GWT - FocusPanel Widget
Advertisements
Introduction
The FocusPanel widget represents a simple panel that makes its contents focusable, and adds the ability to catch mouse and keyboard events.
Class declaration
Following is the declaration for com.google.gwt.user.client.ui.FocusPanel class:
public class FocusPanel
extends SimplePanel
implements HasFocus, SourcesClickEvents,
SourcesMouseEvents, SourcesMouseWheelEvents,
HasAllMouseHandlers, HasClickHandlers,
HasDoubleClickHandlers, HasAllKeyHandlers,
HasAllFocusHandlers
Class constructors
| S.N. | Constructor & Description |
|---|---|
| 1 | FocusPanel() Creates an empty focus panel. |
| 2 | FocusPanel(Widget child) Creates a new focus panel with the given child widget. |
Class methods
| S.N. | Function name & Description |
|---|---|
| 1 | HandlerRegistration addBlurHandler(BlurHandler handler) Adds a BlurEvent handler. |
| 2 | HandlerRegistration addClickHandler(ClickHandler handler) Adds a ClickEvent handler. |
| 3 | void addClickListener(ClickListener listener) Deprecated. Use addClickHandler(com.google.gwt.event.dom.client.ClickHandler) instead |
| 4 | HandlerRegistration addDoubleClickHandler(DoubleClickHandler handler) Adds a DoubleClickEvent handler. |
| 5 | HandlerRegistration addFocusHandler(FocusHandler handler) Adds a FocusEvent handler. |
| 6 | void addFocusListener(FocusListener listener) Deprecated. Use addFocusHandler(com.google.gwt.event.dom.client.FocusHandler) instead |
| 7 | void addKeyboardListener(KeyboardListener listener) Deprecated. Use addKeyDownHandler(com.google.gwt.event.dom.client.KeyDownHandler), addKeyUpHandler(com.google.gwt.event.dom.client.KeyUpHandler) and addKeyPressHandler(com.google.gwt.event.dom.client.KeyPressHandler) instead |
| 8 | HandlerRegistration addKeyDownHandler(KeyDownHandler handler) Adds a KeyDownEvent handler. |
| 9 | HandlerRegistration addKeyPressHandler(KeyPressHandler handler) Adds a KeyPressEvent handler. |
| 10 | HandlerRegistration addKeyUpHandler(KeyUpHandler handler) Adds a KeyUpEvent handler. |
| 11 | HandlerRegistration addMouseDownHandler(MouseDownHandler handler) Adds a MouseDownEvent handler. |
| 12 | void addMouseListener(MouseListener listener) Deprecated. Use addMouseOverHandler(com.google.gwt.event.dom.client.MouseOverHandler), addMouseMoveHandler(com.google.gwt.event.dom.client.MouseMoveHandler), addMouseDownHandler(com.google.gwt.event.dom.client.MouseDownHandler), addMouseUpHandler(com.google.gwt.event.dom.client.MouseUpHandler) and addMouseOutHandler(com.google.gwt.event.dom.client.MouseOutHandler) instead |
| 13 | HandlerRegistration addMouseMoveHandler(MouseMoveHandler handler) Adds a MouseMoveEvent handler. |
| 14 | HandlerRegistration addMouseOutHandler(MouseOutHandler handler) Adds a MouseOutEvent handler. |
| 15 | HandlerRegistration addMouseOverHandler(MouseOverHandler handler) Adds a MouseOverEvent handler. |
| 16 | HandlerRegistration addMouseUpHandler(MouseUpHandler handler) Adds a MouseUpEvent handler. |
| 17 | HandlerRegistration addMouseWheelHandler(MouseWheelHandler handler) Adds a MouseWheelEvent handler. |
| 18 | void addMouseWheelListener(MouseWheelListener listener) Deprecated. Use addMouseWheelHandler(com.google.gwt.event.dom.client.MouseWheelHandler) instead |
| 19 | int getTabIndex() Gets the widget's position in the tab index. |
| 20 | void removeClickListener(ClickListener listener) Deprecated. Use the HandlerRegistration.removeHandler() method on the object returned by addClickHandler(com.google.gwt.event.dom.client.ClickHandler) instead |
| 21 | void removeFocusListener(FocusListener listener) Deprecated. Use the HandlerRegistration.removeHandler() method on the object returned by addFocusHandler(com.google.gwt.event.dom.client.FocusHandler) instead |
| 22 | void removeKeyboardListener(KeyboardListener listener) Deprecated. Use the HandlerRegistration.removeHandler() method on the object returned by an add*Handler method instead |
| 23 | void removeMouseListener(MouseListener listener) Deprecated. Use the HandlerRegistration.removeHandler() method on the object returned by an add*Handler method instead |
| 24 | void removeMouseWheelListener(MouseWheelListener listener) Deprecated. Use the HandlerRegistration.removeHandler() method on the object returned by addMouseWheelHandler(com.google.gwt.event.dom.client.MouseWheelHandler) instead |
| 25 | void setAccessKey(char key) Sets the widget's 'access key'. |
| 26 | void setFocus(boolean focused) Explicitly focus/unfocus this widget. |
| 27 | void setTabIndex(int index) Sets the widget's position in the tab 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.SimplePanel
java.lang.Object
FocusPanel Widget Example
This example will take you through simple steps to show usage of a FocusPanel 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;
}
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>FocusPanel 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 FocusPanel widget.
package com.tutorialspoint.client;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.user.client.ui.DecoratorPanel;
import com.google.gwt.user.client.ui.FocusPanel;
import com.google.gwt.user.client.ui.HTML;
import com.google.gwt.user.client.ui.RootPanel;
public class HelloWorld implements EntryPoint {
public void onModuleLoad() {
// Create text
HTML contents = new HTML("This is a FocusPanel."
+" Click on the panel and it will attain focus.");
//create focus panel with content
FocusPanel focusPanel = new FocusPanel(contents);
focusPanel.setSize("400px", "100px");
DecoratorPanel decoratorPanel = new DecoratorPanel();
decoratorPanel.add(focusPanel);
// Add the widgets to the root panel.
RootPanel.get().add(decoratorPanel);
}
}
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:
