/*
* 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.sample.showcase.client;
import com.google.gwt.core.client.GWT;
import com.google.gwt.event.logical.shared.SelectionEvent;
import com.google.gwt.event.logical.shared.SelectionHandler;
import com.google.gwt.http.client.Request;
import com.google.gwt.http.client.RequestBuilder;
import com.google.gwt.http.client.RequestCallback;
import com.google.gwt.http.client.RequestException;
import com.google.gwt.http.client.Response;
import com.google.gwt.i18n.client.Constants;
import com.google.gwt.i18n.client.HasDirection;
import com.google.gwt.i18n.client.LocaleInfo;
import com.google.gwt.user.client.DOM;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.rpc.AsyncCallback;
import com.google.gwt.user.client.ui.DeckPanel;
import com.google.gwt.user.client.ui.HTML;
import com.google.gwt.user.client.ui.LazyPanel;
import com.google.gwt.user.client.ui.TabBar;
import com.google.gwt.user.client.ui.VerticalPanel;
import com.google.gwt.user.client.ui.Widget;
import java.util.HashMap;
import java.util.Map;
/**
* <p>
* A widget used to show GWT examples in the ContentPanel. It includes a tab bar
* with options to view the example, view the source, or view the css style
* rules.
* </p>
* <p>
* This {@link Widget} uses a lazy initialization mechanism so that the content
* is not rendered until the onInitialize method is called, which happens the
* first time the {@link Widget} is added to the page.. The data in the source
* and css tabs are loaded using an RPC call to the server.
* </p>
* <h3>CSS Style Rules</h3>
* <ul class="css">
* <li>.sc-ContentWidget { Applied to the entire widget }</li>
* <li>.sc-ContentWidget-tabBar { Applied to the TabBar }</li>
* <li>.sc-ContentWidget-deckPanel { Applied to the DeckPanel }</li>
* <li>.sc-ContentWidget-name { Applied to the name }</li>
* <li>.sc-ContentWidget-description { Applied to the description }</li>
* </ul>
*/
public abstract class ContentWidget extends LazyPanel implements
SelectionHandler<Integer> {
/**
* The constants used in this Content Widget.
*/
public static interface CwConstants extends Constants {
String contentWidgetExample();
String contentWidgetSource();
String contentWidgetStyle();
}
/**
* The default style name.
*/
private static final String DEFAULT_STYLE_NAME = "sc-ContentWidget";
/**
* The static loading image displayed when loading CSS or source code.
*/
private static String loadingImage;
/**
* The tab bar of options.
*/
protected TabBar tabBar = null;
/**
* An instance of the constants.
*/
private final CwConstants constants;
/**
* The deck panel with the contents.
*/
private DeckPanel deckPanel = null;
/**
* A boolean indicating whether or not the RPC request for the source code has
* been sent.
*/
private boolean sourceLoaded = false;
/**
* The widget used to display source code.
*/
private HTML sourceWidget = null;
/**
* A mapping of themes to style definitions.
*/
private Map<String, String> styleDefs = null;
/**
* The widget used to display css style.
*/
private HTML styleWidget = null;
/**
* Whether the demo widget has been initialized.
*/
private boolean widgetInitialized;
/**
* Whether the demo widget is (asynchronously) initializing.
*/
private boolean widgetInitializing;
/**
* A vertical panel that holds the demo widget once it is initialized.
*/
private VerticalPanel widgetVpanel;
/**
* Constructor.
*
* @param constants the constants
*/
public ContentWidget(CwConstants constants) {
this.constants = constants;
tabBar = new TabBar();
}
/**
* Add an item to this content widget. Should not be called before
* {@link #onInitializeComplete} has been called.
*
* @param w the widget to add
* @param tabText the text to display in the tab
*/
public void add(Widget w, String tabText) {
tabBar.addTab(tabText);
deckPanel.add(w);
}
@Override
public void ensureWidget() {
super.ensureWidget();
ensureWidgetInitialized(widgetVpanel);
}
/**
* Get the description of this example.
*
* @return a description for this example
*/
public abstract String getDescription();
/**
* Get the name of this example to use as a title.
*
* @return a name for this example
*/
public abstract String getName();
/**
* @return the tab bar
*/
public TabBar getTabBar() {
return tabBar;
}
/**
* Returns true if this widget has a source section.
*
* @return true if source tab available
*/
public boolean hasSource() {
return true;
}
/**
* Returns true if this widget has a style section.
*
* @return true if style tab available
*/
public boolean hasStyle() {
return true;
}
/**
* When the widget is first initialized, this method is called. If it returns
* a Widget, the widget will be added as the first tab. Return null to disable
* the first tab.
*
* @return the widget to add to the first tab
*/
public abstract Widget onInitialize();
/**
* Called when initialization has completed and the widget has been added to
* the page.
*/
public void onInitializeComplete() {
}
public void onSelection(SelectionEvent<Integer> event) {
// Show the associated widget in the deck panel
int tabIndex = event.getSelectedItem().intValue();
deckPanel.showWidget(tabIndex);
// Load the source code
String tabHTML = getTabBar().getTabHTML(tabIndex);
if (!sourceLoaded && tabHTML.equals(constants.contentWidgetSource())) {
sourceLoaded = true;
String className = this.getClass().getName();
className = className.substring(className.lastIndexOf(".") + 1);
requestSourceContents(ShowcaseConstants.DST_SOURCE_EXAMPLE + className
+ ".html", sourceWidget, null);
}
// Load the style definitions
if (hasStyle() && tabHTML.equals(constants.contentWidgetStyle())) {
final String theme = Showcase.CUR_THEME;
if (styleDefs.containsKey(theme)) {
styleWidget.setHTML(styleDefs.get(theme));
} else {
styleDefs.put(theme, "");
RequestCallback callback = new RequestCallback() {
public void onError(Request request, Throwable exception) {
styleDefs.put(theme, "Style not available.");
}
public void onResponseReceived(Request request, Response response) {
styleDefs.put(theme, response.getText());
}
};
String srcPath = ShowcaseConstants.DST_SOURCE_STYLE + theme;
if (LocaleInfo.getCurrentLocale().isRTL()) {
srcPath += "_rtl";
}
String className = this.getClass().getName();
className = className.substring(className.lastIndexOf(".") + 1);
requestSourceContents(srcPath + "/" + className + ".html", styleWidget,
callback);
}
}
}
/**
* Select a tab.
*
* @param index the tab index
*/
public void selectTab(int index) {
tabBar.selectTab(index);
}
protected abstract void asyncOnInitialize(final AsyncCallback<Widget> callback);
/**
* Initialize this widget by creating the elements that should be added to the
* page.
*/
@Override
protected final Widget createWidget() {
deckPanel = new DeckPanel();
setStyleName(DEFAULT_STYLE_NAME);
// Add a tab handler
tabBar.addSelectionHandler(this);
// Create a container for the main example
widgetVpanel = new VerticalPanel();
add(widgetVpanel, constants.contentWidgetExample());
// Add the name
HTML nameWidget = new HTML(getName());
nameWidget.setStyleName(DEFAULT_STYLE_NAME + "-name");
widgetVpanel.add(nameWidget);
// Add the description
HTML descWidget = new HTML(getDescription());
descWidget.setStyleName(DEFAULT_STYLE_NAME + "-description");
widgetVpanel.add(descWidget);
// Add source code tab
if (hasSource()) {
sourceWidget = new HTML();
add(sourceWidget, constants.contentWidgetSource());
} else {
sourceLoaded = true;
}
// Add style tab
if (hasStyle()) {
styleDefs = new HashMap<String, String>();
styleWidget = new HTML();
add(styleWidget, constants.contentWidgetStyle());
}
return deckPanel;
}
@Override
protected void onLoad() {
ensureWidget();
// Select the first tab
if (getTabBar().getTabCount() > 0) {
tabBar.selectTab(0);
}
}
/**
* Load the contents of a remote file into the specified widget.
*
* @param url a partial path relative to the module base URL
* @param target the target Widget to place the contents
* @param callback the callback when the call completes
*/
protected void requestSourceContents(String url, final HTML target,
final RequestCallback callback) {
// Show the loading image
if (loadingImage == null) {
loadingImage = "<img src=\"" + GWT.getModuleBaseURL()
+ "images/loading.gif\">";
}
target.setDirection(HasDirection.Direction.LTR);
DOM.setStyleAttribute(target.getElement(), "textAlign", "left");
target.setHTML(" " + loadingImage);
// Request the contents of the file
RequestBuilder builder = new RequestBuilder(RequestBuilder.GET,
GWT.getModuleBaseURL() + url);
RequestCallback realCallback = new RequestCallback() {
public void onError(Request request, Throwable exception) {
target.setHTML("Cannot find resource");
if (callback != null) {
callback.onError(request, exception);
}
}
public void onResponseReceived(Request request, Response response) {
target.setHTML(response.getText());
if (callback != null) {
callback.onResponseReceived(request, response);
}
}
};
builder.setCallback(realCallback);
// Send the request
try {
builder.send();
} catch (RequestException e) {
realCallback.onError(null, e);
}
}
/**
* Ensure that the demo widget has been initialized. Note that initialization
* can fail if there is a network failure.
*/
private void ensureWidgetInitialized(final VerticalPanel vPanel) {
if (widgetInitializing || widgetInitialized) {
return;
}
widgetInitializing = true;
asyncOnInitialize(new AsyncCallback<Widget>() {
public void onFailure(Throwable reason) {
widgetInitializing = false;
Window.alert("Failed to download code for this widget (" + reason + ")");
}
public void onSuccess(Widget result) {
widgetInitializing = false;
widgetInitialized = true;
Widget widget = result;
if (widget != null) {
vPanel.add(widget);
}
onInitializeComplete();
}
});
}
}