local ui = require("ui")

-- No components: a canvas has one gesture and every pixel is content, so the app takes
-- the touch callbacks raw. It wants the firmware's noise threshold and no gesture slop --
-- a three pixel stroke is a stroke, not a mis-tap.
local theme = ui.theme
local CLEAR = {x = 0, y = 0, w = 64, h = 28}
local BRUSH = 2

local lastX, lastY

local function inClear(x, y)
  return x < CLEAR.w and y < CLEAR.h
end

local function clear()
  gui.clear(theme.bg)
  gui.roundRect(CLEAR.x, CLEAR.y, CLEAR.w, CLEAR.h, theme.radius, theme.bg,
                theme.face[1], theme.face[2], theme.fg)
  gui.drawText("clear", 14, 10, theme.fg)
end

function init()
  clear()
  log.info("paint ready")
end

function on_touch_down(x, y)
  if inClear(x, y) then
    lastX = nil
    return clear()
  end
  lastX, lastY = x, y
  gui.fillCircle(x, y, BRUSH, theme.accent)
end

-- Strokes are joined with a line because the poll rate, not the finger, decides the gap:
-- a fast swipe reports points tens of pixels apart and dots alone would look dotted.
function on_touch_move(x, y)
  if not lastX then return end
  gui.drawLine(lastX, lastY, x, y, theme.accent)
  gui.fillCircle(x, y, BRUSH, theme.accent)
  lastX, lastY = x, y
end

function on_touch_up()
  lastX = nil
end