WA Run offscreen area
WA Run offscreen area ( parameters ) : Mixed
| Parameter | Type | Description | |
|---|---|---|---|
| parameters | Object | → | Object containing the web area's attributes |
| Function result | Mixed | ← | .result property of the onEvent object, or Null if does not return a value |
This command is not thread-safe, it cannot be used in preemptive code.
Description
The WA Run offscreen area command creates a web area in memory which can be used to automatically load and parse web pages.
Note: This command uses the embedded web rendering engine.
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 |
|---|---|---|
| url | text | file object | The URL or file to be loaded in the web area. If omitted or null, a blank page is loaded. |
| area | text | The name of the web 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 web 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 Load, On Unload, On End URL Loading, On URL Loading Error, or On Timer events. |
| 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 callback method or project methods called with the $4d object to close the web area. |
| timeout | real | 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 to be returned (if any) |
| mixed | Any custom attribute to be available in the callback or $4d 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 |
If a null value is passed in parameters, a blank web area will be created and then automatically closed.
Notes:
- The offscreen web area is only available during the execution of the WA Run offscreen area command. It will automatically be destroyed once execution has ended.
- 4D methods can be called from the JavaScript code executed in a web area. See Accessing 4D methods.
The following commands can be used in the callback method:
- ACCEPT
- CANCEL
- SET TIMER
- WA Evaluate JavaScript
- WA EXECUTE JAVASCRIPT FUNCTION
- WA Get current URL
- WA GET LAST URL ERROR
- WA Get page content
- WA Get page title
- WA OPEN URL
- WA REFRESH CURRENT URL
- WA STOP LOADING URL
Example
You want to create and handle an offscreen web area using a function of your OffscreenArea class:
$config:=cs.OffscreenArea.new()
$result:=WA Run offscreen area($config)
If($config.timeoutReached) //automatically returned in case of timeout
ALERT("Timeout reached")
End if
In the OffscreenArea class:
Class constructor
This.url:=File("/RESOURCES/compute.html")
This.area:="myWAOffscreen"
Function onEvent
Case of
:(FORM Event.code=On End URL Loading)
This.result:=WA Evaluate JavaScript(*;This.area;"myJSMethod();")
End case
System variables and sets
The OK system variable is set to 0 if the timeout has been reached or the CANCEL was called in onEvent, otherwise it is set to 1.
See also
FORM Event
Programmed management of Web Areas
WA OPEN WEB INSPECTOR