GWT - DeckPanel Widget

Introduction

The DeckPanel widget represents a panel that displays all of its child widgets in a 'deck', where only one can be visible at a time. It is used by TabPanel.

Class Declaration

Following is the declaration for com.google.gwt.user.client.ui.DeckPanel class −

public class DeckPanel
   extends ComplexPanel
      implements HasAnimation, InsertPanel.ForIsWidget

Class Constructors

Sr.No.	Constructor & Description
1	DeckPanel() Constructor for DeckPanel.

Class Methods

Sr.No.	Function name & Description
1	void add(Widget w) Adds a child widget.
2	int getVisibleWidget() Gets the index of the currently-visible widget.
3	void insert(IsWidget w, int beforeIndex)
4	void insert(Widget w, int beforeIndex) Inserts a child widget before the specified index.
5	boolean isAnimationEnabled() Returns true if animations are enabled, false if not.
6	boolean remove(Widget w) Removes a child widget.
7	void setAnimationEnabled(boolean enable) Enable or disable animations.
8	void showWidget(int index) Shows the widget at the specified index.

Methods Inherited

This class inherits methods from the following classes −

com.google.gwt.user.client.ui.UIObject
com.google.gwt.user.client.ui.Widget
com.google.gwt.user.client.ui.Panel
com.google.gwt.user.client.ui.ComplexPanel
java.lang.Object

DeckPanel Widget Example

This example will take you through simple steps to show usage of a DeckPanel Widget in GWT. Follow the following steps to update the GWT application we created in GWT - Create Application chapter −

Step	Description
1	Create a project with a name HelloWorld under a package com.tutorialspoint as explained in the GWT - Create Application chapter.
2	Modify HelloWorld.gwt.xml, HelloWorld.css, HelloWorld.html and HelloWorld.java as explained below. Keep rest of the files unchanged.
3	Compile and run the application to verify the result of the implemented logic.

Following is the content of the modified module descriptor src/com.tutorialspoint/HelloWorld.gwt.xml.

<?xml version = "1.0" encoding = "UTF-8"?>
<module rename-to = 'helloworld'>
   <!-- Inherit the core Web Toolkit stuff.                        -->
   <inherits name = 'com.google.gwt.user.User'/>

   <!-- Inherit the default GWT style sheet.                       -->
   <inherits name = 'com.google.gwt.user.theme.clean.Clean'/>

   <!-- Specify the app entry point class.                         -->
   <entry-point class = 'com.tutorialspoint.client.HelloWorld'/>

   <!-- Specify the paths for translatable code                    -->
   <source path = 'client'/>
   <source path = 'shared'/>

</module>

Following is the content of the modified Style Sheet file war/HelloWorld.css.

body {
   text-align: center;
   font-family: verdana, sans-serif;
}

h1 {
   font-size: 2em;
   font-weight: bold;
   color: #777777;
   margin: 40px 0px 70px;
   text-align: center;
}
.deckpanel {
  border: 1px solid #BBBBBB;
  padding: 3px;
}

Following is the content of the modified HTML host file war/HelloWorld.html.

<html>
   <head>
      <title>Hello World</title>
      <link rel = "stylesheet" href = "HelloWorld.css"/>
      <script language = "javascript" src = "helloworld/helloworld.nocache.js">
      </script>
   </head>

   <body>
      <h1>DeckPanel Widget Demonstration</h1>
      <div id = "gwtContainer"></div>
   </body>
</html>

Let us have following content of Java file src/com.tutorialspoint/HelloWorld.java which will demonstrate use of DeckPanel widget.

package com.tutorialspoint.client;


import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.DeckPanel;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.VerticalPanel;

public class HelloWorld implements EntryPoint {

   public void onModuleLoad() {
      // Create DeckPanel widget
      final DeckPanel deckPanel = new DeckPanel();
      deckPanel.setSize("300px", "120px");
      deckPanel.setStyleName("deckpanel");
      
      // Create lables to add to deckpanel
      Label label1 = new Label("This is first Page");
      Label label2 = new Label("This is second Page");
      Label label3 = new Label("This is third Page");
      
      // Add labels to deckpanel
      deckPanel.add(label1);
      deckPanel.add(label2);
      deckPanel.add(label3);
      
      //show first label
      deckPanel.showWidget(0);
      
      //create button bar
      HorizontalPanel buttonBar = new HorizontalPanel();
      buttonBar.setSpacing(5);
      
      // create button and add click handlers
      // show different labels on click of different buttons
      Button button1 = new Button("Page 1");
      button1.addClickHandler(new ClickHandler() {
         @Override
         public void onClick(ClickEvent event) {
            deckPanel.showWidget(0);
         }
      });

      Button button2 = new Button("Page 2");
      button2.addClickHandler(new ClickHandler() {
         @Override
         public void onClick(ClickEvent event) {
            deckPanel.showWidget(1);
         }
      });

      Button button3 = new Button("Page 3");
      button3.addClickHandler(new ClickHandler() {
         @Override
         public void onClick(ClickEvent event) {
            deckPanel.showWidget(2);
         }
      });

      buttonBar.add(button1);
      buttonBar.add(button2);
      buttonBar.add(button3);

      VerticalPanel vPanel = new VerticalPanel();
      vPanel.add(deckPanel);
      vPanel.add(buttonBar);

      // Add the widgets to the root panel.
      RootPanel.get().add(vPanel);
   }
}

Once you are ready with all the changes done, let us compile and run the application in development mode as we did in GWT - Create Application chapter. If everything is fine with your application, this will produce following result −

gwt_layout_panels.htm