Automatic Beaming

• Forcing Stem Directions
• Maintain Stem Directions
• Beaming Over All Rests
• Beaming Over Middle Rests
• Stemlets
• Custom Beam Groups

For long scores, manually creating a Beam object for each group of notes is very cumbersome. Luckily, the Beam module provides a static method that allow us to automatically generate beams for our notes. It's appropriately named .generateBeams(). It has two parameters, the notes to automatically beam and a config object. The config object provides many options to beam your notes in different ways, but let's start simple.

var beams = Beam.generateBeams(notes);

beams.forEach(function(beam) {
  beam.setContext(context).draw();
});

Notice two things:

1. Stem directions were changed
2. The default beam groups are per quarter note

.generateBeams() will calculate an appropriate stem direction for the entire beam group, even if it was set to a different position earlier. There are two alternatives for dealing with stem directions with beams.

Force Stem Direction

You can force a stem direction for every note, by passing a stem_direction property to the config object.

var beams = Beam.generateBeams(notes, {
  stem_direction: -1
});

Maintain Stem Directions

By setting maintain_stem_directions to true, the stem directions for each note will not be altered. Take a look at the initial stem directions for the following notes:

By generating the beams using maintain_stem_directions, the beams are further split up within the beat group where the stem direction changed.

var beams = Beam.generateBeams(notes, {
  maintain_stem_directions: true
});

Beaming Rests

By default, rests break up beam groups.

By setting beam_rests to true, the beams will extend over rests.

var beams = Beam.generateBeams(notes, {
  beam_rests: true
});

Beam Middle Rests Only

You can also set the beam_middle_only to true so that beams only extend across rests if they are in between notes.

var beams = Beam.generateBeams(notes, {
  beam_rests: true,
  beam_middle_only: true
});

Stemlets

Additionally, you can generate beams that draw stemlets over rests.

var beams = Vex.Flow.Beam.generateBeams(notes, {
  beam_rests: true,
  show_stemlets: true
});

Custom Beam Groups

You can pass in custom beam group sequences to the groups property of the config object. These beam groups are represented by an array of Vex.Flow.Fractions, where each Fraction represents a single beam group. The following example beams in groups of 3 8th notes.

var beams = Beam.generateBeams(notes, {
  groups: [new Vex.Flow.Fraction(3, 8)]
});

The following example beams notes in sequences of 3 and then 5 8th notes

var beams = Beam.generateBeams(notes, {
  groups: [
    new Vex.Flow.Fraction(3, 8),
    new Vex.Flow.Fraction(5, 8)
  ]
});