controlling spacing of incomplete bars (or note opacity?)

[iainctduncan]

Hi, first off Vexflow is awesome, thanks to everyone who has worked on this!

I am a music and CS academic working on music training tools. I would like to draw notes on bar as they come in from student answers. This means I'm drawing the bar bit by bit. Right now this works fine by just redrawing the whole stave as each question is answered. The thing I have not figured out how to do is stop the note spacing from jumping around. If I draw two quarters only in a bar, or even two quarters plus two rests, they get more horizonal space than 4 quarters. I would like to either

a) force the quarters to have a specific horizontal spacing regardless of what else is in the bar
or
b) if there is a way to set opacity of notes to 0, I could draw the whole bar and simply have the unactivated notes be invisible.

I have tried to find this in the tutorials and docs, but they are (understandably!) dense...

thanks in advance

[AaronDavidNewman]

I just saw this. For the second thing, it's pretty easy to hide a note, just use styles on the 'Note'.

note.setStyle({ fillStyle: "#ffffff00" });

For the first thing, there are many ways to affect the spacing. You do this with the formatter, there are some examples in test programs. It may not be what you expect though, because depending on 'what else is in the bar', it may not even fit, or leave gaps on one side of the measure.

[iainctduncan]

great, thanks!