<!doctype html>
<html lang="ru">
<head>
<meta charset="utf-8" />
<title>
Example
</title>
<script src="http://yandex.st/jquery/2.0.3/jquery.min.js"></script>
<script>
$(document).ready(function () {
var canvas = document.getElementById('area');
var ctx = canvas.getContext("2d");
ctx.fillStyle = "rgba(255,255,255, 0.5)";
ctx.fillRect(0, 0, $("#area").width(), $("#area").height());
console.log($("#area").width());
$(canvas).bind('mousedown', function (e) {
eraser(e, ctx, 40);
$(canvas).bind('mousemove', function (e) {
eraser(e, ctx, 40);
});
});
$(canvas).bind('mouseup', function () {
$(canvas).unbind('mousemove');
});
});
function eraser(e, context, radius) {
var mouseX, mouseY;
//console.log(e.pageX);
mouseX = e.pageX;
mouseY = e.pageY;
context.clearRect(mouseX, mouseY, radius, radius);
}
</script>
</head>
<body>
<div id="wrapper">
<p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip
ex ea commodo consequat. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril
delenit augue duis dolore te feugait nulla facilisi.</p>
</div>
<canvas id="area" style="width: 100%;height: 100%;position:fixed;top:0;left:0;"></canvas>
</body>
</html>
var canvas_down = false;
var canvas = document.getElementById('area');
var ctx = canvas.getContext("2d");
//resize to be sure that pixels == width
window.addEventListener('resize', resizeCanvas, false);
function resizeCanvas() {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
}
resizeCanvas();
ctx.fillStyle = "rgba(255,255,255, 0.9)";
ctx.fillRect(0, 0, $("#area").width(),$("#area").height());
canvas.addEventListener('mousedown', function (e) {
canvas_down = true;
}, false);
canvas.addEventListener('mouseup', function (e) {
canvas_down = false;
}, false);
canvas.addEventListener('mousemove', function (e) {
if (canvas_down)
eraser(e, 25);
}, false);
function eraser(e, radius) {
ctx.beginPath();
var x2 = e.pageX - (radius/2);
var y2 = e.pageY- (radius/2);
ctx.clearRect(x2, y2, radius, radius);
ctx.closePath();
}
Простой