Double buffer arduino sketch

lcd.cpp

#include <Wire.h>
#include <LiquidCrystal.h>

#define LCD_WIDTH      16
#define LCD_HEIGHT     2
#define LCD_SIZE       (LCD_WIDTH * LCD_HEIGHT)


class LCDDoubleBuffer {
public:
  LCDDoubleBuffer(LiquidCrystal *lcd, const int width, const int height) {
    this->_width = width;
    this->_height = height;
    this->_size = width * height;
    this->_lcd = lcd;
    
    this->_win_x = 0;
    this->_win_y = 0;
    
    this->_buffer = new char[this->_size];
  }
  
  ~LCDDoubleBuffer() {
    delete[] this->_buffer;  
  }
  
  const int width() const { return this->_width; }
  const int height() const { return this->_height; }
  
  const int win_x() const { return this->_win_x; }
  const int win_y() const { return this->_win_y; }
  
  char* buffer() { return _buffer; }
  
  void clear() {
    memset(this->_buffer, ' ', sizeof(char) * this->_size);
  }
  
  void render() {
    int buf_y = this->_win_y;
    for (int y = 0; y < LCD_HEIGHT; y ++) {
      
      int buf_x = this->_win_x;
      
      for (int x = 0; x < LCD_WIDTH; x ++) {
        
        this->_lcd->setCursor(x, y);
        
        if (buf_y >= 0 && buf_y < this->_height &&
            buf_x >= 0 && buf_x < this->_width) {
          int ofs = buf_x + (buf_y * this->_width);
          this->_lcd->print(this->_buffer[ofs]);
        } else {
          this->_lcd->print(" ");
        }
        
        buf_x ++;
      }
      
      buf_y ++;
    }
    
  }
  
  void moveTo(const int x, const int y) {
    this->_win_x = x;
    this->_win_y = y;
  }
  
  void moveBy(const int x, const int y) {
    this->_win_x += x;
    this->_win_y += y;
  }
  
  void print(const int x, const int y, const char *s) {
    char *o = this->_buffer + (x + (y * this->_width));
    memcpy(o, s, strlen(s));
  }
  
private:
  int _width, _height, _size;
  char *_buffer;
  LiquidCrystal *_lcd;
  
  int _win_x, _win_y;
};

LiquidCrystal lcd( 8, 9, 4, 5, 6, 7 );
LCDDoubleBuffer dbuf(&lcd, 32, 32);

void setup()
{
  Serial.begin(9600);
  randomSeed(analogRead(0));
  lcd.begin(16, 2);
  dbuf.clear();  
  dbuf.print(0, 0, "Hello, world!");
}

float degs = 0.0f;

void loop()
{
  float a = -3 + (cos(degs) * 5);
  int x = (int)a;

  dbuf.render();
  dbuf.moveTo(x, 0);
  delay(50);
  
  degs += 0.1f;

  if (degs > 360.0f) {
    degs = 0.0f;
  }  
}