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beam-interface

A beam.

#'thickness= weight of beams, in staffspace We take the least squares line through the ideal-length stems, and then damp that using damped = tanh (slope)

this gives an unquantized left and right position for the beam end. Then we take all combinations of quantings near these left and right positions, and give them a score (according to how close they are to the ideal slope, how close the result is to the ideal stems, etc.). We take the best scoring combination.


auto-knee-gap (dimension, in staff space)
If a gap is found between noteheads where a horizontal beam fits that is larger than this number, make a kneed beam.
beamed-stem-shorten (list)
shorten beamed stems in forced direction.
chord-tremolo (boolean)
if set, this beam is a tremolo. TODO: use interface for this!
concaveness-gap (dimension, in staff space)
A beam is considered to be concave if the distance of an inner notehead to the line between two outer noteheads is bigger than this gap.
concaveness-threshold (number)
A beam is considered to be concave is concaveness is bigger than this threshold. Concaveness is calculated as the sum of the vertical distances of inner noteheads that fall outside the interval of the two outer noteheads, to the vertically nearest outer notehead, divided by the square of the inner notes involved.
damping (integer)
amount of beam slope damping should beam slope be damped? 0: no, 1: yes, 100000: horizontal beams .
dir-function (procedure)
function of type (count total)->direction. Default value: beam-dir-majority, also available: beam-dir-mean, beam-dir-median.

The ways to calculate the direction of a beam work as follows:

majority
number count of up or down notes
mean
mean center distance of all notes
median
mean centre distance weighted per note

flag-width-function (procedure)
Procedure that computes the width of a half-beam (a non-connecting beam.).
gap (dimension, in staff space)
Size of a gap in a variable symbol.
gap-count (integer)
Number of gapped beams for tremolo.
knee (boolean)
Is this beam a knee?
least-squares-dy (number)
ideal beam slope, without damping.
neutral-direction (direction)
Where to go if we're on the neutral position of the staff (by default, the middle of the staff; see also grob-property neutral-position). [Ross] has the following to say about this: Some engravers consider the middle line neutral, and take the option of using either up- or down-stems for notes that fall on it. However, more up-to-date engraving no longer permits an option; now a down-stem is always appropriate.
position-callbacks (list)
list of functions set spanner positions.
positions (pair)
cons of staff positions (LEFT . RIGHT
quant-score (number)
Beam quanting score - can be stored for debugging
shorten (dimension, in staff space)
the amount of space that a stem should be shortened (DOCME!)
space-function (procedure)
return interbeam space given Beam grob and multiplicity.
thickness (number)
thickness, measured in stafflinethickness.

This grob interface is used in the following graphical objects: Beam


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