Support centering the first note horizontally in bar

[comus111]

Hi, thanks for this wonderful library!

We are developing music theory exercises app, and want to display the first note horizontally center in the bar.
Is there a plan to support it? This should be a common use case for education and exercises app for better looking.

Actual:

Expected:

[Danielku15]

alphaTab tries to follow the industry best practices in terms of aligning elements. For horizontal placement of notes we follow the Gourlay algorithm. There elements are aligned according to their timely position when they are played. The time "0" starts after the clef and ends at the bar line. This is also known as "rhythmic spacing".

The special exception of having notes of bar-length duration centered was currently not on our radar. I found some references in Behind Bars, the music notation bible, mentioning this is an accepted practice. MuseScore also has this as an open item (musescore/MuseScore#20295)

I added #2464 to track this item as idea. Any contributions are welcome.