Question

I am developing HTML5 based paint application using canvas, and now I want to do history of all canvas changes. I mean a history of user actions.

How can I do this?

Answer 1

Saving the data urls into an Array: http://jsfiddle.net/eGjak/54/.

var cv  = $('#cv').get(0);
var ctx = cv.getContext('2d');

var history = [];

$("#b1").click(function() {
    history.push(cv.toDataURL());

    ctx.beginPath();

    ctx.arc(Math.random() * 200 + 100,
            Math.random() * 200 + 100,
            Math.random() * 200,
            0,
            2 * Math.PI);

    ctx.stroke();
});

$("#b2").click(function() {
    ctx.beginPath();

    var img = new Image;

    img.onload = function() {
        ctx.clearRect(0, 0, 400, 400);
        ctx.drawImage(img, 0, 0);
    };

    img.src = history.pop();
});