Javascript 如何使用FPDF Llibrary从signaturepad到PDF生成捕获的签名

我想使用FPDF库从我的PHP页面生成一个签名到pdf。到目前为止，我的签名工作正常，并且我能够将图像签名从画布保存到输入字段SIGIInput1。到目前为止，我所做的工作如下面的代码集所示

<form method="POST" id="delivery" name="delivery" action="<?php echo $_SERVER['PHP_SELF']; ?>"  accept-charset="utf-8">
    <div id="collected">
     <label for="name" style="left: 10px;text-align:left;" >Collected By :
     </label>
        <input type="text" name="collected_by" class="input-field extralarge-input" style="float:left; text-transform:uppercase;" id="collected_by" required>
        <div id="signature-pad" class="signature-pad" style="float: right;">
           <div class="signature-pad--body">
                <canvas ></canvas>
                <input id="siginput1" type="display" name="siginput1" value="" />
           </div><!--signature-pad--body-->
        <div class="signature-pad--footer">
    <div class="description">Sign above</div>
   <div class="signature-pad--actions">
<div>
 <button type="button" class="button clear" data-action="clear">Clear</button>
  <button type="button" class="button" data-action="undo">Undo</button> </div>
    <div>
        <button type="button" class="button save" data-action="save-png">Save </button>
    </div>
   </div><!--signature-pad--actions-->
  </div><!--signature-pad--footer-->
 </div><!--signature-pad-->
   <script src="jquery/signature_pad.js"></script>
   <script src="jquery/app.js"></script>    

最重要的是，我声明我的变量如下：

 $signature1==$_POST['siginput1'];
 if ( $_POST['siginput1'] ) 
     {
     file_put_contents("myfile.png", file_get_contents($signature1));
     }

最后，这是我在PDF中调用它的部分，但没有显示任何内容：

require('pdf/fpdf.php');    

if(!isset($_SESSION))
{
  session_start();
}
$pdf = new FPDF('P','cm',array(11,18));
$pdf->AddPage();

//header
$pdf->Image('images/bwlogo.png',1,.85,-2500); 
$pdf->SetFont('Arial','',10);
$pdf->SetTextColor(0,0,0);
$pdf->Ln(2);
$pdf->Cell(9.5,0,'DELIVERY NOTE',0,0,'C');
$pdf->Ln(0.5);
$pdf->SetFont('Arial','',7);
$deldate=date('d / m / Y');

$pdf->ln(1);
$pdf->Cell(4.5,.5,$signature1,0,1,'L');
$pdf->Output("F","DeliveryNotes/test.pdf");

---

我能得到任何帮助吗？？？？？

require('pdf/fpdf.php');    

if(!isset($_SESSION))
{
  session_start();
}
$pdf = new FPDF('P','cm',array(11,18));
$pdf->AddPage();

//header
$pdf->Image('images/bwlogo.png',1,.85,-2500); 
$pdf->SetFont('Arial','',10);
$pdf->SetTextColor(0,0,0);
$pdf->Ln(2);
$pdf->Cell(9.5,0,'DELIVERY NOTE',0,0,'C');
$pdf->Ln(0.5);
$pdf->SetFont('Arial','',7);
$deldate=date('d / m / Y');

$pdf->ln(1);
$pdf->Cell(4.5,.5,$signature1,0,1,'L');
$pdf->Output("F","DeliveryNotes/test.pdf");