nodemcu-firmware/lua_examples/graphics_test.lua

-- setup I2c and connect display
function init_i2c_display()
     sda = 5
     scl = 6
     sla = 0x3c
     i2c.setup(0, sda, scl, i2c.SLOW)
     disp = u8g.ssd1306_128x64_i2c(sla)
end


-- graphic test components
function prepare()
     disp:setFont(u8g.font_6x10)
     disp:setFontRefHeightExtendedText()
     disp:setDefaultForegroundColor()
     disp:setFontPosTop()
end

function box_frame(a)
     disp:drawStr(0, 0, "drawBox")
     disp:drawBox(5, 10, 20, 10)
     disp:drawBox(10+a, 15, 30, 7)
     disp:drawStr(0, 30, "drawFrame")
     disp:drawFrame(5, 10+30, 20, 10)
     disp:drawFrame(10+a, 15+30, 30, 7)
end

function disc_circle(a)
     disp:drawStr(0, 0, "drawDisc")
     disp:drawDisc(10, 18, 9)
     disp:drawDisc(24+a, 16, 7)
     disp:drawStr(0, 30, "drawCircle")
     disp:drawCircle(10, 18+30, 9)
     disp:drawCircle(24+a, 16+30, 7)
end

function r_frame(a)
     disp:drawStr(0, 0, "drawRFrame/Box")
     disp:drawRFrame(5, 10, 40, 30, a+1)
     disp:drawRBox(50, 10, 25, 40, a+1)
end

function stringtest(a)
     disp:drawStr(30+a, 31, " 0")
     disp:drawStr90(30, 31+a, " 90")
     disp:drawStr180(30-a, 31, " 180")
     disp:drawStr270(30, 31-a, " 270")
end

function line(a)
     disp:drawStr(0, 0, "drawLine")
     disp:drawLine(7+a, 10, 40, 55)
     disp:drawLine(7+a*2, 10, 60, 55)
     disp:drawLine(7+a*3, 10, 80, 55)
     disp:drawLine(7+a*4, 10, 100, 55)
end

function triangle(a)
     local offset = a
     disp:drawStr(0, 0, "drawTriangle")
     disp:drawTriangle(14,7, 45,30, 10,40)
     disp:drawTriangle(14+offset,7-offset, 45+offset,30-offset, 57+offset,10-offset)
     disp:drawTriangle(57+offset*2,10, 45+offset*2,30, 86+offset*2,53)
     disp:drawTriangle(10+offset,40+offset, 45+offset,30+offset, 86+offset,53+offset)
end

function ascii_1()
     local x, y, s
     disp:drawStr(0, 0, "ASCII page 1")
     for y = 0, 5, 1 do
          for x = 0, 15, 1 do
               s = y*16 + x + 32
               disp:drawStr(x*7, y*10+10, string.char(s))
          end
     end
end

function ascii_2()
     local x, y, s
     disp:drawStr(0, 0, "ASCII page 2")
     for y = 0, 5, 1 do
          for x = 0, 15, 1 do
               s = y*16 + x + 160
               disp:drawStr(x*7, y*10+10, string.char(s))
          end
     end
end


-- the draw() routine
function draw(draw_state)
     local component = bit.rshift(draw_state, 3)

     prepare()

     if (component == 0) then
          box_frame(bit.band(draw_state, 7))
     elseif (component == 1) then
          disc_circle(bit.band(draw_state, 7))
     elseif (component == 2) then
          r_frame(bit.band(draw_state, 7))
     elseif (component == 3) then
          stringtest(bit.band(draw_state, 7))
     elseif (component == 4) then
          line(bit.band(draw_state, 7))
     elseif (component == 5) then
          triangle(bit.band(draw_state, 7))
     elseif (component == 6) then
          ascii_1()
     elseif (component == 7) then
          ascii_2()
     end
end

function graphics_test()
     init_i2c_display()

     print("--- Starting Graphics Test ---")

     -- cycle through all components
     local draw_state
     for draw_state = 0, 7 + 7*8, 1 do
          disp:firstPage()
          repeat
               draw(draw_state)
          until disp:nextPage() == false
          --print(node.heap())
          -- re-trigger Watchdog!
          tmr.wdclr()
     end

     print("--- Graphics Test done ---")
end

graphics_test()