Preventive UI validation using Editor Driver

[questzen]

The question is simple, remember FormButtonBinding, it used to work on a FormPanel (GXT 2.x). The logic is to use a Timer and call a validate function. I am trying to achieve the same using EditorDriver. I have created a simple bean editor and invoked driver. I am able to set the violations on the form fields. However, due to repetitive calls from the server, the error message and icon flicker. How do I achieve this without flicker issues.


Edit: Incase it is not clear, isValidModel() method is used to trigger this. I have not pasted the presenter and view to reduce SPAM


Driver code:

public class RegistrationDetailViewDriver implements HasPreventiveValidation {


    interface Driver extends SimpleBeanEditorDriver<TransactionDetail, RegistrationDetailView> {


    }


    Driver driver = GWT.create(Driver.class);


    private Validator validator = Validation.buildDefaultValidatorFactory().getValidator();


    public RegistrationDetailView edit(TransactionDetail regDetails) {
        RegistrationDetailView editor = BpmUIInjector.INSTANCE.getRegistrationDetailView();
        driver.initialize(editor);
        driver.edit(regDetails);
        return editor;
    }


    public TransactionDetail save() {
        Window.alert("test alert");
        TransactionDetail details = driver.flush();
        return details;
    }


    /* (non-Javadoc)
     * @see com.xxx.tps.bpm.ui.client.shared.driver.HasPreventiveValidtion#isValidModel()
     */
    @SuppressWarnings({ "unchecked", "rawtypes" })
    @Override
    public boolean isValidModel() {
        TransactionDetail transactionDetail = driver.flush();
        Set<ConstraintViolation<TransactionDetail>> violations = validator.validate(transactionDetail);
        boolean valid = violations.isEmpty();
        if(needToChangeView(violations)){
            driver.setConstraintViolations((Set)violations);
        }
        return valid;
    }


    Set<String> oldViolations = new HashSet<String>(4);


    private boolean needToChangeView(Set<ConstraintViolation<TransactionDetail>> violations) {
        boolean onlyOldErrors = true;
        Set<String> newViolations = new HashSet<String>(4);
        for (ConstraintViolation<TransactionDetail> constraintViolation : violations) {
            String key = constraintViolation.getPropertyPath()+"_|_"
                            +constraintViolation.getInvalidValue()+"_|_"
                            +constraintViolation.getMessage()+"_|_"
                            +constraintViolation.getRootBean().toString();
            onlyOldErrors = onlyOldErrors && oldViolations.contains(key);
            newViolations.add(key);
        }
        boolean mismatch = oldViolations.size() != newViolations.size();
        oldViolations = newViolations;
        return !onlyOldErrors || mismatch;
    }
}

and FormButtonBinding code

/**
 * Monitors the valid state of a form and enabled / disabled all buttons.
 */
public class FormButtonBinding {


    private HasPreventiveValidation validator;
    private Widget panel;
    private Timer timer;
    private int interval = 500;
    private Handler listener;
    private List<TextButton> buttons;


    public FormButtonBinding(HasPreventiveValidation validator, Widget panel) {
        this.validator = validator;
        this.panel = panel;
        buttons = new ArrayList<TextButton>();
        timer = new Timer() {
            @Override
            public void run() {
                FormButtonBinding.this.checkPanel();
            }
        };


        listener = new Handler() {
            @Override
            public void onAttachOrDetach(AttachEvent event) {
                if (event.isAttached()) {
                    FormButtonBinding.this.startMonitoring();
                } else {
                    FormButtonBinding.this.stopMonitoring();
                }
            }
        };


        panel.addAttachHandler(listener);
        if (panel.isAttached()) {
            startMonitoring();
        }


    }


    public void addButton(TextButton button) {
        buttons.add(button);
    }


    public int getInterval() {
        return interval;
    }


    public void removeButton(TextButton button) {
        buttons.remove(button);
    }


    public void setInterval(int interval) {
        this.interval = interval;
    }


    public void startMonitoring() {
        if (panel.isAttached()) {
            timer.run();
            timer.scheduleRepeating(interval);
        }
    }


    public void stopMonitoring() {
        timer.cancel();
    }


    protected boolean checkPanel() {
        if(validator == null){
            return true;
        }
        boolean v = validator.isValidModel();
        for (TextButton button : buttons) {
            if (v != button.isEnabled()) {
                button.setEnabled(v);
            }
        }
        return v;


    }


}