5.19. Embedded Resources

You can embed images in Vaadin UIs with the Image component, Adobe Flash graphics with Flash, and other web content with BrowserFrame. There is also a generic Embedded component for embedding other object types. The embedded content is referenced as resources, as described in Section 4.4, “Images and Other Resources”.

The following example displays an image as a class resource loaded with the class loader:

Image image = new Image("Yes, logo:",
    new ClassResource("vaadin-logo.png"));

The caption can be given as null to disable it. An empty string displays an empty caption which takes a bit space. The caption is managed by the containing layout.

You can set an altenative text for an embedded resource with setAlternateText(), which can be shown if images are disabled in the browser for some reason. The text can be used for accessibility purposes, such as for text-to-speech generation.

5.19.1. Embedded Image

The Image component allows embedding an image resource in a Vaadin UI.

// Serve the image from the theme
Resource res = new ThemeResource("img/myimage.png");

// Display the image without caption
Image image = new Image(null, res);

The Image component has by default undefined size in both directions, so it will automatically fit the size of the embedded image. If you want scrolling with scroll bars, you can put the image inside a Panel that has a defined size to enable scrolling, as described in Section 6.6.1, “Scrolling the Panel Content”. You can also put it inside some other component container and set the overflow: auto CSS property for the container element in a theme to enable automatic scrollbars.

Generating and Reloading Images

You can also generate the image content dynamically using a StreamResource, as described in Section 4.4.5, “Stream Resources”, or with a RequestHandler.

If the image changes, the browser needs to reload it. Simply updating the stream resource is not enough. Because of how caching is handled in some browsers, you can cause a reload easiest by renaming the filename of the resource with a unique name, such as one including a timestamp. You should set cache time to zero with setCacheTime() for the resource object when you create it.

// Create the stream resource with some initial filename
StreamResource imageResource =
    new StreamResource(imageSource, "initial-filename.png");

// Instruct browser not to cache the image

// Display the image
Image image = new Image(null, imageResource);

When refreshing, you also need to call markAsDirty() for the Image object.

// This needs to be done, but is not sufficient

// Generate a filename with a timestamp
SimpleDateFormat df = new SimpleDateFormat("yyyyMMddHHmmssSSS");
String filename = "myfilename-" + df.format(new Date()) + ".png";

// Replace the filename in the resource

5.19.2. Adobe Flash Graphics

The Flash component allows embedding Adobe Flash animations in Vaadin UIs.

Flash flash = new Flash(null,
    new ThemeResource("img/vaadin_spin.swf"));

You can set Flash parameters with setParameter(), which takes a parameter's name and value as strings. You can also set the codeBase, archive, and standBy attributes for the Flash object element in HTML.

5.19.3. BrowserFrame

The BrowserFrame allows embedding web content inside an HTML <iframe> element. You can refer to an external URL with ExternalResource.

As the BrowserFrame has undefined size by default, it is critical that you define a meaningful size for it, either fixed or relative.

BrowserFrame browser = new BrowserFrame("Browser",
    new ExternalResource("http://demo.vaadin.com/sampler/"));

Notice that web pages can prevent embedding them in an <iframe>.

5.19.4. Generic Embedded Objects

The generic Embedded component allows embedding all sorts of objects, such as SVG graphics, Java applets, and PDF documents, in addition to the images, Flash graphics, and browser frames which you can embed with the specialized components.

For example, to display a Flash animation:

// A resource reference to some object
Resource res = new ThemeResource("img/vaadin_spin.swf");

// Display the object
Embedded object = new Embedded("My Object", res);

Or an SVG image:

// A resource reference to some object
Resource res = new ThemeResource("img/reindeer.svg");

// Display the object
Embedded object = new Embedded("My SVG", res);
object.setMimeType("image/svg+xml"); // Unnecessary

The MIME type of the objects is usually detected automatically from the filename extension with the FileTypeResolver utility in Vaadin. If not, you can set it explicitly with setMimeType(), as was done in the example above (where it was actually unnecessary).

Some embeddable object types may require special support in the browser. You should make sure that there is a proper fallback mechanism if the browser does not support the embedded type.

I. Introduction
1. Introduction
1.1. Overview
1.2. Example Application Walkthrough
1.3. Support for the Eclipse IDE
1.4. Goals and Philosophy
1.5. Background
2. Getting Started with Vaadin
2.1. Overview
2.2. Setting up the Development Environment
2.3. Overview of Vaadin Libraries
2.4. Installing Vaadin Plugin for Eclipse
2.5. Creating and Running a Project with Eclipse
2.6. Using Vaadin with Maven
2.7. Creating a Project with NetBeans IDE
2.8. Creating a Project with IntelliJ IDEA
2.9. Vaadin Installation Package
2.10. Using Vaadin with Scala
3. Architecture
3.1. Overview
3.2. Technological Background
3.3. Client-Side Engine
3.4. Events and Listeners
II. Server-Side Framework
4. Writing a Server-Side Web Application
4.1. Overview
4.2. Building the UI
4.3. Handling Events with Listeners
4.4. Images and Other Resources
4.5. Handling Errors
4.6. Notifications
4.7. Application Lifecycle
4.8. Deploying an Application
5. User Interface Components
5.1. Overview
5.2. Interfaces and Abstractions
5.3. Common Component Features
5.4. Field Components
5.5. Component Extensions
5.6. Label
5.7. Link
5.8. TextField
5.9. TextArea
5.10. PasswordField
5.11. RichTextArea
5.12. Date and Time Input with DateField
5.13. Button
5.14. CheckBox
5.15. Selecting Items
5.16. Table
5.17. Tree
5.18. MenuBar
5.19. Embedded Resources
5.20. Upload
5.21. ProgressBar
5.22. Slider
5.23. Calendar
5.24. Component Composition with CustomComponent
5.25. Composite Fields with CustomField
6. Managing Layout
6.1. Overview
6.2. UI, Window, and Panel Content
6.3. VerticalLayout and HorizontalLayout
6.4. GridLayout
6.5. FormLayout
6.6. Panel
6.7. Sub-Windows
6.8. HorizontalSplitPanel and VerticalSplitPanel
6.9. TabSheet
6.10. Accordion
6.11. AbsoluteLayout
6.12. CssLayout
6.13. Layout Formatting
6.14. Custom Layouts
7. Visual User Interface Design with Eclipse
7.1. Overview
7.2. Creating a New Composite
7.3. Using The Visual Editor
7.4. Structure of a Visually Editable Component
8. Themes
8.1. Overview
8.2. Introduction to Cascading Style Sheets
8.3. Syntactically Awesome Stylesheets (Sass)
8.4. Creating and Using Themes
8.5. Creating a Theme in Eclipse
8.6. Responsive Themes
9. Binding Components to Data
9.1. Overview
9.2. Properties
9.3. Holding properties in Items
9.4. Creating Forms by Binding Fields to Items
9.5. Collecting Items in Containers
10. Vaadin SQLContainer
10.1. Architecture
10.2. Getting Started with SQLContainer
10.3. Filtering and Sorting
10.4. Editing
10.5. Caching, Paging and Refreshing
10.6. Referencing Another SQLContainer
10.7. Using FreeformQuery and FreeformStatementDelegate
10.8. Non-implemented methods of Vaadin container interfaces
10.9. Known Issues and Limitations
11. Advanced Web Application Topics
11.1. Handling Browser Windows
11.2. Embedding UIs in Web Pages
11.3. Debug Mode and Window
11.4. Request Handlers
11.5. Shortcut Keys
11.6. Printing
11.7. Google App Engine Integration
11.8. Common Security Issues
11.9. Navigating in an Application
11.10. Advanced Application Architectures
11.11. Managing URI Fragments
11.12. Drag and Drop
11.13. Logging
11.14. JavaScript Interaction
11.15. Accessing Session-Global Data
11.16. Server Push
12. Portal Integration
12.1. Overview
12.2. Creating a Portlet Project in Eclipse
12.3. Portlet UI
12.4. Deploying to a Portal
12.5. Installing Vaadin in Liferay
12.6. Handling Portlet Requests
12.7. Handling Portlet Mode Changes
12.8. Non-Vaadin Portlet Modes
12.9. Vaadin IPC for Liferay
III. Client-Side Framework
13. Client-Side Vaadin Development
13.1. Overview
13.2. Installing the Client-Side Development Environment
13.3. Client-Side Module Descriptor
13.4. Compiling a Client-Side Module
13.5. Creating a Custom Widget
13.6. Debugging Client-Side Code
14. Client-Side Applications
14.1. Overview
14.2. Client-Side Module Entry-Point
14.3. Compiling and Running a Client-Side Application
14.4. Loading a Client-Side Application
15. Client-Side Widgets
15.1. Overview
15.2. GWT Widgets
15.3. Vaadin Widgets
16. Integrating with the Server-Side
16.1. Overview
16.2. Starting It Simple With Eclipse
16.3. Creating a Server-Side Component
16.4. Integrating the Two Sides with a Connector
16.5. Shared State
16.6. RPC Calls Between Client- and Server-Side
16.7. Component and UI Extensions
16.8. Styling a Widget
16.9. Component Containers
16.10. Creating Add-ons
16.11. Migrating from Vaadin 6
16.12. Integrating JavaScript Components and Extensions
IV. Vaadin Add-ons
17. Using Vaadin Add-ons
17.1. Overview
17.2. Downloading Add-ons from Vaadin Directory
17.3. Installing Add-ons in Eclipse with Ivy
17.4. Using Add-ons in a Maven Project
17.5. Troubleshooting
18. Vaadin Charts
18.1. Overview
18.2. Installing Vaadin Charts
18.3. Basic Use
18.4. Chart Types
18.5. Chart Configuration
18.6. Chart Data
18.7. Advanced Uses
18.8. Timeline
19. Vaadin JPAContainer
19.1. Overview
19.2. Installing
19.3. Defining a Domain Model
19.4. Basic Use of JPAContainer
19.5. Entity Providers
19.6. Filtering JPAContainer
19.7. Querying with the Criteria API
19.8. Automatic Form Generation
19.9. Using JPAContainer with Hibernate
20. Mobile Applications with TouchKit
20.1. Overview
20.2. Considerations Regarding Mobile Browsing
20.3. Installing Vaadin TouchKit
20.4. Importing the Vornitologist Demo
20.5. Creating a New TouchKit Project
20.6. Elements of a TouchKit Application
20.7. Mobile User Interface Components
20.8. Advanced Mobile Features
20.9. Offline Mode
20.10. Building an Optimized Widget Set
20.11. Testing and Debugging on Mobile Devices
21. Vaadin TestBench
21.1. Overview
21.2. Installing Vaadin TestBench
21.3. Preparing an Application for Testing
21.4. Using Vaadin TestBench Recorder
21.5. Developing JUnit Tests
21.6. Taking and Comparing Screenshots
21.7. Running Tests in a Distributed Environment
21.8. Headless Testing
21.9. Known Issues
A. Songs of Vaadin