Class: PSD::Curves

Inherits:
LayerInfo show all
Defined in:
lib/psd/layer/info/curves.rb

Instance Attribute Summary collapse

Attributes inherited from LayerInfo

#data

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from LayerInfo

#initialize, #skip

Constructor Details

This class inherits a constructor from PSD::LayerInfo

Instance Attribute Details

#curvesObject (readonly)

Returns the value of attribute curves


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# File 'lib/psd/layer/info/curves.rb', line 9

def curves
  @curves
end

Class Method Details

.should_parse?(key) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/psd/layer/info/curves.rb', line 5

def self.should_parse?(key)
  key == 'curv'
end

Instance Method Details

#parseObject


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# File 'lib/psd/layer/info/curves.rb', line 11

def parse
  # Padding, spec is wrong. Maybe Photoshop bug?
  @file.seek 1, IO::SEEK_CUR

  # Version
  @file.seek 2, IO::SEEK_CUR

  tag = @file.read_int
  curve_count = 0

  # Legacy data, it looks like there are 32 positions
  # where you can adjust the curve, and there is a chunk
  # of 32 bytes that determine whether that chunk is set.
  32.times do |i|
    curve_count += 1 if tag & (1 << i) > 0
  end

  @curves = []
  curve_count.times do |i|
    # Before each curve is a channel index
    count = 0
    curve = {}
    32.times do |j|
      if tag & (1 << j) > 0
        if count == i
          curve[:channel_index] = j
          break
        end

        count += 1
      end
    end

    point_count = @file.read_short
    curve[:points] = point_count.times.map do
      {
        output_value: @file.read_short,
        input_value: @file.read_short
      }
    end

    @curves << curve
  end

  if @file.tell < @section_end - 4
    tag = @file.read_string(4)
    raise "Extra curves key error: #{tag}" if tag != 'Crv '

    @file.seek 2, IO::SEEK_CUR

    curve_count = @file.read_int
    curve_count.times do
      curve = { channel_index: @file.read_short }

      point_count = @file.read_short
      curve[:points] = point_count.times.map do
        {
          output_value: @file.read_short,
          input_value: @file.read_short
        }
      end

      @curves << curve
    end
  end
end