#include  <Wire.h>        // Only needed for Arduino 1.6.5 and earlier
  #include  <SSD1306Wire.h> // legacy include: `#include "SSD1306.h"

  // Display Instance
  SSD1306Wire display(0x3c, 21, 22);

  void oled_init() {
    display.init();
    display.flipScreenVertically();
    display.setFont(ArialMT_Plain_10);
    display.clear();
    display.display();
  }

  void drawTextFlowDemo(String Text) {
    display.setFont(ArialMT_Plain_10);
    display.setTextAlignment(TEXT_ALIGN_LEFT);
    display.drawStringMaxWidth(0, 0, 128, Text);
  }
  
  void drawTextAlignmentDemo() {
    // Text alignment demo
    display.setFont(ArialMT_Plain_10);
  
    // The coordinates define the left starting point of the text
    display.setTextAlignment(TEXT_ALIGN_LEFT);
    display.drawString(0, 10, "Left aligned (0,10)");
  
    // The coordinates define the center of the text
    display.setTextAlignment(TEXT_ALIGN_CENTER);
    display.drawString(64, 22, "Center aligned (64,22)");
  
    // The coordinates define the right end of the text
    display.setTextAlignment(TEXT_ALIGN_RIGHT);
    display.drawString(128, 33, "Right aligned (128,33)");
  }
  
  void drawRectDemo() {
    // Draw a pixel at given position
    for (int i = 0; i < 10; i++) {
      display.setPixel(i, i);
      display.setPixel(10 - i, i);
    }
      display.drawRect(12, 12, 20, 20);
  
      // Fill the rectangle
      display.fillRect(14, 14, 17, 17);
  
      // Draw a line horizontally
      display.drawHorizontalLine(0, 40, 20);
  
      // Draw a line horizontally
      display.drawVerticalLine(40, 0, 20);
  }
  
  void drawCircleDemo() {
    for (int i=1; i < 8; i++) {
      display.setColor(WHITE);
      display.drawCircle(32, 32, i*3);
      if (i % 2 == 0) {
        display.setColor(BLACK);
      }
      display.fillCircle(96, 32, 32 - i* 3);
    }
  }
  
  void drawProgressBarDemo(int Value) {
    int progress = Value;
    // draw the progress bar
    display.drawProgressBar(0, 50, 120, 10, progress);
  
    // draw the percentage as String
    display.setTextAlignment(TEXT_ALIGN_CENTER);
    display.drawString(64, 35, String(progress) + "%");
  }
  
  void oled_clear() {
    display.clear();
  }

  void oled_show() {
    display.display();
  }