Implementing Real-Time Mobile Signature Capture with jSignature and PHP

Online signature capture is often required in approval workflows; this article demonstrates how to achieve real‑time mobile signature using the jSignature library together with jQuery and a PHP backend.

First, download the jSignature library ( https://www.phpclasses.org/file/42277.html) and the accompanying Chinese documentation ( https://www.php.cn/js-tutorial-489429.html), as well as jQuery ( https://jquery.com/download/), preferably version jquery-3.2.1.js.

Front‑end HTML :

<style>
    .main_sign{padding:10px 10px;color:black;background-color:darkgrey;}
    .main_sign .sign_btn{padding:5px 10px;}
    #signature{border:2px dotted black;}
</style>
<div class="main_sign" id="writers">
    <div id='signature' style='background-color: #d2d2e8;'></div>
    <button type="button" class="sign_btn" id="reset" style="margin: 10px 5px;">重写</button>
    <button type="button" class="sign_btn" id="yes" style="margin: 10px 5px;">确认</button>
    <div id="show_img" style="display: none;"><img src="" id="images"></div>
</div>

1. Instantiate jSignature :

$(document).ready(function(){
    var arguments = {
        width: '100%',
        height: '200px',
    };
    $("#signature").jSignature(arguments);
});

2. Reset signature :

$("#reset").click(function(){
    $("#signature").jSignature("reset"); // clear canvas
    $("#images").attr('src','');
});

3. Submit signature (TP5.1 + AJAX) :

// Convert canvas to image and send to backend
$("#yes").click(function(){
    var $signature = $("#signature");
    var datapair = $signature.jSignature("getData", "image");
    $("#images").attr('src','data:' + datapair[0] + "," + datapair[1]);
    var src_data = $("#images").attr('src'); // base64 data
    $.ajax({
        url:"{:url('getSignInfo')}",
        data:{src_data:src_data},
        type:"post",
        dataType:"json",
        success:function(data){
            window.location.href = data.dump_url;
        },
        error:function(){
            console.log("错误");
        }
    });
});

4. Backend data reception (getSignInfo.php) :

$data = Request::param();
$src = $this->base64ContentToImage($data['src_data'],$path);

The variable $src holds the saved image path; $path is the directory for storing signature images.

5. Convert base64 to image (base64ContentToImage method) :

public function base64ContentToImage($base64_image_content,$path){
    $dir = "./".$path;
    if(!file_exists($dir)){
        mkdir(iconv("GBK", "UTF-8", $dir),0777,true);
    }
    if(preg_match('/^(data:\s*image\/(\w+);base64,)/',$base64_image_content,$result)){
        $type = $result[2];
        $new_file = $path."/".date('Ymd',time())."/";
        if(!file_exists($new_file)){
            mkdir($new_file,0700);
        }
        $new_file = $new_file.time().".{$type}";
        if(file_put_contents($new_file, base64_decode(str_replace($result[1], '', $base64_image_content)))){
            return '/'.$new_file;
        }else{
            return false;
        }
    }else{
        return false;
    }
}

Following these steps enables a fully functional mobile signature capture component that records the signature as a base64 image, saves it on the server, and provides a downloadable link.