com.google.gwt.cell.client.AbstractCell Maven / Gradle / Ivy
/*
* Copyright 2010 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.gwt.cell.client;
import com.google.gwt.dom.client.BrowserEvents;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.NativeEvent;
import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.safehtml.shared.SafeHtmlBuilder;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
/**
* A default implementation of the {@link Cell} interface.
*
*
*
Examples
*
* - Read only cell
* - {@example com.google.gwt.examples.cell.CellExample}
* - Cell with events
* - {@example com.google.gwt.examples.cell.CellWithEventsExample}
* - Interactive cell
* - {@example com.google.gwt.examples.cell.InteractionCellExample}
* - Editable cell
* - {@example com.google.gwt.examples.cell.EditableCellExample}
*
*
*
* @param the type that this Cell represents
*/
public abstract class AbstractCell implements Cell {
/**
* The unmodifiable set of events consumed by this cell.
*/
private Set consumedEvents;
/**
* Construct a new {@link AbstractCell} with the specified consumed events.
* The input arguments are passed by copy.
*
* @param consumedEvents the {@link com.google.gwt.dom.client.BrowserEvents
* events} that this cell consumes
*
* @see com.google.gwt.dom.client.BrowserEvents
*/
public AbstractCell(String... consumedEvents) {
Set events = null;
if (consumedEvents != null && consumedEvents.length > 0) {
events = new HashSet();
for (String event : consumedEvents) {
events.add(event);
}
}
init(events);
}
/**
* Construct a new {@link AbstractCell} with the specified consumed events.
*
* @param consumedEvents the events that this cell consumes
*/
public AbstractCell(Set consumedEvents) {
init(consumedEvents);
}
public boolean dependsOnSelection() {
return false;
}
public Set getConsumedEvents() {
return consumedEvents;
}
public boolean handlesSelection() {
return false;
}
/**
* Returns false. Subclasses that support editing should override this method
* to return the current editing status.
*/
public boolean isEditing(Context context, Element parent, C value) {
return false;
}
/**
* {@inheritDoc}
*
*
* If you override this method to add support for events, remember to pass the
* event types that the cell expects into the constructor.
*
*/
public void onBrowserEvent(Context context, Element parent, C value,
NativeEvent event, ValueUpdater valueUpdater) {
String eventType = event.getType();
// Special case the ENTER key for a unified user experience.
if (BrowserEvents.KEYDOWN.equals(eventType) && event.getKeyCode() == KeyCodes.KEY_ENTER) {
onEnterKeyDown(context, parent, value, event, valueUpdater);
}
}
public abstract void render(Context context, C value, SafeHtmlBuilder sb);
/**
* {@inheritDoc}
*
*
* This method is a no-op and returns false. If your cell is editable or can
* be focused by the user, override this method to reset focus when the
* containing widget is refreshed.
*
*/
public boolean resetFocus(Context context, Element parent, C value) {
return false;
}
public void setValue(Context context, Element parent, C value) {
SafeHtmlBuilder sb = new SafeHtmlBuilder();
render(context, value, sb);
parent.setInnerSafeHtml(sb.toSafeHtml());
}
/**
* Called when the user triggers a keydown event with the ENTER
* key while focused on the cell. If your cell interacts with the user, you
* should override this method to provide a consistent user experience. Your
* widget must consume keydown events for this method to be
* called.
*
* @param context the {@link Context} of the cell
* @param parent the parent Element
* @param value the value associated with the cell
* @param event the native browser event
* @param valueUpdater a {@link ValueUpdater}, or null if not specified
*/
protected void onEnterKeyDown(Context context, Element parent, C value,
NativeEvent event, ValueUpdater valueUpdater) {
}
/**
* Initialize the cell.
*
* @param consumedEvents the events that the cell consumes
*/
private void init(Set consumedEvents) {
if (consumedEvents != null) {
this.consumedEvents = Collections.unmodifiableSet(consumedEvents);
}
}
}