Parsing a currency value in a LiveCycle Designer form

If we have a string value like "$1,234.56" that we want to convert into a JavaScript number value we have a several options
.


We could clean the string up, removing the "$" and "," characters and using the parseFloat function.
 


We could call the FormCalc Parse function and an example of calling FormCalc from JavaScript is on John Brinkman's blog.
 


Or we could assign the string to the formattedValue of a hidden DecimalField and then use the rawValue.  This has the same advantages of the FormCalc parse function, with all it's locale processing, without the overhead of calling FormCalc from JavaScript.
 


All we have to do is set the display pattern of the hidden decimal field to suit, in the example that is;

    num{$zzz,zzz,zz9.88}|num{$zzzzzzzz9.88}

So our parseCurrency code now looks like;

function parseCurrency(string)

{
    var result = 0;

    if (string !== null && string !== undefined)

    {
        HiddenDecimalField.rawValue = null;

        HiddenDecimalField.formattedValue = string;

        if (!HiddenDecimalField.isNull)

        {

            result = HiddenDecimalField.rawValue;
        }
    }
    return result;

}

We have set the rawValue to null before assigning the formattedValue because the rawValue will remain unchanged if the value is not valid.
 


One got cha with using DecimalFields is the JavaScript type returned by the rawValue is normally a number but if you clear the "Limit Trailing Digits" checkbox you get a string rawValue,

In this case change;
 


result = HiddenDecimalField.rawValue;
 


to



result = parseFloat(HiddenDecimalField.rawValue);
 


You can also use this approach to parse a date with a hidden DateTime field.

Download sample form parseCurrency.

Displaying the Acrobat progress bar in a LiveCycle Designer (XFA) Form

NOTE: As of Reader version 21.001.20135 (Feb 2021) it seems you must begin the Thermometer before you can set the value.

 

When Reader has a lengthy operation to complete it displays a progress bar in the bottom right hand corner, for example;

This is available to a Designer form via the Thermometer object, for example;
 


function showProgress(t)

{
    for (var ii = 0; ii < t.duration; ii++)
    {
        for (var i = 0; i < 500000; i++) {}

        t.value += 1;
        t.text = "Step " + ii;
        if (t.cancelled)
        {
            return false;
        }
    }
    return true;

}


var t = app.thermometer;

t.duration = 10;

t.begin();


t.value = 0;

t.text = "";

var completed = showProgress(t);

if (completed)

{
    app.alert("completed");

}

else

{
    app.alert("cancelled");

} 


Download the sample form, Thermometer.pdf.

Using the Doc.scroll method in a LiveCycle Designer Form

It is common to use the xfa.host.setFocus method to position the user on a particular field in the form. Say they have just clicked the submit button and you have detected that they have left a mandatory field empty.  You give them an error message and use xfa.host.setFocus to position them on the field.
 

The problem with this approach is that setFocus always tries to position the field in the middle of the screen.  This may then mean that the question at the top of the screen, were the eye is naturally drawn to, may not be related the message we have just shown the user.
 


We may also want to move to a non-interactive object on the form, maybe a text object that forms a section heading, or some help text.
 


To achieve this we can use the Doc.scroll method, but this means we need to calculate the y coordinate of the object.  The code I have used to perform the calculation comes from John Brinkman's blog, Layout Methods to Find Page Positions.  All we then need to do is rotate the coordinate (so the point 0,0 is at the bottom left corner of the page)
.


This method is written in JavaScript but is dependent on the FormCalc function UnitValue. To use this code in your forms you need to copy the first subform in the sample called FormCalc (see John's blog Calling FormCalc Functions from JavaScript for more details in this technique) and the script object XFAUtil. 
  


The scrollTo function definition is;



/** Scrolls the specified control to the top of the current view and optional sets focus the the specified control.
 
 * @param {form object} target   (required) -- the control to place at the top of the current view.
 
 * @param {form object} setFocus (optional) -- the control that receives focus.
 
 */

function scrollTo(target, setFocus)
 


To see this in action download the ScrollTo.pdf sample and select a form object from the drop down and click the "ScrollTo" button or "Set Focus" to compare the two methods.



I'm not sure how widely known it is, but the Adobe Reader keyboard short-cut for returning to the previous position in the form is Alt+Left Arrow (or Command + Left Arrow on a Mac).

Reading image properties in an Adobe LiveCycle Designer Form

A LiveCycle Designer form allows a user to insert a picture using an ImageField.  However, there is nothing built-in to allow access the properties of an image.  This set of script fragments makes the Exif, GPS and XMP properties of a JPEG image available.

You can also use these code fragments to determine if the image is a JPEG, GIF, PNG or TIFF.

If you just want to check the size of an image then you can use the rawValue property but as the value is base 64 encoded you will need to allow for an overhead of 33%, so ImageField1.rawValue.length * 3 / 4 will give a rough image size in bytes.

LiveCycle Designer forms allow for JPG, GIF, TIF, and PNG formats.  An ImageField allows the user to select one of these images but only if the file extension matches one of those four.  If the file extension is JPEG, JPE, or TIFF then the image will not show up in the "Select Image File" dialog.  If this is a problem for your users then you can use the importDataObject, something like;

if (event.target.importDataObject("name")) // user did not cancel the "select a data file to import" dialog
{
 var attachmentObject = event.target.getDataObject("name");
 var filetype = attachmentObject.path.substring(attachmentObject.path.lastIndexOf(".") + 1);
 if (filetype === "jpg")
 {
  var imageStream = event.target.getDataObjectContents("name");
  var imageStreamEncoded = Net.streamEncode(imageStream, "base64");
  ImageField1.rawValue = util.stringFromStream(imageStreamEncoded);
 }
}

Back to this sample, to find the date a picture was taken we can now use;

var stream = ByteStream.newByteStream(Base64.decode(ImageField1.rawValue));
var image = JPEG.newJPEG(stream);
if (image.isJPEG)
{
 app.alert(image.getDateTime());
}
else
{
 image = GIF.newGIF(stream);
 if (image.isGIF)
 {
 }
 else
 {
  image = TIFF.newTIFF(stream);
  if (image.isTIFF)
  {
  }
  else
  {
   image = PNG.newPNG(stream);
   if (image.isPNG)
   {
   }
  }
 }
}

There is a bug in the base 64 decode routines built into Adobe Reader but this has not yet proved to be a problem as it only seems to occur towards the end of the file were typically the image data is stored.  However, included in this sample is a JavaScript based base 64 decoded.  This does execute slower so I would only use it if this proves to be a problem, just change the first line to;

var stream = ByteStream.newByteStream(Base64.decode(this.rawValue));

In the sample form there are four options;

• Turn on JavaScript decoding
• Display a message if a decode error occurs
• Stop decoding when the SOF jpeg tag is found.  The only thing that may be missed is the JPEG comment tag, but this seems to be rarely used or superseded by the Exif properties.  This option should speed up the decode.
• Turn on and off displaying of the decode time.

The code in the sample form starts in the change event of the image field in the top right hand corner (with the "Click here to add photo" caption).  This loads the image and then executes the initialize event of the main ImageField to display all the image properties.  I did it this way because I am using the dataWindow object to allowing scrolling though pictures, without the dataWindow you could perform all processing in the ImageField's change event.

 The form template (without pictures of my cat) can also be downloaded, ImageViewer.xdp