VP Run offscreen area

VP Run offscreen area ( parameters : Object) : Mixed

Parameter	Type		Description
parameters	Object	->	Object containing the offscreen area's attributes
Result	Mixed	<-	.result property of the .onEvent object, or Null if does not return a value

Description

The VP Run offscreen area command creates an offscreen area in memory which can be used to process 4D View Pro area commands and functions.

In parameters object, pass any of the following optional properties. These properties will be available through the This command within the onEvent method and reference the instance:

Property	Type	Description
area	text	The name of the offscreen area. If omitted or null, a generic name is assigned (e.g., "OffscreenArea1").
onEvent	object (formula)	A callback method that will be launched when the offscreen area is ready. It can be either: an onEvent function of a class, or a Formula object By default, the callback method is called on the On VP Ready, On Load, On Unload, On End URL Loading, On URL Loading Error, On VP Range Changed, or On Timer events. The callback method can be used to access the 4D View Pro form object variable.
autoQuit	boolean	True (default value) if the command must stop the formula execution when the On End URL Loading or On URL Loading Error events occur. If false, you must use the CANCEL or ACCEPT commands in the onEvent callback method.
timeout	number	Maximum time (expressed in seconds) before the area automatically closes if no event is generated. If set to 0, no limitation is applied. Default value: 60
result	mixed	Result of the processing (if any)
<customProperty>	mixed	Any custom attribute to be available in the onEvent callback method.

The following property is automatically added by the command if necessary:

Property	Type	Description
timeoutReached	boolean	Added with true value if timeout has been exceeded

The offscreen area is only available during the execution of the VP Run offscreen area command. It will automatically be destroyed once execution has ended.

The following commands can be used in the callback method:

• ACCEPT
• CANCEL
• SET TIMER
• WA Evaluate JavaScript
• WA EXECUTE JAVASCRIPT FUNCTION

Example 1

You want to create an offscreen 4D View Pro area and get the value of a cell:

// cs.OffscreenArea class declaration 
Class constructor ($path : Text)
 This.filePath:=$path
 
// This function will be called on each event of the offscreen area 
Function onEvent()
 Case of
  :(FORM Event.code=On VP Ready)
      VP IMPORT DOCUMENT(This.area;This.filePath)
       This.result:=VP Get value(VP Cell(This.area;6;22))
 
       ALERT("The G23 cell contains the value: "+String(This.result))
 End case

The OffscreenArea callback method:

$o:=cs.OffscreenArea.new()
$result:=VP Run offscreen area($o)

Example 2

You want to load a large document offscreen, wait for all calculations to complete evaluating, and export it as a PDF:

//cs.OffscreenArea class declaration
Class constructor($pdfPath : Text)
 This.pdfPath:=$pdfPath
 This.autoQuit:=False
 This.isWaiting:=False
 
Function onEvent()
 Case of
     :(FORM Event.code=On VP Ready)
 // Document import
   VP IMPORT DOCUMENT(This.area;$largeDocument4VP)
         This.isWaiting:=True
 
 // Start a timer to verify if all calculations are finished.
 // If during this period the "On VP Range Changed" is thrown, the timer will be restarted
 // The time must be defined according to the computer configuration.
   SET TIMER(60)
 
  :(FORM Event.code=On VP Range Changed)
 // End of calculation detected. Restarts the timer
         If(This.isWaiting)
           SET TIMER(60)
         End if
 
  :(FORM Event.code=On Timer)
 // To be sure to not restart the timer if you call others 4D View command after this point
         This.isWaiting:=False
 


 // Stop the timer
   SET TIMER(0)
 
 // Start the PDF export
        VP EXPORT DOCUMENT(This.area;This.pdfPath;New object("formula";Formula(ACCEPT)))
 
     :(FORM Event.code=On URL Loading Error)

         CANCEL 
 End case

The OffscreenArea callback method:

$o:=cs.OffscreenArea.new()
 
$result:=VP Run offscreen area($o)

See also

Blog post: End of document loading