\version "2.15.43"
\include "english.ly"

% calculate x-alignment based on attribute text + dynamic text
% this has to be a markup-command to get stencil-extent based on (interpret-markup layout props ...)
#(define-markup-command (center-dyn layout props atr-text dyn)(markup? string?)
  "x-align on center of dynamic"
  (let* (
          (text (string-append atr-text " "))
          (atr-stencil (interpret-markup layout props (markup #:normal-text #:italic text)))
          (dyn-stencil (interpret-markup layout props (markup #:dynamic dyn)))
          (atr-x-ext (ly:stencil-extent atr-stencil X))
          (dyn-x-ext (ly:stencil-extent dyn-stencil X))
          (atr-x (- (cdr atr-x-ext)(car atr-x-ext)))
          (dyn-x (- (cdr dyn-x-ext)(car dyn-x-ext)))
          (x-align
            (* (-
                 (/ (+ atr-x (/ dyn-x 2)) (+ atr-x dyn-x) )
                 0.5) 2)
          )
        )
        (interpret-markup layout props (markup #:halign x-align #:concat (#:normal-text #:italic text #:dynamic dyn)))
))
% define a 'new' attributed dynamic script
#(define (make-atr-dynamic-script atr dyn)
        (let ((dynamic (make-dynamic-script (markup #:center-dyn atr dyn))))
             (ly:music-set-property! dynamic 'tweaks (acons 'X-offset 0 (ly:music-property dynamic 'tweaks)))
             dynamic))

% define some attributed dynamics
pocof = #(make-atr-dynamic-script "poco" "f")
menof = #(make-atr-dynamic-script "meno" "f")
submf = #(make-atr-dynamic-script "subito" "mf")

% Solution 1: Using a simple markup with a particular halign value
% Drawback: It's a markup, not a dynamic command, so \dynamicDown
%           etc. will have no effect
semppMarkup = \markup { \halign #1.4 \italic "subito" \dynamic "mf" }

% Solution 2: Using a dynamic script & shifting with
%             \once \override ... #'X-offset = ..
% Drawback: \once \override needed for every invocation
semppK =
#(make-dynamic-script
  (markup #:line
          (#:normal-text
           #:italic "subito"
           #:dynamic "mf")))

% Solution 3: Padding the dynamic script so the center-alignment
%             puts it at the correct position
% Drawback: the padding really reserves the space, nothing else can be there
semppT =
#(make-dynamic-script
  (markup #:line
          (#:normal-text
           #:italic "subito"
           #:dynamic "mf"
           #:hspace 7.1)))

% Solution 4: Dynamic, setting the dimensions of the additional text to 0
% Drawback: To lilypond "sempre" has no extent, so it might put
%           other stuff there => collisions
% Drawback: Also, there seems to be some spacing, so it's not exactly the
%           same alignment as without the additional text
semppM =
#(make-dynamic-script
  (markup #:line
          (#:with-dimensions '(0 . 0) '(0 . 0)
                             #:right-align
                             #:normal-text
                             #:italic "subito"
                             #:dynamic "mf")))

% Solution 5: Dynamic with explicit shifting inside the scheme function
semppG =
#(make-dynamic-script
  (markup #:hspace 0
          #:translate '(-18.85 . 0)
          #:line (#:normal-text
                  #:italic "subito"
                  #:dynamic "mf")))

% Solution 6: Dynamic with explicit alignment. This has only effect
%             if one sets X-offset!
% Drawback: One needs to set DynamicText #'X-offset!
% Drawback: Aligned at the right edge of the additional text,
%           not at the center of pp
semppMII =
#(make-dynamic-script
  (markup #:line (#:right-align
                  #:normal-text
                  #:italic "subito"
                  #:dynamic "mf")))



\relative c'' {
	\time 3/4
	d2.\mf\> |
	a2 d8\!\smf( e) |	
	
	R2.
	
	d2.\mf\> |
	a2 d8\!-\markup{ \italic \tiny subito } \mf( e) |	

	R2.
	
	\textLengthOn
	d2.\mf\> |
	a2 d8\!-\markup{ \italic \tiny subito \dynamic mf}( e) |
	\textLengthOff
	
% uncomment the textLengthOn to see if it makes a difference
%\textLengthOn

% http://lsr.dsi.unimi.it/LSR/Item?id=739		
	R2.
	d2.\mf\> |
	a2 d8\!-\submf( e) |	

% http://lsr.dsi.unimi.it/LSR/Item?id=393
% Solution 1
	R2.
	d2.\mf\> |
	a2 d8\!-\semppMarkup( e) |	
	
% Solution 2
	R2.
	d2.\mf\> |
	a2 d8\!-\semppK( e) |	
	
% Solution 3
	R2.
	d2.\mf\> |
	a2 d8\!-\semppT( e) |	
	
% Solution 4
	R2.
	d2.\mf\> |
	a2 d8\!-\semppM( e) |	
	
% Solution 5
	R2.
	d2.\mf\> |
	a2 d8\!-\semppG( e) |	
	
% Solution 6
	R2.
	d2.\mf\> |
	a2 d8\!-\semppMII( e) |		
	
}