Question

所以我一直在寻找一个实际可行的签名捕获脚本，并将签名保存到MySQL，我终于找到了我想要的但是有2个问题。

我无法弄清楚为什么画布在按下清除按钮时不会清除签名。
按下保存签名按钮时，它不会将图像提交给MySQL。

这段代码很老了，我试图联系开发人员，但没有得到回复，所以我希望我能在这里得到一些帮助。

这是html：

        <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml">

    <head>
    <meta content="text/html; charset=utf-8" http-equiv="Content-Type" />
    <title>Signature Pad</title>
    <script type="text/javascript" src="jquery.min.js"></script>
    </head>
    <body>
    <center>
        <fieldset style="width: 435px">
            <br/>
            <br/>
            <div id="signaturePad" style="border: 1px solid #ccc; height: 55px; width: 400px;"></div>
            <br/>
            <button id="clearSig" type="button">Clear Signature</button>&nbsp;
            <button id="saveSig" type="button">Save Signature</button>
            <div id="imgData"></div>
            <div id="imgData"></div>
            <br/>
            <br/>
        </fieldset>
    </center>
    </body>
    </html>

剩下的php和脚本：

    $(document).ready(function () {
    /** Set Canvas Size **/
    var canvasWidth = 400;
    var canvasHeight = 75;

    /** IE SUPPORT **/
    var canvasDiv = document.getElementById('signaturePad');
    canvas = document.createElement('canvas');
    canvas.setAttribute('width', canvasWidth);
    canvas.setAttribute('height', canvasHeight);
    canvas.setAttribute('id', 'canvas');
    canvasDiv.appendChild(canvas);
    if (typeof G_vmlCanvasManager != 'undefined') {
        canvas = G_vmlCanvasManager.initElement(canvas);
    }
    context = canvas.getContext("2d");

    var clickX = new Array();
    var clickY = new Array();
    var clickDrag = new Array();
    var paint;

    /** Redraw the Canvas **/
    function redraw() {
        canvas.width = canvas.width; // Clears the canvas

        context.strokeStyle = "#000000";
        context.lineJoin = "miter";
        context.lineWidth = 2;

        for (var i = 0; i < clickX.length; i++) {
            context.beginPath();
            if (clickDrag[i] && i) {
                context.moveTo(clickX[i - 1], clickY[i - 1]);
            } else {
                context.moveTo(clickX[i] - 1, clickY[i]);
            }
            context.lineTo(clickX[i], clickY[i]);
            context.closePath();
            context.stroke();
        }
    }

    /** Save Canvas **/
    $("#saveSig").click(function saveSig() {
        var sigData = canvas.toDataURL("image/png");
        $("#imgData").html('Thank you! Your signature was saved');
        var ajax = XMLHttpRequest();
        ajax.open("POST", 'http://www.your-domain.com/folder/post-html.php');
        ajax.setRequestHeader('Content-Type', 'application/upload');
        ajax.send(sigData);
    });

    /** Clear Canvas **/
    function clearSig() {
        clickX = new Array();
        clickY = new Array();
        clickDrag = new Array();
        canvas.width = canvas.width;
        canvas.height = canvas.height;
    }

    /**Draw when moving over Canvas **/
    $('#signaturePad').mousemove(function (e) {
        if (paint) {
            addClick(e.pageX - this.offsetLeft, e.pageY - this.offsetTop, true);
            redraw();
        }
    });

    /**Stop Drawing on Mouseup **/
    $('#signaturePad').mouseup(function (e) {
        paint = false;
    });

    /** Starting a Click **/
    function addClick(x, y, dragging) {
        clickX.push(x);
        clickY.push(y);
        clickDrag.push(dragging);
    }

    $('#signaturePad').mousedown(function (e) {
        var mouseX = e.pageX - this.offsetLeft;
        var mouseY = e.pageY - this.offsetTop;

        paint = true;
        addClick(e.pageX - this.offsetLeft, e.pageY - this.offsetTop);
        redraw();
    });

});

MySQL部分：

    <?php
if (isset($GLOBALS["HTTP_RAW_POST_DATA"]))
{
$session_id = $_SERVER['REMOTE_ADDR'];
// Get the data
$imageData=$GLOBALS['HTTP_RAW_POST_DATA'];

// Remove the headers (data:,) part.
// A real application should use them according to needs such as to check image type
$filteredData=substr($imageData, strpos($imageData, ",")+1);

// Need to decode before saving since the data we received is already base64 encoded
$unencodedData=base64_decode($filteredData);

//echo "unencodedData".$unencodedData;
$imageName = "sign_" . rand(5,1000) . rand(1, 10) . rand(10000, 150000) . rand(1500, 100000000) . ".png";
//Set the absolute path to your folder (i.e. /usr/home/your-domain/your-folder/
$filepath = "htdocs/alpha/site6/signature/images/" . $imageName;

$fp = fopen("$filepath", 'wb' );
fwrite( $fp, $unencodedData);
fclose( $fp );

//Connect to a mySQL database and store the user's information so you can link to it later
$link = mysql_connect('localhost','root', 'pwd') OR DIE(mysql_error);
mysql_select_db("trial", $link);
mysql_query("INSERT INTO customer (`session`, `image_location`) VALUES ('$session_id', '$imageName')") OR DIE(mysql_error());
mysql_close($link);
}
?>

Answer 1

我只能给出部分答案，因为我无法帮助PHP部分。

我把代码放在一个jsfiddle中，并在这里进行了一些修正：
http://jsfiddle.net/AbdiasSoftware/M8pzB/

你可以看到清除按钮按我的建议工作（除了我在评论中使用ctx而不是上下文）。

我还从HTML中删除了一个双ID'ed div（imgData）。

明确的功能：

$('#clearSig').click(
    function clearSig() {
        clickX = new Array();
        clickY = new Array();
        clickDrag = new Array();
        context.clearRect(0, 0, canvas.width, canvas.height);
});

我在HTML中添加了一个调试标记，显示现在所有内容都可以发送到服务器。由于我无法测试这部分，我只能建议您从该部分开始调试。

我还为画布中生成的数据网址添加了URI编码，这是必要的。

传输MIME可以是text/plain，而您传输的是字符串。由于您使用jQuery，您可以使用内置函数进行ajax-transfer：
http://api.jquery.com/jQuery.ajax/

在PHP端，然后解码URI，像你一样去除data-url的头部，然后如果你想将它存储为二进制，则对它进行base64解码。请注意，在MySQL中，您需要将其存储为BLOB（不要与HTML5的Blob对象混淆）。

无法获取html5 Canvas签名板提交到数据库

1 个答案: