module ChunkyPNG::Canvas::Adam7Interlacing

def adam7_merge_pass(pass, canvas, subcanvas)

Parameters:

subcanvas (ChunkyPNG::Canvas) -- The pass image that should be merged
canvas (ChunkyPNG::Canvas) -- The image that is being constructed.
pass (Integer) -- The pass number, should be in 0..6.

def adam7_merge_pass(pass, canvas, subcanvas)
  x_shift, x_offset, y_shift, y_offset = adam7_multiplier_offset(pass)
  for y in 0...subcanvas.height do
    for x in 0...subcanvas.width do
      new_x = (x << x_shift) | x_offset
      new_y = (y << y_shift) | y_offset
      canvas[new_x, new_y] = subcanvas[x, y]
    end
  end
end

Instance Methods