Issues around instrument changes and key signatures and clefs

[sammik]

Issue type

Engraving bug

Bug description

1. If the instrument in an instrumentChange is changed to an instrument that matches the preceding transposition, an unnecessary key signature remains there

IC1.mp4

2. If the instrument in an instrumentChange is changed to an instrument that matches the transposition of a subsequent instrumentChange, an unnecessary key signature remains on the later one

IC2.mp4

3. If the instrument in an instrumentChange is changed to an instrument with a different transposition, and than removed, an nwanted key signature is left in the score (for this to be obvious, an initial key signature other than C major is necessary). This is a regression from 4.0.2.

IC3.mp4

4. missing clef in instrument change for various instruments
   in 4.0.2:
   
   EDIT: added video to explicitely see, what is the problem with clef:

IC-clef.mp4

5. wrongly transposed key signatures in concert pitch, if user changes key signature before instrument change

IC5.mp4

6. key signatures became standard (non instrument change) if user changes instrument in instrument change

IC6.mp4

Steps to reproduce

Issue one

1. add two different instrumnet change transpositions
2. change second one to instrument in same transposition as first one is
3. see - unneeded key signatures are in second instrumentChange

Issue two

1. add two different instrumnet change transpositions
2. change first one to instrument in same transposition as second one is
3. see - unneeded key signatures are in second instrumentChange

MuseScore Version

4.1 and master

Regression

1., 2. and 5. are not regressions
3., 4. and 6. are regressions from 4.0.2

Operating system

Ubuntu 22.04

[oktophonie]

Is no. 4 really a problem? I wouldn't expect to see a clef there.

[sammik]

Well, it shouldnt be visible there in transposing pitch, but definitely should be there as object (which is defined as pair "concert - 8ba treble / transposing - treble".

Now, if you switch to concert pitch, clef is missing there.

I think, proper "bass clarinet cleff" should be there.

Similar situation is with key signatures. There is key signature, if you change flute to clarinet. But in concertpitch, it shouldnt be (visible) there.

So I think, we should place theese objects (clefs, key signatures) in all places, where they change, and find some way, how just hide them if they are not neccessary (in concert pitch, or in transposing pitch, depending on preceding one).

[sammik]

working on it

[wizofaus]

@sammik you mentioned you started on this last July but there's been no update (or PR) since? Can take it over if you want, can you share what you found/did so far?

[sammik]

@sammik you mentioned you started on this last July but there's been no update (or PR) since? Can take it over if you want, can you share what you found/did so far?

@wizofaus see: #14714 (comment)

[wizofaus]

Ok, I'm not sure what to make of that, in fact the issue changing between pitched and unpitched percussion is exactly one that I had encountered myself. Still, that was all 6 months ago, which is a long time between drinks considering how rapidly the codebase is changing.

[sammik]

Solution, I used was:

• every instrument change will be connected with its own key, cleff and stafftype
• these (key, cleff, stafftype) are shown (rendered) only when needed

This simple rules made code much cleaner, as all ad hoc conditions needed before could be removed

It brought some other problems, as instrument change is segment base and could be in the middle of the bar, but stafftype change is measure based.

Ideal solution would be to refactor stafftype change to be segment - based. Temporary solution was to restrict also instrument change to be at the begining of the measure (or split measure, if it was not).

Main problem is stafftype change itself. It has many issues, which should be solved first.