\version "2.19.15"

\paper {
  ragged-right = ##t
}

#(define (bound-coord bound refp)
   (if (not (= (ly:item-break-dir bound) CENTER))
       (cdr (ly:generic-bound-extent bound refp))
       (ly:grob-relative-coordinate bound refp X)))

#(define slanted-bracket
   (lambda (grob)
     (let* ((bound-L (ly:spanner-bound grob LEFT))
            (bound-R (ly:spanner-bound grob RIGHT))
            (common (ly:grob-common-refpoint bound-L bound-R X))
            (coord-L (bound-coord bound-L common))
            (coord-R (bound-coord bound-R common))
            (height (ly:grob-property grob 'edge-height))
            (shorten (ly:grob-property grob 'shorten-pair))
            (flare '(0.25 . 0.25))
            (th (ly:output-def-lookup (ly:grob-layout grob) 'line-thickness))
            (main
             (make-line-stencil 
              th 
              (+ coord-L (car flare) (car shorten)) 0
              (+ coord-R (- (cdr flare)) (cdr shorten)) (car height)))
            (wing-L (make-line-stencil
                     th
                     0 (car height)
                     (car flare) 0))
            (wing-R (make-line-stencil
                     th
                     0 (car height)
                     (cdr flare) (- (car height) (cdr height))))
            (main
             (if (= (ly:item-break-dir bound-L) CENTER)
                 (ly:stencil-combine-at-edge main X LEFT wing-L 0)
                 main))
            (main
             (if (= (ly:item-break-dir bound-R) CENTER)
                 (ly:stencil-combine-at-edge main X RIGHT wing-R 0)
                 main))
            (main
             (ly:stencil-translate-axis
              main
              (- (ly:grob-relative-coordinate bound-L common X))
              X)))
       main)))

{
  \set Staff.pedalSustainStyle = #'bracket
  %\override Staff.PianoPedalBracket.edge-height = #'(2 . 0.5)
  %\override Staff.PianoPedalBracket.shorten-pair = #'(-2 . 0)
  \override Staff.PianoPedalBracket.stencil = #slanted-bracket
  c4\sustainOn g c d
  %\break
  c4 g c d
  %\break
  c4 g c d
  c1\sustainOff
}

{
  \set Staff.pedalSustainStyle = #'bracket
  \override Staff.PianoPedalBracket.stencil = #slanted-bracket
  \clef bass
  % move right end to right
  \override Staff.PianoPedalBracket.shorten-pair = #'(0 . 0.75)
  d8-5\sustainOn
  \clef treble d'8_5 [ <d'_2 f'_1> a8_5]
  a8_5 a a \sustainOff a
}