Support Rehearsal Marks / directions

As per the attached file, the measure directive

      <direction placement="above">
        <direction-type>
          <rehearsal>Section name</rehearsal>
        </direction-type>
      </direction>

is not handled. Would be great to process it 🙏

[sschmidTU]

Done.

Samples: test_rehearsal_marks_2_samples.zip (added to our test samples: test/data/test_rehearsal_marks*.musicxml)

new EngravingRules:

osmd.rules.RenderRehearsalMarks = true; // default
osmd.rules.RehearsalMarkXOffset = 0; // default: avoid collision with metronome number
osmd.rules.RehearsalMarkYOffset = 0; // default: avoid collision with chord symbols
osmd.rules.RehearsalMarkFontSize = 10; // vexflow default: 12, too big with chord symbols
osmd.rules.RehearsalMarkXOffsetSystemStartMeasure = -20; // default. for 5 pixels to the right, try -15
// this one only applies to "the first measure in a new line" (new line = new system)

Now released in OSMD 0.9.2 (see changelog).

[sschmidTU]

I don’t think a Vexflow issue just for this would be the way to go, since Vexflow doesn’t have collision checks for anything above or below the staff, it would need a system for all of that. We already check for placement and collision for many such elements like measure numbers and lyrics, and add new elements to the skyline and bottomline (highest/lowest point where we draw elements for a given x), so doing likewise for rehearsal directions in OSMD should be the way to go.