SignatureCapture Module

The SignatureCapture Module creates a rectangular box that the user can draw within using the device’s stylus to record handwritten data. Common usages for this tag include the capture of client/customer signatures and the input of handwritten text/notations.

• Syntax
• Methods
• Parameters
• Events
• Remarks
• Requirements
• HTML/JavaScript Examples

Syntax

Methods

Items listed in this section indicate methods or, in some cases, indicate parameters which will be retrieved.

Parameters

Items listed in this section indicate parameters, or attributes which can be set.

Events

Values are returned to the caller in RhoElements via Events. Most modules contain events and those returned from this module are given below along with the event parameters. Events can cause a navigation to a new URL or a JavaScript function on the page to be invoked. Each event will in most cases have a number of parameters associated with it which will either be strings or JavaScript arrays. Event parameters can be accessed either directly or via JSON objects.

signatureSaveEvent

The Signature Save Event is called when the captured signature has been successfully transfered to the specified destination. When ‘Capture’ is called with the HTTP protocol, the destination server message is returned. When ‘Capture’ is called with the FTP protocol, either ‘OK: File Sent’, ‘OK: File Received’ or ‘ERROR’ is returned. This tag should be used in conjunction with the Capture method.

signatureCaptureEvent

Specifying a SignatureCaptureEvent will cause the signature to be returned as a Data URI object when the capture() method is invoked. A Data URI is a base 64 encoding of the signature and can be used to easily embed the signature on the page, store the image in a database or transfer the image to a server.

vectorEvent

Signature data is formatted into a series of vectors and returned to the application via this callback function. The received data may not represent the entire signature as the vectors will be sent in batches if the signature is large. A single vector (array entry) contains an X, Y coordinate and the beginning / end of the signature is defined by (0xFFFF, 0xFFFF). This event is independent of the SignatureSaveEvent or capture method, when specified the event will be called whenever a ‘pen up’ occurs in the signature box.

Remarks

Scrolling

The signature capture area is not compatible with scrolling the browser window.

Parameters which clear the Signature

The signature capture area is designed to be set up prior to capturing the signature, as such the following parameters will clear any current signature: “Width”, “Height”, “PenColor”, “BGColor”.

Common Issues

The ‘Visibility:Visible’ parameter must be set in order to display the signature capture area.

Setting up a Transfer to a remote HTTP or FTP location

Signature Capture is designed to be configured before any transfer is made to a remote location. If the ‘Destination’ paramter is specified as either HTTP or an FTP location the ‘destination’ / ‘username’ / ‘password’ parameters can not be guaranteed to stay the same after capture() has been called, therefore configure your destination for each capture, as in the above examples.

Format of the Destination URL

The protocol, port number, username (optional) and password (optional) are all derived from the URL string and should be specified in the following manner: [protocol]://[username]:[password@]Server[:Port]FileNameAndPath. FTP Example: ftp://admin:root@192.168.1.1:2500/Folder/Sig.bmp. HTTP Example: http://admin:root@192.168.1.1:8080/Folder/Upload.aspx. File Example: file://\path\Sig.bmp. Remember to also wrap your URL with url(‘’) when being used as part of a meta tag, as shown in the examples above.

Supported Output File Formats

All devices support “.bmp” as the default file format for the saved signature. ET1 also supports “.png” format.

Requirements

HTML/JavaScript Examples

The following META Tag example sets up a yellow rectangular area that has a border with a pen color of burgundy. When the Capture method is invoked via JavaScript the signature will be transferred to a server via HTTP and an alert will inform the user whether or not the transfer succeeded.

<META HTTP-Equiv="SignatureCapture" Content="width:200">
<META HTTP-Equiv="SignatureCapture" Content="height:100">
<META HTTP-Equiv="SignatureCapture" Content="left:20">
<META HTTP-Equiv="SignatureCapture" Content="top:60">
<META HTTP-Equiv="SignatureCapture" Content="penwidth:2">
<META HTTP-Equiv="SignatureCapture" Content="name:Sig">
<META HTTP-Equiv="SignatureCapture" Content="pencolor:#AA0000">
<META HTTP-Equiv="SignatureCapture" Content="bgcolor:#FFFF00">
<META HTTP-Equiv="SignatureCapture" Content="Visibility:Visible">
<META HTTP-Equiv="SignatureCapture" Content="Destination:url('HTTP://192.168.1.1:80/RhoElementsLog/upload.aspx')">
<META HTTP-Equiv="SignatureCapture" Content="SignatureSaveEvent:url('javascript:alert('%s');')">

The following JavaScript will show a Signature Capture box with default settings when the JavaScript function onDisplay is called:

<script>
   function onDisplay()
   {
      signatureCapture.visibility  = 'visible';
   }
</script>

The following example shows signature being captured as a Data URI and displayed on the page

<META HTTP-Equiv="SignatureCapture" Content="Height:200">
<META HTTP-Equiv="SignatureCapture" Content="BGColor:#FFFF00">
<META HTTP-Equiv="SignatureCapture" Content="Width:400">
<META HTTP-Equiv="SignatureCapture" Content="Visibility:Visible">
<META HTTP-Equiv="SignatureCapture" Content="PenColor:#FF00FF">
<META HTTP-Equiv="SignatureCapture" Content="PenWidth:4">
<META HTTP-Equiv="SignatureCapture" Content="signatureCaptureEvent:url('JavaScript:onSignatureCapture(%json)');">

<script type="text/javascript">
function onSignatureCapture(jsonObject)
{
    signatureImage.src = jsonObject.imageData;
}
</script>

</HEAD>
  <BODY>
  <BR><BR><BR><BR>
  <img src="" id="signatureImage"<>/img>
</BODY>  

The following example shows signature vectors being displayed in an HTML table

<META HTTP-Equiv="SignatureCapture" Content="Height:200">
<META HTTP-Equiv="SignatureCapture" Content="BGColor:#FFFF00">
<META HTTP-Equiv="SignatureCapture" Content="Width:400">
<META HTTP-Equiv="SignatureCapture" Content="Visibility:Visible">
<META HTTP-Equiv="SignatureCapture" Content="PenColor:#FF00FF">
<META HTTP-Equiv="SignatureCapture" Content="PenWidth:4">
<META HTTP-Equiv="SignatureCapture" Content="VectorEvent:url('JavaScript:onVectors(%s);')">

<script type="text/javascript">
function onVectors(data)
{
  var VectorAsHTML = "<TABLE><TR><TH>X</TH><TH>Y</TH><TH>X</TH><TH>Y</TH><TH>X</TH><TH>Y</TH></TR>";
  for (var i=0; i<data.length; i = i + 6)
  {
    VectorAsHTML = VectorAsHTML + "<TR>"
    VectorAsHTML = VectorAsHTML + "<TD>" + data[i] + "</TD><TD>" + data[i+1] + "</TD>";
    VectorAsHTML = VectorAsHTML + "<TD>" + data[i+2] + "</TD><TD>" + data[i+3] + "</TD>";
    VectorAsHTML = VectorAsHTML + "<TD>" + data[i+4] + "</TD><TD>" + data[i+5] + "</TD>";
    VectorAsHTML = VectorAsHTML + "</TR>"
  }
  VectorAsHTML + "</TABLE>"
  vectorOut.innerHTML = VectorAsHTML;
}
</script>

</HEAD>
  <BODY>
  <BR><BR><BR><BR>
  <BR><BR><BR><BR><BR>
  <DIV id="vectorOut">Vectors Will Appear Here:</div>
  </BODY>