/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.waveprotocol.wave.client.editor.toolbar;
import org.waveprotocol.wave.client.editor.EditorContext;
import org.waveprotocol.wave.client.editor.EditorUpdateEvent;
import org.waveprotocol.wave.client.editor.EditorUpdateEvent.EditorUpdateListener;
import org.waveprotocol.wave.model.document.util.Range;
import org.waveprotocol.wave.model.util.CopyOnWriteSet;
/**
* An {@link EditorUpdateListener} to assist implementing standard rich text
* toolbar buttons whose state is kept synchronized with the current selection.
* <p>
* See {@link org.waveprotocol.wave.client.wavepanel.impl.toolbar.EditToolbar}
* for example uses.
* <p>
* Note: each {@link Controller} could have been an {@link EditorUpdateListener}
* on its own, but each one would have had to ask the editor for the current
* selection, whereas this class does so once only for all controllers, helping
* sharing costs. Also, grouping all toolbar buttons that way makes it easy to
* enable/disable the whole toolbar when you switch the editor's editing state.
*
* @author kalman@google.com (Benjamin Kalman)
*/
public class ButtonUpdater implements EditorUpdateListener {
/** Something that needs updating. */
public interface Controller {
void update(Range selectionRange);
}
// CopyOnWriteSet is used to ensure that the collection does not change
// while iterating.
private final CopyOnWriteSet<Controller> updateables = CopyOnWriteSet.create();
/** The editor this updater is attached to. */
private final EditorContext editor;
public ButtonUpdater(EditorContext editor) {
this.editor = editor;
}
/**
* Adds a controller to the update list.
*
* @return the controller, for convenience.
*/
public <T extends Controller> T add(T controller) {
updateables.add(controller);
return controller;
}
@Override
public void onUpdate(EditorUpdateEvent event) {
updateButtonStates();
}
public void updateButtonStates() {
if (updateables.isEmpty()) {
return;
}
Range selectionRange = editor.getSelectionHelper().getOrderedSelectionRange();
if (selectionRange == null) {
return;
}
for (Controller update : updateables) {
update.update(selectionRange);
}
}
}