<canvas id="mycanvas" width="1280" height="512"></canvas>

    内容：<input type="text" id="mytxt1" value="HTML5TRICKS" />

    文字背景图：<select id="dbg">

        <option value="bg4.png">bg4.png</option>

        <option value="bg5.png">bg5.png</option>

    </select>

    <input type="button" id="send" value="生成签名档" />

    <a href="#" id="imgdownload">下载图片</a>

    <script>

        var mycanvas = document.getElementById("mycanvas");

        var mytxt1 = document.getElementById("mytxt1");

        var dbg = document.getElementById("dbg");

        var imgdownload = document.getElementById("imgdownload");

        var ctx = mycanvas.getContext("2d");

        var bg = new Image();

        var bg2 = new Image();

        bg.src = 'imgs/bg3.png';

        bg2.src = 'imgs/bg4.png';

        bg2.onload = ShowImg;

        function ShowImg() {

            bg2.src = 'imgs/' + dbg.value;

            ctx.drawImage(bg, 0, 0, mycanvas.width, mycanvas.height);

            ctx.save();

            var fpadd = 200; //规定内间距

            var fsz = Math.ceil((mycanvas.width - fpadd * 2) / mytxt1.value.length); //根据字数计算字体大小

            ctx.font = fsz + "px hychf";

            var tw = ctx.measureText(mytxt1.value).width; //文字真实宽度

            var ftop = (mycanvas.height - fsz) / 2 - 30; //根据字体大小计算文字top

            var fleft = (mycanvas.width - tw) / 2 + 16; //根据字体大小计算文字left

            ctx.textBaseline = "top"; //设置绘制文本时的文本基线。

            var woodfill = ctx.createPattern(bg2, "repeat"); //设置图片为笔刷

            ctx.fillStyle = woodfill;

            ctx.shadowBlur = 10; //阴影程度

            ctx.shadowOffsetX = 20;

            ctx.shadowOffsetY = 20;

            ctx.shadowColor = "rgba(0,0,0,1)";

            ctx.fillText(mytxt1.value, fleft, ftop);

            ctx.lineWidth = 1;

            ctx.strokeStyle = "rgba(255,255,255,0.4)";

            ctx.strokeText(mytxt1.value, fleft, ftop);

            ctx.restore();

        }

        document.getElementById("send").onclick = ShowImg;

        imgdownload.onclick = function () {

            if (!mytxt1.value) { alert('请输入内容'); return false; }

            this.href = mycanvas.toDataURL();

            this.target = "_blank";

            this.download = mytxt1.value + ".png";

        }

    </script>

 body

        {

            background-color: #ddd;

            -webkit-user-select: none;

            font-family: hychf, "黑体";

            margin:;

        }

        @font-face

        {

            font-family: hychf;

            src: url('fonts/hychf.ttf');

        }

        canvas

        {

            border: 1px solid #777;

            display: block;

            margin: auto;

        }

        #imgdownload

        {

            width: 100px;

            height: 30px;

            display: block;

            text-decoration: none;

            text-align: center;

            line-height: 30px;

            border: 1px solid #000;

            border-radius: 6px;

        }