Module: OutroRails::CircleOfFifthsHelper

Defined in:
app/helpers/outro_rails/circle_of_fifths_helper.rb

Constant Summary collapse

WEDGE_DEGREES = 
360.0 / 12
WEDGE_GAP_DEGREES = 
1.0

Instance Method Summary collapse

Instance Method Details

#circle_point(cx, cy, radius, degrees) ⇒ Object 



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# File 'app/helpers/outro_rails/circle_of_fifths_helper.rb', line 8

def circle_point(cx, cy, radius, degrees)
  radians = (degrees - 90) * Math::PI / 180

  [ (cx + radius * Math.cos(radians)).round(2),
    (cy + radius * Math.sin(radians)).round(2) ]
end

#key_signature_label(key) ⇒ Object 



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# File 'app/helpers/outro_rails/circle_of_fifths_helper.rb', line 37

def key_signature_label(key)
  count = key.signature
  return "no sharps or flats" if count.zero?

  pluralize(count.abs, count.positive? ? "sharp" : "flat")
end

#wedge_label_point(cx, cy, inner_radius, outer_radius, index) ⇒ Object 



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# File 'app/helpers/outro_rails/circle_of_fifths_helper.rb', line 30

def wedge_label_point(cx, cy, inner_radius, outer_radius, index)
  circle_point(cx,
               cy,
               (inner_radius + outer_radius) / 2.0,
               index * WEDGE_DEGREES)
end

#wedge_path(cx, cy, inner_radius, outer_radius, index) ⇒ Object 



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# File 'app/helpers/outro_rails/circle_of_fifths_helper.rb', line 15

def wedge_path(cx, cy, inner_radius, outer_radius, index)
  from = (index * WEDGE_DEGREES) - (WEDGE_DEGREES / 2) + WEDGE_GAP_DEGREES
  to   = (index * WEDGE_DEGREES) + (WEDGE_DEGREES / 2) - WEDGE_GAP_DEGREES

  o1 = circle_point(cx, cy, outer_radius, from)
  o2 = circle_point(cx, cy, outer_radius, to)
  i2 = circle_point(cx, cy, inner_radius, to)
  i1 = circle_point(cx, cy, inner_radius, from)

  "M #{o1[0]} #{o1[1]} " \
    "A #{outer_radius} #{outer_radius} 0 0 1 #{o2[0]} #{o2[1]} " \
    "L #{i2[0]} #{i2[1]} " \
    "A #{inner_radius} #{inner_radius} 0 0 0 #{i1[0]} #{i1[1]} Z"
end