user/src/com/google/gwt/user/cellview/client/CellList.java - gwt - Git at Google

 /*
  * 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.core.client.GWT;
 import com.google.gwt.core.client.Scheduler;
 import com.google.gwt.dom.client.DivElement;
 import com.google.gwt.dom.client.Document;
 import com.google.gwt.dom.client.Element;
 import com.google.gwt.dom.client.EventTarget;
 import com.google.gwt.dom.client.Style.Display;
 import com.google.gwt.resources.client.ClientBundle;
 import com.google.gwt.resources.client.CssResource;
 import com.google.gwt.resources.client.CssResource.ImportedWithPrefix;
 import com.google.gwt.resources.client.ImageResource;
 import com.google.gwt.resources.client.ImageResource.ImageOptions;
 import com.google.gwt.resources.client.ImageResource.RepeatStyle;
 import com.google.gwt.safehtml.client.SafeHtmlTemplates;
 import com.google.gwt.safehtml.shared.SafeHtml;
 import com.google.gwt.safehtml.shared.SafeHtmlBuilder;
 import com.google.gwt.safehtml.shared.SafeHtmlUtils;
 import com.google.gwt.user.cellview.client.HasDataPresenter.LoadingState;
 import com.google.gwt.user.client.Event;
 import com.google.gwt.view.client.CellPreviewEvent;
 import com.google.gwt.view.client.ProvidesKey;
 import com.google.gwt.view.client.SelectionModel;

 import java.util.List;
 import java.util.Set;

 /**
  * A single column list of cells.
  *
  * <p>
  * <h3>Examples</h3>
  * <dl>
  * <dt>Trivial example</dt>
  * <dd>{@example com.google.gwt.examples.cellview.CellListExample}</dd>
  * <dt>ValueUpdater example</dt>
  * <dd>{@example com.google.gwt.examples.cellview.CellListValueUpdaterExample}</dd>
  * <dt>Key provider example</dt>
  * <dd>{@example com.google.gwt.examples.view.KeyProviderExample}</dd>
  * </dl>
  * </p>
  *
  * @param <T> the data type of list items
  */
 public class CellList<T> extends AbstractHasData<T> {

   /**
    * A ClientBundle that provides images for this widget.
    */
   public interface Resources extends ClientBundle {
     /**
      * The background used for selected items.
      */
     @ImageOptions(repeatStyle = RepeatStyle.Horizontal, flipRtl = true)
     ImageResource cellListSelectedBackground();

     /**
      * The styles used in this widget.
      */
     @Source(Style.DEFAULT_CSS)
     Style cellListStyle();
   }

   /**
    * Styles used by this widget.
    */
   @ImportedWithPrefix("gwt-CellList")
   public interface Style extends CssResource {
     /**
      * The path to the default CSS styles used by this resource.
      */
     String DEFAULT_CSS = "com/google/gwt/user/cellview/client/CellList.css";

     /**
      * Applied to even items.
      */
     String cellListEvenItem();

     /**
      * Applied to the keyboard selected item.
      */
     String cellListKeyboardSelectedItem();

     /**
      * Applied to odd items.
      */
     String cellListOddItem();

     /**
      * Applied to selected items.
      */
     String cellListSelectedItem();

     /**
      * Applied to the widget.
      */
     String cellListWidget();
   }

   interface Template extends SafeHtmlTemplates {
     @Template("<div onclick=\"\" __idx=\"{0}\" class=\"{1}\" style=\"outline:none;\" >{2}</div>")
     SafeHtml div(int idx, String classes, SafeHtml cellContents);

     @Template("<div onclick=\"\" __idx=\"{0}\" class=\"{1}\" style=\"outline:none;\" tabindex=\"{2}\">{3}</div>")
     SafeHtml divFocusable(int idx, String classes, int tabIndex,
         SafeHtml cellContents);

     @Template("<div onclick=\"\" __idx=\"{0}\" class=\"{1}\" style=\"outline:none;\" tabindex=\"{2}\" accesskey=\"{3}\">{4}</div>")
     SafeHtml divFocusableWithKey(int idx, String classes, int tabIndex,
         char accessKey, SafeHtml cellContents);
   }

   /**
    * The default page size.
    */
   private static final int DEFAULT_PAGE_SIZE = 25;

   private static Resources DEFAULT_RESOURCES;

   private static final Template TEMPLATE = GWT.create(Template.class);

   private static Resources getDefaultResources() {
     if (DEFAULT_RESOURCES == null) {
       DEFAULT_RESOURCES = GWT.create(Resources.class);
     }
     return DEFAULT_RESOURCES;
   }

   private final Cell<T> cell;
   private boolean cellIsEditing;
   private final Element childContainer;

   private SafeHtml emptyListMessage = SafeHtmlUtils.fromSafeConstant("");
   private final Element emptyMessageElem;

   private final Style style;

   private ValueUpdater<T> valueUpdater;

   /**
    * Construct a new {@link CellList}.
    *
    * @param cell the cell used to render each item
    */
   public CellList(final Cell<T> cell) {
     this(cell, getDefaultResources(), null);
   }

   /**
    * Construct a new {@link CellList} with the specified {@link Resources}.
    *
    * @param cell the cell used to render each item
    * @param resources the resources used for this widget
    */
   public CellList(final Cell<T> cell, Resources resources) {
     this(cell, resources, null);
   }

   /**
    * Construct a new {@link CellList} with the specified {@link ProvidesKey key provider}.
    *
    * @param cell the cell used to render each item
    * @param keyProvider an instance of ProvidesKey<T>, or null if the record
    *        object should act as its own key
    */
   public CellList(final Cell<T> cell, ProvidesKey<T> keyProvider) {
     this(cell, getDefaultResources(), keyProvider);
   }

   /**
    * Construct a new {@link CellList} with the specified {@link Resources}
    * and {@link ProvidesKey key provider}.
    *
    * @param cell the cell used to render each item
    * @param resources the resources used for this widget
    * @param keyProvider an instance of ProvidesKey<T>, or null if the record
    *        object should act as its own key
    */
   public CellList(final Cell<T> cell, Resources resources, ProvidesKey<T> keyProvider) {
     super(Document.get().createDivElement(), DEFAULT_PAGE_SIZE, keyProvider);
     this.cell = cell;
     this.style = resources.cellListStyle();
     this.style.ensureInjected();

     String widgetStyle = this.style.cellListWidget();
     if (widgetStyle != null) {
       // The widget style is null when used in CellBrowser.
       addStyleName(widgetStyle);
     }

     // Create the DOM hierarchy.
     childContainer = Document.get().createDivElement();

     emptyMessageElem = Document.get().createDivElement();
     showOrHide(emptyMessageElem, false);

     DivElement outerDiv = getElement().cast();
     outerDiv.appendChild(childContainer);
     outerDiv.appendChild(emptyMessageElem);

     // Sink events that the cell consumes.
     CellBasedWidgetImpl.get().sinkEvents(this, cell.getConsumedEvents());
   }

   /**
    * Get the message that is displayed when there is no data.
    *
    * @return the empty message
    * @see #setEmptyListMessage(SafeHtml)
    */
   public SafeHtml getEmptyListMessage() {
     return emptyListMessage;
   }

   /**
    * Get the {@link Element} for the specified index. If the element has not
    * been created, null is returned.
    *
    * @param indexOnPage the index on the page
    * @return the element, or null if it doesn't exists
    * @throws IndexOutOfBoundsException if the index is outside of the current
    *           page
    */
   public Element getRowElement(int indexOnPage) {
     getPresenter().flush();
     checkRowBounds(indexOnPage);
     if (childContainer.getChildCount() > indexOnPage) {
       return childContainer.getChild(indexOnPage).cast();
     }
     return null;
   }

   /**
    * Set the message to display when there is no data.
    *
    * @param html the message to display when there are no results
    * @see #getEmptyListMessage()
    */
   public void setEmptyListMessage(SafeHtml html) {
     this.emptyListMessage = html;
     emptyMessageElem.setInnerHTML(html.asString());
   }

   /**
    * Set the value updater to use when cells modify items.
    *
    * @param valueUpdater the {@link ValueUpdater}
    */
   public void setValueUpdater(ValueUpdater<T> valueUpdater) {
     this.valueUpdater = valueUpdater;
   }

   @Override
   protected boolean dependsOnSelection() {
     return cell.dependsOnSelection();
   }

   /**
    * Called when a user action triggers selection.
    *
    * @param event the event that triggered selection
    * @param value the value that was selected
    * @param indexOnPage the index of the value on the page
    * @deprecated use
    *             {@link #addCellPreviewHandler(com.google.gwt.view.client.CellPreviewEvent.Handler)}
    *             instead
    */
   @Deprecated
   protected void doSelection(Event event, T value, int indexOnPage) {
   }

   /**
    * Fire an event to the cell.
    *
    * @param context the {@link Context} of the cell
    * @param event the event that was fired
    * @param parent the parent of the cell
    * @param value the value of the cell
    */
   protected void fireEventToCell(Context context, Event event, Element parent,
       T value) {
     Set<String> consumedEvents = cell.getConsumedEvents();
     if (consumedEvents != null && consumedEvents.contains(event.getType())) {
       boolean cellWasEditing = cell.isEditing(context, parent, value);
       cell.onBrowserEvent(context, parent, value, event, valueUpdater);
       cellIsEditing = cell.isEditing(context, parent, value);
       if (cellWasEditing && !cellIsEditing) {
         CellBasedWidgetImpl.get().resetFocus(new Scheduler.ScheduledCommand() {
           public void execute() {
             setFocus(true);
           }
         });
       }
     }
   }

   /**
    * Return the cell used to render each item.
    */
   protected Cell<T> getCell() {
     return cell;
   }

   /**
    * Get the parent element that wraps the cell from the list item. Override
    * this method if you add structure to the element.
    *
    * @param item the row element that wraps the list item
    * @return the parent element of the cell
    */
   protected Element getCellParent(Element item) {
     return item;
   }

   @Override
   protected Element getChildContainer() {
     return childContainer;
   }

   @Override
   protected Element getKeyboardSelectedElement() {
     // Do not use getRowElement() because that will flush the presenter.
     int rowIndex = getKeyboardSelectedRow();
     if (rowIndex >= 0 && childContainer.getChildCount() > rowIndex) {
       return childContainer.getChild(rowIndex).cast();
     }
     return null;
   }

   @Override
   protected boolean isKeyboardNavigationSuppressed() {
     return cellIsEditing;
   }

   @Override
   protected void onBlur() {
     // Remove the keyboard selection style.
     Element elem = getKeyboardSelectedElement();
     if (elem != null) {
       elem.removeClassName(style.cellListKeyboardSelectedItem());
     }
   }

   @SuppressWarnings("deprecation")
   @Override
   protected void onBrowserEvent2(Event event) {
     // Get the event target.
     EventTarget eventTarget = event.getEventTarget();
     if (!Element.is(eventTarget)) {
       return;
     }
     final Element target = event.getEventTarget().cast();

     // Forward the event to the cell.
     String idxString = "";
     Element cellTarget = target;
     while ((cellTarget != null)
         && ((idxString = cellTarget.getAttribute("__idx")).length() == 0)) {
       cellTarget = cellTarget.getParentElement();
     }
     if (idxString.length() > 0) {
       // Select the item if the cell does not consume events. Selection occurs
       // before firing the event to the cell in case the cell operates on the
       // currently selected item.
       String eventType = event.getType();
       boolean isClick = "click".equals(eventType);
       int idx = Integer.parseInt(idxString);
       int indexOnPage = idx - getPageStart();
       if (!isRowWithinBounds(indexOnPage)) {
         // If the event causes us to page, then the index will be out of bounds.
         return;
       }

       // Get the cell parent before doing selection in case the list is redrawn.
       boolean isSelectionHandled = cell.handlesSelection()
           || KeyboardSelectionPolicy.BOUND_TO_SELECTION == getKeyboardSelectionPolicy();
       Element cellParent = getCellParent(cellTarget);
       T value = getVisibleItem(indexOnPage);
       Context context = new Context(idx, 0, getValueKey(value));
       CellPreviewEvent<T> previewEvent = CellPreviewEvent.fire(this, event,
           this, context, value, cellIsEditing, isSelectionHandled);
       if (isClick && !cellIsEditing && !isSelectionHandled) {
         doSelection(event, value, indexOnPage);
       }

       // Focus on the cell.
       if (isClick) {
         /*
          * If the selected element is natively focusable, then we do not want to
          * steal focus away from it.
          */
         boolean isFocusable = CellBasedWidgetImpl.get().isFocusable(target);
         isFocused = isFocused || isFocusable;
         getPresenter().setKeyboardSelectedRow(indexOnPage, !isFocusable, false);
       }

       // Fire the event to the cell if the list has not been refreshed.
       if (!previewEvent.isCanceled()) {
         fireEventToCell(context, event, cellParent, value);
       }
     }
   }

   @Override
   protected void onFocus() {
     // Add the keyboard selection style.
     Element elem = getKeyboardSelectedElement();
     if (elem != null) {
       elem.addClassName(style.cellListKeyboardSelectedItem());
     }
   }

   @Override
   protected void renderRowValues(SafeHtmlBuilder sb, List<T> values, int start,
       SelectionModel<? super T> selectionModel) {
     String keyboardSelectedItem = " " + style.cellListKeyboardSelectedItem();
     String selectedItem = " " + style.cellListSelectedItem();
     String evenItem = style.cellListEvenItem();
     String oddItem = style.cellListOddItem();
     int keyboardSelectedRow = getKeyboardSelectedRow() + getPageStart();
     int length = values.size();
     int end = start + length;
     for (int i = start; i < end; i++) {
       T value = values.get(i - start);
       boolean isSelected = selectionModel == null ? false
           : selectionModel.isSelected(value);

       StringBuilder classesBuilder = new StringBuilder();
       classesBuilder.append(i % 2 == 0 ? evenItem : oddItem);
       if (isSelected) {
         classesBuilder.append(selectedItem);
       }

       SafeHtmlBuilder cellBuilder = new SafeHtmlBuilder();
       Context context = new Context(i, 0, getValueKey(value));
       cell.render(context, value, cellBuilder);

       if (i == keyboardSelectedRow) {
         // This is the focused item.
         if (isFocused) {
           classesBuilder.append(keyboardSelectedItem);
         }
         char accessKey = getAccessKey();
         if (accessKey != 0) {
           sb.append(TEMPLATE.divFocusableWithKey(i, classesBuilder.toString(),
               getTabIndex(), accessKey, cellBuilder.toSafeHtml()));
         } else {
           sb.append(TEMPLATE.divFocusable(i, classesBuilder.toString(),
               getTabIndex(), cellBuilder.toSafeHtml()));
         }
       } else {
         sb.append(TEMPLATE.div(i, classesBuilder.toString(),
             cellBuilder.toSafeHtml()));
       }
     }
   }

   @Override
   protected boolean resetFocusOnCell() {
     int row = getKeyboardSelectedRow();
     if (isRowWithinBounds(row)) {
       Element rowElem = getKeyboardSelectedElement();
       Element cellParent = getCellParent(rowElem);
       T value = getVisibleItem(row);
       Context context = new Context(row + getPageStart(), 0, getValueKey(value));
       return cell.resetFocus(context, cellParent, value);
     }
     return false;
   }

   @Override
   protected void setKeyboardSelected(int index, boolean selected,
       boolean stealFocus) {
     if (!isRowWithinBounds(index)) {
       return;
     }

     Element elem = getRowElement(index);
     if (!selected || isFocused || stealFocus) {
       setStyleName(elem, style.cellListKeyboardSelectedItem(), selected);
     }
     setFocusable(elem, selected);
     if (selected && stealFocus && !cellIsEditing) {
       elem.focus();
       onFocus();
     }
   }

   /**
    * @deprecated this method is never called by AbstractHasData, render the
    *             selected styles in
    *             {@link #renderRowValues(SafeHtmlBuilder, List, int, SelectionModel)}
    */
   @Override
   @Deprecated
   protected void setSelected(Element elem, boolean selected) {
     setStyleName(elem, style.cellListSelectedItem(), selected);
   }

   @Override
   void setLoadingState(LoadingState state) {
     showOrHide(emptyMessageElem, state == LoadingState.EMPTY);
     // TODO(jlabanca): Add a loading icon.
   }

   /**
    * Show or hide an element.
    *
    * @param element the element
    * @param show true to show, false to hide
    */
   private void showOrHide(Element element, boolean show) {
     if (show) {
       element.getStyle().clearDisplay();
     } else {
       element.getStyle().setDisplay(Display.NONE);
     }
   }
 }
	/*
	* 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.core.client.GWT;
	import com.google.gwt.core.client.Scheduler;
	import com.google.gwt.dom.client.DivElement;
	import com.google.gwt.dom.client.Document;
	import com.google.gwt.dom.client.Element;
	import com.google.gwt.dom.client.EventTarget;
	import com.google.gwt.dom.client.Style.Display;
	import com.google.gwt.resources.client.ClientBundle;
	import com.google.gwt.resources.client.CssResource;
	import com.google.gwt.resources.client.CssResource.ImportedWithPrefix;
	import com.google.gwt.resources.client.ImageResource;
	import com.google.gwt.resources.client.ImageResource.ImageOptions;
	import com.google.gwt.resources.client.ImageResource.RepeatStyle;
	import com.google.gwt.safehtml.client.SafeHtmlTemplates;
	import com.google.gwt.safehtml.shared.SafeHtml;
	import com.google.gwt.safehtml.shared.SafeHtmlBuilder;
	import com.google.gwt.safehtml.shared.SafeHtmlUtils;
	import com.google.gwt.user.cellview.client.HasDataPresenter.LoadingState;
	import com.google.gwt.user.client.Event;
	import com.google.gwt.view.client.CellPreviewEvent;
	import com.google.gwt.view.client.ProvidesKey;
	import com.google.gwt.view.client.SelectionModel;

	import java.util.List;
	import java.util.Set;

	/**
	* A single column list of cells.
	*
	* <p>
	* <h3>Examples</h3>
	* <dl>
	* <dt>Trivial example</dt>
	* <dd>{@example com.google.gwt.examples.cellview.CellListExample}</dd>
	* <dt>ValueUpdater example</dt>
	* <dd>{@example com.google.gwt.examples.cellview.CellListValueUpdaterExample}</dd>
	* <dt>Key provider example</dt>
	* <dd>{@example com.google.gwt.examples.view.KeyProviderExample}</dd>
	* </dl>
	* </p>
	*
	* @param <T> the data type of list items
	*/
	public class CellList<T> extends AbstractHasData<T> {

	/**
	* A ClientBundle that provides images for this widget.
	*/
	public interface Resources extends ClientBundle {
	/**
	* The background used for selected items.
	*/
	@ImageOptions(repeatStyle = RepeatStyle.Horizontal, flipRtl = true)
	ImageResource cellListSelectedBackground();

	/**
	* The styles used in this widget.
	*/
	@Source(Style.DEFAULT_CSS)
	Style cellListStyle();
	}

	/**
	* Styles used by this widget.
	*/
	@ImportedWithPrefix("gwt-CellList")
	public interface Style extends CssResource {
	/**
	* The path to the default CSS styles used by this resource.
	*/
	String DEFAULT_CSS = "com/google/gwt/user/cellview/client/CellList.css";

	/**
	* Applied to even items.
	*/
	String cellListEvenItem();

	/**
	* Applied to the keyboard selected item.
	*/
	String cellListKeyboardSelectedItem();

	/**
	* Applied to odd items.
	*/
	String cellListOddItem();

	/**
	* Applied to selected items.
	*/
	String cellListSelectedItem();

	/**
	* Applied to the widget.
	*/
	String cellListWidget();
	}

	interface Template extends SafeHtmlTemplates {
	@Template("<div onclick=\"\" __idx=\"{0}\" class=\"{1}\" style=\"outline:none;\" >{2}</div>")
	SafeHtml div(int idx, String classes, SafeHtml cellContents);

	@Template("<div onclick=\"\" __idx=\"{0}\" class=\"{1}\" style=\"outline:none;\" tabindex=\"{2}\">{3}</div>")
	SafeHtml divFocusable(int idx, String classes, int tabIndex,
	SafeHtml cellContents);

	@Template("<div onclick=\"\" __idx=\"{0}\" class=\"{1}\" style=\"outline:none;\" tabindex=\"{2}\" accesskey=\"{3}\">{4}</div>")
	SafeHtml divFocusableWithKey(int idx, String classes, int tabIndex,
	char accessKey, SafeHtml cellContents);
	}

	/**
	* The default page size.
	*/
	private static final int DEFAULT_PAGE_SIZE = 25;

	private static Resources DEFAULT_RESOURCES;

	private static final Template TEMPLATE = GWT.create(Template.class);

	private static Resources getDefaultResources() {
	if (DEFAULT_RESOURCES == null) {
	DEFAULT_RESOURCES = GWT.create(Resources.class);
	}
	return DEFAULT_RESOURCES;
	}

	private final Cell<T> cell;
	private boolean cellIsEditing;
	private final Element childContainer;

	private SafeHtml emptyListMessage = SafeHtmlUtils.fromSafeConstant("");
	private final Element emptyMessageElem;

	private final Style style;

	private ValueUpdater<T> valueUpdater;

	/**
	* Construct a new {@link CellList}.
	*
	* @param cell the cell used to render each item
	*/
	public CellList(final Cell<T> cell) {
	this(cell, getDefaultResources(), null);
	}

	/**
	* Construct a new {@link CellList} with the specified {@link Resources}.
	*
	* @param cell the cell used to render each item
	* @param resources the resources used for this widget
	*/
	public CellList(final Cell<T> cell, Resources resources) {
	this(cell, resources, null);
	}

	/**
	* Construct a new {@link CellList} with the specified {@link ProvidesKey key provider}.
	*
	* @param cell the cell used to render each item
	* @param keyProvider an instance of ProvidesKey<T>, or null if the record
	* object should act as its own key
	*/
	public CellList(final Cell<T> cell, ProvidesKey<T> keyProvider) {
	this(cell, getDefaultResources(), keyProvider);
	}

	/**
	* Construct a new {@link CellList} with the specified {@link Resources}
	* and {@link ProvidesKey key provider}.
	*
	* @param cell the cell used to render each item
	* @param resources the resources used for this widget
	* @param keyProvider an instance of ProvidesKey<T>, or null if the record
	* object should act as its own key
	*/
	public CellList(final Cell<T> cell, Resources resources, ProvidesKey<T> keyProvider) {
	super(Document.get().createDivElement(), DEFAULT_PAGE_SIZE, keyProvider);
	this.cell = cell;
	this.style = resources.cellListStyle();
	this.style.ensureInjected();

	String widgetStyle = this.style.cellListWidget();
	if (widgetStyle != null) {
	// The widget style is null when used in CellBrowser.
	addStyleName(widgetStyle);
	}

	// Create the DOM hierarchy.
	childContainer = Document.get().createDivElement();

	emptyMessageElem = Document.get().createDivElement();
	showOrHide(emptyMessageElem, false);

	DivElement outerDiv = getElement().cast();
	outerDiv.appendChild(childContainer);
	outerDiv.appendChild(emptyMessageElem);

	// Sink events that the cell consumes.
	CellBasedWidgetImpl.get().sinkEvents(this, cell.getConsumedEvents());
	}

	/**
	* Get the message that is displayed when there is no data.
	*
	* @return the empty message
	* @see #setEmptyListMessage(SafeHtml)
	*/
	public SafeHtml getEmptyListMessage() {
	return emptyListMessage;
	}

	/**
	* Get the {@link Element} for the specified index. If the element has not
	* been created, null is returned.
	*
	* @param indexOnPage the index on the page
	* @return the element, or null if it doesn't exists
	* @throws IndexOutOfBoundsException if the index is outside of the current
	* page
	*/
	public Element getRowElement(int indexOnPage) {
	getPresenter().flush();
	checkRowBounds(indexOnPage);
	if (childContainer.getChildCount() > indexOnPage) {
	return childContainer.getChild(indexOnPage).cast();
	}
	return null;
	}

	/**
	* Set the message to display when there is no data.
	*
	* @param html the message to display when there are no results
	* @see #getEmptyListMessage()
	*/
	public void setEmptyListMessage(SafeHtml html) {
	this.emptyListMessage = html;
	emptyMessageElem.setInnerHTML(html.asString());
	}

	/**
	* Set the value updater to use when cells modify items.
	*
	* @param valueUpdater the {@link ValueUpdater}
	*/
	public void setValueUpdater(ValueUpdater<T> valueUpdater) {
	this.valueUpdater = valueUpdater;
	}

	@Override
	protected boolean dependsOnSelection() {
	return cell.dependsOnSelection();
	}

	/**
	* Called when a user action triggers selection.
	*
	* @param event the event that triggered selection
	* @param value the value that was selected
	* @param indexOnPage the index of the value on the page
	* @deprecated use
	* {@link #addCellPreviewHandler(com.google.gwt.view.client.CellPreviewEvent.Handler)}
	* instead
	*/
	@Deprecated
	protected void doSelection(Event event, T value, int indexOnPage) {
	}

	/**
	* Fire an event to the cell.
	*
	* @param context the {@link Context} of the cell
	* @param event the event that was fired
	* @param parent the parent of the cell
	* @param value the value of the cell
	*/
	protected void fireEventToCell(Context context, Event event, Element parent,
	T value) {
	Set<String> consumedEvents = cell.getConsumedEvents();
	if (consumedEvents != null && consumedEvents.contains(event.getType())) {
	boolean cellWasEditing = cell.isEditing(context, parent, value);
	cell.onBrowserEvent(context, parent, value, event, valueUpdater);
	cellIsEditing = cell.isEditing(context, parent, value);
	if (cellWasEditing && !cellIsEditing) {
	CellBasedWidgetImpl.get().resetFocus(new Scheduler.ScheduledCommand() {
	public void execute() {
	setFocus(true);
	}
	});
	}
	}
	}

	/**
	* Return the cell used to render each item.
	*/
	protected Cell<T> getCell() {
	return cell;
	}

	/**
	* Get the parent element that wraps the cell from the list item. Override
	* this method if you add structure to the element.
	*
	* @param item the row element that wraps the list item
	* @return the parent element of the cell
	*/
	protected Element getCellParent(Element item) {
	return item;
	}

	@Override
	protected Element getChildContainer() {
	return childContainer;
	}

	@Override
	protected Element getKeyboardSelectedElement() {
	// Do not use getRowElement() because that will flush the presenter.
	int rowIndex = getKeyboardSelectedRow();
	if (rowIndex >= 0 && childContainer.getChildCount() > rowIndex) {
	return childContainer.getChild(rowIndex).cast();
	}
	return null;
	}

	@Override
	protected boolean isKeyboardNavigationSuppressed() {
	return cellIsEditing;
	}

	@Override
	protected void onBlur() {
	// Remove the keyboard selection style.
	Element elem = getKeyboardSelectedElement();
	if (elem != null) {
	elem.removeClassName(style.cellListKeyboardSelectedItem());
	}
	}

	@SuppressWarnings("deprecation")
	@Override
	protected void onBrowserEvent2(Event event) {
	// Get the event target.
	EventTarget eventTarget = event.getEventTarget();
	if (!Element.is(eventTarget)) {
	return;
	}
	final Element target = event.getEventTarget().cast();

	// Forward the event to the cell.
	String idxString = "";
	Element cellTarget = target;
	while ((cellTarget != null)
	&& ((idxString = cellTarget.getAttribute("__idx")).length() == 0)) {
	cellTarget = cellTarget.getParentElement();
	}
	if (idxString.length() > 0) {
	// Select the item if the cell does not consume events. Selection occurs
	// before firing the event to the cell in case the cell operates on the
	// currently selected item.
	String eventType = event.getType();
	boolean isClick = "click".equals(eventType);
	int idx = Integer.parseInt(idxString);
	int indexOnPage = idx - getPageStart();
	if (!isRowWithinBounds(indexOnPage)) {
	// If the event causes us to page, then the index will be out of bounds.
	return;
	}

	// Get the cell parent before doing selection in case the list is redrawn.
	boolean isSelectionHandled = cell.handlesSelection()
	\|\| KeyboardSelectionPolicy.BOUND_TO_SELECTION == getKeyboardSelectionPolicy();
	Element cellParent = getCellParent(cellTarget);
	T value = getVisibleItem(indexOnPage);
	Context context = new Context(idx, 0, getValueKey(value));
	CellPreviewEvent<T> previewEvent = CellPreviewEvent.fire(this, event,
	this, context, value, cellIsEditing, isSelectionHandled);
	if (isClick && !cellIsEditing && !isSelectionHandled) {
	doSelection(event, value, indexOnPage);
	}

	// Focus on the cell.
	if (isClick) {
	/*
	* If the selected element is natively focusable, then we do not want to
	* steal focus away from it.
	*/
	boolean isFocusable = CellBasedWidgetImpl.get().isFocusable(target);
	isFocused = isFocused \|\| isFocusable;
	getPresenter().setKeyboardSelectedRow(indexOnPage, !isFocusable, false);
	}

	// Fire the event to the cell if the list has not been refreshed.
	if (!previewEvent.isCanceled()) {
	fireEventToCell(context, event, cellParent, value);
	}
	}
	}

	@Override
	protected void onFocus() {
	// Add the keyboard selection style.
	Element elem = getKeyboardSelectedElement();
	if (elem != null) {
	elem.addClassName(style.cellListKeyboardSelectedItem());
	}
	}

	@Override
	protected void renderRowValues(SafeHtmlBuilder sb, List<T> values, int start,
	SelectionModel<? super T> selectionModel) {
	String keyboardSelectedItem = " " + style.cellListKeyboardSelectedItem();
	String selectedItem = " " + style.cellListSelectedItem();
	String evenItem = style.cellListEvenItem();
	String oddItem = style.cellListOddItem();
	int keyboardSelectedRow = getKeyboardSelectedRow() + getPageStart();
	int length = values.size();
	int end = start + length;
	for (int i = start; i < end; i++) {
	T value = values.get(i - start);
	boolean isSelected = selectionModel == null ? false
	: selectionModel.isSelected(value);

	StringBuilder classesBuilder = new StringBuilder();
	classesBuilder.append(i % 2 == 0 ? evenItem : oddItem);
	if (isSelected) {
	classesBuilder.append(selectedItem);
	}

	SafeHtmlBuilder cellBuilder = new SafeHtmlBuilder();
	Context context = new Context(i, 0, getValueKey(value));
	cell.render(context, value, cellBuilder);

	if (i == keyboardSelectedRow) {
	// This is the focused item.
	if (isFocused) {
	classesBuilder.append(keyboardSelectedItem);
	}
	char accessKey = getAccessKey();
	if (accessKey != 0) {
	sb.append(TEMPLATE.divFocusableWithKey(i, classesBuilder.toString(),
	getTabIndex(), accessKey, cellBuilder.toSafeHtml()));
	} else {
	sb.append(TEMPLATE.divFocusable(i, classesBuilder.toString(),
	getTabIndex(), cellBuilder.toSafeHtml()));
	}
	} else {
	sb.append(TEMPLATE.div(i, classesBuilder.toString(),
	cellBuilder.toSafeHtml()));
	}
	}
	}

	@Override
	protected boolean resetFocusOnCell() {
	int row = getKeyboardSelectedRow();
	if (isRowWithinBounds(row)) {
	Element rowElem = getKeyboardSelectedElement();
	Element cellParent = getCellParent(rowElem);
	T value = getVisibleItem(row);
	Context context = new Context(row + getPageStart(), 0, getValueKey(value));
	return cell.resetFocus(context, cellParent, value);
	}
	return false;
	}

	@Override
	protected void setKeyboardSelected(int index, boolean selected,
	boolean stealFocus) {
	if (!isRowWithinBounds(index)) {
	return;
	}

	Element elem = getRowElement(index);
	if (!selected \|\| isFocused \|\| stealFocus) {
	setStyleName(elem, style.cellListKeyboardSelectedItem(), selected);
	}
	setFocusable(elem, selected);
	if (selected && stealFocus && !cellIsEditing) {
	elem.focus();
	onFocus();
	}
	}

	/**
	* @deprecated this method is never called by AbstractHasData, render the
	* selected styles in
	* {@link #renderRowValues(SafeHtmlBuilder, List, int, SelectionModel)}
	*/
	@Override
	@Deprecated
	protected void setSelected(Element elem, boolean selected) {
	setStyleName(elem, style.cellListSelectedItem(), selected);
	}

	@Override
	void setLoadingState(LoadingState state) {
	showOrHide(emptyMessageElem, state == LoadingState.EMPTY);
	// TODO(jlabanca): Add a loading icon.
	}

	/**
	* Show or hide an element.
	*
	* @param element the element
	* @param show true to show, false to hide
	*/
	private void showOrHide(Element element, boolean show) {
	if (show) {
	element.getStyle().clearDisplay();
	} else {
	element.getStyle().setDisplay(Display.NONE);
	}
	}
	}