Mask Image example

ApplicationHelper.rb

module ApplicationHelper
  
  
  def teste
    
    #profile_url = Net::HTTP.get_response(URI.parse("http://graph.facebook.com/#{100000335750045}/picture?type=large"))['location']
    #second_image  = Net::HTTP.get_response(URI.parse("https://taylorgraceauthor.files.wordpress.com/2015/11/6917465-french-flag-wallpaper.jpg"))['location']
    
    #Deve ter transparencia
    first = "#{Rails.public_path}/mask.png"
    
    #Imagem de fundo
    second = "#{Rails.public_path}/firefox.png"
    
    first_image  = MiniMagick::Image.new(first)
    second_image = MiniMagick::Image.new(second)
    
    first_image.format 'png'
    second_image.format 'png'
    
    result = first_image.composite(second_image, 'png') do |c|
      c.compose "DstOver"    # OverCompositeOp
      #c.geometry "+200+200"
      #c.alpha 'on'
      #c.channel 'a'
      #c.evaluate 'set', '25%'
      #c.channel "A"
      #c.alpha 'transparent'
    end
    result.format 'png'
    result.write "#{Rails.public_path}/output1.png"

    
    
  end
  
end