应用程序窗口上的鼠标事件

Question

I've an eclipse e4 application. I'm trying to run some code say xyz() when the window is resized. The issue is that while resizing the resize listener is called multiple times and I want to call xyz() only once after the user has done resizing. The only way that I can think is to capture the mouseUp event on the window itself, but couldn't figure an API to get the same.

Sample code

public class CTGHandler{
    @Execute
    public void execute(final EPartService partService, final EModelService modelService){
        MPart mPart = modelService.createModelElement(MPart.class);
        mPart.setLabel("CTGLive"); //$NON-NLS-1$
        mPart.setContributionURI("bundleclass://test.ui.ctg/test.ui.ctg.CTGPart"); //$NON-NLS-1$
        partService.showPart(mPart, PartState.ACTIVATE);
    }
}

public class CTGPart    {
    @Inject
    private IEventBroker eventBroker;

    @Inject
    public CTGPart(){
        //Do something here...
    }

    @PostConstruct
    public void init(final Composite parent){
        Composite grandParent = parent.getParent().getParent().getParent();
        System.out.println(grandParent); //Prints "Shell {CTGApp}"

        grandParent.addControlListener(new ControlListener() {              
            @Override
            public void controlResized(ControlEvent e){
                System.out.println(e); // Prints "ControlEvent{Shell {CTGApp} time=9286942 data=null}" multiple times for a single resize event
                // because there is no way the framework can understand if the resize was complete
                xyz();// called each time, but I want this to be called only once 
            }

            @Override
            public void controlMoved(ControlEvent e)
            {}
        });
        // MouseUp event on the application window so that xyz(); can be called once and we can get rid of grandParent.addControlListener(){...}
    }

}

Answer 1

You might find it better to defer the processing of the resize event using a ScheduledFuture and a ScheduledExecutorService .

If you keep a reference to the Future you can cancel the previous one and schedule a new one. This way you can collapse many events triggered in a short time period into a single slightly delayed event. You need to pick a good delay time to balance the number of events that will be swallowed against the delay that will occur after the last future has been scheduled.

grandParent.addControlListener(new ControlListener() { 
    ScheduledExecutorService scheduledExecutorService =
        Executors.newScheduledThreadPool(1);
    ScheduledFuture scheduledFuture;
    @Override
    public void controlResized(ControlEvent e){
        if(scheduledFuture != null) {
            scheduledFuture.cancel();
        }
        scheduledFuture = scheduledExecutorService.schedule(new Callable() {
            public Object call() throws Exception {
                xyz();
                return null;
            }
            }, 1, TimeUnit.SECONDS);
    }

    @Override
    public void controlMoved(ControlEvent e)
    {}
});

If you get a lot of events you should create a static Callable rather than create a new one each time.