Use LazyPanel for deferred rendering in ShowCase
git-svn-id: https://google-web-toolkit.googlecode.com/svn/releases/1.6@4146 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/samples/showcase/src/com/google/gwt/sample/showcase/client/ContentWidget.java b/samples/showcase/src/com/google/gwt/sample/showcase/client/ContentWidget.java
index 5861141..4f97aaf 100644
--- a/samples/showcase/src/com/google/gwt/sample/showcase/client/ContentWidget.java
+++ b/samples/showcase/src/com/google/gwt/sample/showcase/client/ContentWidget.java
@@ -26,9 +26,9 @@
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.ui.Composite;
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;
@@ -43,10 +43,9 @@
* 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.
+ * This {@link Widget} extends {@link LazyPanel} so that the content is not
+ * rendered until the widget first becomes visible. 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">
@@ -57,7 +56,7 @@
* <li>.sc-ContentWidget-description { Applied to the description }</li>
* </ul>
*/
-public abstract class ContentWidget extends Composite implements
+public abstract class ContentWidget extends LazyPanel implements
SelectionHandler<Integer> {
/**
* The constants used in this Content Widget.
@@ -83,7 +82,7 @@
/**
* An instance of the constants.
*/
- private CwConstants constants;
+ private final CwConstants constants;
/**
* The deck panel with the contents.
@@ -91,11 +90,6 @@
private DeckPanel deckPanel = null;
/**
- * A boolean indicating whether or not this widget has been initialized.
- */
- private boolean initialized = false;
-
- /**
* A boolean indicating whether or not the RPC request for the source code has
* been sent.
*/
@@ -129,13 +123,11 @@
public ContentWidget(CwConstants constants) {
this.constants = constants;
tabBar = new TabBar();
- deckPanel = new DeckPanel();
- initWidget(deckPanel);
- setStyleName(DEFAULT_STYLE_NAME);
}
/**
- * Add an item to this content widget.
+ * 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
@@ -185,57 +177,8 @@
}
/**
- * Initialize this widget by creating the elements that should be added to the
- * page.
- */
- public final void initialize() {
- if (initialized == false) {
- initialized = true;
-
- // Add a tab handler
- tabBar.addSelectionHandler(this);
-
- // Create a container for the main example
- final VerticalPanel vPanel = new VerticalPanel();
- add(vPanel, constants.contentWidgetExample());
-
- // Add the name
- HTML nameWidget = new HTML(getName());
- nameWidget.setStyleName(DEFAULT_STYLE_NAME + "-name");
- vPanel.add(nameWidget);
-
- // Add the description
- HTML descWidget = new HTML(getDescription());
- descWidget.setStyleName(DEFAULT_STYLE_NAME + "-description");
- vPanel.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());
- }
-
- // Initialize the widget and add it to the page
- Widget widget = onInitialize();
- if (widget != null) {
- vPanel.add(widget);
- }
- onInitializeComplete();
- }
- }
-
- /**
- * When the widget is first initialize, this method is called. If it returns a
- * Widget, the widget will be added as the first tab. Return null to disable
+ * 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
@@ -302,10 +245,60 @@
tabBar.selectTab(index);
}
+ /**
+ * Initialize this widget by creating the elements that should be added to the
+ * page.
+ */
+ 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
+ final VerticalPanel vPanel = new VerticalPanel();
+ add(vPanel, constants.contentWidgetExample());
+
+ // Add the name
+ HTML nameWidget = new HTML(getName());
+ nameWidget.setStyleName(DEFAULT_STYLE_NAME + "-name");
+ vPanel.add(nameWidget);
+
+ // Add the description
+ HTML descWidget = new HTML(getDescription());
+ descWidget.setStyleName(DEFAULT_STYLE_NAME + "-description");
+ vPanel.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());
+ }
+
+ // Initialize the showcase widget (if any) and add it to the page
+ Widget widget = onInitialize();
+ if (widget != null) {
+ vPanel.add(widget);
+ }
+ onInitializeComplete();
+
+ return deckPanel;
+ }
+
@Override
protected void onLoad() {
- // Initialize this widget if we haven't already
- initialize();
+ ensureWidget();
// Select the first tab
if (getTabBar().getTabCount() > 0) {
