love-tilesheet-tool/lib/tilesheet.lua

local load_image = function(file_path)
  local file = io.open(file_path, "rb")
  local raw_data = file:read("*all")
  file:close()

  local love_file_data = love.filesystem.newFileData(raw_data, file_path)
  local love_image = love.graphics.newImage(love_file_data)
  return love_image
end

local tilesheet = {}

local tile_metatable = {
  __index = {
    draw = function(self, ...)
      love.graphics.draw(self.image, self.quad, ...)
    end,
  }
}

local tilesheet.load = function(data_or_path)
  local tile_image, tile_size, tile_usage
  local tiles = {}

  if type(data_or_path) == "table" then
    tile_image = load_image(data_or_path.image_path)
    tile_size = data_or_path.tile_size

    local image_width, image_height = tile_image:getDimensions()
    tile_usage = {}
    for x = 1, image_width / tile_size do
      tile_usage[x] = {}
      for y = 1, image_height / tile_size do
        tile_usage[x][y] = false
      end
    end

    for name, tile_data in pairs(data_or_path.tiles) do
      tiles[name] = setmetatable({
        image = tile_image,
        quad = love.graphics.newQuad( (tile_data.x - 1) * tile_size, (tile_data.y - 1) * tile_size, tile_size, tile_size, tile_image ),
      }, tile_metatable)

      tile_usage[tile_data.x][tile_data.y] = true
    end

  else
    tile_image = load_image(data_or_path)
  end

  tilesheet.active_sheet = {
    image = tile_image,
    size = tile_size,          -- unset on new
    tiles = tiles,             -- empty on new
    tile_usage = tile_usage,   -- unset on new
  }

  return tiles
end

return setmetatable(tilesheet, {
  __call = function(self, ...) return tilesheet.load(...) end
})