Line drawing program for Processing for Java

linedrawing1.pde

import de.looksgood.ani.*;

PGraphics topLayer, bottomLayer;

int widthandheight = 10;
int smallestwidthandheight = 5;
float numSeconds = 1.5;
int boxColor = 255;
int x, y;
boolean debugMode = false;
int stepSize = 5;
int prevX, prevY;

void setup() {
  frameRate(60);
  randomSeed(0);
  size(800, 800);
  background(0);
  surface.setTitle("Blocks game");
  Ani.init(this);
  topLayer = createGraphics(800,800);
  bottomLayer = createGraphics(800,800);
}

void draw() {
  background(0);
  
  topLayer.beginDraw();
  topLayer.line(prevX, prevY, x, y);
  topLayer.stroke(255);
  topLayer.endDraw();

  bottomLayer.beginDraw();
  bottomLayer.line(prevX, prevY, x, y);
  bottomLayer.stroke(random(255), random(255), random(255));
  bottomLayer.strokeWeight(10);
  bottomLayer.strokeCap(ROUND);
  bottomLayer.endDraw();
  
  fill(random(0,255),random(0,255),random(0,255));
  rect(x, y, widthandheight, widthandheight); 
  prevX = x;
  prevY = y;
  
  image(bottomLayer, 0, 0);
  image(topLayer, 0, 0);
}

void mousePressed() {
  if (debugMode == true) {
    debugPrint("mouseX", str(mouseX));
    debugPrint("mouseY", str(mouseY));
  }
  Ani.to(this, numSeconds, "x", mouseX);
  Ani.to(this, numSeconds, "y", mouseY);
  //Ani.to(this, numSeconds, "widthandheight", widthandheight+=stepSize);
}

void debugPrint(String variableName, String output) {
  println(variableName);
  println("---------------------");
  println(output);
}

In order to run inside Processing, please go to the "Sketch" menu item, select "Import Library..." -> "Add Library...", go to the "Libraries" pane and then, search "Ani" and press the "Install" button. That's it!