Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2019 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 * Alexander Fedorov <alexander.fedorov@arsysop.ru> - Bug 548314 *******************************************************************************/ package org.eclipse.jface.viewers; import java.util.ArrayList; import java.util.List; import org.eclipse.core.runtime.Assert; import org.eclipse.core.runtime.ListenerList; import org.eclipse.jface.util.SafeRunnable; import org.eclipse.swt.SWT; import org.eclipse.swt.events.SelectionEvent; import org.eclipse.swt.widgets.Composite; import org.eclipse.swt.widgets.Table; import org.eclipse.swt.widgets.TableColumn; import org.eclipse.swt.widgets.TableItem; import org.eclipse.swt.widgets.Widget; /** * A concrete viewer based on an SWT <code>Table</code> * control with checkboxes on each node. * <p>This class supports setting an {@link ICheckStateProvider} to * set the checkbox states. To see standard SWT behavior, view * SWT Snippet274.</p> * <p> * This class is not intended to be subclassed outside the viewer framework. * It is designed to be instantiated with a pre-existing SWT table control and configured * with a domain-specific content provider, label provider, element filter (optional), * and element sorter (optional). * </p> * @noextend This class is not intended to be subclassed by clients. */ public class CheckboxTableViewer extends TableViewer implements ICheckable { /** * List of check state listeners (element type: <code>ICheckStateListener</code>). */ private ListenerList<ICheckStateListener> checkStateListeners = new ListenerList<>(); /** * Provides the desired state of the check boxes. */ private ICheckStateProvider checkStateProvider; /** * Creates a table viewer on a newly-created table control under the given parent. * The table control is created using the SWT style bits: * <code>SWT.CHECK</code> and <code>SWT.BORDER</code>. * The table has one column. * The viewer has no input, no content provider, a default label provider, * no sorter, and no filters. * <p> * This is equivalent to calling <code>new CheckboxTableViewer(parent, SWT.BORDER)</code>. * See that constructor for more details. * </p> * * @param parent the parent control * * @deprecated use newCheckList(Composite, int) or new CheckboxTableViewer(Table) * instead (see below for details) */ @Deprecated public CheckboxTableViewer(Composite parent) { this(parent, SWT.BORDER); } /** * Creates a table viewer on a newly-created table control under the given parent. * The table control is created using the given SWT style bits, plus the * <code>SWT.CHECK</code> style bit. * The table has one column. * The viewer has no input, no content provider, a default label provider, * no sorter, and no filters. * <p> * This also adds a <code>TableColumn</code> for the single column, * and sets a <code>TableLayout</code> on the table which sizes the column to fill * the table for its initial sizing, but does nothing on subsequent resizes. * </p> * <p> * If the caller just needs to show a single column with no header, * it is preferable to use the <code>newCheckList</code> factory method instead, * since SWT properly handles the initial sizing and subsequent resizes in this case. * </p> * <p> * If the caller adds its own columns, uses <code>Table.setHeadersVisible(true)</code>, * or needs to handle dynamic resizing of the table, it is recommended to * create the <code>Table</code> itself, specifying the <code>SWT.CHECK</code> style bit * (along with any other style bits needed), and use <code>new CheckboxTableViewer(Table)</code> * rather than this constructor. * </p> * * @param parent the parent control * @param style SWT style bits * * @deprecated use newCheckList(Composite, int) or new CheckboxTableViewer(Table) * instead (see above for details) */ @Deprecated public CheckboxTableViewer(Composite parent, int style) { this(createTable(parent, style)); } /** * Creates a table viewer on a newly-created table control under the given parent. * The table control is created using the given SWT style bits, plus the * <code>SWT.CHECK</code> style bit. * The table shows its contents in a single column, with no header. * The viewer has no input, no content provider, a default label provider, * no sorter, and no filters. * <p> * No <code>TableColumn</code> is added. SWT does not require a * <code>TableColumn</code> if showing only a single column with no header. * SWT correctly handles the initial sizing and subsequent resizes in this case. * * @param parent the parent control * @param style SWT style bits * * @since 2.0 * @return CheckboxTableViewer */ public static CheckboxTableViewer newCheckList(Composite parent, int style) { Table table = new Table(parent, SWT.CHECK | style); return new CheckboxTableViewer(table); } /** * Creates a table viewer on the given table control. * The <code>SWT.CHECK</code> style bit must be set on the given table control. * The viewer has no input, no content provider, a default label provider, * no sorter, and no filters. * * @param table the table control */ public CheckboxTableViewer(Table table) { super(table); } @Override public void addCheckStateListener(ICheckStateListener listener) { checkStateListeners.add(listener); } /** * Sets the {@link ICheckStateProvider} for this {@link CheckboxTreeViewer}. * The check state provider will supply the logic for deciding whether the * check box associated with each item should be checked, grayed or * unchecked. * @param checkStateProvider The provider. * @since 3.5 */ public void setCheckStateProvider(ICheckStateProvider checkStateProvider) { this.checkStateProvider = checkStateProvider; refresh(); } /* * Extends this method to update check box states. */ @Override protected void doUpdateItem(Widget widget, Object element, boolean fullMap) { super.doUpdateItem(widget, element, fullMap); if (!widget.isDisposed()) { if (checkStateProvider != null) { setChecked(element, checkStateProvider.isChecked(element)); setGrayed(element, checkStateProvider.isGrayed(element)); } } } /** * Creates a new table control with one column. * * @param parent the parent control * @param style style bits * @return a new table control */ protected static Table createTable(Composite parent, int style) { Table table = new Table(parent, SWT.CHECK | style); // Although this table column is not needed, and can cause resize problems, // it can't be removed since this would be a breaking change against R1.0. // See bug 6643 for more details. new TableColumn(table, SWT.NONE); TableLayout layout = new TableLayout(); layout.addColumnData(new ColumnWeightData(100)); table.setLayout(layout); return table; } /** * Notifies any check state listeners that a check state changed has been received. * Only listeners registered at the time this method is called are notified. * * @param event a check state changed event * * @see ICheckStateListener#checkStateChanged */ private void fireCheckStateChanged(final CheckStateChangedEvent event) { for (ICheckStateListener l : checkStateListeners) { SafeRunnable.run(new SafeRunnable() { @Override public void run() { l.checkStateChanged(event); } }); } } @Override public boolean getChecked(Object element) { Widget widget = findItem(element); if (widget instanceof TableItem) { return ((TableItem) widget).getChecked(); } return false; } /** * Returns a list of elements corresponding to checked table items in this * viewer. * <p> * This method is typically used when preserving the interesting * state of a viewer; <code>setCheckedElements</code> is used during the restore. * </p> * * @return the array of checked elements * @see #setCheckedElements */ public Object[] getCheckedElements() { TableItem[] children = getTable().getItems(); List<Object> v = new ArrayList<>(children.length); for (TableItem item : children) { Object data = item.getData(); if (data != null) { if (item.getChecked()) { v.add(data); } } } return v.toArray(); } /** * Returns the grayed state of the given element. * * @param element the element * @return <code>true</code> if the element is grayed, * and <code>false</code> if not grayed */ public boolean getGrayed(Object element) { Widget widget = findItem(element); if (widget instanceof TableItem) { return ((TableItem) widget).getGrayed(); } return false; } /** * Returns a list of elements corresponding to grayed nodes in this * viewer. * <p> * This method is typically used when preserving the interesting * state of a viewer; <code>setGrayedElements</code> is used during the restore. * </p> * * @return the array of grayed elements * @see #setGrayedElements */ public Object[] getGrayedElements() { TableItem[] children = getTable().getItems(); List<Object> v = new ArrayList<>(children.length); for (TableItem item : children) { Object data = item.getData(); if (data != null) { if (item.getGrayed()) { v.add(data); } } } return v.toArray(); } @Override public void handleSelect(SelectionEvent event) { if (event.detail == SWT.CHECK) { super.handleSelect(event); // this will change the current selection TableItem item = (TableItem) event.item; Object data = item.getData(); if (data != null) { fireCheckStateChanged(new CheckStateChangedEvent(this, data, item.getChecked())); } } else { super.handleSelect(event); } } @Override protected void preservingSelection(Runnable updateCode) { if (!getPreserveSelection()) { return; } //If a check provider is present, it determines the state across input //changes. if (checkStateProvider != null) { //Try to preserve the selection, let the ICheckProvider manage //the check states super.preservingSelection(updateCode); return; } //Preserve checked items TableItem[] children = getTable().getItems(); CustomHashtable checked = newHashtable(children.length * 2 + 1); CustomHashtable grayed = newHashtable(children.length * 2 + 1); for (TableItem item : children) { Object data = item.getData(); if (data != null) { if (item.getChecked()) { checked.put(data, data); } if (item.getGrayed()) { grayed.put(data, data); } } } super.preservingSelection(updateCode); children = getTable().getItems(); for (TableItem item : children) { Object data = item.getData(); if (data != null) { item.setChecked(checked.containsKey(data)); item.setGrayed(grayed.containsKey(data)); } } } @Override public void removeCheckStateListener(ICheckStateListener listener) { checkStateListeners.remove(listener); } /** * Sets to the given value the checked state for all elements in this viewer. * Does not fire events to check state listeners. * * @param state <code>true</code> if the element should be checked, * and <code>false</code> if it should be unchecked */ public void setAllChecked(boolean state) { TableItem[] children = getTable().getItems(); for (TableItem item : children) { if (item.getData() != null) { if (item.getChecked() != state) item.setChecked(state); } } } /** * Sets to the given value the grayed state for all elements in this viewer. * * @param state <code>true</code> if the element should be grayed, * and <code>false</code> if it should be ungrayed */ public void setAllGrayed(boolean state) { TableItem[] children = getTable().getItems(); for (TableItem item : children) { if (item.getData() != null) { if (item.getGrayed() != state) item.setGrayed(state); } } } @Override public boolean setChecked(Object element, boolean state) { Assert.isNotNull(element); Widget widget = findItem(element); if (widget instanceof TableItem) { TableItem item = (TableItem) widget; if (item.getChecked() != state) item.setChecked(state); return true; } return false; } /** * Sets which nodes are checked in this viewer. * The given list contains the elements that are to be checked; * all other nodes are to be unchecked. * Does not fire events to check state listeners. * <p> * This method is typically used when restoring the interesting * state of a viewer captured by an earlier call to <code>getCheckedElements</code>. * </p> * * @param elements the list of checked elements (element type: <code>Object</code>) * @see #getCheckedElements */ public void setCheckedElements(Object[] elements) { assertElementsNotNull(elements); CustomHashtable set = newHashtable(elements.length * 2 + 1); for (Object element : elements) { set.put(element, element); } TableItem[] items = getTable().getItems(); for (TableItem item : items) { Object element = item.getData(); if (element != null) { boolean check = set.containsKey(element); // only set if different, to avoid flicker if (item.getChecked() != check) { item.setChecked(check); } } } } /** * Sets the grayed state for the given element in this viewer. * * @param element the element * @param state <code>true</code> if the item should be grayed, * and <code>false</code> if it should be ungrayed * @return <code>true</code> if the element is visible and the gray * state could be set, and <code>false</code> otherwise */ public boolean setGrayed(Object element, boolean state) { Assert.isNotNull(element); Widget widget = findItem(element); if (widget instanceof TableItem) { TableItem item = (TableItem) widget; if (item.getGrayed() != state) item.setGrayed(state); return true; } return false; } /** * Sets which nodes are grayed in this viewer. * The given list contains the elements that are to be grayed; * all other nodes are to be ungrayed. * <p> * This method is typically used when restoring the interesting * state of a viewer captured by an earlier call to <code>getGrayedElements</code>. * </p> * * @param elements the array of grayed elements * * @see #getGrayedElements */ public void setGrayedElements(Object... elements) { assertElementsNotNull(elements); CustomHashtable set = newHashtable(elements.length * 2 + 1); for (Object element : elements) { set.put(element, element); } TableItem[] items = getTable().getItems(); for (TableItem item : items) { Object element = item.getData(); if (element != null) { boolean gray = set.containsKey(element); // only set if different, to avoid flicker if (item.getGrayed() != gray) { item.setGrayed(gray); } } } } }