Class: PhotoUtils::Aperture

Inherits:
Value show all
Defined in:
lib/photo_utils/aperture.rb

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Value

#<=>, #==, #decr, #incr, #initialize

Methods inherited from Float

#format, #prec

Constructor Details

This class inherits a constructor from PhotoUtils::Value

Class Method Details

.new_from_fstop(f) ⇒ Object 



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# File 'lib/photo_utils/aperture.rb', line 5

def self.new_from_fstop(f)
  new(f)
end

.new_from_v(v) ⇒ Object 



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# File 'lib/photo_utils/aperture.rb', line 9

def self.new_from_v(v)
  new(Math.sqrt(2 ** v.to_f))
end

Instance Method Details

#absolute(focal_length) ⇒ Object 



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# File 'lib/photo_utils/aperture.rb', line 56

def absolute(focal_length)
  focal_length / self
end

#format_fstop(stop_steps = 3) ⇒ Object 



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# File 'lib/photo_utils/aperture.rb', line 17

def format_fstop(stop_steps=3)
  rounded_f = Aperture.new_from_v((to_v.to_f * stop_steps).to_i / stop_steps.to_f).format(10)
  frac = rounded_f.to_f - rounded_f.to_i
  if frac != 0
    "f/#{rounded_f.to_f}"
  else
    "f/#{rounded_f.to_i}"
  end
end

#format_us ⇒ Object 



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# File 'lib/photo_utils/aperture.rb', line 27

def format_us
  # Av 8 is equivalent to f/16 and US 16
  steps = to_v.to_i - 8
  us = 16
  if steps < 0
    steps.abs.times { us /= 2 }
  else
    steps.times { us *= 2 }
  end
  "US #{us}"
end

#format_value ⇒ Object 



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# File 'lib/photo_utils/aperture.rb', line 39

def format_value
  "Av:#{to_v.format(10)}"
end

#to_s(format = :fstop, stop_steps = 3) ⇒ Object 



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# File 'lib/photo_utils/aperture.rb', line 43

def to_s(format=:fstop, stop_steps=3)
  case format
  when :us
    format_us
  when :fstop
    format_fstop(stop_steps)
  when :value
    format_value
  else
    raise "Unknown format: #{format.inspect}"
  end
end

#to_v ⇒ Object 



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# File 'lib/photo_utils/aperture.rb', line 13

def to_v
  Math.log2(self ** 2)
end