/*
* 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.user.cellview.client;
import com.google.gwt.cell.client.Cell;
import com.google.gwt.cell.client.Cell.Context;
import com.google.gwt.cell.client.ValueUpdater;
import com.google.gwt.dom.client.Document;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.Style.Unit;
import com.google.gwt.editor.client.IsEditor;
import com.google.gwt.editor.client.LeafValueEditor;
import com.google.gwt.editor.client.adapters.TakesValueEditor;
import com.google.gwt.event.logical.shared.ValueChangeEvent;
import com.google.gwt.event.logical.shared.ValueChangeHandler;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.resources.client.CommonResources;
import com.google.gwt.safehtml.shared.SafeHtmlBuilder;
import com.google.gwt.user.client.Event;
import com.google.gwt.user.client.ui.HasValue;
import com.google.gwt.user.client.ui.Widget;
import com.google.gwt.view.client.HasKeyProvider;
import com.google.gwt.view.client.ProvidesKey;
/**
* A {@link Widget} that wraps a {@link Cell}.
*
* @param <C> the type that the Cell represents
*/
public class CellWidget<C> extends Widget implements HasKeyProvider<C>, HasValue<C>,
IsEditor<LeafValueEditor<C>> {
/**
* Create the default element used to wrap the Cell. The default element is a
* div with display set to inline-block.
*
* @return the default wrapper element
*/
private static Element createDefaultWrapperElement() {
Element div = Document.get().createDivElement();
div.setClassName(CommonResources.getInlineBlockStyle());
return div;
}
/**
* The cell being wrapped.
*/
private final Cell<C> cell;
/**
* For use with the editor framework.
*/
private LeafValueEditor<C> editor;
/**
* The key provider for the value.
*/
private final ProvidesKey<C> keyProvider;
/**
* The current cell value.
*/
private C value;
/**
* The {@link ValueUpdater} used to trigger value update events.
*/
private final ValueUpdater<C> valueUpdater = new ValueUpdater<C>() {
public void update(C value) {
// no need to redraw, the Cell took care of it
setValue(value, true, false);
}
};
/**
* Construct a new {@link CellWidget} with the specified cell and an initial
* value of <code>null</code>.
*
* @param cell the cell to wrap
*/
public CellWidget(Cell<C> cell) {
this(cell, null, null);
}
/**
* Construct a new {@link CellWidget} with the specified cell and key
* provider, and an initial value of <code>null</code>.
*
* @param cell the cell to wrap
* @param keyProvider the key provider used to get keys from values
*/
public CellWidget(Cell<C> cell, ProvidesKey<C> keyProvider) {
this(cell, null, keyProvider);
}
/**
* Construct a new {@link CellWidget} with the specified cell and initial
* value.
*
* @param cell the cell to wrap
* @param initialValue the initial value of the Cell
*/
public CellWidget(Cell<C> cell, C initialValue) {
this(cell, initialValue, null);
}
/**
* Construct a new {@link CellWidget} with the specified cell, initial value,
* and key provider.
*
* @param cell the cell to wrap
* @param initialValue the initial value of the Cell
* @param keyProvider the key provider used to get keys from values
*/
public CellWidget(Cell<C> cell, C initialValue, ProvidesKey<C> keyProvider) {
this(cell, initialValue, keyProvider, createDefaultWrapperElement());
}
/**
* Creates a {@link CellWidget} with the specified cell, initial value, key
* provider, using the specified element as the wrapper around the cell.
*
* @param cell the cell to wrap
* @param initialValue the initial value of the Cell
* @param keyProvider the key provider used to get keys from values
* @param elem the browser element to use
*/
protected CellWidget(Cell<C> cell, C initialValue, ProvidesKey<C> keyProvider, Element elem) {
this.cell = cell;
this.keyProvider = keyProvider;
setElement(elem);
CellBasedWidgetImpl.get().sinkEvents(this, cell.getConsumedEvents());
setValue(initialValue);
}
public HandlerRegistration addValueChangeHandler(ValueChangeHandler<C> handler) {
return addHandler(handler, ValueChangeEvent.getType());
}
public LeafValueEditor<C> asEditor() {
if (editor == null) {
editor = TakesValueEditor.of(this);
}
return editor;
}
/**
* Get the {@link Cell} wrapped by this widget.
*
* @return the {@link Cell} being wrapped
*/
public Cell<C> getCell() {
return cell;
}
public ProvidesKey<C> getKeyProvider() {
return keyProvider;
}
public C getValue() {
return value;
}
@Override
public void onBrowserEvent(Event event) {
CellBasedWidgetImpl.get().onBrowserEvent(this, event);
super.onBrowserEvent(event);
// Forward the event to the cell.
String eventType = event.getType();
if (cell.getConsumedEvents().contains(eventType)) {
cell.onBrowserEvent(createContext(), getElement(), value, event, valueUpdater);
}
}
/**
* Redraw the widget.
*/
public void redraw() {
SafeHtmlBuilder sb = new SafeHtmlBuilder();
cell.render(createContext(), value, sb);
getElement().setInnerHTML(sb.toSafeHtml().asString());
/*
* The rendered Cell should fill the root element so height and width styles
* applied to the widget also apply to the Cell. If there is exactly one
* child element, the height and width are set to 100% to fill the parent.
*/
Element child = getElement().getFirstChildElement();
if (child != null && child.getNextSiblingElement() == null) {
child.getStyle().setHeight(100, Unit.PCT);
child.getStyle().setWidth(100, Unit.PCT);
}
}
/**
* {@inheritDoc}
* <p>
* This method will redraw the widget if the new value does not equal the
* existing value.
* </p>
*/
public void setValue(C value) {
setValue(value, false, true);
}
/**
* {@inheritDoc}
* <p>
* This method will redraw the widget if the new value does not equal the
* existing value.
* </p>
*/
public void setValue(C value, boolean fireEvents) {
setValue(value, fireEvents, true);
}
/**
* Sets this object's value and optionally redraw the widget. Fires
* {@link com.google.gwt.event.logical.shared.ValueChangeEvent} when
* fireEvents is true and the new value does not equal the existing value.
* Redraws the widget when redraw is true and the new value does not equal the
* existing value.
*
* @param value the object's new value
* @param fireEvents fire events if true and value is new
* @param redraw redraw the widget if true and value is new
*/
public void setValue(C value, boolean fireEvents, boolean redraw) {
C oldValue = getValue();
if (value != oldValue && (oldValue == null || !oldValue.equals(value))) {
this.value = value;
if (redraw) {
redraw();
}
if (fireEvents) {
ValueChangeEvent.fire(this, value);
}
}
}
/**
* Get the {@link Context} for the cell.
*/
private Context createContext() {
return new Context(0, 0, getKey(value));
}
/**
* Get the key for the specified value.
*
* @param value the value
* @return the key
*/
private Object getKey(C value) {
return (keyProvider == null || value == null) ? value : keyProvider.getKey(value);
}
}