From 0b032b61be1224b2cce061df60aa89ea5aa89c07 Mon Sep 17 00:00:00 2001
From: Mike Solomon <mike@mikesolomon.org>
Date: Thu, 31 Oct 2013 08:40:23 +0100
Subject: [PATCH] Adds ly:generic-bound-extent function.

This allows for spanner functions written in Scheme to use bound
extents instead of the full extents of their bounds.

Adds a regtest to show this at work with BendAfter.

Note that this can likely be replaced in the future with horizontal
skylines.
---
 input/regression/bend-bound.ly      | 23 +++++++++++++++++++++++
 lily/axis-group-interface-scheme.cc | 14 ++++++++++++++
 scm/output-lib.scm                  |  6 +++---
 3 files changed, 40 insertions(+), 3 deletions(-)
 create mode 100644 input/regression/bend-bound.ly

diff --git a/input/regression/bend-bound.ly b/input/regression/bend-bound.ly
new file mode 100644
index 0000000000..bceb10564e
--- /dev/null
+++ b/input/regression/bend-bound.ly
@@ -0,0 +1,23 @@
+\version "2.17.30"
+
+\header {
+  texidoc = "Bends should not be effected by the full width of a
+@code{NonMusicalPaperColumn}. The bends should have identical X
+spans in the two examples.
+"
+}
+
+music = \repeat unfold 16 { c''4\bendAfter #-4 }
+sixteens = \repeat unfold 64 { c'16 }
+
+\new Score {
+  << \music \sixteens >>
+}
+
+\new Score \with {
+  currentBarNumber = #200
+  barNumberVisibility = #(every-nth-bar-number-visible 1)
+  \override BarNumber.break-visibility = #end-of-line-invisible
+} {
+  << \music \sixteens >>
+}
diff --git a/lily/axis-group-interface-scheme.cc b/lily/axis-group-interface-scheme.cc
index 69b7c82fdf..68b3dd3746 100644
--- a/lily/axis-group-interface-scheme.cc
+++ b/lily/axis-group-interface-scheme.cc
@@ -46,6 +46,20 @@ LY_DEFINE (ly_relative_group_extent, "ly:relative-group-extent",
   return ly_interval2scm (ext);
 }
 
+LY_DEFINE (ly_generic_bound_extent, "ly:generic-bound-extent",
+           2, 0, 0, (SCM grob, SCM common),
+           "Determine the extent of @var{grob} relative to @var{common} along"
+           " the X axis, finding its extent as a bound when it a has"
+           " @code{bound-alignment-interfaces} property list set and"
+           " otherwise the full extent.")
+{
+  LY_ASSERT_SMOB (Grob, grob, 1);
+  LY_ASSERT_SMOB (Grob, common, 2);
+
+  Interval ext = Axis_group_interface::generic_bound_extent (unsmob_grob (grob), unsmob_grob (common), X_AXIS);
+  return ly_interval2scm (ext);
+}
+
 LY_DEFINE (ly_axis_group_interface__add_element, "ly:axis-group-interface::add-element",
            2, 0, 0, (SCM grob, SCM grob_element),
            "Set @var{grob} the parent of @var{grob-element} on all axes of"
diff --git a/scm/output-lib.scm b/scm/output-lib.scm
index 02170918a1..89d20b9550 100644
--- a/scm/output-lib.scm
+++ b/scm/output-lib.scm
@@ -912,8 +912,8 @@ and duration-log @var{log}."
 
          (left-x (+ padding
                     (max
-                     (interval-end (ly:grob-robust-relative-extent
-                                    left-span common X))
+                     (interval-end (ly:generic-bound-extent
+                                    left-span common))
                      (if
                       (and dots
                            (close
@@ -923,7 +923,7 @@ and duration-log @var{log}."
                        (ly:grob-robust-relative-extent dots common X))
                       (- INFINITY-INT)))))
          (right-x (max (- (interval-start
-                           (ly:grob-robust-relative-extent right-span common X))
+                           (ly:generic-bound-extent right-span common))
                           padding)
                        (+ left-x minimum-length)))
          (self-x (ly:grob-relative-coordinate spanner common X))
-- 
2.39.5