1 /******************************************************************************* 2 * Copyright (c) 2009, 2015 Matthew Hall and others. 3 * 4 * This program and the accompanying materials 5 * are made available under the terms of the Eclipse Public License 2.0 6 * which accompanies this distribution, and is available at 7 * https://www.eclipse.org/legal/epl-2.0/ 8 * 9 * SPDX-License-Identifier: EPL-2.0 10 * 11 * Contributors: 12 * Matthew Hall - initial API and implementation (bug 264286) 13 *******************************************************************************/ 14 15 package org.eclipse.jface.databinding.swt; 16 17 import org.eclipse.core.databinding.observable.value.IObservableValue; 18 import org.eclipse.core.databinding.observable.value.IVetoableValue; 19 import org.eclipse.core.databinding.observable.value.ValueChangingEvent; 20 import org.eclipse.core.databinding.property.value.IValueProperty; 21 import org.eclipse.swt.widgets.Widget; 22 23 /** 24 * {@link IValueProperty} for observing an SWT Widget 25 * 26 * @param <S> type of the source widget 27 * @param <T> type of the value of the property 28 * 29 * @since 1.3 30 * @noimplement This interface is not intended to be implemented by clients. 31 */ 32 public interface IWidgetValueProperty<S extends Widget, T> extends IValueProperty<S, T> { 33 /** 34 * Returns an {@link ISWTObservableValue} observing this value property on 35 * the given widget 36 * 37 * @param widget 38 * the source widget 39 * @return an observable value observing this value property on the given 40 * widget 41 */ 42 @Override observe(S widget)43 public ISWTObservableValue<T> observe(S widget); 44 45 /** 46 * Returns an {@link ISWTObservableValue} observing this value property on the 47 * given widget, which delays notification of value changes until at least 48 * <code>delay</code> milliseconds have elapsed since that last change event, or 49 * until a FocusOut event is received from the widget (whichever happens first). 50 * <p> 51 * This observable helps to boost performance in situations where an observable 52 * has computationally expensive listeners (e.g. changing filters in a viewer) 53 * or many dependencies (master fields with multiple detail fields). A common 54 * use of this observable is to delay validation of user input until the user 55 * stops typing in a UI field. 56 * <p> 57 * To notify about pending changes, the returned observable fires a stale event 58 * when the wrapped observable value fires a change event, and remains stale 59 * until the delay has elapsed and the value change is fired. A call to 60 * {@link IObservableValue#getValue} while a value change is pending will fire 61 * the value change immediately, short-circuiting the delay. 62 * <p> 63 * Only updates resulting from the observed widget are delayed. Calls directly 64 * to {@link IObservableValue#setValue} are not, and they cancel pending delayed 65 * values. 66 * <p> 67 * Note that this observable will not forward {@link ValueChangingEvent} events 68 * from a wrapped {@link IVetoableValue}. 69 * <p> 70 * This method is equivalent to 71 * <code>SWTObservables.observeDelayedValue(delay, observe(widget))</code>. 72 * 73 * @param delay the delay in milliseconds. 74 * @param widget the source widget 75 * @return an observable value observing this value property on the given 76 * widget, and which delays change notifications for <code>delay</code> 77 * milliseconds. 78 */ observeDelayed(int delay, S widget)79 public ISWTObservableValue<T> observeDelayed(int delay, S widget); 80 } 81