Package com.google.gwt.user.cellview.client

Class 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);
  }
}

    • 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

      • 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)

      • 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

      • 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()

      • 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. NOTE: Most browsers fire FocusEvents asynchronously. Especially within GWT tests, you'll need to make your test asynchronous to properly do verifications. See GWTTestCase#delayTestFinish for more information on how to do this.
        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