Re: [cssparser-developers] Migrating from CSS4J

[Vincent M. <vi...@ma...>]

Hi Ronald,

> On 17 May 2017, at 21:24, Ronald Brill <rb...@rb...> wrote:
> 
> Hi Vincent,
> 
> thanks for considering CSSParser as alternative solution.
> CSSParser is a smaller/more focused solution; only parsing the css into some tree sturcture is the current focus of the project. There is no support to parse (X)Html and also no
> help for mixing the two trees into one.
> As far as i know there are two main use cases for CSSParser at the moment:
> * parsing a css for error detection or optimization and optional writing back the optimized version (The cleanup/optimization is not part of CSSParser)
> * parsing a css to support html processing
> 
> The second case is what is done by HtmlUnit (i'm also involved with this project). HtmlUnit uses NekoHtml to parse (X)Html and CSSParser for css. Then HtmlUnit uses both
> informations to simulate real browser behavior.
> If you like i can think a bit if your use case is someting that can be done with HtmlUnit - give me a sign and i will have a look ;-)
> 
> Outside of this i'm a bit curious about your case. Usually the css is separated from the Html by idea. Why you like to merge this?

Thanks for your reply. Yes I agree that the use case may look weird from the outside :) So let me explain.

This is for the XWiki PDF export. The big steps are (better explained here: http://platform.xwiki.org/xwiki/bin/view/AdminGuide/Configuration#HCustomizingthePDFexportLook26Feel):

* Render a wiki page into XHTML
* Apply CSS4J to merge the pdf.css and user-customized CSS for PDF export into the generated XHTML
* Apply a xhtml2fo.xsl XSL stylesheet to generate XSL-FO
* Use Apache FOP to convert from XSL-FO to PDF

The problem is probably because XSL-FO doesn’t support defining the styles into CSS so in any case there’s a need to convert the CSS into something usable by XSL-FO processors such as Apache FOP. I did a quick search and found http://stackoverflow.com/questions/17495152/using-external-css-in-xsl-fo but that is far from simple and requires to convert CSS into some XSL.

Thanks
-Vincent

> 	RBRi
> 
> On Tue, 16 May 2017 18:18:56 +0200 Vincent Massol wrote:
>> 
>> Hi guys,
>> 
>> On the XWiki project (http://xwiki.org) we're currently using CSS4J but it's painful (several bugs, no issue tracker, no mailing list) so we're considering migrating to another
> library and we're looking at CSSParser.
>> 
>> We use CSS4J to do the following: apply some CSS content to XHTML.
>> 
>> For example:
>> 
>> CSS:
>> "span { color:red; }"
>> 
>> XHTML:
>> ...
>> <div id="xwikicontent">
>> <p><span style="background: white;">Hello</span></p>
>> </div>
>> 
>> 
>> Result:
>> ...
>> <div id="xwikicontent">
>> <p><span style="background: white; color: red;">Hello</span></p>
>> </div>
>> 
>> 
>> Is that possible to do with CSSParser?
>> 
>> FTR this is our code where we use CSS4J:
>> *
> https://github.com/xwiki/xwiki-platform/blob/30d27eb8ec23f7c5a28ca505a75f1c73f8fe0073/xwiki-platform-core/xwiki-platform-oldcore/src/main/java/com/xpn/xw
> iki/pdf/impl/PdfExportImpl.java#L460-L460
>> *
> https://github.com/xwiki/xwiki-platform/blob/30d27eb8ec23f7c5a28ca505a75f1c73f8fe0073/xwiki-platform-core/xwiki-platform-oldcore/src/main/java/com/xpn/xw
> iki/pdf/impl/PdfExportImpl.java#L506
>> 
>> Thanks
>> -Vincent
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