HTml js 生成图片（转） 

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<div>
    <textarea id="txt" style="width:450px;height:400px;">如果您的长微博字数超过了140个字的限制，在这里输入微博内容，点击右方的“生成图片”，鼠标右击右边“文字”，“图片另存为...”，保存图片后，就可以直接发到微博里了，赶紧试试吧！ </textarea>
</div>
<div style="width:200px;height:100px;float:left;clear:right;">
    <table>
        <tbody>
        <tr>
            <td>
                <label>字体大小:</label><input size="4" id="fontSize" value="15" />px
            </td>
        </tr>
        <tr>
            <td>
                <label>字体精细:</label><select id="fontWeight"> <option value="normal">正常</option>
                <option value="bold">粗</option>
            </select>
            </td>
        </tr>
        <tr>
            <td>
                <label>每行显示:</label><input size="4" id="len" value="40" />个字
            </td>
        </tr>
        <tr>
            <td>
                <canvas id="text" width="100" height="100"></canvas>
                <p>
                    Red： <input type="range" id="red" min="0" max="255" value="0" onchange="changeColor();" />
                </p>
                <p>
                    Green：<input type="range" id="green" min="0" max="255" value="0" onchange="changeColor();" />
                </p>
                <p>
                    Blue： <input type="range" id="blue" min="0" max="255" value="0" onchange="changeColor();" />
                </p>
                目前的颜色:<span id="showcolor"></span>
            </td>
        </tr>
        <tr>
            <td>
                <button onclick="textToImg();;">生成图片</button>
            </td>
        </tr>
        </tbody>
    </table>
</div>
<canvas id="canvas" style="display:block;"></canvas>
<div>
    <img id="img" style="border:1px solid;" />
</div>
<script type="text/javascript">
    function $(id) {
        return document.getElementById(id);
    }
    function textToImg() {
        var len = $('len').value || 30;
        var i = 0;
        var fontSize = $('fontSize').value || 15;
        var fontWeight = $('fontWeight').value || 'normal';
        var txt = $("txt").value;
        var canvas = $('canvas');
        if (txt == '') {
            alert('请输入文字！');
            $("txt").focus();
        }
        if (len > txt.length) {
            len = txt.length;
        }
        canvas.width = fontSize * len;
        canvas.height = fontSize * (3 / 2)
                * (Math.ceil(txt.length / len) + txt.split('\n').length - 1);
        var context = canvas.getContext('2d');
        context.clearRect(0, 0, canvas.width, canvas.height);
        context.fillStyle = $("showcolor").innerHTML;
        context.font = fontWeight + ' ' + fontSize + 'px sans-serif';
        context.textBaseline = 'top';
        canvas.style.display = 'none';
        console.log(txt.length);
        function fillTxt(text) {
            while (text.length > len) {
                var txtLine = text.substring(0, len);
                text = text.substring(len);
                context.fillText(txtLine, 0, fontSize * (3 / 2) * i++,
                        canvas.width);
            }
            context.fillText(text, 0, fontSize * (3 / 2) * i, canvas.width);
        }
        var txtArray = txt.split('\n');
        for ( var j = 0; j < txtArray.length; j++) {
            fillTxt(txtArray[j]);
            context.fillText('\n', 0, fontSize * (3 / 2) * i++, canvas.width); }
            var imageData = context.getImageData(0, 0, canvas.width, canvas.height);
        var img = $("img"); img.src = canvas.toDataURL("image/png"); }
        function changeColor() {
            var c = $("text");
            var ctx = c.getContext("2d");
            var red = $("red"); var green = $("green");
            var blue = $("blue");
            ctx.fillStyle = "rgb(" + red.value + "," + green.value + "," + blue.value + ")";
            $("showcolor").innerHTML = ctx.fillStyle; ctx.fillRect(0, 0, 100, 100); }
    //$('canvas').getContext('2d').fillStyle=$("showcolor").innerHTML; }
</script>
<script>
    changeColor();
</script>
</body>
</html>

转：http://www.cnblogs.com/zendu/p/4987985.html

posted @ 2017-06-10 14:06  Jm_jing  阅读(498)  评论(0)    收藏  举报