Java tutorial
/******************************************************************************* * Copyright (c) 2006, 2015 IBM Corporation 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: * IBM Corporation - initial API and implementation * Tom Schindl<tom.schindl@bestsolution.at> - bugfix in: 214355 * Matthew Hall - bugs 215531, 226765, 222991, 238296, 226292, 266038, * 283351 *******************************************************************************/ package org.eclipse.jface.databinding.viewers; import java.util.Set; import org.eclipse.core.databinding.observable.IObservableCollection; import org.eclipse.core.databinding.observable.list.IListChangeListener; import org.eclipse.core.databinding.observable.list.IObservableList; import org.eclipse.core.databinding.observable.list.ListChangeEvent; import org.eclipse.core.databinding.observable.list.ListDiffVisitor; import org.eclipse.core.databinding.observable.set.IObservableSet; import org.eclipse.core.runtime.Assert; import org.eclipse.jface.internal.databinding.viewers.ObservableCollectionContentProvider; import org.eclipse.jface.internal.databinding.viewers.ViewerElementSet; import org.eclipse.jface.viewers.AbstractListViewer; import org.eclipse.jface.viewers.AbstractTableViewer; import org.eclipse.jface.viewers.IStructuredContentProvider; import org.eclipse.jface.viewers.Viewer; /** * A {@link IStructuredContentProvider content provider} for * {@link AbstractTableViewer} or {@link AbstractListViewer} that provides * elements of an {@link IObservableList} when set as the viewer's input. * Objects of this class listen for changes to the observable list, and will * insert and remove viewer elements to reflect observed changes. * * @param <E> type of the values that are provided by this object TODO: Probably * remove this! * * @noextend This class is not intended to be subclassed by clients. * @since 1.1 */ public class ObservableListContentProvider<E> implements IStructuredContentProvider { private ObservableCollectionContentProvider<E> impl; private static class Impl<E> extends ObservableCollectionContentProvider<E> implements IListChangeListener<E> { private Viewer viewer; Impl(IViewerUpdater<E> explicitViewerUpdater) { super(explicitViewerUpdater); } @Override public void inputChanged(Viewer viewer, Object oldInput, Object newInput) { this.viewer = viewer; super.inputChanged(viewer, oldInput, newInput); } @Override protected void checkInput(Object input) { Assert.isTrue(input instanceof IObservableList, "This content provider only works with input of type IObservableList"); //$NON-NLS-1$ } @Override protected void addCollectionChangeListener(IObservableCollection<E> collection) { ((IObservableList<E>) collection).addListChangeListener(this); } @Override protected void removeCollectionChangeListener(IObservableCollection<E> collection) { ((IObservableList<E>) collection).removeListChangeListener(this); } @Override public void handleListChange(ListChangeEvent<? extends E> event) { if (isViewerDisposed()) return; // Determine which elements were added and removed final Set<E> knownElementAdditions = ViewerElementSet.withComparer(comparer); final Set<E> knownElementRemovals = ViewerElementSet.withComparer(comparer); final boolean[] suspendRedraw = new boolean[] { false }; event.diff.accept(new ListDiffVisitor<E>() { @Override public void handleAdd(int index, E element) { knownElementAdditions.add(element); } @Override public void handleRemove(int index, E element) { knownElementRemovals.add(element); } @Override public void handleMove(int oldIndex, int newIndex, E element) { suspendRedraw[0] = true; super.handleMove(oldIndex, newIndex, element); } @Override public void handleReplace(int index, E oldElement, E newElement) { suspendRedraw[0] = true; super.handleReplace(index, oldElement, newElement); } }); knownElementAdditions.removeAll(knownElements); knownElementRemovals.removeAll(event.getObservableList()); knownElements.addAll(knownElementAdditions); if (realizedElements != null) { realizedElements.removeAll(knownElementRemovals); } if (suspendRedraw[0]) viewer.getControl().setRedraw(false); try { event.diff.accept(new ListDiffVisitor<E>() { @Override public void handleAdd(int index, E element) { viewerUpdater.insert(element, index); } @Override public void handleRemove(int index, E element) { viewerUpdater.remove(element, index); } @Override public void handleReplace(int index, E oldElement, E newElement) { viewerUpdater.replace(oldElement, newElement, index); } @Override public void handleMove(int oldIndex, int newIndex, E element) { viewerUpdater.move(element, oldIndex, newIndex); } }); } finally { if (suspendRedraw[0]) viewer.getControl().setRedraw(true); } if (realizedElements != null) { realizedElements.addAll(knownElementAdditions); } knownElements.removeAll(knownElementRemovals); } } /** * Constructs an ObservableListContentProvider. Must be called from the * display thread. */ public ObservableListContentProvider() { this(null); } /** * Constructs an ObservableListContentProvider with the given viewer * updater. Must be called from the display thread. * * @param viewerUpdater * the viewer updater to use when elements are added, removed, * moved or replaced in the input observable list. * @since 1.3 */ public ObservableListContentProvider(IViewerUpdater<E> viewerUpdater) { impl = new Impl<>(viewerUpdater); } @Override public void inputChanged(Viewer viewer, Object oldInput, Object newInput) { impl.inputChanged(viewer, oldInput, newInput); } @Override public Object[] getElements(Object inputElement) { return impl.getElements(inputElement); } /** * Disposes of this content provider. This is called by the viewer when a * content provider is replaced, or when the viewer itself is disposed. * <p> * The viewer should not be updated during this call, as it is in the * process of being disposed. * </p> * <p> * <em>Note:</em> Data binding content providers become unusable on * disposal. * </p> */ @Override public void dispose() { impl.dispose(); } /** * Returns the set of elements known to this content provider. Label * providers may track this set if they need to be notified about additions * before the viewer sees the added element, and notified about removals * after the element was removed from the viewer. This is intended for use * by label providers, as it will always return the items that need labels. * * @return readableSet of items that will need labels */ public IObservableSet<E> getKnownElements() { return impl.getKnownElements(); } /** * Returns the set of known elements which have been realized in the viewer. * Clients may track this set in order to perform custom actions on elements * while they are known to be present in the viewer. * * @return the set of known elements which have been realized in the viewer. * @since 1.3 */ public IObservableSet<E> getRealizedElements() { return impl.getRealizedElements(); } }