Image Splitter — Ruby source

# Image splitter — tile geometry — Ruby port of the image-splitter tool.

module ImageSplitter
  # One cut of the grid: the source rectangle that becomes a tile. In the
  # browser tool this rect is drawImage'd into its own canvas and encoded
  # to PNG; the geometry here is the deterministic part of that pipeline.
  Tile = Struct.new(:x, :y, :width, :height) do
    def to_s = "src=(#{x}, #{y}) #{width}x#{height}"
  end

  # Split a width x height image into rows x cols tiles, row-major.
  # Mirrors splitToTiles in typescript.ts: tileW = floor(width / cols),
  # tileH = floor(height / rows) — Integer division IS Math.floor for
  # positives, so a 1024px width over 3 cols yields 341px tiles and the
  # last 1px column is dropped, exactly like the TS.
  def self.split_tiles(width, height, rows, cols)
    tile_w = width / cols
    tile_h = height / rows
    (0...rows).flat_map do |row|
      (0...cols).map do |col|
        Tile.new(col * tile_w, row * tile_h, tile_w, tile_h)
      end
    end
  end
end

# 1024x768 image, 2 rows x 3 cols -> six 341x384 tiles.
ImageSplitter.split_tiles(1024, 768, 2, 3).each { |tile| puts tile }