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Adding PDF contentApplications running in Adobe® AIR® can render not only SWF and HTML content, but also PDF content. AIR applications render PDF content using the HTMLLoader class, the WebKit engine, and the Adobe® Reader® browser plug-in. In an AIR application, PDF content can either stretch across the full height and width of your application or alternatively as a portion of the interface. The Adobe Reader browser plug-in controls display of PDF files in an AIR application, so modifications to the Reader toolbar interface (such as those for position, anchoring, and visibility) persist in subsequent viewing of PDF files in both AIR applications and the browser. Important: In
order to render PDF content in AIR, the user must have Adobe Reader or
Adobe® Acrobat® version 8.1 or higher installed.
Detecting PDF CapabilityIf the user does not have an installed version of Adobe Reader or Adobe Acrobat 8.1 or higher, PDF content is not displayed in an AIR application. To detect if a user can render PDF content, first check the HTMLLoader.pdfCapability property. This property is set to one of the following constants of the HTMLPDFCapability class:
On Windows, if Adobe Acrobat or Adobe Reader version 7.x or above is currently running on the user's system, that version is used even if a later version that supports loading PDF loaded is installed. In this case, if the value of the pdfCampability property is HTMLPDFCapability.STATUS_OK, when an AIR application attempts to load PDF content, the older version of Acrobat or Reader displays an alert (and no exception is thrown in the AIR application). If this is a possible situation for your end users, consider providing them with instructions to close Acrobat while running your application. You may want to display these instructions if the PDF content does not load within an acceptable time frame. On Linux, AIR looks for Adobe Reader in the PATH exported by the user (if it contains the acroread command) and in the /opt/Adobe/Reader directory. The following code detects whether a user can display PDF content in an AIR application, and if not traces the error code that corresponds to the HTMLPDFCapability error object: if(HTMLLoader.pdfCapability == HTMLPDFCapability.STATUS_OK)
{
trace("PDF content can be displayed");
}
else
{
trace("PDF cannot be displayed. Error code:", HTMLLoader.pdfCapability);
}
Loading PDF contentYou can add a PDF to an AIR application by creating an HTMLLoader instance, setting its dimensions, and loading the path of a PDF. The following example loads a PDF from an external site. Replace the URLRequest with the path to an available external PDF. var request:URLRequest = new URLRequest("http://www.example.com/test.pdf");
pdf = new HTMLLoader();
pdf.height = 800;
pdf.width = 600;
pdf.load(request);
container.addChild(pdf);
You can also load content from file URLs and AIR-specific URL schemes, such as app and app-storage. For example, the following code loads the test.pdf file in the PDFs subdirectory of the application directory: app:/js_api_reference.pdf For more information on AIR URL schemes, see Using AIR URL schemes in URLs. Scripting PDF contentYou can use JavaScript to control PDF content just as you can in a web page in the browser. JavaScript extensions to Acrobat provide the following features, among others:
Full details on JavaScript extensions for Adobe Acrobat are provided at the Adobe Acrobat Developer Connection at http://www.adobe.com/devnet/acrobat/javascript.html. HTML-PDF communication basicsJavaScript in an HTML page can send a message to JavaScript in PDF content by calling the postMessage() method of the DOM object representing the PDF content. For example, consider the following embedded PDF content: <object id="PDFObj" data="test.pdf" type="application/pdf" width="100%" height="100%"/> The following JavaScript code in the containing HTML content sends a message to the JavaScript in the PDF file: pdfObject = document.getElementById("PDFObj");
pdfObject.postMessage(["testMsg", "hello"]);
The PDF file can include JavaScript for receiving this message. You can add JavaScript code to PDF files in some contexts, including the document-, folder-, page-, field-, and batch-level contexts. Only the document-level context, which defines scripts that are evaluated when the PDF document opens, is discussed here. A PDF file can add a messageHandler property to the hostContainer object. The messageHandler property is an object that defines handler functions to respond to messages. For example, the following code defines the function to handle messages received by the PDF file from the host container (which is the HTML content embedding the PDF file): this.hostContainer.messageHandler = {onMessage: myOnMessage};
function myOnMessage(aMessage)
{
if(aMessage[0] == "testMsg")
{
app.alert("Test message: " + aMessage[1]);
}
else
{
app.alert("Error");
}
}
JavaScript code in the HTML page can call the postMessage() method of the PDF object contained in the page. Calling this method sends a message ("Hello from HTML") to the document-level JavaScript in the PDF file: <html>
<head>
<title>PDF Test</title>
<script>
function init()
{
pdfObject = document.getElementById("PDFObj");
try {
pdfObject.postMessage(["alert", "Hello from HTML"]);
}
catch (e)
{
alert( "Error: \n name = " + e.name + "\n message = " + e.message );
}
}
</script>
</head>
<body onload='init()'>
<object
id="PDFObj"
data="test.pdf"
type="application/pdf"
width="100%" height="100%"/>
</body>
</html>
For a more advanced example, and for information on using Acrobat 8 to add JavaScript a PDF file, see Cross-scripting PDF content in Adobe AIR. Scripting PDF content from ActionScriptActionScript code (in SWF content) cannot directly communicate with JavaScript in PDF content. However, ActionScript can communicate with the JavaScript in the HTML page loaded in an HTMLLoader object that loads PDF content, and that JavaScript code can communicate with the JavaScript in the loaded PDF file. For more information, see Programming in HTML and JavaScript. Known limitations for PDF content in AIRPDF content in Adobe AIR has the following limitations:
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