. So,
>>> patching it seems the best approach. --[[Joey]] 

>>>> I had a quick look to this issue. Internal links are generated at
>>>> 11 places in the Perl code and would need to be patched (this
>>>> number could be lowered a bit if a htmllink-like function existed
>>>> for CGI urls; such a function would use `cgiurl`, and be used in
>>>> most places where `cgiurl` is currently called by plugins).
>>>> 
>>>> Also, more than 30 `<a>` links appear in templates, most of those
>>>> being internal links.
>>>> 
>>>> Sure, patching those few dozen places is trivial. On the other
>>>> hand, I'm wondering how doable it would be to make sure, on the
>>>> long run, any generated internal link has the right CSS class
>>>> applied. One would need to write tests running against the code
>>>> with all plugins enabled, all templates put to work, in order to
>>>> ensure consistency is maintained. --[[intrigeri]]

-----
If you're going to be patching htmllink anyway, might I suggest something more flexible, like being able to configure the link format?
(Yes, PmWiki allows this, that's where I got the idea)
That is, rather than having "&lt;a href=". blah . blah ...
one could use a sprintf with a default format which could be configured in the setup file.

For example:

    $format = ($config{createlink_format}
               ? $config{createlink_format}
               : '<span class=\"createlink\"><a href="%s" rel="nofollow">?</a>%s</span>');
    return sprintf($format,
        cgiurl(do => "create", page => lc($link), from => $lpage),
        $linktext);

I admit, I've been wanting something like this for a long time, because I dislike the existing createlink format...

--[[KathrynAndersen]]