Fix DynamicTextSpanner left alignment.

When a DynamicTextSpanner directly follows a DynamicScript, padding is
required to ensure the 'left 'text doesn't collide with the
dynamic sign.  Unfortunately, this default value skews the
spanner's left bound to the right when no dynamic script is present.

This patch caters for both situations by resetting 'left 'padding
and 'left 'attach-dir as required, adding extra padding read from the
property 'right-padding to fine-tune the space between the text elements.

* add regtests demonstrating 'right-padding and correct alignment

* remove hard-coded 'bound-details setting in New_dynamic_engraver, which
  prevented user override

* add dynamic-text-interface with user property 'right-padding

* add 'before-line-breaking callback dynamic-text-spanner::before-line-breaking
  which checks whether the left bound is a DynamicText; if this is true,
  set nested properties 'left 'attach-dir/'padding to prevent collision

6 files changed, 57 insertions, 12 deletions

diff --git a/input/regression/dynamics-text-left-text-alignment.ly b/input/regression/dynamics-text-left-text-alignment.ly
new file mode 100644
index 0000000000..03893c0896
--- /dev/null
+++ b/input/regression/dynamics-text-left-text-alignment.ly
@@ -0,0 +1,13 @@
+\version "2.13.11"
+\header {
+  texidoc = "The left text of a @code{DynamicTextSpanner} is
+left-aligned to its anchor note.
+"
+}
+
+\relative c' {
+  \crescTextCresc
+  \dimTextDim
+  c4\< c c c\!
+  c4\> c c c\!
+}
diff --git a/input/regression/dynamics-text-right-padding.ly b/input/regression/dynamics-text-right-padding.ly
new file mode 100644
index 0000000000..e3c8a09604
--- /dev/null
+++ b/input/regression/dynamics-text-right-padding.ly
@@ -0,0 +1,12 @@
+\version "2.13.11"
+\header {
+  texidoc = "The space between an absolute dynamic and a dynamic text
+span can be changed using @code{'right-padding}.
+"
+}
+
+\relative c' {
+  \dimTextDim
+  \once \override DynamicText #'right-padding = #0
+  c4\fff\> c c c\!
+}
diff --git a/lily/new-dynamic-engraver.cc b/lily/new-dynamic-engraver.cc
index ea4c99d22a..af943c4aa8 100644
--- a/lily/new-dynamic-engraver.cc
+++ b/lily/new-dynamic-engraver.cc
@@ -166,16 +166,7 @@ New_dynamic_engraver::process_music ()
       if (finished_spanner_)
 	finished_spanner_->set_bound (RIGHT, script_);
       if (current_spanner_)
-	{
-	  current_spanner_->set_bound (LEFT, script_);
-
-	  if (!Hairpin::has_interface (current_spanner_))
-	    set_nested_property (current_spanner_,
-				 scm_list_3 (ly_symbol2scm ("bound-details"),
-					     ly_symbol2scm ("left"),
-					     ly_symbol2scm ("attach-dir")),
-				 scm_from_int (RIGHT));
-	}
+	current_spanner_->set_bound (LEFT, script_);
     }
 }
 
diff --git a/scm/define-grob-interfaces.scm b/scm/define-grob-interfaces.scm
index d0abebed7b..b068da91ad 100644
--- a/scm/define-grob-interfaces.scm
+++ b/scm/define-grob-interfaces.scm
@@ -57,6 +57,11 @@ note)."
  '(avoid-slur))
 
 (ly:add-interface
+ 'dynamic-text-interface
+ "An absolute text dynamic."
+ '(right-padding))
+
+(ly:add-interface
  'dynamic-text-spanner-interface
  "Dynamic text spanner."
  '(text))
diff --git a/scm/define-grobs.scm b/scm/define-grobs.scm
index 7c459a0bca..781d3e0b03 100644
--- a/scm/define-grobs.scm
+++ b/scm/define-grobs.scm
@@ -660,6 +660,7 @@
 	(font-shape . italic)
 	(outside-staff-priority . 250)
 	(positioning-done . ,ly:script-interface::calc-positioning-done)
+	(right-padding . 0.5)
 	(self-alignment-X . ,CENTER)
 	(self-alignment-Y . ,CENTER)
 	(stencil . ,ly:text-interface::print)
@@ -667,6 +668,7 @@
 	(Y-offset . ,ly:self-alignment-interface::y-aligned-on-self)
 	(meta . ((class . Item)
 		 (interfaces . (dynamic-interface
+				dynamic-text-interface
 				font-interface
 				script-interface
 				self-alignment-interface
@@ -674,6 +676,7 @@
 
     (DynamicTextSpanner
      . (
+	(before-line-breaking . ,dynamic-text-spanner::before-line-breaking)
 	(bound-details . ((right . ((attach-dir .  ,LEFT)
 				    (Y . 0)
 				    (padding . 0.75)
@@ -684,8 +687,8 @@
 
 			  (left . ((attach-dir .  ,LEFT)
 				   (Y . 0)
-				   (stencil-offset . (0 . -0.5))
-				   (padding . 0.5)
+				   (stencil-offset . (-0.75 . -0.5))
+				   (padding . 0.75)
 				   ))
 			  (left-broken . ((attach-dir .  ,RIGHT)
 				   ))
diff --git a/scm/output-lib.scm b/scm/output-lib.scm
index a7ba96b589..e98937e821 100644
--- a/scm/output-lib.scm
+++ b/scm/output-lib.scm
@@ -644,6 +644,27 @@ and duration-log @var{log}."
       START
       STOP))
 
+(define-public (dynamic-text-spanner::before-line-breaking grob)
+  "Monitor left bound of @code{DynamicTextSpanner} for absolute dynamics.
+If found, ensure @code{DynamicText} does not collide with spanner text by
+changing @code{'attach-dir} and @code{'padding}.  Reads the
+@code{'right-padding} property of @code{DynamicText} to fine tune space
+between the two text elements."
+  (let ((left-bound (ly:spanner-bound grob LEFT)))
+    (if (grob::has-interface left-bound 'dynamic-text-interface)
+	(let* ((details (ly:grob-property grob 'bound-details))
+	       (left-details (ly:assoc-get 'left details))
+	       (my-padding (ly:assoc-get 'padding left-details))
+	       (script-padding (ly:grob-property left-bound 'right-padding 0)))
+
+	  (and (number? my-padding)
+	       (ly:grob-set-nested-property! grob
+					     '(bound-details left attach-dir)
+					     RIGHT)
+	       (ly:grob-set-nested-property! grob
+					     '(bound-details left padding)
+					     (+ my-padding script-padding)))))))
+
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; lyrics