Add -dmusic-strings-to-paths and enable for SVG backend.

Add -dmusic-strings-to-paths and enable for SVG backend.

* Using a -dmusic-strings-to-paths option generalizes the check
  (lily/pango-font.cc) to see if the "utf-8-string" stencil
  expression should be used for a backend.

* Enable the new option only if it's found in a list of supported
  backends (scm/lily.scm).  Currently, only the SVG backend
  supports this.  In the future, more backends might support this
  option.

* Update comments.

[joeneeman, 2010-01-10 05:03:30]

http://codereview.appspot.com/186054/diff/1/2
File lily/pango-font.cc (right):

http://codereview.appspot.com/186054/diff/1/2#newcode384
lily/pango-font.cc:384: bool to_paths = get_program_option
("music-strings-to-paths");
It would be more consistent, I think, to use a global variable here.

http://codereview.appspot.com/186054/diff/1/2#newcode386
lily/pango-font.cc:386: if (has_utf8_string && ((to_paths && !music_string) ||
!to_paths))
If I understand this correctly, the SVG backend will now output feta characters
using utf-8-string by default (ie. unless the user manually specifies
-dmusic-strings-to-paths)?

[Patrick McCarty, 2010-01-10 06:40:56]

On 2010/01/10 05:03:30, joeneeman wrote:
> http://codereview.appspot.com/186054/diff/1/2
> File lily/pango-font.cc (right):
> 
> http://codereview.appspot.com/186054/diff/1/2#newcode384
> lily/pango-font.cc:384: bool to_paths = get_program_option
> ("music-strings-to-paths");
> It would be more consistent, I think, to use a global variable here.

Done.

> http://codereview.appspot.com/186054/diff/1/2#newcode386
> lily/pango-font.cc:386: if (has_utf8_string && ((to_paths && !music_string) ||
> !to_paths))
> If I understand this correctly, the SVG backend will now output feta
characters
> using utf-8-string by default (ie. unless the user manually specifies
> -dmusic-strings-to-paths)?

It's actually the opposite.  -dmusic-strings-to-paths is true by default for the
SVG backend, which is now set in scm/lily.scm.  The backend will only use
utf-8-string when a "non-music string" is encountered.

The user can override the defaults by specifying

  #(ly:set-option 'music-strings-to-paths #f)

in their file.

Sorry this is so complicated.  :-(  Is there a way to make this check more
clear?

[joeneeman, 2010-01-10 08:09:32]

On 2010/01/10 06:40:56, Patrick McCarty wrote:
> On 2010/01/10 05:03:30, joeneeman wrote:
> > http://codereview.appspot.com/186054/diff/1/2
> > File lily/pango-font.cc (right):
> > 
> > http://codereview.appspot.com/186054/diff/1/2#newcode384
> > lily/pango-font.cc:384: bool to_paths = get_program_option
> > ("music-strings-to-paths");
> > It would be more consistent, I think, to use a global variable here.
> 
> Done.
> 
> > http://codereview.appspot.com/186054/diff/1/2#newcode386
> > lily/pango-font.cc:386: if (has_utf8_string && ((to_paths && !music_string)
||
> > !to_paths))
> > If I understand this correctly, the SVG backend will now output feta
> characters
> > using utf-8-string by default (ie. unless the user manually specifies
> > -dmusic-strings-to-paths)?
> 
> It's actually the opposite.  -dmusic-strings-to-paths is true by default for
the
> SVG backend, which is now set in scm/lily.scm.  The backend will only use
> utf-8-string when a "non-music string" is encountered.

Oops, I missed the second chunk of lily.scm. LGTM