gridpoint.rb

require 'constants'

# Represent a cell position in the grid
GridPoint = Struct.new(:row, :col) do
  include Constants

  def self.from_point(pos)
    from_xy(pos.x, pos.y)
  end

  def self.from_xy(x, y)
    new(
      ((y - Constants::GRID_ORIGIN.y) / Constants::CELL_SIZE.height).floor,
      ((x - Constants::GRID_ORIGIN.x) / Constants::CELL_SIZE.width).floor
    )
  end

  def out_of_range?(height, width = nil)
    return true if row < 0 || col < 0

    if height.respond_to? :height
      width  = height.width
      height = height.height
    end

    row >= height || col >= width
  end

  def offset(dr, dc = nil)
    if dr.respond_to? :row
      GridPoint.new(row + dr.row, col + dr.col)
    else
      GridPoint.new(row + dr, col + dc)
    end
  end

  def to_point
    Constants::GRID_ORIGIN.offset(col * Constants::CELL_SIZE.width, row * Constants::CELL_SIZE.height)
  end
end