The 'music always fits the page concept' has me baffled
This may seem odd and obsessive, but as a programmer, something has me baffled in regards to music publishing.
Measures (or bars) are wider the more notes they consist of. I find it perplexing that there's never an issue where, when rendering a page of music, the measures always seem to fit on each row of staves. You'd think that, at one point, you might have one measure that would be too wide. In fact, that has to be the case, so I wonder how that is rectified. Does the program simply squish all the notes on the line together just a teeny tiny bit so it's not really noticeable and it makes it to where all of the measures fit on the line?
Comments
Music engraving is an optical art form.
You are correct in your observation that measures get stretched (or shrunk) to accomodate more (or fewer) notes.
Normally, a line break will occur at the end of a measure - at a bar line, so stretching or shrinking of measures is necessary to ensure that the score has justified margins both on the left and on the right.
However, if unavoidable, a very long measure can continue onto the next line.
As a programmer, you may be interested in this (lengthy) essay discussing the nuances between hand engraved and computer engraved scores:
http://www.lilypond.org/doc/v2.18/Documentation/essay/the-lilypond-story
...and the subtle spacing decisions that are required for a computer rendering to mimic a hand engraved score.
Regards.
The short version of how MuseScore does things:
First, we calculate the minimum width of each measure, to see how many measures will fit on a line. if a measure won't fit, it goes to the next line. This leaves each line under full. So then we right-justify it - stretching each measure out.