Changeset 33538 in vbox for trunk/doc/manual/en_US/SDKRef.xml

Timestamp:

Oct 28, 2010 8:56:39 AM (14 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

67138

Message:

SDK manual: event aggregation explanation

File:

• trunk/doc/manual/en_US/SDKRef.xml (modified) (1 diff)

trunk/doc/manual/en_US/SDKRef.xml

@@ -2103 +2103 @@
       support callbacks. The new mechanism with events and event listeners
       works with all of these.</para>
+      <para>To simplify developement of application using events, 
+      concept of event aggregator was introduced. Essentially it's
+      mechanism to aggregate multiple event sources into single one,
+      and then work with this single aggregated event source instead of
+      original sources. As an example, one can evaluate demo recorder
+      in VirtualBox Python shell, shipped with SDK - it records mouse 
+      and keyboard events, represented as separate event sources.
+      Code is essentially like this:<screen>
+          listener = console.eventSource.createListener()
+          agg = console.eventSource.createAggregator([console.keyboard.eventSource, console.mouse.eventSource])
+          agg.registerListener(listener, [ctx['global'].constants.VBoxEventType_Any], False)
+          registered = True
+          end = time.time() + dur
+          while  time.time() < end:
+              ev = agg.getEvent(listener, 1000)
+              processEent(ev)
+          agg.unregisterListener(listener)</screen>
+         Without using aggregators consumer have to poll on both 
+         sources, or start multiple threads to block on those sources.
+      </para>
     </sect1>
   </chapter>