/*
* 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.view.client;
import com.google.gwt.cell.client.Cell;
import com.google.gwt.cell.client.ValueUpdater;
import com.google.gwt.event.shared.HandlerRegistration;
/**
* A model of a tree.
*/
public interface TreeViewModel {
/**
* Default implementation of {@link NodeInfo}.
*/
class DefaultNodeInfo<T> implements NodeInfo<T> {
private final Cell<T> cell;
private final AbstractDataProvider<T> dataProvider;
private final CellPreviewEvent.Handler<T> selectionEventManager;
private HandlerRegistration selectionEventManagerReg;
private final SelectionModel<? super T> selectionModel;
private final ValueUpdater<T> valueUpdater;
private HasData<T> display;
/**
* Construct a new {@link DefaultNodeInfo}.
*
* @param dataProvider the {@link AbstractDataProvider} that provides the
* child values
* @param cell the {@link Cell} used to render the child values
*/
public DefaultNodeInfo(AbstractDataProvider<T> dataProvider, Cell<T> cell) {
this(dataProvider, cell, null, null);
}
/**
* Construct a new {@link DefaultNodeInfo}.
*
* @param dataProvider the {@link AbstractDataProvider} that provides the
* child values
* @param cell the {@link Cell} used to render the child values update when
* the selection changes
* @param selectionModel the {@link SelectionModel} used for selection
* @param valueUpdater the {@link ValueUpdater}
*/
public DefaultNodeInfo(AbstractDataProvider<T> dataProvider,
final Cell<T> cell, SelectionModel<? super T> selectionModel,
final ValueUpdater<T> valueUpdater) {
this(dataProvider, cell, selectionModel,
DefaultSelectionEventManager.<T> createDefaultManager(), valueUpdater);
}
/**
* Construct a new {@link DefaultNodeInfo}.
*
* @param dataProvider the {@link AbstractDataProvider} that provides the
* child values
* @param cell the {@link Cell} used to render the child values update when
* the selection changes
* @param selectionModel the {@link SelectionModel} used for selection
* @param selectionEventManager the {@link CellPreviewEvent.Handler} that
* handles user selection interaction
* @param valueUpdater the {@link ValueUpdater}
*/
public DefaultNodeInfo(AbstractDataProvider<T> dataProvider,
final Cell<T> cell, SelectionModel<? super T> selectionModel,
CellPreviewEvent.Handler<T> selectionEventManager,
final ValueUpdater<T> valueUpdater) {
this.dataProvider = dataProvider;
this.cell = cell;
this.selectionModel = selectionModel;
this.valueUpdater = valueUpdater;
this.selectionEventManager = selectionEventManager;
}
public Cell<T> getCell() {
return cell;
}
public ProvidesKey<T> getProvidesKey() {
return dataProvider;
}
public SelectionModel<? super T> getSelectionModel() {
return selectionModel;
}
public ValueUpdater<T> getValueUpdater() {
return valueUpdater;
}
public void setDataDisplay(HasData<T> display) {
this.display = display;
if (selectionEventManager != null) {
selectionEventManagerReg = display.addCellPreviewHandler(selectionEventManager);
}
dataProvider.addDataDisplay(display);
}
public void unsetDataDisplay() {
if (display != null) {
dataProvider.removeDataDisplay(display);
if (selectionEventManagerReg != null) {
selectionEventManagerReg.removeHandler();
selectionEventManagerReg = null;
}
display = null;
}
}
}
/**
* The info needed to create the children of a tree node.
*/
interface NodeInfo<T> {
/**
* Get the {@link Cell} used to render the children of this node.
*
* @return the {@link Cell}
*/
Cell<T> getCell();
/**
* Return the key provider for children of this node.
*
* @return the {@link ProvidesKey}
*/
ProvidesKey<T> getProvidesKey();
/**
* Get the {@link SelectionModel} used for the children of this node. To
* unify selection across all items of the same type, or across the entire
* tree, return the same instance of {@link SelectionModel} from all
* {@link NodeInfo}.
*
* @return the {@link SelectionModel}
*/
SelectionModel<? super T> getSelectionModel();
/**
* Get the value updater associated with the cell.
*
* @return the value updater
*/
ValueUpdater<T> getValueUpdater();
/**
* Set the display that is listening to this {@link NodeInfo}. The
* implementation should attach the display to the source of data.
*
* @param display the {@link HasData}
*/
void setDataDisplay(HasData<T> display);
/**
* Unset the display from the {@link NodeInfo}. The implementation should
* detach the display from the source of data.
*/
void unsetDataDisplay();
}
/**
* Get the {@link NodeInfo} that will provide the {@link ProvidesKey},
* {@link Cell}, and {@link HasData} instances to retrieve and display the
* children of the specified value.
*
* @param value the value in the parent node
* @return the {@link NodeInfo}
*/
<T> NodeInfo<?> getNodeInfo(T value);
/**
* Check if the value is known to be a leaf node.
*
* @param value the value at the node
*
* @return true if the node is known to be a leaf node, false otherwise
*/
boolean isLeaf(Object value);
}