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

java.lang.Object
  com.google.gwt.user.client.ui.UIObject
      com.google.gwt.user.client.ui.Widget
          com.google.gwt.user.client.ui.Composite
              com.google.gwt.user.cellview.client.AbstractCellTree
                  com.google.gwt.user.cellview.client.CellBrowser

All Implemented Interfaces:

HasAttachHandlers, HasCloseHandlers<TreeNode>, HasOpenHandlers<TreeNode>, HasHandlers, HasKeyboardSelectionPolicy, EventListener, HasAnimation, HasVisibility, IsRenderable, IsWidget, ProvidesResize, RequiresResize

public class CellBrowser
extends AbstractCellTree
implements ProvidesResize, RequiresResize, HasAnimation

A "browsable" view of a tree in which only a single node per level may be open at one time.

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

Example

Trivial example

public class CellBrowserExample 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 browser.
    TreeViewModel model = new CustomTreeModel();

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

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

Complex example

public class CellBrowserExample2 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<CellBrowserExample2.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 browser.
    TreeViewModel model = new CustomTreeModel();

    /*
     * Create the browser 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();
     */
    CellBrowser browser = new CellBrowser(model, null);
    browser.setKeyboardSelectionPolicy(KeyboardSelectionPolicy.ENABLED);

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

treeNodes

final java.util.List<CellBrowser.TreeNodeImpl<?>> treeNodes

The visible CellBrowser.TreeNodeImpls. Visible for testing.

CellBrowser

@Deprecated
public CellBrowser(TreeViewModel viewModel,
                              T rootValue)

Deprecated. please use CellBrowser.Builder

Construct a new CellBrowser.

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

CellBrowser

@Deprecated
public CellBrowser(TreeViewModel viewModel,
                              T rootValue,
                              CellBrowser.Resources resources)

Deprecated. please use CellBrowser.Builder

Construct a new CellBrowser with the specified CellBrowser.Resources.

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 CellBrowser.Resources used for images

CellBrowser

protected CellBrowser(CellBrowser.Builder<T> builder)

getDefaultColumnWidth

public int getDefaultColumnWidth()

Get the default width of new columns.

Returns:

the default width in pixels

See Also:

setDefaultColumnWidth(int)

getMinimumColumnWidth

public int getMinimumColumnWidth()

Get the minimum width of columns.

Returns:

the minimum width in pixels

See Also:

setMinimumColumnWidth(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

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

onResize

public void onResize()

Description copied from interface: RequiresResize

This method must be called whenever the implementor's size has been modified.

Specified by:

onResize in interface RequiresResize

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

setDefaultColumnWidth

public void setDefaultColumnWidth(int width)

Set the default width of new columns.

Parameters:

width - the default width in pixels

See Also:

getDefaultColumnWidth()

setMinimumColumnWidth

public void setMinimumColumnWidth(int minWidth)

Set the minimum width of columns.

Parameters:

minWidth - the minimum width in pixels

See Also:

getMinimumColumnWidth()

createPager

protected <C> Widget createPager(HasData<C> display)

Create a pager to control the list view.

Type Parameters:

C - the item type in the list view

Parameters:

display - the list view to add paging too

Returns:

the pager