Tag: Print

No flash events after PrintJob.start()

While developing the print functionality within a framework I got stuck on the behaviour of the Flash Player print implementation.

I couldn’t solve the following steps:

  1. Start the PrintJob and display the print dialog
  2. Procceed the following tasks for every print page:
    • Load dynamic data into view templates (images, text, video…)
    • Wait for the onLoadComplete event and add the displayed contents using PrintJob.addPage()
    • Repeat for next page…
  3. Call PrintJob.send()

I really thought this would be an easy task but now I think it’s not possible. Several attempts later I figured out that after calling PrintJob.start() there is no way to use the flash event model! This means loading contents after calling PrintJob.start() is impossible!

WOW!

So I used a workaround: I create all the print pages like I mentioned before, but without calls on the PrintJob-API. I simply store every print page as BitmapData and afterwards I create the PrintJob within a loop.

Now I have multiple other problems:

  • Hundreds of pages use a huge amount of RAM and often crash the application.
  • The bitmap resolution sucks so printout text quality is unsatisfying and due to point 1 I have no chance to work with higher quality.
  • I must avoid skript timeouts because after preparing all the bitmaps it takes much more that 15 seconds to add all these pages to a PrintJob.

Did I slip something?

Finally I created a small example to show you the disfunctionality (PrintJobProblem.as):

package  
{
	import flash.display.Sprite;
	import flash.events.Event;
	import flash.geom.Rectangle;
	import flash.printing.PrintJob;
	import flash.text.TextField;
	import flash.text.TextFieldAutoSize;
	import flash.utils.getTimer;	
 
	/**
	 * @author Markus Raab - derRaab.com / superclass.de
	 */
	public class PrintJobProblem extends Sprite 
	{
		private var _numPrintOuts : int;
		private var _printOutIndex : int;
		private var _printJob : PrintJob;
 
		/**
		 * Starts a event based printout test after a loop based
		 * test has successfully finished.
		 */
		public function PrintJobProblem()
		{
			_numPrintOuts = 2;
 
			runLoopBasedTest( );
			runEventBasedTest( );
		}
 
		/**
		 * Demonstrates and ensures the functionality.
		 */
		private function runLoopBasedTest() : void
		{
			_printJob = new PrintJob();
 
			if ( _printJob.start() )
			{	
				for ( var i : int = 0; i < _numPrintOuts; i++ )
				{
					addPage( i );
				}
 
				_printJob.send();
			}
		}
 
		/**
		 * Demonstrates that after calling PrintJob.start() the internal
		 * eventmodel doesn't dispatch any events at all. Everything is blocked
		 * until the script times out.
		 */
		private function runEventBasedTest() : void
		{
			_printJob = new PrintJob();
 
			if ( _printJob.start() )
			{
				trace( getTimer(), "PrintJob.start() called" );
				_printOutIndex = 0;
 
				startAddPagesOnEnterFrame();
			}
		}
 
		private function startAddPagesOnEnterFrame() : void
		{
			addEventListener( Event.ENTER_FRAME, onAddPagesOnEnterFrameEvent );
		}
 
		private function onAddPagesOnEnterFrameEvent(event : Event) : void
		{
			if ( _printOutIndex == _numPrintOuts )
			{
				stopAddPagesOnEnterFrame();
 
				_printJob.send();
				trace( getTimer(), "PrintJob.send()" );
			}
			else
			{
				addPage( _printOutIndex++ );
			}
		}
 
		private function stopAddPagesOnEnterFrame() : void
		{
			removeEventListener( Event.ENTER_FRAME, onAddPagesOnEnterFrameEvent );
		}
 
		private function addPage( pageIndex : int ) : void
		{
			var page : Sprite = createPrintPage( pageIndex );
 
			stage.addChild( page );
 
			var viewWidth : Number = page.width;
			var viewHeight : Number = page.height;
 
			var scaleX : Number = _printJob.pageWidth / viewWidth;
			var scaleY : Number = _printJob.pageHeight / viewHeight;
			var scale : Number = Math.min( scaleX, scaleY );
 
			page.scaleX = page.scaleY = scale;
 
			var printRect : Rectangle = new Rectangle( 0, 0, viewWidth, viewHeight );
 
			try
			{
				_printJob.addPage( page, printRect );
			}
			catch( e: Error )
			{
				trace( getTimer(), "PrintJob.addPage() failed" );
			}
 
			stage.removeChild( page );
		}
 
		private function createPrintPage( pageIndex : int) : Sprite
		{
			var page : Sprite = new Sprite();
 
			var textField : TextField = new TextField();
				textField.autoSize = TextFieldAutoSize.LEFT;
				textField.text = "Page " + pageIndex;
 
			page.addChild( textField );	
 
			return page;
		}
	}
}