/*
* 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.event.shared.EventHandler;
import com.google.gwt.event.shared.GwtEvent;
import com.google.gwt.event.shared.HasHandlers;
import com.google.gwt.view.client.HasData;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Represents a column sort event.
*/
public class ColumnSortEvent extends GwtEvent<ColumnSortEvent.Handler> {
/**
* Handler for {@link ColumnSortEvent}.
*/
public static interface Handler extends EventHandler {
/**
* Called when {@link ColumnSortEvent} is fired.
*
* @param event the {@link ColumnSortEvent} that was fired
*/
void onColumnSort(ColumnSortEvent event);
}
/**
* A default handler used with views attached to asynchronous data providers
* such as {@link com.google.gwt.view.client.AsyncDataProvider AsyncDataProvider}.
* This handler calls
* {@link HasData#setVisibleRangeAndClearData(com.google.gwt.view.client.Range, boolean)},
* which clears the current data and triggers the data provider's range change
* handler.
*/
public static class AsyncHandler implements Handler {
private final HasData<?> hasData;
public AsyncHandler(HasData<?> hasData) {
this.hasData = hasData;
}
public void onColumnSort(ColumnSortEvent event) {
hasData.setVisibleRangeAndClearData(hasData.getVisibleRange(), true);
}
}
/**
* <p>
* A default handler used to sort a {@link List} backing a table. If the
* sorted column has an associated {@link Comparator}, the list is sorted
* using the comparator.
* </p>
*
* <p>
* This can be used in conjunction with
* {@link com.google.gwt.view.client.ListDataProvider}.
* </p>
*
* @param <T> the data type of the list
*/
public static class ListHandler<T> implements Handler {
private final Map<Column<?, ?>, Comparator<T>> comparators = new HashMap<Column<?, ?>, Comparator<T>>();
private List<T> list;
public ListHandler(List<T> list) {
this.list = list;
}
/**
* Returns the comparator that has been set for the specified column, or
* null if no comparator has been set.
*
* @param column the {@link Column}
*/
public Comparator<T> getComparator(Column<T, ?> column) {
return comparators.get(column);
}
public List<T> getList() {
return list;
}
public void onColumnSort(ColumnSortEvent event) {
// Get the sorted column.
Column<?, ?> column = event.getColumn();
if (column == null) {
return;
}
// Get the comparator.
final Comparator<T> comparator = comparators.get(column);
if (comparator == null) {
return;
}
// Sort using the comparator.
if (event.isSortAscending()) {
Collections.sort(list, comparator);
} else {
Collections.sort(list, new Comparator<T>() {
public int compare(T o1, T o2) {
return -comparator.compare(o1, o2);
}
});
}
}
/**
* Set the comparator used to sort the specified column in ascending order.
*
* @param column the {@link Column}
* @param comparator the {@link Comparator} to use for the {@link Column}
*/
public void setComparator(Column<T, ?> column, Comparator<T> comparator) {
comparators.put(column, comparator);
}
public void setList(List<T> list) {
assert list != null : "list cannot be null";
this.list = list;
}
}
/**
* Handler type.
*/
private static Type<Handler> TYPE;
/**
* Fires a cell preview event on all registered handlers in the handler
* manager. If no such handlers exist, this implementation will do nothing.
*
* @param source the source of the event
* @param sortList the {@link ColumnSortList} of sorted columns
* @return the {@link ColumnSortEvent} that was fired
*/
public static ColumnSortEvent fire(HasHandlers source, ColumnSortList sortList) {
ColumnSortEvent event = new ColumnSortEvent(sortList);
if (TYPE != null) {
source.fireEvent(event);
}
return event;
}
/**
* Gets the type associated with this event.
*
* @return returns the handler type
*/
public static Type<Handler> getType() {
if (TYPE == null) {
TYPE = new Type<Handler>();
}
return TYPE;
}
private final ColumnSortList sortList;
/**
* Construct a new {@link ColumnSortEvent}.
*
* @param sortList the {@link ColumnSortList}
*/
protected ColumnSortEvent(ColumnSortList sortList) {
this.sortList = sortList;
}
@Override
public Type<Handler> getAssociatedType() {
return TYPE;
}
/**
* Get the {@link Column} that was sorted.
*
* @return the sorted {@link Column}, or null if not sorted
*/
public Column<?, ?> getColumn() {
return (sortList == null || sortList.size() == 0) ? null
: sortList.get(0).getColumn();
}
/**
* Get the {@link ColumnSortList} that contains the ordered list of sorted
* columns.
*
* @return the {@link ColumnSortList}
*/
public ColumnSortList getColumnSortList() {
return sortList;
}
/**
* Check if the {@link Column} is sorted in ascending order.
*
* @return true if ascending, false if descending or not sorted
*/
public boolean isSortAscending() {
return (sortList == null || sortList.size() == 0) ? false
: sortList.get(0).isAscending();
}
@Override
protected void dispatch(Handler handler) {
handler.onColumnSort(this);
}
}