How to draw a touch straight line in HTML5 canvas

Question

I'm trying to create a drawing tool set for the iPad and so far I've done the square, but I'm not sure how I would go about coding a straight line ? Here's the code for my finished square, maybe it'll be a help. I would like to know how to code a straight line. After that, what if I wanted to draw circles as well? What in this code would I need to change?

Here's the code:

JavaScript (Square/Rectangle)

// "Draw Rectangle" Button
function rect(){
var canvas = document.getElementById('canvasSignature'), ctx = canvas.getContext('2d'), rect = {}, drag = false;

function init() {
  canvas.addEventListener("touchstart", touchHandler, false);
  canvas.addEventListener("touchmove", touchHandler, false);
  canvas.addEventListener("touchend", touchHandler, false);
}


function touchHandler(event) {
  if (event.targetTouches.length == 1) { //one finger touche
    var touch = event.targetTouches[0];

    if (event.type == "touchstart") {
      rect.startX = touch.pageX;
      rect.startY = touch.pageY;
      drag = true;
    } else if (event.type == "touchmove") {
      if (drag) {
        rect.w = touch.pageX - rect.startX;
        rect.h = touch.pageY - rect.startY ;
        draw();
      }
    } else if (event.type == "touchend" || event.type == "touchcancel") {
      drag = false;
    }
  }
}

function draw() {
  ctx.fillRect(rect.startX, rect.startY, rect.w, rect.h);


  ctx.clearRect(0, 0, canvas.width, canvas.height);



  ctx.fillStyle = "orange";
}

init();
}

Answer 1

Just substitute this:

ctx.fillRect(rect.startX, rect.startY, rect.w, rect.h);

ctx.clearRect(0, 0, canvas.width, canvas.height);

with something like this:

ctx.fillLine(rect.startX, rect.startY, rect.w, rect.h);

ctx.clearLine(0, 0, canvas.width, canvas.height);

this is of course not 100% valid code, but the concept should work and you'll get the point