#include <SPI.h> //for IIC -Inter intergrated circuit
#include <Wire.h>
#include <Adafruit_GFX.h> // for graphic
#include <Adafruit_SSD1306.h> //for oled screen
//all these 4 heads files are necessary

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET     4 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
// no need to change, always as default

#define LOGO_HEIGHT   32
#define LOGO_WIDTH    32
// 'DINO', 32x32px
//https://javl.github.io/image2cpp/
const unsigned char bitmap_DINO [] PROGMEM = {
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
	0x00, 0x00, 0x3f, 0xf0, 0x00, 0x00, 0xff, 0xf8, 0x00, 0x00, 0xef, 0xf8, 0x00, 0x00, 0xff, 0xf8, 
	0x00, 0x00, 0xff, 0xf8, 0x00, 0x00, 0xff, 0xf8, 0x00, 0x00, 0xff, 0xf8, 0x00, 0x00, 0xfe, 0x00, 
	0x00, 0x00, 0xff, 0xc0, 0x08, 0x01, 0xf8, 0x00, 0x08, 0x01, 0xf8, 0x00, 0x08, 0x07, 0xf8, 0x00, 
	0x0c, 0x1f, 0xff, 0x00, 0x0e, 0x3f, 0xf9, 0x00, 0x0f, 0xff, 0xf8, 0x00, 0x0f, 0xff, 0xf8, 0x00, 
	0x0f, 0xff, 0xf8, 0x00, 0x07, 0xff, 0xf8, 0x00, 0x03, 0xff, 0xf0, 0x00, 0x03, 0xff, 0xf0, 0x00, 
	0x01, 0xff, 0xe0, 0x00, 0x00, 0x7f, 0xc0, 0x00, 0x00, 0x3d, 0xc0, 0x00, 0x00, 0x30, 0xc0, 0x00, 
	0x00, 0x30, 0xc0, 0x00, 0x00, 0x20, 0xc0, 0x00, 0x00, 0x30, 0xe0, 0x00, 0x00, 0x00, 0x00, 0x00
};

int val = 0;

void setup() {
  Serial.begin(9600);
  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3c, safety precheck
    Serial.println(F("SSD1306 allocation failed"));
    while(true){} // Don't proceed, loop forever
  }
  // Clear the buffer
  display.clearDisplay();

  // Draw a single pixel in white
  display.drawPixel(10, 10, SSD1306_WHITE);

  // Show the display buffer on the screen. You MUST call display() after
  // drawing commands to make them visible on screen!
  display.display();
  delay(1000);
}

void loop() {
  val = analogRead(A0);
  display.clearDisplay();

  display.setTextSize(1);      // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE); // Draw white text
  display.setCursor(90, 0);     // Start at top-left corner
  display.print(val);

  display.setCursor(0, 0);     // Start at top-left corner
  display.print("A0 detected: ");

  display.fillRect(10, 20, val / 1023.0 * 80.0, 30, SSD1306_INVERSE);

  display.display();
  delay(1000);
}

void testdrawchar(void) {
  display.clearDisplay();

  display.setTextSize(1);      // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE); // Draw white text
  display.setCursor(0, 0);     // Start at top-left corner
  display.print(val);

  display.display();
  delay(1000);
}


void testdrawline() {
  display.clearDisplay(); // Clear display buffer

  display.drawLine(0, 0, 127, 63, SSD1306_WHITE);
  //0, 0 indicates the position of one end, 127, 63 indicates position of the other end.
  display.display(); // Update screen with each newly-drawn line
  delay(1000);
}

void testdrawrect(void) {
  display.clearDisplay();

  display.drawRect(10, 20, 50, 30, SSD1306_WHITE);
  //10, 20 are for the position, 50 is the width of rect, 30 is the height of rect.
  display.display(); // Update screen with each newly-drawn rectangle
  delay(1000);
}

void testfillrect(void) {
  display.clearDisplay();

  display.fillRect(10, 20, 50, 30, SSD1306_INVERSE);
  //same as drawrect attributes
  display.display();
  delay(1000);
}

void testdrawcircle(void) {
  display.clearDisplay();
  byte radius = 10;//local variable called radius to change the size of circle

  display.drawCircle(40, 50, radius, SSD1306_WHITE);
  //40, 50 indicates the center of the position
  display.display();
  delay(1000);
}

void testfillcircle(void) {
  display.clearDisplay();
  byte radius = 10;

  display.fillCircle(40, 50, radius, SSD1306_INVERSE);
  //same as drawCircle
  display.display();
  delay(1000);
}

void testdrawroundrect(void) {
  display.clearDisplay();

  byte width = 25; byte height = 10; byte round_val = 2;
  // round_val controls the edge sharpness, it becomes normal rect when val is 0.
  display.drawRoundRect(10, 20, width, height, round_val, SSD1306_WHITE);
  //10, 20 indicates start position
  display.display();
  delay(1000);
}

void testfillroundrect(void) {
  display.clearDisplay();
  byte width = 25; byte height = 10; byte round_val = 2;
  display.fillRoundRect(10, 20, width, height, round_val, SSD1306_INVERSE);
  //same as testdrawroundrect
  display.display();
  delay(1000);
}

void testdrawtriangle(void) {
  display.clearDisplay();

  display.drawTriangle(
  10, 10,
  50, 40,
  10, 60, SSD1306_WHITE);
  //coordinate of three points 
  
  display.display();
  delay(1000);
}

void testfilltriangle(void) {
  display.clearDisplay();

  display.fillTriangle(
  10, 10,
  50, 40,
  10, 60, SSD1306_INVERSE);
  //coordinate of three points 
  
  display.display();
  delay(1000);
}


void testdrawbitmap(void) {
  display.clearDisplay();

  display.drawBitmap(18, 20, bitmap_DINO, LOGO_WIDTH, LOGO_HEIGHT, 1);
  //18， 20 indicates the start position of the picture.
  display.display();
  delay(1000);
}