let b2;

let thickness = 1;

let colorPicker;

​

function setup() {

  createCanvas(700, 700);

  background(255);

  b1 = createButton("+");

  b2 = createButton("-");

  colorPicker = createColorPicker();

}

​

function draw() {

  b1.mousePressed(addThick);

  b2.mousePressed(removeThick);

  if(mouseIsPressed) {

    strokeWeight(thickness);

    stroke(colorPicker.value());

    line(pmouseX, pmouseY, mouseX, mouseY);

  }

}

​

function addThick() {

  thickness += 2;

}

​

function removeThick() {

  thickness -= 2;

}