/*******************************************************************************
* Copyright (c) 2005, 2007 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.jface.internal.databinding.provisional.swt;
import org.eclipse.core.databinding.observable.ChangeEvent;
import org.eclipse.core.databinding.observable.IChangeListener;
import org.eclipse.core.databinding.observable.IObservable;
import org.eclipse.core.databinding.observable.ObservableTracker;
import org.eclipse.core.runtime.Assert;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.TableItem;
/**
* NON-API - This class can be used to update a table with automatic dependency tracking.
* @since 1.1
*
*/
public abstract class TableUpdater {
private class UpdateRunnable implements Runnable, IChangeListener,
DisposeListener {
private TableItem item;
private boolean dirty = false;
private IObservable[] dependencies = new IObservable[0];
UpdateRunnable(TableItem item) {
this.item = item;
item.addDisposeListener(this);
}
// Runnable implementation. This method runs at most once per repaint
// whenever the
// value gets marked as dirty.
public void run() {
if (theTable != null && !theTable.isDisposed() && item != null && !item.isDisposed()) {
if (theTable.isVisible()) {
int tableHeight = theTable.getClientArea().height;
int numVisibleItems = tableHeight / theTable.getItemHeight();
int indexOfItem = theTable.indexOf(item);
int topIndex = theTable.getTopIndex();
if (indexOfItem >= topIndex && indexOfItem <= topIndex+numVisibleItems) {
updateIfNecessary();
return;
}
}
theTable.clear(theTable.indexOf(item));
}
}
private void updateIfNecessary() {
if (dirty) {
dependencies = ObservableTracker.runAndMonitor(new Runnable() {
public void run() {
updateItem(item);
}
}, this, null);
dirty = false;
}
}
// IChangeListener implementation (listening to the ComputedValue)
public void handleChange(ChangeEvent event) {
// Whenever this updator becomes dirty, schedule the run() method
makeDirty();
}
protected final void makeDirty() {
if (!dirty) {
dirty = true;
stopListening();
SWTUtil.runOnce(theTable.getDisplay(), this);
}
}
private void stopListening() {
// Stop listening for dependency changes
for (int i = 0; i < dependencies.length; i++) {
IObservable observable = dependencies[i];
observable.removeChangeListener(this);
}
}
// DisposeListener implementation
public void widgetDisposed(DisposeEvent e) {
stopListening();
dependencies = null;
item = null;
}
}
private class PrivateInterface implements Listener, DisposeListener {
// Listener implementation
public void handleEvent(Event e) {
if (e.type == SWT.SetData) {
UpdateRunnable runnable = (UpdateRunnable) e.item.getData();
if (runnable == null) {
runnable = new UpdateRunnable((TableItem) e.item);
e.item.setData(runnable);
runnable.makeDirty();
} else {
runnable.updateIfNecessary();
}
}
}
// DisposeListener implementation
public void widgetDisposed(DisposeEvent e) {
TableUpdater.this.dispose();
}
}
private PrivateInterface privateInterface = new PrivateInterface();
private Table theTable;
/**
* Creates an updator for the given control.
*
* @param toUpdate
* table to update
*/
public TableUpdater(Table toUpdate) {
Assert.isLegal((toUpdate.getStyle() & SWT.VIRTUAL) != 0, "TableUpdater requires virtual table"); //$NON-NLS-1$
theTable = toUpdate;
theTable.addDisposeListener(privateInterface);
theTable.addListener(SWT.SetData, privateInterface);
}
/**
* This is called automatically when the control is disposed. It may also be
* called explicitly to remove this updator from the control. Subclasses
* will normally extend this method to detach any listeners they attached in
* their constructor.
*/
public void dispose() {
theTable.removeDisposeListener(privateInterface);
theTable.removeListener(SWT.SetData, privateInterface);
}
/**
* Updates the control. This method will be invoked once after the updator
* is created, and once before any repaint during which the control is
* visible and dirty.
*
* <p>
* Subclasses should overload this method to provide any code that changes
* the appearance of the widget.
* </p>
* @param item the item to update
*/
protected abstract void updateItem(TableItem item);
}