patch for properly scaled fractions

[Werner LEMBERG]

I suggest the patch at the end of this email to get properly scaled
fractions.  The two images demonstrate this, using the input below.
Note that the correct command to position the plus sign is
\translate-scaled; this is something which should probably be added to
the documentation.

However, it's still not perfect yet: For smaller sizes, the whitespace
surrounding the plus sign is too large since it isn't scaled.  I
consider this as, well, a bad feature, and I suggest to change it too.


    Werner


======================================================================


\version "2.11.0"

\header { texidoc = "
" }

meter =
  #(define-music-function (parser location size) (number?) #{
    R1^\markup { \fontsize #$size { \fraction \number "1" \number "4"
                                    \lower #.5 \number "+"
                                    \fraction \number "10" \number "8" } } #})

meterscaled =
  #(define-music-function (parser location size) (number?) #{
    R1^\markup { \fontsize #$size { \fraction \number "1" \number "4"
                                    \translate-scaled #'(0 . -.5) \number "+"
                                    \fraction \number "10" \number "8" } } #})


{
  \meter #-8.0 | \meter #-6.0 | \meter #-4.0 |
    \meter #-2.0 | \meter #0.0 |
  \break
  \meterscaled #-8.0 | \meterscaled #-6.0 | \meterscaled #-4.0 |
    \meterscaled #-2.0 | \meterscaled #0.0 |
}

\paper {
  ragged-right = ##t
}

% EOF


======================================================================


--- define-markup-commands.scm.old      2006-11-27 22:15:07.000000000 +0100
+++ define-markup-commands.scm  2006-11-28 15:28:17.000000000 +0100
@@ -1339,21 +1339,26 @@
 (define-markup-command (fraction layout props arg1 arg2) (markup? markup?)
   "Make a fraction of two markups."
   (let* ((m1 (interpret-markup layout props arg1))
-         (m2 (interpret-markup layout props arg2)))
+         (m2 (interpret-markup layout props arg2))
+         (factor (magstep (chain-assoc-get 'font-size props 0)))
+         (boxdimen (cons (* factor -0.05) (* factor 0.05)))
+         (padding (* factor 0.2))
+         (baseline (* factor 0.6))
+         (offset (* factor 0.75)))
     (set! m1 (ly:stencil-aligned-to m1 X CENTER))
     (set! m2 (ly:stencil-aligned-to m2 X CENTER))
     (let* ((x1 (ly:stencil-extent m1 X))
            (x2 (ly:stencil-extent m2 X))
-           (line (ly:round-filled-box (interval-union x1 x2) '(-0.05 . 0.05) 
0.0))
+           (line (ly:round-filled-box (interval-union x1 x2) boxdimen 0.0))
            ;; should stack mols separately, to maintain LINE on baseline
-           (stack (stack-lines -1 0.2 0.6 (list m1 line m2))))
+           (stack (stack-lines DOWN padding baseline (list m1 line m2))))
       (set! stack
            (ly:stencil-aligned-to stack Y CENTER))
       (set! stack
            (ly:stencil-aligned-to stack X LEFT))
       ;; should have EX dimension
       ;; empirical anyway
-      (ly:stencil-translate-axis stack 0.75 Y))))
+      (ly:stencil-translate-axis stack offset Y))))