org.eclipse.jface.databinding.swt.IWidgetValueProperty Maven / Gradle / Ivy
/*******************************************************************************
* Copyright (c) 2009, 2015 Matthew Hall and others.
*
* This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* which accompanies this distribution, and is available at
* https://www.eclipse.org/legal/epl-2.0/
*
* SPDX-License-Identifier: EPL-2.0
*
* Contributors:
* Matthew Hall - initial API and implementation (bug 264286)
*******************************************************************************/
package org.eclipse.jface.databinding.swt;
import org.eclipse.core.databinding.observable.value.IObservableValue;
import org.eclipse.core.databinding.observable.value.IVetoableValue;
import org.eclipse.core.databinding.observable.value.ValueChangingEvent;
import org.eclipse.core.databinding.property.value.IValueProperty;
import org.eclipse.swt.widgets.Widget;
/**
* {@link IValueProperty} for observing an SWT Widget
*
* @param type of the source widget
* @param type of the value of the property
*
* @since 1.3
* @noimplement This interface is not intended to be implemented by clients.
*/
public interface IWidgetValueProperty extends IValueProperty {
/**
* Returns an {@link ISWTObservableValue} observing this value property on
* the given widget
*
* @param widget
* the source widget
* @return an observable value observing this value property on the given
* widget
*/
@Override
public ISWTObservableValue observe(S widget);
/**
* Returns an {@link ISWTObservableValue} observing this value property on the
* given widget, which delays notification of value changes until at least
* delay milliseconds have elapsed since that last change event, or
* until a FocusOut event is received from the widget (whichever happens first).
*
* This observable helps to boost performance in situations where an observable
* has computationally expensive listeners (e.g. changing filters in a viewer)
* or many dependencies (master fields with multiple detail fields). A common
* use of this observable is to delay validation of user input until the user
* stops typing in a UI field.
*
* To notify about pending changes, the returned observable fires a stale event
* when the wrapped observable value fires a change event, and remains stale
* until the delay has elapsed and the value change is fired. A call to
* {@link IObservableValue#getValue} while a value change is pending will fire
* the value change immediately, short-circuiting the delay.
*
* Only updates resulting from the observed widget are delayed. Calls directly
* to {@link IObservableValue#setValue} are not, and they cancel pending delayed
* values.
*
* Note that this observable will not forward {@link ValueChangingEvent} events
* from a wrapped {@link IVetoableValue}.
*
* This method is equivalent to
* SWTObservables.observeDelayedValue(delay, observe(widget)).
*
* @param delay the delay in milliseconds.
* @param widget the source widget
* @return an observable value observing this value property on the given
* widget, and which delays change notifications for delay
* milliseconds.
*/
public ISWTObservableValue observeDelayed(int delay, S widget);
}