Canvas Crop area

by devangkantharia

HTML

<canvas id="myCanvas" width="578" height="200"></canvas>

CSS

body {
    margin: 0px;
    padding: 0px;
}

JavaScript

function writeMessage(canvas, message) {
    var context = canvas.getContext('2d');
    context.clearRect(0, 0, canvas.width, canvas.height);
    context.font = '18pt Calibri';
    context.fillStyle = 'black';
    context.fillText(message, 10, 25);
}

function getMousePos(canvas, evt) {
    var rect = canvas.getBoundingClientRect();
    return {
        x: evt.clientX - rect.left,
        y: evt.clientY - rect.top
    };
}
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');

canvas.addEventListener('mousemove', function (evt) {
    var mousePos = getMousePos(canvas, evt);
    var message = 'Mouse position: ' + mousePos.x + ',' + mousePos.y;
    writeMessage(canvas, message);
}, false);