class Timeline{
  float lineY;
  float interval;
  int lastMillis;
  int y;
  int x;
  int w;
  int panLineX;
  color strokeColor = 50;  
  boolean isPlaying = false;
  
  public Timeline(int _x, int _w){
    x = _x;
    w = _w;
    y = 0;
    lineY = height/2;
    interval = 40;
    lastMillis = 0;
    panLineX = x+(w/2);
  }
  
  void update(){
    drawSpace();    
    drawPanLine();
    drawTimeLine();
    displayText();
  }
 
  void drawSpace(){
    fill(255, 20);
    noStroke();
    rectMode(CORNER);
    rect(x, y, w, height);
  }
  
  void drawPanLine(){
    stroke(strokeColor);
    for(int i=0; i<height; i++){
      if(i%10>3){
        point(panLineX, i);
      }  
    }  
  }
  
  void drawTimeLine(){
    stroke(strokeColor);
    line(x, lineY, x+w, lineY);
    if(isPlaying){
      if(millis()-lastMillis>=interval){
        lineY--;
        if(lineY<=0){
          lineY= height;
        }
        lastMillis = millis();
      }    
    }
  }
  
  void play(){
    isPlaying = true;
  }
  
  void stop(){
    isPlaying = false;
  }
  
  void displayText(){
    fill(strokeColor);
    textAlign(CENTER);
    text("L", panLineX-20, 20);
    text("R", panLineX+20, 20);
  }
  
  void setInterval(float _interval){
    interval = _interval;
  }
}