canvas打字效果 | 打字效果

运用fillText，写的打字效果。
唯一麻烦的地方是，换行问题，
我是把字符串转化为数组，数组一个单位完成，就换行，继续下一个单位。
<!doctype html>

<html>

<head>

<meta charset="utf-8">

<title>canvas</title>

<style type="text/css">

canvas { border: 1px solid black; }

#change{width:200px; line-height:30px; color:#fff; text-align:center; background:blue;}

</style>

<script type="text/javascript" charset="utf-8">

var text = "东临碣石，以观沧海。|水何澹澹，山岛竦峙。|树木丛生，百草丰茂。|秋风萧瑟，洪波涌起。|日月之行，若出其中。|星汉灿烂，若出其里。|幸甚至哉，歌以咏志。";

var arr = text.split("|");

var line = 0;

var timer = 0;

var i = 0;

var newText = "";

function Typing(id) {

    var canvas = document.getElementById(id);

    if (canvas == null) {

        return false;

    }

    scrollit();

}

function scrollit() {

    newText = arr[line].slice(0, i++) + "_";

    var context = canvas.getContext("2d");

    // 擦除文字

    context.clearRect(0, 20 + line * 30, 600, 20 + 30 * (line + 1));

    var gradient = context.createLinearGradient(0, 0, 200, 0);

    gradient.addColorStop("0", "magenta");

    gradient.addColorStop("0.5", "blue");

    gradient.addColorStop("1.0", "red");

    context.fillStyle = gradient;

    context.font = "20px Verdana";

    context.textBaseline = "hanging";

    if (i > arr[line].length) {

        newText = arr[line].slice(0, arr[line].length);

        context.fillText(newText, 30, 20 + 30 * line);

        // 换行

        i = 0;

        line++;

        if (line < arr.length) {

            clearTimeout(timer);

            scrollit();

        };

    } else {

        context.fillText(newText, 30, 20 + 30 * line);

        timer = setTimeout(scrollit, 200);

    }

}

window.onload = function() {

    Typing("canvas");

}

</script>

</head>

<body>

<canvas id="canvas" width="600" height="400"></canvas>

<img id="newImg" src="" alt="" widt="100" height="100">

<div id="demo">hh</div>

</html>