/*
* Copyright 2008 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.museum.client.defaultmuseum;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.museum.client.common.AbstractIssue;
import com.google.gwt.user.client.Command;
import com.google.gwt.user.client.DeferredCommand;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.Composite;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.RichTextArea;
import com.google.gwt.user.client.ui.VerticalPanel;
import com.google.gwt.user.client.ui.Widget;
/**
* <h1>Attaching and detaching a RichTextArea too fast crashes GWT</h1>
*
* <p>
* The RichTextArea uses a Timer or iframe.onload event (depending on the
* browser) to trigger the event system initialization. Basically, that
* introduces a small delay between the time the RichTextArea is attached to the
* page and the time that the event handlers are added.
* </p>
* <p>
* However, if you programmatically (or just very quickly) remove the
* RichTextArea from the page, you will immediately trigger the teardown methods
* that remove the event listeners. In some browsers, removing the event
* listeners before they are added throws a JavaScript exception do to an
* undefined variable, which messes up the rest of the onDetach mechanism, which
* gets your attach state out of sync, which means your app stops working
* properly.
* </p>
* <p>
* I am able to reliably reproduce these errors by attaching and removing a
* RichTextArea very quickly, even in user time. The errors affect all browsers,
* but Firefox is by far the most affected because it catches the iframe.onload
* event, whereas the others just use a 1ms timer. Also, Safari and IE seem to
* handle the javascript exceptions a little cleaner.
* </p>
*/
public class Issue1897 extends AbstractIssue {
/**
* A set of options used to set the caption and content in the caption panel.
*/
private class ControlPanel extends Composite {
private final HorizontalPanel hPanel = new HorizontalPanel();
public ControlPanel() {
initWidget(hPanel);
hPanel.setSpacing(10);
// Add option to attach RichTextArea
Button attachButton = new Button("Attach RichText", new ClickHandler() {
public void onClick(ClickEvent event) {
if (rta.isAttached()) {
Window.alert("RichTextArea is already attached.");
}
wrapper.add(rta);
}
});
hPanel.add(attachButton);
// Add option to detach RichTextArea
Button detachButton = new Button("Detach RichText", new ClickHandler() {
public void onClick(ClickEvent event) {
if (!rta.isAttached()) {
Window.alert("RichTextArea is already detached.");
return;
}
wrapper.remove(rta);
}
});
hPanel.add(detachButton);
// Add option to attach and detach RichTextArea
Button quickDetachButton = new Button("Attach/Detach RichText",
new ClickHandler() {
public void onClick(ClickEvent event) {
if (rta.isAttached()) {
Window.alert("RichTextArea is already attached.");
return;
}
wrapper.add(rta);
wrapper.remove(rta);
}
});
hPanel.add(quickDetachButton);
}
}
private RichTextArea rta;
private VerticalPanel wrapper;
@Override
public Widget createIssue() {
rta = new RichTextArea();
rta.setPixelSize(200, 100);
// Combine the control panel and RichTextArea in a wrapper
wrapper = new VerticalPanel();
wrapper.setSpacing(10);
wrapper.add(new ControlPanel());
wrapper.add(rta);
// Remove the RichTextArea after the wrapper is attached to the DOM
DeferredCommand.addCommand(new Command() {
public void execute() {
wrapper.remove(rta);
}
});
return wrapper;
}
@Override
public String getInstructions() {
return "You should <b>not</b> see a RichTextArea, and no errors should "
+ "occur. If you click the Attach/Detach button, the RichTextArea will"
+ " be programmatically attached and detached from the DOM structure, "
+ "and you should not see any errors.";
}
@Override
public String getSummary() {
return "Attaching and detaching a RichTextArea too fast crashes GWT";
}
@Override
public boolean hasCSS() {
return true;
}
}