From 27f9ebef47a058db8befc5cb05bd63375144fc01 Mon Sep 17 00:00:00 2001
From: Thomas Morley <thomasmorley65@gmail.com>
Date: Mon, 2 Jan 2017 14:12:42 +0000
Subject: [PATCH] Issue 4983 Let crossStaff hide non-default-style flags

Return empty-stencil for all flags using the code provided in
flag-styles.scm, if the style property is 'no-flag as set by
the crossStaff-function.
---
 scm/flag-styles.scm | 34 ++++++++++++++++++----------------
 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/scm/flag-styles.scm b/scm/flag-styles.scm
index a2ddf3a9dd..ab61921851 100644
--- a/scm/flag-styles.scm
+++ b/scm/flag-styles.scm
@@ -97,14 +97,16 @@ All lengths are scaled according to the font size of the note."
            ;; Log for 1/8 is 3, so we need to subtract 3
            (flag-stencil (buildflag stencil (- log 3) stencil spacing))
            (stroke-style (ly:grob-property grob 'stroke-style)))
-      (if (equal? stroke-style "grace")
-          (add-stroke-straight flag-stencil grob
-                               dir log
-                               stroke-style
-                               flag-end flag-length
-                               thickness
-                               (* half-stem-thickness 2))
-          flag-stencil))))
+      (cond ((eq? (ly:grob-property grob 'style) 'no-flag)
+             empty-stencil)
+            ((equal? stroke-style "grace")
+             (add-stroke-straight flag-stencil grob
+                                  dir log
+                                  stroke-style
+                                  flag-end flag-length
+                                  thickness
+                                  (* half-stem-thickness 2)))
+            (else flag-stencil)))))
 
 (define-public (modern-straight-flag grob)
   "Modern straight flag style (for composers like Stockhausen, Boulez, etc.).
@@ -174,10 +176,12 @@ flag stencil."
          (dir (if (eqv? (ly:grob-property stem-grob 'direction) UP) "u" "d"))
          (flag (retrieve-glyph-flag flag-style dir dir-modifier grob))
          (stroke-style (ly:grob-property grob 'stroke-style)))
-    (if (null? stroke-style)
-        flag
-        (add-stroke-glyph flag grob dir stroke-style flag-style))))
-
+    (cond ((eq? (ly:grob-property grob 'style) 'no-flag)
+           empty-stencil)
+          ((null? stroke-style)
+           flag)
+          (else
+           (add-stroke-glyph flag grob dir stroke-style flag-style)))))
 
 
 (define-public (mensural-flag grob)
@@ -205,7 +209,6 @@ a flag always touches a staff line."
     (create-glyph-flag "mensural" modifier grob)))
 
 
-
 (define ((glyph-flag flag-style) grob)
   "Simulatesthe default way of generating flags: Look up glyphs
 @code{flags.style[ud][1234]} from the feta font and use it for the flag
@@ -214,13 +217,11 @@ stencil."
 (export glyph-flag)
 
 
-
 (define-public (normal-flag grob)
   "Create a default flag."
   (create-glyph-flag "" "" grob))
 
 
-
 (define-public (default-flag grob)
   "Create a flag stencil for the stem.  Its style will be derived from the
 @code{'style} Flag property.  By default, @code{lilypond} uses a
@@ -242,5 +243,6 @@ at will.  The correct way to do this is:
     (cond
      ((equal? flag-style "") (normal-flag grob))
      ((equal? flag-style "mensural") (mensural-flag grob))
-     ((equal? flag-style "no-flag") (no-flag grob))
+     ((equal? flag-style "no-flag") empty-stencil)
      (else ((glyph-flag flag-style) grob)))))
+
-- 
2.39.2