Class: Heatmap::Image

Inherits:
Object
  • Object
show all
Defined in:
lib/heatmap/image.rb

Constant Summary collapse

POINT = 
File.new(File.dirname(__FILE__) + "/../assets/point.png", 'r')
GRADIENT = 
File.new(File.dirname(__FILE__) + "/../assets/gradient.png", 'r')

Instance Method Summary collapse

Constructor Details

#initialize(area, file) ⇒ Image

Returns a new instance of Image.

Raises:

  • (ArgumentError) 


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# File 'lib/heatmap/image.rb', line 7

def initialize(area, file)
  raise(ArgumentError, "Area needs to be an array of Heatmap::Area objects") if area.empty?

  file   = File.new(file, 'w')
  bounds = Heatmap::Geometry.bounds(area, 100)

  # Creating a blank canvas
  system("convert -size #{bounds.width}x#{bounds.height} pattern:gray100 #{file.path}")

  # Drawing each area
  compose = ["convert #{file.path}"]
  compose << area.map{|area| "-page #{area.x_y} #{POINT.path}" }
  compose << "-layers flatten #{file.path}"
  system(compose * ' ')

  # Applying color with a LUT
  system("convert -channel ALL -clut #{file.path} #{GRADIENT.path} #{file.path}")

  # Apply a default 50% opacity
  system("mogrify -channel A -fx \"A*0.50\" #{file.path}")

  file.close
end