Managed Printing in Mozilla browsers

FusionCharts provides advanced print management using JavaScript for Mozilla/WebKit/Gecko based browsers like Firefox, Safari etc. Even though displayed properly on screen, printed output had been not proper in these browsers. So long! FusionCharts JavaScript class offers a separate Print Manger class to take care of this. The implementation of Print Manager is fairly simple. You would just need to add a single line of code in JavaScript which enables Print Manager for all charts present in a web page. Once enabled, all the charts present in a page are prepared to print correctly. Once the charts are ready, which can be tracked by listening to an event raised by the Print Manager, you can use browser's File → Print menu, JavaScript's native window.print() function or Print Manager's advanced function - managedPrint(). In any of these actions, the charts would come-up properly in the print media.

The Print Manager internally does the following to achieve this:

  • Once a chart is rendered it silently gathers all the image data of the present state of the chart
  • It converts the image data into image using canvas HTML object
  • It hides the canvas image below the chart
  • When print is invoked, a parallel CSS based print media layout » using @media print is created
  • In this print media layout the Flash based chart is hidden and the canvas image is displayed
  • This layout with the canvas image is sent to the printer for print

Let's now go through a sample code which will provide you first-hand experience of what has been said above.

Code examples discussed in this section are present in Download Package > Code > JavaScript > Basics folder.

 
<html>
  <head> 	
    <title>FusionCharts Print Manager</title> 	
    <script type="text/javascript" src="FusionCharts/FusionCharts.js"></script>
  </head>   
  <body>     
    <div id="chartContainer">FusionCharts will load here!</div>          
    <script type="text/javascript"><!-- 	
      FusionCharts.printManager.enabled(true);

      var myChart = new FusionCharts( "FusionCharts/Column3D.swf", "myChartId", "400", "300", "0", "1" );
      myChart.setXMLUrl("Data.xml");
      myChart.render("chartContainer");
					
      FusionCharts.addEventListener ( 
          FusionChartsEvents.PrintReadyStateChange , 
          function (identifier, parameter) {
            if(parameter.ready){ 
               alert("Chart is now ready for printing.");
               document.getElementById('printButton').disabled = false;
            }
        });
    // --></script> 	   
    <input type="button" onclick="FusionCharts.printManager.managedPrint()"
        value="Managed Print" disabled="disabled" id="printButton" >
  </body> 
</html>

See it live!

In the above code:

  • We first enable FusionCharts Print Manager using FusionCharts.printManager.enabled(true)
  • Next, we create a Column 3D chart. We add a button which on click will call managedPrint() function of FusionCharts.printManager class
  • Thereafter, We add a listener for the global event PrintReadyStateChange to the global object FusionCharts

Note that PrintReadyStateChange event is a global event. Thus, this event can not be listened from individual chart instance. Hence, only FusionCharts static class can listen to this event.

  • The parameters event argument contains a property ready. This returns true when the Print Manager is ready to print all charts in a page
  • Hence, in this event we show an information alert and also enable the button, which was disabled prior to this.

Now, if you try printing from File → Print menu or using a button or function that call window.print() function. You can also click "Managed Print" button to print the chart.

Advanced Functions

Print Manger class provides two more functions that helps in advanced configurations. The functions are described below:

  1. isReady() : This function returns true or false based on the status of Print Manger. When the print manager is fully ready with all the equivalent canvas images of all the charts present in a page, it returns true.
  2. configure() : This function helps in configuring the Print Manager. It takes an Object as parameter. The object can have the following properties:
    • enabled : This is a boolean property where you can explicitly define here whether to enable managed printing feature or not
    • invokeCSS : This is a boolean property which sets whether CSS based print media layout should be created for managed print or not.
    • message : This property takes a string as message. While the print manager is still not ready with the converted images of the charts, this text message is placed instead of the chart images. The default value is "Chart is being prepared for print.".

    Note that this function should be called before calling FusionCharts.printManager.enabled( true );

To see implementation code snippets using these advanced functions go through API Reference > Functions page.

Please note that Print Manager takes a bit of time to prepare all the charts ready for printing. It depends on the size of the chart as well as the processing power of the client side computer. If print action is invoked while the Print Manager is not yet ready with the image, the chart does not show up in the print media. However, if the function managedPrint() is called, it automatically waits for the all the chart to get ready before it proceeds to call the window.print() function.
Hence, it is recommended to call managedPrint() function instead of the other actions.