Canvas - Get Mouse Coord on Click

by rasata

HTML

<input id="info" type="text" readonly>
<canvas id="game" width="500" height="500"></canvas>

CSS

canvas, input {
    margin: 10px;
    text-align: center;
}

JavaScript

var canvas;
var x, y;
var dx=4;
var dy=4;
var d = 20;
var width, height;

function init() {
    canvasE = document.getElementById('game');
    canvas= canvasE.getContext('2d');
    width = canvasE.width;
    height = canvasE.height;
    x = d+dx+1;
    y = d+dy+1;
    //canvasE.addEventListener("click", onClick, false);
    canvasE.addEventListener("onmousemove", onMouseMove, false);
    clear();
}

function drawCircle() {
 clear();
 canvas.arc(x-1,y-1,d,0,Math.PI*2,true);
 canvas.beginPath();
 canvas.fillStyle="#0000ff";
 // Draws a circle of radius 20 at the coordinates 100,100 on the canvas
 canvas.arc(x-1,y-1,d,0,Math.PI*2,true);
 canvas.closePath();
 canvas.fill(); 
}

function clear() {
    canvas.fillStyle="#ffffff";
    canvas.fillRect(0,0,width,height);
    canvas.fillStyle="#888888";
    canvas.strokeRect(0,0,width,height);
}

function onMouseMove(e){
	onClick(e);
}

function onClick(e) {
    var element = canvasE;
    var offsetX = 0, offsetY = 0

        if (element.offsetParent) {
      do {
        offsetX += element.offsetLeft;
        offsetY += element.offsetTop;
      } while ((element = element.offsetParent));
    }

    x = e.pageX - offsetX;
    y = e.pageY - offsetY;
    
    drawCircle();
    document.getElementById("info").value = "x: " + x + ", y: " + y;
}

init();