AbstractImagePrototype (GWT Javadoc)

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## com.google.gwt.user.client.ui
Class AbstractImagePrototype

    java.lang.Object
      com.google.gwt.user.client.ui.AbstractImagePrototype

    public abstract class AbstractImagePrototype

extends java.lang.Object

An opaque representation of a particular image such that the image can be accessed either as an HTML fragment or as an `Image` object. An image prototype can be thought of as an abstract image factory with additional capabilities.

The `applyTo(Image)` method provides an efficient way to replace the contents of an existing `Image`. This is useful in cases where an image changes its appearance based on a user's action. Instead of creating two `Image` objects then alternately hiding/showing them, one can use the `applyTo(Image)` method of two `AbstractImagePrototype` objects to transform a single `Image` object between two (or more) visual representations. The use of `AbstractImagePrototypes` results in an cleaner and more efficient implementation.

This class also provide methods for working with raw elements, using `createElement()` and `applyTo(ImagePrototypeElement)`.

This class is also a useful way to encapsulate complex HTML that represents an image without actually instantiating `Image` objects. When constructing large HTML fragments, especially those that contain many images, `getHTML()` can be much more efficient.

Nested Class Summary
`static class` | `AbstractImagePrototype.ImagePrototypeElement` This corresponds to the top Element of the DOM structure created by `createElement()`.

Constructor Summary
`AbstractImagePrototype()`

Method Summary
`void` | `applyTo(AbstractImagePrototype.ImagePrototypeElement imageElement)` Transforms an existing `AbstractImagePrototype.ImagePrototypeElement` into the image represented by this prototype.
`abstract void` | `applyTo(Image image)` Transforms an existing `Image` into the image represented by this prototype.
`static AbstractImagePrototype` | `create(ImageResource resource)` Create an AbstractImagePrototype backed by a ClientBundle ImageResource.
`AbstractImagePrototype.ImagePrototypeElement` | `createElement()` Creates a new `AbstractImagePrototype.ImagePrototypeElement` based on the image represented by this prototype.
`abstract Image` | `createImage()` Creates a new `Image` instance based on the image represented by this prototype.
`java.lang.String` | `getHTML()` Gets an HTML fragment that displays the image represented by this prototype.
`SafeHtml` | `getSafeHtml()` Gets an HTML fragment that displays the image represented by this prototype.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### AbstractImagePrototype

    public AbstractImagePrototype()

Method Detail

### create

    public static AbstractImagePrototype create(ImageResource resource)

  Create an AbstractImagePrototype backed by a ClientBundle ImageResource. This method provides an API compatibility mapping for the new ImageResource API.

  Parameters:
    `resource` - an ImageResource produced by a ClientBundle
  Returns:
    an AbstractImagePrototype that displays the contents of the ImageResource

### applyTo

    public abstract void applyTo(Image image)

  Transforms an existing `Image` into the image represented by this prototype.

  Parameters:
    `image` - the instance to be transformed to match this prototype

### applyTo

    public void applyTo(AbstractImagePrototype.ImagePrototypeElement imageElement)

  Transforms an existing `AbstractImagePrototype.ImagePrototypeElement` into the image represented by this prototype.

  Parameters:
    `imageElement` - an `ImagePrototypeElement` created by `createElement()`

### createElement

    public AbstractImagePrototype.ImagePrototypeElement createElement()

  Creates a new `AbstractImagePrototype.ImagePrototypeElement` based on the image represented by this prototype. The DOM structure may not necessarily a simple `<img>` element. It may be a more complex structure that should be treated opaquely.

  Returns:
    the `ImagePrototypeElement` corresponding to the image represented by this prototype

### createImage

    public abstract Image createImage()

  Creates a new `Image` instance based on the image represented by this prototype.

  Returns:
    a new `Image` based on this prototype

### getHTML

    public java.lang.String getHTML()

  Gets an HTML fragment that displays the image represented by this prototype. The HTML returned is not necessarily a simple `<img>` element. It may be a more complex structure that should be treated opaquely.

  The default implementation calls `getSafeHtml()`.

  Returns:
    the HTML representation of this prototype

### getSafeHtml

    public SafeHtml getSafeHtml()

  Gets an HTML fragment that displays the image represented by this prototype. The HTML returned is not necessarily a simple `<img>` element. It may be a more complex structure that should be treated opaquely.

  The default implementation throws an `UnsupportedOperationException`.

  Returns:
    the HTML representation of this prototype

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