get("#348") -- rgb functions

get("#388") -- rect functions

w, h = img.width, img.height

g = 3 -- grid size

maxBlackPixels = g-1

minSize = {20, 20} -- exclude the really small white spaces

gw, gh = math.floor(w/g), math.floor(h/g) -- width & height of grid

function makeGrid()

  grid = {}

  for gy = 0, h-g, g do

    for gx = 0, w-g, g do

      local black = 0

      for y = gy, gy+g-1 do

        for x = gx, gx+g-1 do

          local b = bright(rgb(img.getInt(x, y)))

          if b < 0.94 then

            black = black+1

            if black > maxBlackPixels then

              goto next

            end

          end

        end

      end

      grid[(gy/g)*gw+(gx/g)+1] = true

      ::next::

    end

  end

end

-- stack layout: {{x, y}, ...}

local r

function fill(stack)

  while #stack > 0 do

    local x, y = unpack(stack[#stack])

    stack[#stack] = nil

    if not (x < 0 or y < 0 or x >= gw or y >= gh) then

      local idx = y*gw+x+1

      if grid[idx] then

        grid[idx] = nil

        local me = newRectangle(x, y, 1, 1)

        if r == nil then

          r = me

        else

          r = mergeRectangles(r, me)

        end

        stack[#stack+1] = {x-1, y}

        stack[#stack+1] = {x+1, y}

        stack[#stack+1] = {x, y-1}

        stack[#stack+1] = {x, y+1}

      end

    end

  end

end

function makeSpaces()

  spaces = {}

  for y = 0, gh-1 do

    for x = 0, gw-1 do

      r = nil -- must be global

      fill {{x, y, 1}}

      if r and r.width >= minSize[1] and r.height >= minSize[2] then

        --table.insert(result, (x*g).."/"..(y*g).."-"..c)

        r = scaleRectangle(r, g)

        --r = shrinkRectangle(r, img)

        table.insert(spaces, r)

      end

    end

  end

end