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com.google.gwt.user.cellview.client
Class CellTree

java.lang.Object
  extended by com.google.gwt.user.client.ui.UIObject
      extended by com.google.gwt.user.client.ui.Widget
          extended by com.google.gwt.user.client.ui.Composite
              extended by com.google.gwt.user.cellview.client.AbstractCellTree
                  extended by com.google.gwt.user.cellview.client.CellTree
All Implemented Interfaces:
HasAttachHandlers, HasCloseHandlers<TreeNode>, HasOpenHandlers<TreeNode>, HasHandlers, HasKeyboardSelectionPolicy, EventListener, Focusable, HasAnimation, HasVisibility, IsRenderable, IsWidget
public class CellTree
extends AbstractCellTree
implements HasAnimation, Focusable

A view of a tree.

This widget will only work in standards mode, which requires that the HTML page in which it is run have an explicit <!DOCTYPE> declaration.

Examples

Trivial example
public class CellTreeExample implements EntryPoint {

  /**
   * The model that defines the nodes in the tree.
   */
  private static class CustomTreeModel implements TreeViewModel {

    /**
     * Get the {@link NodeInfo} that provides the children of the specified
     * value.
     */
    public <T> NodeInfo<?> getNodeInfo(T value) {
      /*
       * Create some data in a data provider. Use the parent value as a prefix
       * for the next level.
       */
      ListDataProvider<String> dataProvider = new ListDataProvider<String>();
      for (int i = 0; i < 2; i++) {
        dataProvider.getList().add(value + "." + String.valueOf(i));
      }

      // Return a node info that pairs the data with a cell.
      return new DefaultNodeInfo<String>(dataProvider, new TextCell());
    }

    /**
     * Check if the specified value represents a leaf node. Leaf nodes cannot be
     * opened.
     */
    public boolean isLeaf(Object value) {
      // The maximum length of a value is ten characters.
      return value.toString().length() > 10;
    }
  }

  public void onModuleLoad() {
    // Create a model for the tree.
    TreeViewModel model = new CustomTreeModel();

    /*
     * Create the tree using the model. We specify the default value of the
     * hidden root node as "Item 1".
     */
    CellTree tree = new CellTree(model, "Item 1");

    // Add the tree to the root layout panel.
    RootLayoutPanel.get().add(tree);
  }
}
Complex example
public class CellTreeExample2 implements EntryPoint {

  /**
   * A list of songs.
   */
  private static class Playlist {
    private final String name;
    private final List<String> songs = new ArrayList<String>();

    public Playlist(String name) {
      this.name = name;
    }

    /**
     * Add a song to the playlist.
     * 
     * @param name the name of the song
     */
    public void addSong(String name) {
      songs.add(name);
    }

    public String getName() {
      return name;
    }

    /**
     * Return the list of songs in the playlist.
     */
    public List<String> getSongs() {
      return songs;
    }
  }

  /**
   * A composer of classical music.
   */
  private static class Composer {
    private final String name;
    private final List<Playlist> playlists = new ArrayList<Playlist>();

    public Composer(String name) {
      this.name = name;
    }

    /**
     * Add a playlist to the composer.
     * 
     * @param playlist the playlist to add
     */
    public Playlist addPlaylist(Playlist playlist) {
      playlists.add(playlist);
      return playlist;
    }

    public String getName() {
      return name;
    }

    /**
     * Return the rockin' playlist for this composer.
     */
    public List<Playlist> getPlaylists() {
      return playlists;
    }
  }

  /**
   * The model that defines the nodes in the tree.
   */
  private static class CustomTreeModel implements TreeViewModel {

    private final List<Composer> composers;

    /**
     * This selection model is shared across all leaf nodes. A selection model
     * can also be shared across all nodes in the tree, or each set of child
     * nodes can have its own instance. This gives you flexibility to determine
     * how nodes are selected.
     */
    private final SingleSelectionModel<String> selectionModel = new SingleSelectionModel<String>();

    public CustomTreeModel() {
      // Create a database of information.
      composers = new ArrayList<Composer>();

      // Add compositions by Beethoven.
      {
        Composer beethoven = new Composer("Beethoven");
        composers.add(beethoven);

        Playlist concertos = beethoven.addPlaylist(new Playlist("Concertos"));
        concertos.addSong("No. 1 - C");
        concertos.addSong("No. 2 - B-Flat Major");
        concertos.addSong("No. 3 - C Minor");
        concertos.addSong("No. 4 - G Major");
        concertos.addSong("No. 5 - E-Flat Major");

        Playlist quartets = beethoven.addPlaylist(new Playlist("Quartets"));
        quartets.addSong("Six String Quartets");
        quartets.addSong("Three String Quartets");
        quartets.addSong("Grosse Fugue for String Quartets");

        Playlist sonatas = beethoven.addPlaylist(new Playlist("Sonatas"));
        sonatas.addSong("Sonata in A Minor");
        sonatas.addSong("Sonata in F Major");

        Playlist symphonies = beethoven.addPlaylist(new Playlist("Symphonies"));
        symphonies.addSong("No. 2 - D Major");
        symphonies.addSong("No. 2 - D Major");
        symphonies.addSong("No. 3 - E-Flat Major");
        symphonies.addSong("No. 4 - B-Flat Major");
        symphonies.addSong("No. 5 - C Minor");
        symphonies.addSong("No. 6 - F Major");
        symphonies.addSong("No. 7 - A Major");
        symphonies.addSong("No. 8 - F Major");
        symphonies.addSong("No. 9 - D Minor");
      }

      // Add compositions by Brahms.
      {
        Composer brahms = new Composer("Brahms");
        composers.add(brahms);
        Playlist concertos = brahms.addPlaylist(new Playlist("Concertos"));
        concertos.addSong("Violin Concerto");
        concertos.addSong("Double Concerto - A Minor");
        concertos.addSong("Piano Concerto No. 1 - D Minor");
        concertos.addSong("Piano Concerto No. 2 - B-Flat Major");

        Playlist quartets = brahms.addPlaylist(new Playlist("Quartets"));
        quartets.addSong("Piano Quartet No. 1 - G Minor");
        quartets.addSong("Piano Quartet No. 2 - A Major");
        quartets.addSong("Piano Quartet No. 3 - C Minor");
        quartets.addSong("String Quartet No. 3 - B-Flat Minor");

        Playlist sonatas = brahms.addPlaylist(new Playlist("Sonatas"));
        sonatas.addSong("Two Sonatas for Clarinet - F Minor");
        sonatas.addSong("Two Sonatas for Clarinet - E-Flat Major");

        Playlist symphonies = brahms.addPlaylist(new Playlist("Symphonies"));
        symphonies.addSong("No. 1 - C Minor");
        symphonies.addSong("No. 2 - D Minor");
        symphonies.addSong("No. 3 - F Major");
        symphonies.addSong("No. 4 - E Minor");
      }

      // Add compositions by Mozart.
      {
        Composer mozart = new Composer("Mozart");
        composers.add(mozart);
        Playlist concertos = mozart.addPlaylist(new Playlist("Concertos"));
        concertos.addSong("Piano Concerto No. 12");
        concertos.addSong("Piano Concerto No. 17");
        concertos.addSong("Clarinet Concerto");
        concertos.addSong("Violin Concerto No. 5");
        concertos.addSong("Violin Concerto No. 4");
      }
    }

    /**
     * Get the {@link NodeInfo} that provides the children of the specified
     * value.
     */
    public <T> NodeInfo<?> getNodeInfo(T value) {
      if (value == null) {
        // LEVEL 0.
        // We passed null as the root value. Return the composers.

        // Create a data provider that contains the list of composers.
        ListDataProvider<Composer> dataProvider = new ListDataProvider<CellTreeExample2.Composer>(
            composers);

        // Create a cell to display a composer.
        Cell<Composer> cell = new AbstractCell<Composer>() {
          @Override
          public void render(Context context, Composer value, SafeHtmlBuilder sb) {
            if (value != null) {
              sb.appendEscaped(value.getName());
            }
          }
        };

        // Return a node info that pairs the data provider and the cell.
        return new DefaultNodeInfo<Composer>(dataProvider, cell);
      } else if (value instanceof Composer) {
        // LEVEL 1.
        // We want the children of the composer. Return the playlists.
        ListDataProvider<Playlist> dataProvider = new ListDataProvider<Playlist>(
            ((Composer) value).getPlaylists());
        Cell<Playlist> cell = new AbstractCell<Playlist>() {
          @Override
          public void render(Context context, Playlist value, SafeHtmlBuilder sb) {
            if (value != null) {
              sb.appendEscaped(value.getName());
            }
          }
        };
        return new DefaultNodeInfo<Playlist>(dataProvider, cell);
      } else if (value instanceof Playlist) {
        // LEVEL 2 - LEAF.
        // We want the children of the playlist. Return the songs.
        ListDataProvider<String> dataProvider = new ListDataProvider<String>(
            ((Playlist) value).getSongs());

        // Use the shared selection model.
        return new DefaultNodeInfo<String>(dataProvider, new TextCell(),
            selectionModel, null);
      }

      return null;
    }

    /**
     * Check if the specified value represents a leaf node. Leaf nodes cannot be
     * opened.
     */
    public boolean isLeaf(Object value) {
      // The leaf nodes are the songs, which are Strings.
      if (value instanceof String) {
        return true;
      }
      return false;
    }

  }

  public void onModuleLoad() {
    // Create a model for the tree.
    TreeViewModel model = new CustomTreeModel();

    /*
     * Create the tree using the model. We use <code>null</code> as the default
     * value of the root node. The default value will be passed to
     * CustomTreeModel#getNodeInfo();
     */
    CellTree tree = new CellTree(model, null);
    tree.setKeyboardSelectionPolicy(KeyboardSelectionPolicy.ENABLED);

    // Open the first playlist by default.
    TreeNode rootNode = tree.getRootTreeNode();
    TreeNode firstPlaylist = rootNode.setChildOpen(0, true);
    firstPlaylist.setChildOpen(0, true);

    // Add the tree to the root layout panel.
    RootLayoutPanel.get().add(tree);
  }
}

Nested Class Summary
static interface CellTree.BasicResources
          Resources that match the GWT standard style theme.
(package private) static interface CellTree.BasicStyle
          Styles used by CellTree.BasicResources.
static interface CellTree.CellTreeMessages
          Constants for labeling the cell tree.
static class CellTree.NodeAnimation
          A node animation.
static interface CellTree.Resources
          A ClientBundle that provides images for this widget.
static class CellTree.RevealAnimation
          A CellTree.NodeAnimation that reveals the contents of child nodes.
static class CellTree.SlideAnimation
          A CellTree.NodeAnimation that slides children into view.
static interface CellTree.Style
          Styles used by this widget.
(package private) static interface CellTree.Template
           
 
Nested classes/interfaces inherited from class com.google.gwt.user.client.ui.UIObject
UIObject.DebugIdImpl, UIObject.DebugIdImplEnabled
 
Nested classes/interfaces inherited from interface com.google.gwt.user.cellview.client.HasKeyboardSelectionPolicy
HasKeyboardSelectionPolicy.KeyboardSelectionPolicy
 
Field Summary
(package private)  boolean cellIsEditing
          A boolean indicating whether or not a cell is being edited.
(package private)  boolean isFocused
          A boolean indicating that the widget has focus.
(package private)  boolean isRefreshing
          Set to true while the elements are being refreshed.
(package private)  CellTreeNodeView<?> rootNode
          The hidden root node in the tree.
 
Fields inherited from class com.google.gwt.user.client.ui.UIObject
DEBUG_ID_PREFIX
 
Constructor Summary
CellTree(TreeViewModel viewModel, T rootValue)
          Construct a new CellTree.
CellTree(TreeViewModel viewModel, T rootValue, CellTree.Resources resources)
          Construct a new CellTree.
CellTree(TreeViewModel viewModel, T rootValue, CellTree.Resources resources, CellTree.CellTreeMessages messages)
          Construct a new CellTree.
CellTree(TreeViewModel viewModel, T rootValue, CellTree.Resources resources, CellTree.CellTreeMessages messages, int defaultNodeSize)
          Construct a new CellTree.
 
Method Summary
(package private)  void cancelTreeNodeAnimation()
          Cancel a pending animation.
protected  char getAccessKey()
          Get the access key.
 CellTree.NodeAnimation getAnimation()
          Get the animation used to open and close nodes in this tree if animations are enabled.
(package private)  SafeHtml getClosedImageHtml(boolean isTop)
          Get the HTML to render the closed image.
 int getDefaultNodeSize()
          Get the default maximum number of children to display under each tree node.
(package private)  int getImageWidth()
          Get the width required for the images.
(package private)  CellTreeNodeView<?> getKeyboardSelectedNode()
          Return the node that has keyboard selection.
 TreeNode getKeyboardSelectedTreeNode()
          Returns the TreeNode that is selected when the CellTree has keyboard focus.
(package private)  SafeHtml getLoadingImageHtml()
          Return the HTML to render the loading image.
(package private)  SafeHtml getOpenImageHtml(boolean isTop)
          Get the HTML to render the open image.
 TreeNode getRootTreeNode()
          Get the root TreeNode.
(package private)  CellTree.Style getStyle()
          Return the Style used by the tree.
 int getTabIndex()
          Gets the widget's position in the tab index.
(package private)  void handleKeyNavigation(int keyCode)
          Handle keyboard navigation.
 boolean isAnimationEnabled()
          Returns true if animations are enabled, false if not.
(package private)  void keyboardSelect(CellTreeNodeView<?> node, boolean stealFocus)
          Select a node using the keyboard.
(package private)  void maybeAnimateTreeNode(CellTreeNodeView<?> node)
          Animate the current state of a CellTreeNodeView in this tree.
protected  void onBlur()
          Called when the keyboard selected node loses focus.
 void onBrowserEvent(Event event)
          Fired whenever a browser event is received.
protected  void onFocus()
          Called when the keyboard selected node gains focus.
(package private)  void resetFocus()
          If this widget has focus, reset it.
 void setAccessKey(char key)
          Sets the widget's 'access key'.
 void setAnimation(CellTree.NodeAnimation animation)
          Set the animation used to open and close nodes in this tree.
 void setAnimationEnabled(boolean enable)
          Enable or disable animations.
 void setDefaultNodeSize(int defaultNodeSize)
          Set the default number of children to display beneath each child node.
 void setFocus(boolean focused)
          Explicitly focus/unfocus this widget.
 void setKeyboardSelectedTreeNode(TreeNode parentNode, int childIndex, boolean stealFocus)
          Sets the node that will be selected when the CellTree gains keyboard focus.
 void setTabIndex(int index)
          Sets the widget's position in the tab index.
 
Methods inherited from class com.google.gwt.user.cellview.client.AbstractCellTree
addCloseHandler, addOpenHandler, getKeyboardSelectionPolicy, getNodeInfo, getTreeViewModel, isKeyboardSelectionDisabled, isLeaf, setKeyboardSelectionPolicy
 
Methods inherited from class com.google.gwt.user.client.ui.Composite
claimElement, getWidget, initializeClaimedElement, initWidget, isAttached, onAttach, onDetach, render, render, resolvePotentialElement, setWidget
 
Methods inherited from class com.google.gwt.user.client.ui.Widget
addAttachHandler, addBitlessDomHandler, addDomHandler, addHandler, asWidget, asWidgetOrNull, createHandlerManager, delegateEvent, doAttachChildren, doDetachChildren, fireEvent, getHandlerCount, getLayoutData, getParent, isOrWasAttached, onLoad, onUnload, removeFromParent, setLayoutData, sinkEvents, unsinkEvents
 
Methods inherited from class com.google.gwt.user.client.ui.UIObject
addStyleDependentName, addStyleName, ensureDebugId, ensureDebugId, ensureDebugId, getAbsoluteLeft, getAbsoluteTop, getElement, getOffsetHeight, getOffsetWidth, getStyleElement, getStyleName, getStyleName, getStylePrimaryName, getStylePrimaryName, getTitle, isVisible, isVisible, onEnsureDebugId, removeStyleDependentName, removeStyleName, setElement, setElement, setHeight, setPixelSize, setSize, setStyleDependentName, setStyleName, setStyleName, setStyleName, setStyleName, setStylePrimaryName, setStylePrimaryName, setTitle, setVisible, setVisible, setWidth, sinkBitlessEvent, toString
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface com.google.gwt.event.shared.HasHandlers
fireEvent
 

Field Detail

cellIsEditing

boolean cellIsEditing
A boolean indicating whether or not a cell is being edited.

isFocused

boolean isFocused
A boolean indicating that the widget has focus.

isRefreshing

boolean isRefreshing
Set to true while the elements are being refreshed. Events are ignored during this time.

rootNode

final CellTreeNodeView<?> rootNode
The hidden root node in the tree. Visible for testing.

Constructor Detail

CellTree

public CellTree(TreeViewModel viewModel,
                T rootValue)
Construct a new CellTree.

Type Parameters:
T - the type of data in the root node
Parameters:
viewModel - the TreeViewModel that backs the tree
rootValue - the hidden root value of the tree

CellTree

public CellTree(TreeViewModel viewModel,
                T rootValue,
                CellTree.Resources resources)
Construct a new CellTree. Uses default translations that means that messages will be always in English.

Type Parameters:
T - the type of data in the root node
Parameters:
viewModel - the TreeViewModel that backs the tree
rootValue - the hidden root value of the tree
resources - the resources used to render the tree

CellTree

public CellTree(TreeViewModel viewModel,
                T rootValue,
                CellTree.Resources resources,
                CellTree.CellTreeMessages messages)
Construct a new CellTree.

Type Parameters:
T - the type of data in the root node
Parameters:
viewModel - the TreeViewModel that backs the tree
rootValue - the hidden root value of the tree
resources - the resources used to render the tree
messages - translation messages. Users should inherit an empty interface from CellTree.CellTreeMessages and add annotations needed for their specific translation systems. Then create the new interface with GWT.create and pass as this argument.

CellTree

public CellTree(TreeViewModel viewModel,
                T rootValue,
                CellTree.Resources resources,
                CellTree.CellTreeMessages messages,
                int defaultNodeSize)
Construct a new CellTree.

Type Parameters:
T - the type of data in the root node
Parameters:
viewModel - the TreeViewModel that backs the tree
rootValue - the hidden root value of the tree
resources - the resources used to render the tree
messages - translation messages. Users should inherit an empty interface from CellTree.CellTreeMessages and add annotations needed for their specific translation systems. Then create the new interface with GWT.create and pass as this argument.
defaultNodeSize - default number of children to display beneath each child node
Method Detail

getAnimation

public CellTree.NodeAnimation getAnimation()
Get the animation used to open and close nodes in this tree if animations are enabled.

Returns:
the animation
See Also:
isAnimationEnabled(), setAnimation(NodeAnimation)

getDefaultNodeSize

public int getDefaultNodeSize()
Get the default maximum number of children to display under each tree node.

Returns:
the default node size
See Also:
setDefaultNodeSize(int)

getRootTreeNode

public TreeNode getRootTreeNode()
Description copied from class: AbstractCellTree
Get the root TreeNode.

Specified by:
getRootTreeNode in class AbstractCellTree
Returns:
the TreeNode at the root of the tree

getTabIndex

public int getTabIndex()
Description copied from interface: Focusable
Gets the widget's position in the tab index.

Specified by:
getTabIndex in interface Focusable
Returns:
the widget's tab index

isAnimationEnabled

public boolean isAnimationEnabled()
Description copied from interface: HasAnimation
Returns true if animations are enabled, false if not.

Specified by:
isAnimationEnabled in interface HasAnimation

onBrowserEvent

public void onBrowserEvent(Event event)
Description copied from interface: EventListener
Fired whenever a browser event is received.

Specified by:
onBrowserEvent in interface EventListener
Overrides:
onBrowserEvent in class Composite
Parameters:
event - the event received

setAccessKey

public void setAccessKey(char key)
Sets the widget's 'access key'. This key is used (in conjunction with a browser-specific modifier key) to automatically focus the widget.

Setting the key to (int) 0 will disable the access key.

Specified by:
setAccessKey in interface Focusable
Parameters:
key - the widget's access key
See Also:
getAccessKey()

setAnimation

public void setAnimation(CellTree.NodeAnimation animation)
Set the animation used to open and close nodes in this tree. You must call setAnimationEnabled(boolean) to enable or disable animation.

Parameters:
animation - a CellTree.NodeAnimation
See Also:
setAnimationEnabled(boolean), getAnimation()

setAnimationEnabled

public void setAnimationEnabled(boolean enable)
Description copied from interface: HasAnimation
Enable or disable animations.

Specified by:
setAnimationEnabled in interface HasAnimation
Parameters:
enable - true to enable, false to disable

setDefaultNodeSize

public void setDefaultNodeSize(int defaultNodeSize)
Set the default number of children to display beneath each child node. If more nodes are available, a button will appear at the end of the list allowing the user to show more items. Changing this value will not affect other tree nodes that are already open (including the hidden root node).

Parameters:
defaultNodeSize - the max
See Also:
getDefaultNodeSize()

setFocus

public void setFocus(boolean focused)
Description copied from interface: Focusable
Explicitly focus/unfocus this widget. Only one widget can have focus at a time, and the widget that does will receive all keyboard events.

Specified by:
setFocus in interface Focusable
Parameters:
focused - whether this widget should take focus or release it

setKeyboardSelectedTreeNode

public void setKeyboardSelectedTreeNode(TreeNode parentNode,
                                        int childIndex,
                                        boolean stealFocus)
Sets the node that will be selected when the CellTree gains keyboard focus.

Parameters:
parentNode - a node in the tree that is currently open
childIndex - the index of the child to select
stealFocus - if true, also change keyboard focus to this CellTree.

setTabIndex

public void setTabIndex(int index)
Description copied from interface: Focusable
Sets the widget's position in the tab index. If more than one widget has the same tab index, each such widget will receive focus in an arbitrary order. Setting the tab index to -1 will cause this widget to be removed from the tab order.

Specified by:
setTabIndex in interface Focusable
Parameters:
index - the widget's tab index

getAccessKey

protected char getAccessKey()
Get the access key.

Returns:
the access key, or -1 if not set
See Also:
setAccessKey(char)

onBlur

protected void onBlur()
Called when the keyboard selected node loses focus.

onFocus

protected void onFocus()
Called when the keyboard selected node gains focus.

cancelTreeNodeAnimation

void cancelTreeNodeAnimation()
Cancel a pending animation.

getClosedImageHtml

SafeHtml getClosedImageHtml(boolean isTop)
Get the HTML to render the closed image.

Parameters:
isTop - true if the top element, false if not
Returns:
the HTML string

getImageWidth

int getImageWidth()
Get the width required for the images.

Returns:
the maximum width required for images.

getKeyboardSelectedNode

CellTreeNodeView<?> getKeyboardSelectedNode()
Return the node that has keyboard selection.

getKeyboardSelectedTreeNode

public TreeNode getKeyboardSelectedTreeNode()
Returns the TreeNode that is selected when the CellTree has keyboard focus.

getLoadingImageHtml

SafeHtml getLoadingImageHtml()
Return the HTML to render the loading image.

getOpenImageHtml

SafeHtml getOpenImageHtml(boolean isTop)
Get the HTML to render the open image.

Parameters:
isTop - true if the top element, false if not
Returns:
the HTML string

getStyle

CellTree.Style getStyle()
Return the Style used by the tree.

keyboardSelect

void keyboardSelect(CellTreeNodeView<?> node,
                    boolean stealFocus)
Select a node using the keyboard.

Parameters:
node - the new node to select
stealFocus - true to steal focus, false not to

maybeAnimateTreeNode

void maybeAnimateTreeNode(CellTreeNodeView<?> node)
Animate the current state of a CellTreeNodeView in this tree.

Parameters:
node - the node to animate

resetFocus

void resetFocus()
If this widget has focus, reset it.

handleKeyNavigation

void handleKeyNavigation(int keyCode)
Handle keyboard navigation.

Parameters:
keyCode - the key code that was pressed
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