stencil.scm: add make-path-stencil function

stencil.scm: add make-path-stencil function

supports all path commands both relative and absolute:
lineto, rlineto, curveto, rcurveto, moveto, rmoveto, closepath
also supports single letter syntax used in standard SVG path commands:
L, l, C, c, M, m, Z, z.
Refactors make-connected-path-stencil for backwards compatibility and
continued use

[lemzwerg, 2014-01-18 04:52:50]

https://codereview.appspot.com/54050043/diff/1/scm/stencil.scm
File scm/stencil.scm (right):

https://codereview.appspot.com/54050043/diff/1/scm/stencil.scm#newcode449
scm/stencil.scm:449: coordinates for the origin point of the path (used for
closepath and
A minor thing: We use two spaces after a full stop in documentation strings. 
(At least it should be like that in general.)

[pwm, 2014-01-18 05:14:50]

This patch introduces a make-path-stencil function that offers the benefits of
the current make-connected-path-stencil function without its limitations:

- Like make-connected-path-stencil it automatically calculates the stencil
extents so you don't have to do it manually (no small task when the extents are
somewhere on a curve).

- Allows use of all path commands, both relative and absolute, not just lineto
and curveto.  (i.e. lineto rlineto curveto rcurveto moveto rmoveto closepath) 
This allows "unconnected" paths with multiple segments. (i.e. allows (r)moveto
in the middle of the path expression)

- Allows optional use of single letter syntax used in standard SVG path
commands: L, l, C, c, M, m, Z, z.  This is useful for those familiar with the
SVG syntax, and makes it convenient to take path code from SVG files and insert
it into LilyPond files.  (see
https://developer.mozilla.org/en-US/docs/Web/SVG/Tutorial/Paths)

make-connected-path-stencil is still available for use and/or backwards
compatibility, but refactored so that it calls make-path-stencil after syntax
conversion.  Here are some examples to show the syntax:

\version "2.18.0"
{

  c'1^\markup \stencil
  #(make-path-stencil
    `(rmoveto 0 0
       rlineto 2 0
       rlineto 0 -2
       rlineto -2 0
       closepath
       rmoveto 1.1 -1.1
       rlineto 2 0
       rlineto 0 -2
       rlineto -2 0
       closepath
       rmoveto 1.1 -1.1
       rlineto 2 0
       rlineto 0 -2
       rlineto -2 0
       closepath)
    0.2 1 1 #f)

  c'1^\markup \stencil
  #(make-path-stencil
    '(m -1 1
       c 0 0.75 1 0.75 1 0
       c 0 -0.75 -1 -0.75 -1 0
       c -1 0 -1 1.5 -0.5 1.5
       m 0.5 -1.5
       c -1 0 -1 -1.5 -0.5 -1.5
       m 1.5 1.5
       c 2.5 0 2.5 4 4 4
       m -4 -4
       c 2.5 0 2.5 -4 4 -4)
    0.2 1 1 #f)
}

Here are snippets demonstrating each of the current ways to make a path stencil:
http://lsr.dsi.unimi.it/LSR/Item?id=891
http://lsr.dsi.unimi.it/LSR/Item?id=623

Thanks for reviewing.

[pwm, 2014-01-18 20:47:20]

On 2014/01/18 04:52:50, lemzwerg wrote:
> https://codereview.appspot.com/54050043/diff/1/scm/stencil.scm
> File scm/stencil.scm (right):
> 
> https://codereview.appspot.com/54050043/diff/1/scm/stencil.scm#newcode449
> scm/stencil.scm:449: coordinates for the origin point of the path (used for
> closepath and
> A minor thing: We use two spaces after a full stop in documentation strings. 
> (At least it should be like that in general.)

Ok, will do.  I will wait to see if other changes are needed before doing
another patch.

(Funny, I have always used two spaces until just this past year where at my job
the expectation is now to use one...)

[pwm, 2014-01-21 02:15:25]

https://codereview.appspot.com/54050043/diff/1/scm/stencil.scm
File scm/stencil.scm (right):

https://codereview.appspot.com/54050043/diff/1/scm/stencil.scm#newcode449
scm/stencil.scm:449: coordinates for the origin point of the path (used for
closepath and
On 2014/01/18 04:52:51, lemzwerg wrote:
> A minor thing: We use two spaces after a full stop in documentation strings. 
> (At least it should be like that in general.)

Done.