Declaring a Window Server Event-Handling Class

The following example demonstrates how to declare an active object Window Server event handling class.

Variant : ScreenPlay and non-ScreenPlay . Target audience : Application developers.

The steps are:

• Provide a CActive::RunL() function to handle the completion of an asynchronous request—that is, the event being received.

• Provide a CActive::DoCancel() function to implement a cancellation request.

• Provide a function, here called IssueRequest() , to issue a request to the Window Server for events.

• Create a TWsEvent object to store the events.

      
       
      
      /* An active object that wraps a Window Server session.
   An event being received causes RunL() to be called,
   where the event is processed. */

class CExampleWsClient : public CActive
    {
public:
 ...

    // Active object protocol
    void RunL ();
    void DoCancel();

    // Issue request to Window Server for events
    IssueRequest();

private:

    // Access to Window Server session 
    RWsSession& iWs;

    // Access to screen device 
    CWsScreenDevice& iScreen;

    // Window server general event
    TWsEvent iWsEvent;
    };
     

       
        
       
       /* Request Window Server events */
void CExampleWsClient::IssueRequest()
    {
    iWs.EventReady(&iStatus;); // request an event
    SetActive(); // so we're now active
    }