Hi, I worked for few days to make this possible: press the mouse to draw a freehand line, when mouseReleased, the freehand line creep forward like a worm. I wrote part of the code as follows, but now I cannot go any more front.

1. ArrayList mouseMove;
   PFont font=createFont("TrueFrutigerLight",24,true);
2. void setup() {
     size(600,400);
     smooth();
     mouseMove=new ArrayList();
   }
3. void draw() {
     background(255);
     for(int i=0;i<mouseMove.size();i++) {
       DrawLine myLine=(DrawLine)mouseMove.get(i);
       myLine.dLine();
     }
     if (mousePressed == true) {
       mouseMove.add(new DrawLine(mouseX,mouseY,pmouseX,pmouseY));
     }
     fill(0);
     textFont(font);
     textAlign(CENTER);
     text(mouseMove.size(),width/2,30);
   }
4. /*
   void mouseReleased(){
    for(int j=mouseMove.size()-1;j>0;j--){
    mouseMove.remove(j);
    }
    }*/
5. class DrawLine {
     float x1;
     float y1;
     float x2;
     float y2;
6.   DrawLine(float a,float b,float c,float d) {
       x1=a;
       y1=b;
       x2=c;
       y2=d;
     }
7.   void dLine() {
       stroke(150);
       strokeWeight(2);
       line(x1,y1,x2,y2);
     }
   }
   

how can I get mouse trace position coordinate values from ArrayList? Or you will have better ideas to achieve that.