class ChunkyPNG::Canvas

def replace_canvas!(new_width, new_height, new_pixels)

Replaces the image, given a new width, new height, and a new pixel array. 
def replace_canvas!(new_width, new_height, new_pixels)
  raise ArgumentError, "The provided pixel array should have #{new_width * new_height} items" unless new_pixels.length == new_width * new_height
  @width, @height, @pixels = new_width, new_height, new_pixels
  return self
end