FS#2875 Imports don't work for LESS stylesheets

CSS, XHTML, JS, Browsers

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  2013-11-02 tnharris

  A @import statement in a LESS stylesheet will not be processed. There are two issues behind this.
  
  The lessc compiler needs to know the base path for import statements. This can be solved by adding the directory of each stylesheet to the list of import directories. But could be a problem if two files in different directories import a file with the same name.
  
  css_loadfile rewrites @import statements to add the URL base path assuming that the source is plain CSS. That makes it impossible for the less compiler to find imported files. Additionally, URLs created during less processing don't get converted to absolute paths.
  
• 

  2013-11-05 ChrisS

  I think changing the rewrite in css_loadfile to behave differently for less files by not adding DOKU_BASE, instead keeping the path relative.  I'll post a PR on github shortly.
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  2013-11-05 ChrisS

  What path (or not) do you expect to use in the @import?
  
  I've assumed something similar to normal @import use.
  
  Eg.
  1. in a plugin, foo including files styles.less & bar.less, styles.less contains the line "@import 'bar.less';"
  2. ditto, but contains the line "@import '/path/to/foo/bar.less';"
  
  In the first instance, css_loadfile() would rewrite the line to "@import '/lib/plugins/foo/bar.less';" and in the second instance it would do nothing.  css_parseless() will add DOKU_INC to the $less->importDir[]
• 

  2013-11-05 ChrisS

  see PR#407 --- https://github.com/splitbrain/dokuwiki/pull/407
• 

  2013-11-09 tnharris

  That seems to work, but may be overengineered.
  
  I think the behavior of @import depends on the file doing the including. So check the extension of the file being loaded not the one being imported. Then there will be no need for a callback?
  
  LESS imports[1] are plain strings without "url()" so every url()[2] substitution should be relative to DOKU_BASE (or an absolute URI). Moreover, LESS may generate its own url() strings, so that substitution needs to be done again after lessc. Actually, I'm not sure what to do about this because we don't know the source path from which imported LESS files. i.e. style.ini includes css/screen.less that imports less/icons.less that has a url(../../images/icon.png). The URL should be resolved relative to css/less but the change of directories is buried in the LESS compiler.
  
  [1] http://lesscss.org/#-importing
  [2] http://www.w3.org/TR/2011/REC-CSS2-20110607/cascade.html#at-import
  
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  2013-11-16 tnharris

  I've been using this branch[1] for the past week and had no problem with importing files.
  
  [1] https://github.com/whoopdedo/dokuwiki/commit/fdc61a63d42172d775ecdef57b1463c64c11284e
  
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  2013-11-17 ChrisS

  Tom, we went with my updated code in PR#407.  There was concern in your branch that a less file with a css import would end up with the wrong location/path.