#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

Adafruit_SSD1306 display(128, 64, &Wire, -1, 1000000);

typedef struct renderable {
  bool  active;
  void* handler;
} renderable_t;

uint count;
renderable_t* scene;

void testHandler0(Adafruit_SSD1306 screen) {
  screen.setCursor(0, 0);
  screen.println("Handler 0");
}

void testHandler1(Adafruit_SSD1306 screen) {
  screen.setCursor(0, 32);
  screen.println("Handler 1");
}

void setup() {
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);  // Begin Communication With Display

  display.clearDisplay();                     // Clear Display Buffer
  display.setTextSize(1);                     // Text size should be 1px
  display.setTextColor(SSD1306_INVERSE);      // Toggle pixels
  display.setCursor(0, 0);                    // Reset Cursor
  display.print("Booting...");
  display.display();                          // Display On Screen

  count = 2;
  scene = (renderable_t*)malloc(sizeof(renderable_t) * count);

  scene[0].active = true;
  scene[0].handler = &testHandler0;
  scene[1].active = true;
  scene[1].handler = &testHandler1;
}

void loop() {
  display.clearDisplay();

  for (uint i = 0; i < count; i++) {
    if (scene[i].active) scene[i].handler(display);
  }

  display.display();
  delay(10); // this speeds up the simulation
}