Re: Tweaking notehead direction in chords

[Paul Morris]

On Dec 20, 2012, at 7:51 PM, Thomas Morley <address@hidden> wrote:

> I think there is no way to align moved noteheads left and right from
> the stem _and_ to keep a correct 'stem-attachment in x-axis-direction
> in all thinkable cases.
> The y-value of 'stem-attachment has to be modified in several situations 
> anyway.

Hi Harm,

I had some more time to look at this, and I think I may be catching up with you 
now.  :-)

I now see that using (/ stem-x-width 2) nicely handles all four possibilities 
correctly in terms of positioning note heads relative to the stem on the X-axis 
(upwards or downwards stem, moving a note head to the default or to the 
opposite-of-default side of the stem).  So this is all that is needed to 
correctly align notes vertically on either side of the stem.

But I also see how this means the stem may not attach properly in some cases.  
The main (or only?) instance of this seems to be when a note head that is at 
the end of a stem has been offset to the non-default side of the stem.  It 
overlaps only half of the stem width, and this does not look right.  (I can't 
think of another case where this would be a problem.)

It might be possible to handle this case automatically in the code (at least 
for the X-axis of 'stem-attachment), but I'm not sure it would be worth it 
since it can be tweaked manually using your adjustStem function.  (But just for 
example...)

    if note head is the lowest one on an upwards stem or
    if note head is the highest one on a downwards stem
    and it has been moved to the non-default side of the stem
    then adjust the 'stem-attachment accordingly


Also, it seems that changing the 'stem-attachment property moves the stem and 
not the note.  This preserves the vertical alignment of the notes which is a 
good thing, but it basically reverses the usual pattern of how note heads 
overlap the stem.  (Notes on the non-default side of the stem will now overlap 
the full width of the stem, and notes on the default side will now overlap half 
the width of the stem -- the opposite of the usual pattern.)  There is no way 
around this, since offsetting a note at the end of the stem means you either 
get the stem attachment right, or keep the usual pattern of how note heads 
overlap the stem.  And clearly it's better to get the stem attachment right.

So I don't have any further suggestions for the code.  I will try to find some 
time to come up with a good concise example for the LSR, and put the default 
notes on a separate staff above the offset notes.

Best,
-Paul