-- fullscreen disp 01

function love.load()
  -- init

  -- set filter
  love.graphics.setDefaultFilter("nearest", "nearest")

  -- set canvas size
  scr_w = 640
  scr_h = 480
  canvas = love.graphics.newCanvas(scr_w, scr_h)

  -- get window width and height
  wdw_w, wdw_h = love.graphics.getDimensions()

  scr_scale = math.min((wdw_w / scr_w), (wdw_h / scr_h))
  scr_ofsx = (wdw_w - (scr_w * scr_scale)) / 2
  scr_ofsy = (wdw_h - (scr_h * scr_scale)) / 2

  -- load image
  img = love.graphics.newImage("ufo_64x64_fullcol.png")

  -- make Quad
  imgs = {}
  for i=1,(8 * 4) do
    local ii = i - 1
    local x = (ii % 8) * 64
    local y = math.floor(ii / 8) * 64
    imgs[ii] = love.graphics.newQuad(x, y, 64, 64, img:getDimensions())
  end
  img_count = 9
  img_count_time = 0

  -- framerate steady
  min_dt = 1 / 60
  next_time = love.timer.getTime()
end

function love.update(dt)
  -- update
  next_time = next_time + min_dt

  img_count_time = img_count_time + dt
  img_count = 9 + math.floor(15 * img_count_time) % 15
end

function love.draw()

  -- set canvas
  love.graphics.setCanvas(canvas)

  -- draw BG
  love.graphics.setColor(0, 0, 255)
  love.graphics.rectangle("fill", 0, 0, scr_w, scr_h)

  -- draw sprite
  love.graphics.setColor(255, 255, 255)
  love.graphics.draw(img, imgs[img_count], 32, 32)

  -- unset canvas
  love.graphics.setCanvas()

  -- draw canvas to window
  love.graphics.setColor(255, 255, 255)
  love.graphics.draw(canvas, scr_ofsx, scr_ofsy, 0, scr_scale, scr_scale)

  love.graphics.print("FPS: "..tostring(love.timer.getFPS()), 10, 10)

  if love.system.getOS() == "Windows" then
    -- wait
    local cur_time = love.timer.getTime()
    if next_time <= cur_time then
      next_time = cur_time
    else
      love.timer.sleep(next_time - cur_time)
    end
  end
end

function love.keypressed(key, isrepeat)
  -- ESC to exit
  if key == "escape" then
    love.event.quit()
  end
end