Implement extra-offset for system positioning (issue 324810043 by address@hidden)

[david . nalesnik]

Reviewers: ,

Message:
Please review.  Thanks!



Description:
Implement extra-offset for system positioning

Add the property 'extra-offset to 'line-break-system-details.

It is possible to position systems absolutely using the properties
'X-offset and 'Y-offset of 'line-break-system-details.  Placement,
however, is relative to the top left of the usable space, and can
be difficult to gauge without considerable trial and error.

An 'extra-offset property allows easy movement of systems relative
to where they currently are on the page--either through their
default positioning, or as a result of absolute positioning through
'X-offset and/or 'Y-offset.

System separators will be properly positioned. (Thanks go to Thomas
Morley.)

Please review this at https://codereview.appspot.com/324810043/

Affected files (+89, -6 lines):
  M Documentation/notation/spacing.itely
  A input/regression/page-layout-extra-offset.ly
  M scm/page.scm


Index: Documentation/notation/spacing.itely
diff --git a/Documentation/notation/spacing.itely  
b/Documentation/notation/spacing.itely
index  
fb455c1fdd55f52c4e03459eef336c44f0a6f2e5..9bb7eacca239cf59f9f7e206f6526e57d8d689f0  
100644
--- a/Documentation/notation/spacing.itely
+++ b/Documentation/notation/spacing.itely
@@ -2440,11 +2440,12 @@ padding,  
@code{NonMusicalPaperColumn.line-break-system-details}
 can specify exact vertical positions on the page.

 @code{NonMusicalPaperColumn.line-break-system-details} accepts
-an associative list of three different settings:
+an associative list of four different settings:

 @itemize
 @item @code{X-offset}
 @item @code{Y-offset}
address@hidden @code{extra-offset}
 @item @code{alignment-distances}
 @end itemize

@@ -2557,6 +2558,41 @@ potentially many values, but that we set only one  
value here.  Note,
 too, that the @code{Y-offset} property here determines the exact vertical
 position on the page at which each new system will render.

+In contrast to the absolute positioning available through
address@hidden and @code{X-offset}, relative positioning is possible
+with the @code{extra-offset} property of
address@hidden  Placement is relative to the
+default layout or to the absolute positioning created by setting
address@hidden and @code{Y-offset}.  The property @code{extra-offset}
+accepts a @code{pair} consisting of displacements along the X-axis and
+Y-axis.
+
address@hidden,quote,staffsize=16]
+\header { tagline = ##f }
+\paper { left-margin = 0\mm }
+\book {
+  \score {
+    <<
+      \new Staff <<
+        \new Voice {
+          s1*5 \break
+          \overrideProperty  
Score.NonMusicalPaperColumn.line-break-system-details
+            #'((extra-offset . (0 . 10)))
+          s1*5 \break
+          \overrideProperty  
Score.NonMusicalPaperColumn.line-break-system-details
+            #'((extra-offset . (0 . 10)))
+          s1*5 \break
+        }
+        \new Voice { \repeat unfold 15 { c'4 c' c' c' } }
+      >>
+      \new Staff {
+        \repeat unfold 15 { d'4 d' d' d' }
+      }
+    >>
+  }
+}
address@hidden lilypond
+
 Now that we have set the vertical startpoint of each system
 explicitly, we can also set the vertical distances between staves
 within each system manually.  We do this using the  
@code{alignment-distances}
Index: input/regression/page-layout-extra-offset.ly
diff --git a/input/regression/page-layout-extra-offset.ly  
b/input/regression/page-layout-extra-offset.ly
new file mode 100644
index  
0000000000000000000000000000000000000000..3cc52e1b751736ff3401563f6000071d034393a6
--- /dev/null
+++ b/input/regression/page-layout-extra-offset.ly
@@ -0,0 +1,45 @@
+\version "2.19.60"
+
+\header {
+  texidoc = "By setting @code{extra-offset} within the
address@hidden of @code{NonMusicalPaperColumn},
+systems may be moved in relation either to their default position on the
+printable area of the page or the absolute position pecified by
address@hidden or @code{Y-offset} within
address@hidden"
+
+}
+
+#(set-default-paper-size "a6" 'portrait)
+
+\paper {
+  indent = 0.0
+  oddHeaderMarkup = "header"
+  oddFooterMarkup = "footer"
+  system-separator-markup = \slashSeparator
+  ragged-right = ##t
+}
+
+\book {
+  \score {
+    {
+      \overrideProperty
+      Score.NonMusicalPaperColumn.line-break-system-details
+      #'((extra-offset . (8.0 . 0.0)))
+      c1 c1 \break
+
+      \overrideProperty
+      Score.NonMusicalPaperColumn.line-break-system-details
+      #'((extra-offset . (12.0 . 8.0)))
+      c1 c1 \break
+
+      \overrideProperty
+      Score.NonMusicalPaperColumn.line-break-system-details
+      #'((X-offset . 8.0)
+         (Y-offset . 36.0)
+         (extra-offset . (-8.0 . 30.0))
+      )
+      c1 c1
+    }
+  }
+}
Index: scm/page.scm
diff --git a/scm/page.scm b/scm/page.scm
index  
c6e69658cea45b8c1cfac5f770b7b9ce10c0a3e9..910ace902d41a330a8b7be0d735cc6ea212b95de  
100644
--- a/scm/page.scm
+++ b/scm/page.scm
@@ -227,7 +227,7 @@
                                                         
system-separator-markup)
                                      #f))

-       (page-stencil (ly:make-stencil '()))
+       (page-stencil empty-stencil)

        (last-system #f)
        (last-y 0.0)
@@ -243,12 +243,14 @@
        (add-system
         (lambda (system)
           (let* ((stencil (paper-system-stencil system))
-                 (y (ly:prob-property system 'Y-offset 0))
+                 (extra-offset (ly:prob-property system 'extra-offset  
(cons 0 0)))
+                 (x (+ (ly:prob-property system 'X-offset 0.0)
+                       (car extra-offset)))
+                 (y (+ (ly:prob-property system 'Y-offset 0.0)
+                       (cdr extra-offset)))
                  (is-title (paper-system-title?
                             system)))
-            (add-to-page stencil
-                         (ly:prob-property system 'X-offset 0.0)
-                         y)
+            (add-to-page stencil x y)
             (if (and (ly:stencil? system-separator-stencil)
                      last-system
                      (not (paper-system-title? system))