Introduce new handling for paper margin settings.

* Make default margins accessible in ly/paper-defaults-init.ly

* Introduce a new method: Output_def::normalize (). It checks,
  whether left-margin, right-margin and/or line-width are set.
  Afterwards it computes missing values or takes defaults, if
  necessary. There is no need to specify line-width manually now.

* Make right-margin work

* If only line-width is set, the current behaviour persists.
  (Systems are centered)

* Output a warning if the margin values don't fit with each other or
  systems run off the page due to improper settings

* Modify lilypond-book to set a default line-width in case there
  is no other to base on left-padding (This is ugly, though)

15 files changed, 239 insertions, 24 deletions

diff --git a/input/regression/paper-margins-consistency.ly b/input/regression/paper-margins-consistency.ly
new file mode 100644
index 0000000000..237cd6865c
--- /dev/null
+++ b/input/regression/paper-margins-consistency.ly
@@ -0,0 +1,19 @@
+\version "2.13.4"
+
+#(ly:set-option 'warning-as-error #f)
+
+\header {
+  texidoc = "Margin values must fit the line-width, that means: paper-width =
+  line-width + left-margin + right-margin. In case they do not, default margins
+  are set and a warning is printed."
+}
+
+someNotes = \relative c' { \repeat unfold 40 { c4 d e f }}
+
+\paper {
+  left-margin = 20 \mm
+  right-margin = 40 \mm
+  line-width = 100 \mm
+}
+
+\score { \someNotes }
diff --git a/input/regression/paper-margins-left-margin.ly b/input/regression/paper-margins-left-margin.ly
new file mode 100644
index 0000000000..bcae7c94e4
--- /dev/null
+++ b/input/regression/paper-margins-left-margin.ly
@@ -0,0 +1,13 @@
+\version "2.13.4"
+
+\header {
+  texidoc = "Here only left-margin is given, right-margin will remain default."
+}
+
+someNotes = \relative c' { \repeat unfold 40 { c4 d e f }}
+
+\paper {
+  left-margin = 40 \mm
+}
+
+\score { \someNotes }
diff --git a/input/regression/paper-margins-line-width.ly b/input/regression/paper-margins-line-width.ly
new file mode 100644
index 0000000000..b741e6ee96
--- /dev/null
+++ b/input/regression/paper-margins-line-width.ly
@@ -0,0 +1,13 @@
+\version "2.13.4"
+
+\header {
+  texidoc = "If only line-width is given, systems are vertically centered."
+}
+
+someNotes = \relative c' { \repeat unfold 40 { c4 d e f }}
+
+\paper {
+  line-width = 100 \mm
+}
+
+\score { \someNotes }
diff --git a/input/regression/paper-margins-no-checks.ly b/input/regression/paper-margins-no-checks.ly
new file mode 100644
index 0000000000..e3ab45902b
--- /dev/null
+++ b/input/regression/paper-margins-no-checks.ly
@@ -0,0 +1,18 @@
+\version "2.13.4"
+
+\header {
+  texidoc = "All checks can be avoided by setting check-consistency to ##f in \paper."
+}
+
+someNotes = \relative c' { \repeat unfold 40 { c4 d e f }}
+
+\paper {
+  left-margin = 20 \mm
+  right-margin = 40 \mm
+  line-width = 200 \mm
+  check-consistency = ##f
+}
+
+\score { \someNotes }
+
+
diff --git a/input/regression/paper-margins-overrun.ly b/input/regression/paper-margins-overrun.ly
new file mode 100644
index 0000000000..8db56add45
--- /dev/null
+++ b/input/regression/paper-margins-overrun.ly
@@ -0,0 +1,18 @@
+\version "2.13.4"
+
+#(ly:set-option 'warning-as-error #f)
+
+\header {
+  texidoc = "Normally, margin settings must not cause systems to run off the page."
+}
+
+#(set-default-paper-size "a4")
+
+someNotes = \relative c' { \repeat unfold 40 { c4 d e f }}
+
+\paper {
+  left-margin = 20 \mm
+  line-width = 200 \mm
+}
+
+\score { \someNotes }
diff --git a/input/regression/paper-margins-right-margin.ly b/input/regression/paper-margins-right-margin.ly
new file mode 100644
index 0000000000..6b50659912
--- /dev/null
+++ b/input/regression/paper-margins-right-margin.ly
@@ -0,0 +1,13 @@
+\version "2.13.4"
+
+\header {
+  texidoc = "Here only right-margin is given, left-margin will remain default."
+}
+
+someNotes = \relative c' { \repeat unfold 40 { c4 d e f }}
+
+\paper {
+  right-margin = 40 \mm
+}
+
+\score { \someNotes }
diff --git a/input/regression/paper-margins.ly b/input/regression/paper-margins.ly
new file mode 100644
index 0000000000..25e92b84c7
--- /dev/null
+++ b/input/regression/paper-margins.ly
@@ -0,0 +1,14 @@
+\version "2.13.4"
+
+\header {
+  texidoc = "Paper margin settings do not have to be complete. Missing values are
+  added automatically. If no paper settings are specified, default values are
+  used."
+}
+
+someNotes = \relative c' { \repeat unfold 40 { c4 d e f }}
+
+\paper { }
+
+\score { \someNotes }
+
diff --git a/lily/book.cc b/lily/book.cc
index 303af1b8e3..86eeda1b39 100644
--- a/lily/book.cc
+++ b/lily/book.cc
@@ -277,6 +277,7 @@ Book::process (Output_def *default_paper,
     }
   else
     {
+      paper_book->paper_->normalize ();
       /* Process scores */
   /* Render in order of parsing.  */
       for (SCM s = scm_reverse (scores_); scm_is_pair (s); s = scm_cdr (s))
diff --git a/lily/include/output-def.hh b/lily/include/output-def.hh
index b683cc61f1..9e28d18729 100644
--- a/lily/include/output-def.hh
+++ b/lily/include/output-def.hh
@@ -58,13 +58,14 @@ public:
   SCM c_variable (string id) const;
   SCM lookup_variable (SCM sym) const;
   void set_variable (SCM sym, SCM val);
+  void normalize ();
   Real get_dimension (SCM symbol) const;
 };
 SCM get_font_table (Output_def *def);
 void assign_context_def (Output_def *m, SCM transdef);
 SCM find_context_def (Output_def const *m, SCM name);
 
-Interval line_dimensions_int (Output_def*def, int);
+Interval line_dimensions_int (Output_def *def, int);
  
 
 Font_metric *select_encoded_font (Output_def *layout, SCM chain);
diff --git a/lily/output-def.cc b/lily/output-def.cc
index f9fbda9fb6..8ee7952bd9 100644
--- a/lily/output-def.cc
+++ b/lily/output-def.cc
@@ -11,6 +11,7 @@
 #include "context-def.hh"
 #include "file-path.hh"
 #include "global-context.hh"
+#include "international.hh"
 #include "interval.hh"
 #include "main.hh"
 #include "output-def.hh"
@@ -29,7 +30,7 @@ Output_def::Output_def ()
   parent_ = 0;
 
   smobify_self ();
-  
+
   scope_ = ly_make_anonymous_module (false);
 }
 
@@ -75,7 +76,7 @@ assign_context_def (Output_def * m, SCM transdef)
     {
       SCM sym = tp->get_context_name ();
       m->set_variable (sym, transdef);
-    }  
+    }
 }
 
 /* find the translator for NAME. NAME must be a symbol. */
@@ -109,10 +110,10 @@ Output_def::lookup_variable (SCM sym) const
   SCM var = ly_module_lookup (scope_, sym);
   if (SCM_VARIABLEP (var) && SCM_VARIABLE_REF (var) != SCM_UNDEFINED)
     return SCM_VARIABLE_REF (var);
-  
+
   if (parent_)
     return parent_->lookup_variable (sym);
-  
+
   return SCM_UNDEFINED;
 }
 
@@ -128,7 +129,93 @@ Output_def::set_variable (SCM sym, SCM val)
   scm_module_define (scope_, sym, val);
 }
 
-  
+void
+Output_def::normalize ()
+{
+  Real paper_width;
+  SCM scm_paper_width = c_variable ("paper-width");
+
+  Real left_margin, left_margin_default;
+  SCM scm_left_margin_default = c_variable ("left-margin-default");
+  SCM scm_left_margin = c_variable ("left-margin");
+
+  Real right_margin, right_margin_default;
+  SCM scm_right_margin_default = c_variable ("right-margin-default");
+  SCM scm_right_margin = c_variable ("right-margin");
+
+  if (scm_paper_width == SCM_UNDEFINED
+      || scm_left_margin_default == SCM_UNDEFINED
+      || scm_right_margin_default == SCM_UNDEFINED)
+    {
+      programming_error ("called normalize() on paper with missing settings");
+      return;
+    }
+  else
+    {
+      paper_width = scm_to_double (scm_paper_width);
+      left_margin_default = scm_to_double (scm_left_margin_default);
+      right_margin_default = scm_to_double (scm_right_margin_default);
+    }
+
+  Real line_width;
+  Real line_width_default = paper_width - left_margin_default - right_margin_default;
+  SCM scm_line_width = c_variable ("line-width");
+
+  if (scm_line_width == SCM_UNDEFINED)
+    {
+      left_margin = ((scm_left_margin == SCM_UNDEFINED) ? left_margin_default : scm_to_double(scm_left_margin));
+      right_margin = ((scm_right_margin == SCM_UNDEFINED) ? right_margin_default : scm_to_double(scm_right_margin));
+      line_width = paper_width - left_margin - right_margin;
+    }
+  else
+    {
+      line_width = scm_to_double (scm_line_width);
+      if (scm_left_margin == SCM_UNDEFINED)
+        {
+          if (scm_right_margin == SCM_UNDEFINED) // Vertically center systems if only line-width is given
+            {
+              left_margin = (paper_width - line_width) / 2;
+              right_margin = left_margin;
+            }
+          else
+            {
+              right_margin = scm_to_double (scm_right_margin);
+              left_margin = paper_width - line_width - right_margin;
+            }
+        }
+      else
+        {
+          left_margin = scm_to_double (scm_left_margin);
+          right_margin = ((scm_right_margin == SCM_UNDEFINED)
+                           ? (paper_width - line_width - left_margin)
+                           : scm_to_double (scm_right_margin));
+        }
+    }
+
+  if (to_boolean (c_variable ("check-consistency")))
+    {
+      // Consistency checks. If values don't match, set defaults.
+      if (abs(paper_width - line_width - left_margin - right_margin) > 1e-6)
+        {
+          line_width = line_width_default;
+          left_margin = left_margin_default;
+          right_margin = right_margin_default;
+          warning (_ ("margins do not fit with line-width, setting default values"));
+        }
+      else if ((left_margin < 0) || (right_margin < 0))
+        {
+          line_width = line_width_default;
+          left_margin = left_margin_default;
+          right_margin = right_margin_default;
+          warning (_ ("systems run off the page due to improper paper settings, setting default values"));
+        }
+    }
+
+  set_variable (ly_symbol2scm ("left-margin"), scm_from_double (left_margin));
+  set_variable (ly_symbol2scm ("right-margin"), scm_from_double (right_margin));
+  set_variable (ly_symbol2scm ("line-width"), scm_from_double (line_width));
+}
+
 /* FIXME.  This is broken until we have a generic way of
    putting lists inside the \layout block.  */
 Interval
diff --git a/lily/paper-book.cc b/lily/paper-book.cc
index 3db1321f5e..12a7f09f15 100644
--- a/lily/paper-book.cc
+++ b/lily/paper-book.cc
@@ -159,12 +159,21 @@ Paper_book::output (SCM output_channel)
 {
   int first_page_number = robust_scm2int (paper_->c_variable ("first-page-number"), 1);
   int first_performance_number = 0;
+
+  /* FIXME: We need a line-width for ps output (framework-ps.scm:92). If we don't have any, we take the paper-width
+     unless we know better which line-width to choose (e.g. if there are \bookparts with different line-widths)
+     and why we need it at all. */
+
+  if (paper_->c_variable ("line-width") == SCM_UNDEFINED)
+    paper_->set_variable (ly_symbol2scm ("line-width"), paper_->c_variable ("paper-width"));
+ 
   if (!output_aux (output_channel,
 		   true,
 		   &first_page_number,
 		   &first_performance_number))
     return;
-      
+    
+ 
   SCM scopes = SCM_EOL;
   if (ly_is_module (header_))
     scopes = scm_cons (header_, scopes);
diff --git a/ly/paper-defaults-init.ly b/ly/paper-defaults-init.ly
index 1ee92ed197..4db5459fa7 100644
--- a/ly/paper-defaults-init.ly
+++ b/ly/paper-defaults-init.ly
@@ -86,11 +86,17 @@
 
   \include "titling-init.ly"
 
+  check-consistency = ##t
+
   top-margin = 5 \mm
   bottom-margin = 6 \mm
+
+  left-margin-default = 10 \mm
+  right-margin-default = 10 \mm
+
   head-separation = 4 \mm
   foot-separation = 4 \mm
 
   first-page-number = #1
-  print-first-page-number =##f
+  print-first-page-number = ##f
 }
diff --git a/scm/page.scm b/scm/page.scm
index ca4e0d8659..959402c406 100644
--- a/scm/page.scm
+++ b/scm/page.scm
@@ -184,11 +184,7 @@
   (let*
       ((paper-height (ly:output-def-lookup layout 'paper-height))
        (paper-width (ly:output-def-lookup layout 'paper-width))
-       (lmargin (ly:output-def-lookup layout 'left-margin #f))
-       (left-margin (if lmargin
-		       lmargin
-		       (/ (- paper-width
-			     (ly:output-def-lookup layout 'line-width)) 2)))
+       (left-margin (ly:output-def-lookup layout 'left-margin))
        (bottom-edge (- paper-height
 		       (ly:output-def-lookup layout 'bottom-margin)) )
        (top-margin (ly:output-def-lookup layout 'top-margin))
diff --git a/scm/paper.scm b/scm/paper.scm
index 01fa8c06e2..1eb3b59a1a 100644
--- a/scm/paper.scm
+++ b/scm/paper.scm
@@ -16,6 +16,7 @@
 		    indent
 		    ledger-line-thickness
 		    left-margin
+                    left-margin-default
 		    line-thickness
 		    line-width
 		    mm
@@ -23,6 +24,7 @@
 		    paper-width
 		    pt
 		    right-margin
+                    right-margin-default
 		    short-indent
 		    staff-height
 		    staff-space
@@ -207,23 +209,17 @@ size. SZ is in points"
     ("f4" . (cons (* 210 mm) (* 330 mm)))
    ))
 
-;; todo: take dimension arguments.
+; todo: take dimension arguments.
 
 (define (set-paper-dimensions m w h)
   "M is a module (i.e. layout->scope_ )"
-  (let* ((mm (eval 'mm m)))
+  (begin
+    ;; page layout - what to do with (printer specific!) margin settings?
     (module-define! m 'paper-width w)
     (module-define! m 'paper-height h)
-    (module-define! m 'line-width (- w
-				     (ly:modules-lookup (list m) 'left-margin (* 10 mm))
-				     (ly:modules-lookup (list m) 'right-margin (* 10 mm))))
-
     (module-define! m 'indent (/ w 14))
-    (module-define! m 'short-indent 0)
-
-    ;; page layout - what to do with (printer specific!) margin settings?
-
-    ))
+    (module-define! m 'short-indent 0))
+    (module-remove! m 'line-width))
 
 (define (internal-set-paper-size module name landscape?)
   (define (swap x)
diff --git a/scripts/lilypond-book.py b/scripts/lilypond-book.py
index 6abbe5393b..29cde34202 100644
--- a/scripts/lilypond-book.py
+++ b/scripts/lilypond-book.py
@@ -1116,6 +1116,17 @@ class LilypondSnippet (Snippet):
         if not INDENT in self.option_dict:
             self.option_dict[INDENT] = '0\\mm'
 
+        # Set a default line-width if there is none. We need this, because
+	# lilypond-book has set left-padding by default and therefore does
+	# #(define line-width (- line-width (* 3 mm)))
+	# TODO: Junk this ugly hack if the code gets rewritten to concatenate
+	# all settings before writing them in the \paper block.
+        if not LINE_WIDTH in self.option_dict:
+	    if not QUOTE in self.option_dict:
+	        if not LILYQUOTE in self.option_dict:
+		    self.option_dict[LINE_WIDTH] = "#(- paper-width \
+left-margin-default right-margin-default)"
+
     def compose_ly (self, code):
         if FRAGMENT in self.option_dict:
             body = FRAGMENT_LY