​

function setup() {

  createCanvas(400, 400);

  myCanvas = createGraphics(width, height);

}

​

function draw() {

  background(220);

  ellipse(random(width), random(height), 50);

  if (mouseIsPressed)

    {

        myCanvas.ellipse(mouseX, mouseY, 20);

    }

  image(myCanvas, 0, 0);

}