Re: disabling point-and-click for displayed chords?

[Adam Spiers]

On Tue, Jan 15, 2013 at 3:05 PM, Adam Spiers
<address@hidden> wrote:
> On Tue, Jan 15, 2013 at 9:41 AM, David Kastrup <address@hidden> wrote:
>> Adam Spiers <address@hidden> writes:
>>
>>> I need to generate point-and-click links for notes but not for
>>> displayed chord names.  However, \pointAndClickTypes only filters by
>>> music event class, and if my understanding is correct, events in a
>>> certain music class have no notion of which context they are being
>>> applied in, and so this filter cannot distinguish between a note-event
>>> in a Voice context and a note-event in a ChordNames context.

[snipped]

>>> Am I correct, and if so, is there any workaround?  I naively tried:
>>>
>>>     \score {
>>>       <<
>>>         \pointAndClickTypes #'()
>>>         \allchords
>>>         \pointAndClickTypes #'(note-event)
>>>         \new Staff {
>>>           \allnotes
>>>         }
>>>       >>
>>>       ...
>>>     }
>>>
>>> but it still created point-and-click annotations for everything.
>>
>> You could use an engraver in ChordNames for wiping out the (event) cause
>> of the last involved grob.  Then the point-and-click location would no
>> longer be available...
>
> That makes sense.  Do you mean an existing engraver though, or a new
> one?  The only existing one which looks promising is
> Output_property_engraver (which I had never heard of before).  Does
> that mean I do this via \applyOutput?

I got this to work for a single note via:

    #(define (delete-grob-cause grob origctx curctx)
      (let* ((cause (ly:grob-property grob 'cause))
             (music-origin (if (ly:stream-event? cause)
                            (ly:event-property cause 'origin))))
      (ly:debug "removing grob origin '~a'" music-origin)))
      (ly:grob-set-property! grob 'cause #f))

and then:

    \applyOutput #'ChordNames #delete-grob-cause

However, this only worked for the single note following the command.
I searched hard for a way to apply it to all notes, but this was the
best advice I could find:

  http://thread.gmane.org/gmane.comp.gnu.lilypond.general/18699/focus=18700

and both options presented were behind my expertise.

However, I did find another solution which worked great:

diff --git a/scm/output-ps.scm b/scm/output-ps.scm
index dd92175..04b248f 100644
--- a/scm/output-ps.scm
+++ b/scm/output-ps.scm
@@ -142,7 +142,9 @@

 (define (grob-cause offset grob)
   (if (ly:get-option 'point-and-click)
-      (let* ((cause (ly:grob-property grob 'cause))
+      (let* ((name (assoc-get 'name (ly:grob-property grob 'meta)))
+             (class (assoc-get 'class (ly:grob-property grob 'meta)))
+             (cause (ly:grob-property grob 'cause))
             (music-origin (if (ly:stream-event? cause)
                               (ly:event-property cause 'origin)))
             (point-and-click (ly:get-option 'point-and-click)))
@@ -153,7 +155,8 @@
                    (ly:in-event-class? cause point-and-click))
                   (else (any (lambda (t)
                                (ly:in-event-class? cause t))
-                             point-and-click))))
+                             point-and-click)))
+             (not (equal? name 'ChordName)))
            (let* ((location (ly:input-file-line-char-column music-origin))
                   (raw-file (car location))
                   (file (if (is-absolute? raw-file)

Clearly this patch is not appropriate for submission as is.  However,
I think it would be worth either extending \pointAndClickTypes to
support filtering by context, or adding a new command such as
\pointAndClickContexts.  If there is agreement with this idea I am
happy to submit an issue and drum up a patch, but I'd appreciate
guidance on the best interface syntax.  For instance, I'm not sure
whether it's better to treat the argument as a list of contexts to
include:

  \pointAndClickExcludedContexts #'(Voice DrumVoice)

or contexts to exclude:

  \pointAndClickContexts #'(ChordNames)

or should both inclusion and exclusion be supported, either via
separate commands or a single command, e.g.

  \pointAndClickContexts #'(Voice DrumVoice -ChordNames)

And how would any of these commands interact with the existing
\pointAndClickTypes command?  Presumably they'd have to be treated as
an additional level of filtering.

Thanks,
Adam