resize and crop using using MiniMagick

resize_and_crop.rb

def resize_and_crop(blob, w0, h0, w1, h1)
  image = MiniMagick::Image.read(blob)
  
  rw = w1.to_f / w0
  rh = h1.to_f / h0

  unless rw > 1 or rh > 1
    w,h = w1, h1
    sx, sy = 0, 0
    
    if rw > rh
      h = (h0 * rw).to_i
      sy = (h - h1) / 2
    else
      w = (w0 * rh).to_i
      sx = (w - w1) / 2
    end

    image.thumbnail("#{w}x#{h}")
    image.crop("#{w1}x#{h1}+#{sx}+#{sy}")
  end
  
  image.to_blob
end