Key signatures for modes. Fix 748.

Compute midi key signatures for modes with fractional alterations,
using code from Graham Breed.
Provide a keyAlterationOrder for the modes in arabic.ly.

4 files changed, 52 insertions, 18 deletions

diff --git a/input/regression/midi-key-signature.ly b/input/regression/midi-key-signature.ly
new file mode 100644
index 0000000000..8eafbad703
--- /dev/null
+++ b/input/regression/midi-key-signature.ly
@@ -0,0 +1,15 @@
+\version "2.13.53"
+\header {
+  texidoc = "MIDI key signatures are output, using an approximate
+key signature if MIDI format cannot represent the true key signature"
+}
+
+\include "arabic.ly"
+\score {
+  \relative do' {
+    \key fa \bayati
+    fa4 solsb lab sib
+  }
+  \midi { }
+  \layout { }
+}
diff --git a/lily/key-engraver.cc b/lily/key-engraver.cc
index 66b6e00a2b..db223e6606 100644
--- a/lily/key-engraver.cc
+++ b/lily/key-engraver.cc
@@ -194,7 +194,7 @@ Key_engraver::read_event (Stream_event const *r)
 	  }
 
       if (warn)
-	r->origin ()->warning ("No ordering for key signature alterations");      
+	r->origin ()->warning ("Incomplete keyAlterationOrder for key signature");
     }
   
   context ()->set_property ("keySignature", scm_reverse (accs));
diff --git a/ly/arabic.ly b/ly/arabic.ly
index 48414b473d..61790e5542 100644
--- a/ly/arabic.ly
+++ b/ly/arabic.ly
@@ -33,52 +33,72 @@ dwn = {
 %
 
 bayati = #`(
-    (0 . 0)
+    (0 . ,NATURAL)
     (1 . ,SEMI-FLAT)
     (2 . ,FLAT)
-    (3 . 0)
-    (4 . 0)
+    (3 . ,NATURAL)
+    (4 . ,NATURAL)
     (5 . ,FLAT)
     (6 . ,FLAT)
   )
 
 kurd = #`(
-    (0 . 0)
+    (0 . ,NATURAL)
     (1 . ,FLAT)
     (2 . ,FLAT)
-    (3 . 0)
-    (4 . 0)
+    (3 . ,NATURAL)
+    (4 . ,NATURAL)
     (5 . ,FLAT)
     (6 . ,FLAT)
     )
 
 rast = #`(
-    (0 . 0)
-    (1 . 0)
+    (0 . ,NATURAL)
+    (1 . ,NATURAL)
     (2 . ,SEMI-FLAT)
-    (3 . 0)
-    (4 . 0)
-    (5 . 0)
+    (3 . ,NATURAL)
+    (4 . ,NATURAL)
+    (5 . ,NATURAL)
     (6 . ,SEMI-FLAT)
   )
 
 sikah = #`(
-    (0 . 0)
+    (0 . ,NATURAL)
     (1 . ,SEMI-FLAT)
     (2 . ,SEMI-FLAT)
     (3 . ,SEMI-SHARP)
-    (4 . 0)
+    (4 . ,NATURAL)
     (5 . ,SEMI-FLAT)
     (6 . ,SEMI-FLAT)
   )
 
 iraq = #`(
-    (0 . 0)
+    (0 . ,NATURAL)
     (1 . ,SEMI-FLAT)
     (2 . ,SEMI-FLAT)
-    (3 . 0)
+    (3 . ,NATURAL)
     (4 . ,SEMI-FLAT)
     (5 . ,SEMI-FLAT)
     (6 . ,SEMI-FLAT)
   )
 
+\layout {
+  \context {
+    \Score
+      keyAlterationOrder =
+      #`(
+	 (6 . ,FLAT) (2 . ,FLAT) (5 . ,FLAT ) (1 . ,FLAT)
+	 (4 . ,FLAT) (0 . ,FLAT) (3 . ,FLAT)
+	 (6 . ,SEMI-FLAT) (2 . ,SEMI-FLAT) (5 . ,SEMI-FLAT ) (1 . ,SEMI-FLAT)
+	 (4 . ,SEMI-FLAT) (0 . ,SEMI-FLAT) (3 . ,SEMI-FLAT)
+	 (3 . ,SHARP) (0 . ,SHARP) (4 . ,SHARP) (1 . ,SHARP)
+	 (5 . ,SHARP) (2 . ,SHARP) (6 . ,SHARP)
+	 (3 . ,SEMI-SHARP) (0 . ,SEMI-SHARP) (4 . ,SEMI-SHARP) (1 . ,SEMI-SHARP)
+	 (5 . ,SEMI-SHARP) (2 . ,SEMI-SHARP) (6 . ,SEMI-SHARP)
+	 (6 . ,DOUBLE-FLAT) (2 . ,DOUBLE-FLAT) (5 . ,DOUBLE-FLAT ) (1 . ,DOUBLE-FLAT)
+	 (4 . ,DOUBLE-FLAT) (0 . ,DOUBLE-FLAT) (3 . ,DOUBLE-FLAT)
+	 (3 . ,DOUBLE-SHARP) (0 . ,DOUBLE-SHARP) (4 . ,DOUBLE-SHARP) (1 . ,DOUBLE-SHARP)
+	 (5 . ,DOUBLE-SHARP) (2 . ,DOUBLE-SHARP) (6 . ,DOUBLE-SHARP)
+	)
+  }
+}
diff --git a/scm/midi.scm b/scm/midi.scm
index 7f26bea0dc..a3540e60ca 100644
--- a/scm/midi.scm
+++ b/scm/midi.scm
@@ -284,8 +284,7 @@
 (define-public (alterations-in-key pitch-list)
   "Count number of sharps minus number of flats."
 
-  (* (apply + (map cdr pitch-list)) 2))
-
+  (apply + (map (lambda (p) (round (* (cdr p) 2))) pitch-list)) )
 
 
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