gfx sample

for (int y = 0; y <= screen_size.height; y++) {
    if(yy==(screen_size.height/frame_buffer_parts)) {
      yy=0;
      esp_lcd_panel_draw_bitmap(panel_handle, 0, y-(screen_size.height/frame_buffer_parts), screen_size.width, y, frame_buffer.begin());
      if(y==screen_size.height) {
        break;
      }
    }
    posReal = startReal;
    for (int x = 0; x < screen_size.width; x++) {
      a = posReal;
      b = posImag;
      for (n = iterations; n > 0 ; n--) {
        a2 = (a * a) >> res_bits;
        b2 = (b * b) >> res_bits;
        if ((a2 + b2) >= (4 << res_bits))
          break;
        b  = posImag + ((a * b) >> (res_bits - 1));
        a  = posReal + a2 - b2;
      }
      frame_buffer_t::pixel_type px;
      px.native_value =  (n * 29)<<8 | (n * 67);
      frame_buffer.point(point16(x,y%(screen_size.height/frame_buffer_parts)),px);
      posReal += incReal;
    }
    posImag -= incImag;
    ++yy;
  }
  elapsedTime = millis()-startTime;
  Serial.print("Took "); Serial.print(elapsedTime); Serial.println(" ms");