Tempo and Rehearsal marks horizontal positioning; issue 3279

Space tempo/rehearsal marks so they do not overlap each other.
Do not use side-position interface for their initial vertical position,
because they are moved to the top-most staff after line-breaking.

9 files changed, 71 insertions, 8 deletions

diff --git a/Documentation/changes.tely b/Documentation/changes.tely
index 951dabd22b..313f3845be 100644
--- a/Documentation/changes.tely
+++ b/Documentation/changes.tely
@@ -62,6 +62,17 @@ which scares away people.
 @end ignore
 
 @item
+Horizontal space is allowed for tempo and rehearsal marks,
+so that these marks do not overlap each other.
+A new command @code{\markLengthOff} turns this feature off.
+@lilypond[quote,relative=0]
+\compressFullBarRests
+\tempo "Molto vivace" c''2 c'
+\mark\default
+\tempo "Meno mosso" R1*16
+@end lilypond
+
+@item
 When @code{\relative} is used without an explicit reference pitch,
 the reference pitch now is the middle of the first octave, making
 the first entered pitch indistinguishable from absolute pitch.
diff --git a/Documentation/learning/tweaks.itely b/Documentation/learning/tweaks.itely
index 9dc53ff8f9..5e8365a908 100644
--- a/Documentation/learning/tweaks.itely
+++ b/Documentation/learning/tweaks.itely
@@ -2285,6 +2285,9 @@ The command to revert to the default behavior is
 @code{\textLengthOff}.  Alternatively, @code{\once} may be used
 with @code{\textLengthOn} if the effect is to be limited to just a
 single musical moment.
+The corresponding spacing behavior for rehearsal marks and tempo
+indications is independently controlled with the commands
+@code{\markLengthOn} and @code{\markLengthOff}.
 
 @cindex markup text, allowing collisions
 
diff --git a/Documentation/notation/rhythms.itely b/Documentation/notation/rhythms.itely
index 08d9b7ca13..9250fd1968 100644
--- a/Documentation/notation/rhythms.itely
+++ b/Documentation/notation/rhythms.itely
@@ -1333,6 +1333,24 @@ written by including an empty string in the input:
 d4 g e c
 @end lilypond
 
+@funindex \markLengthOn
+@funindex markLengthOn
+@funindex \markLengthOff
+@funindex markLengthOff
+
+When tempo indications follow each other closely in the music,
+such as in a part for an instrument with long periods of rests,
+the measures are stretched horizontally so that the tempo indications
+do not overlap.  The commands @code{\markLengthOn} and
+@code{\markLengthOff} control this behavior.
+
+@lilypond[quote,relative=0]
+\compressFullBarRests
+\tempo "Molto vivace"
+R1*12
+\tempo "Meno mosso"
+R1*16
+@end lilypond
 
 @snippets
 
diff --git a/Documentation/notation/text.itely b/Documentation/notation/text.itely
index e6a085fc56..82c7a209a3 100644
--- a/Documentation/notation/text.itely
+++ b/Documentation/notation/text.itely
@@ -268,6 +268,15 @@ c1 c
 c  c
 @end lilypond
 
+@funindex \markLengthOn
+@funindex markLengthOn
+@funindex \markLengthOff
+@funindex markLengthOff
+
+@predefined
+@code{\markLengthOn},
+@code{\markLengthOff}.
+@endpredefined
 
 @snippets
 
diff --git a/input/regression/metronome-marking.ly b/input/regression/metronome-marking.ly
index e987176b7e..ac115273c3 100644
--- a/input/regression/metronome-marking.ly
+++ b/input/regression/metronome-marking.ly
@@ -14,10 +14,10 @@ The marking is left aligned with the time signature, if there is one.
 
 \layout {  ragged-right = ##t }
 
-\version "2.16.0"
+\version "2.17.17"
 
 \relative c'' {
-  \tempo \breve = 100 c1 c1 \tempo 8.. = 50 c1
+  \tempo \breve = 100 c1 c1 \tempo "Allegro" 8.. = 50 c1 \tempo "Adagio" c2 c'
 }
 
 
diff --git a/ly/engraver-init.ly b/ly/engraver-init.ly
index 5902b25da9..d6036bc4ef 100644
--- a/ly/engraver-init.ly
+++ b/ly/engraver-init.ly
@@ -90,6 +90,7 @@
   localKeySignature = #'()
   createSpacing = ##t
   ignoreFiguredBassRest = ##f
+  \markLengthOff
 
   %% explicitly set instrument, so we don't get
   %% weird effects when doing instrument names for
@@ -172,6 +173,7 @@ contained staves are not connected vertically."
   \override BarLine.bar-extent = #'(-2 . 2)
   \override VoltaBracket.staff-padding = #3
   \override StaffSymbol.line-count = #1
+  \markLengthOff
 
   \override Stem.neutral-direction = #UP
   \override Beam.neutral-direction = #UP
@@ -704,6 +706,7 @@ automatically when an output definition (a @code{\\score} or
 %%
   figuredBassFormatter = #format-bass-figure
   metronomeMarkFormatter = #format-metronome-markup
+  \markLengthOn
 
 
   %% See also make-voice-props-set
diff --git a/ly/property-init.ly b/ly/property-init.ly
index 633a12909a..fc7c67179a 100644
--- a/ly/property-init.ly
+++ b/ly/property-init.ly
@@ -564,6 +564,15 @@ textLengthOff = {
   \revert TextScript.outside-staff-horizontal-padding
 }
 
+markLengthOn = {
+  \override Score.MetronomeMark.extra-spacing-width = #'(-0.5 . 0.5)
+  \override Score.RehearsalMark.extra-spacing-width = #'(-0.5 . 0.5)
+}
+
+markLengthOff = {
+  \override Score.MetronomeMark.extra-spacing-width = #'(+inf.0 . -inf.0)
+  \override Score.RehearsalMark.extra-spacing-width = #'(+inf.0 . -inf.0)
+}
 
 %% text spanners
 
diff --git a/scm/define-grobs.scm b/scm/define-grobs.scm
index 81e4377ff4..1b834a2e2d 100644
--- a/scm/define-grobs.scm
+++ b/scm/define-grobs.scm
@@ -1418,15 +1418,16 @@
 	(after-line-breaking . ,ly:side-position-interface::move-to-extremal-staff)
 	(break-visibility . ,end-of-line-invisible)
 	(direction . ,UP)
-	(extra-spacing-width . (+inf.0 . -inf.0))
 	(outside-staff-horizontal-padding . 0.12)
 	(outside-staff-priority . 1000)
-	(padding . 0.8)
+	(outside-staff-padding . 0.5)
 	(side-axis . ,Y)
 	(skyline-horizontal-padding . 0.2)
 	(stencil . ,ly:text-interface::print)
 	(vertical-skylines . ,grob::always-vertical-skylines-from-stencil)
-	(Y-offset . ,side-position-interface::y-aligned-side)
+	(Y-offset . ,(ly:make-unpure-pure-container
+                       side-position-interface::y-aligned-side
+                       outside-staff::pure-Y-offset))
 	(X-offset . ,(ly:make-simple-closure
 		      `(,+
 			,(ly:make-simple-closure
@@ -1786,12 +1787,11 @@
 	(break-align-symbols . (staff-bar key-signature clef))
 	(break-visibility . ,end-of-line-invisible)
 	(direction . ,UP)
-	(extra-spacing-width . (+inf.0 . -inf.0))
 	(font-size . 2)
 	(non-musical . #t)
 	(outside-staff-horizontal-padding . 0.12)
 	(outside-staff-priority . 1500)
-	(padding . 0.8)
+	(outside-staff-padding . 0.5)
 	(self-alignment-X . ,CENTER)
 	(stencil . ,ly:text-interface::print)
 	(vertical-skylines . ,grob::always-vertical-skylines-from-stencil)
@@ -1801,7 +1801,9 @@
 			  (list ly:break-alignable-interface::self-align-callback))
 			,(ly:make-simple-closure
 			  (list ly:self-alignment-interface::x-aligned-on-self)))))
-	(Y-offset . ,side-position-interface::y-aligned-side)
+	(Y-offset . ,(ly:make-unpure-pure-container
+                       side-position-interface::y-aligned-side
+                       outside-staff::pure-Y-offset))
 	(Y-extent . ,grob::always-Y-extent-from-stencil)
 	(meta . ((class . Item)
 		 (interfaces . (break-alignable-interface
diff --git a/scm/output-lib.scm b/scm/output-lib.scm
index 3348ca470d..caa7032c70 100644
--- a/scm/output-lib.scm
+++ b/scm/output-lib.scm
@@ -854,6 +854,14 @@ and duration-log @var{log}."
    the previous calculated offset value."
   prev-offset)
 
+(define-public (outside-staff::pure-Y-offset grob start end)
+  "Initial vertical placement of items such as tempo and
+   rehearsal marks, for use in note-spacing."
+   (* (+ (ly:staff-symbol-staff-radius grob)
+         (ly:grob-property grob 'outside-staff-padding 0.0)
+         1.0)
+      (ly:grob-property grob 'direction CENTER)))
+
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 ;;