org.apache.wicket.markup.html.image.resource
Class DynamicImageResource

java.lang.Object
  org.apache.wicket.Resource
      org.apache.wicket.markup.html.WebResource
          org.apache.wicket.markup.html.DynamicWebResource
              org.apache.wicket.markup.html.image.resource.DynamicImageResource

All Implemented Interfaces:

java.io.Serializable, IClusterable, IRequestListener, IResourceListener

Direct Known Subclasses:

BlobImageResource, BufferedDynamicImageResource, CaptchaImageResource, RenderedDynamicImageResource, ThumbnailImageResource

public abstract class DynamicImageResource
extends DynamicWebResource

An ImageResource subclass for dynamic images (images created programmatically). Subclasses override getImageData() to provide the image data to send back to the user. A given subclass may decide how to produce this data and whether/how to buffer it.

The RenderedDynamicImageResource subclass is designed for images that can be regenerated when the component is deserialized (the image data is transient). A good example of a RenderedDynamicImageResource is the DefaultButtonImageResource class, which can regenerate a given button image at any time. This makes it very lightweight when clustered. The BufferedDynamicImageResource class, on the other hand, is designed for images that cannot be regenerated on demand. It buffers its image data in a non-transient way, which means that the entire image will be serialized and copied when the resource is replicated in a cluster!

The helper method toImageData(BufferedImage) is provided so that subclasses can easily turn a BufferedImage into a suitable return value when implementing getImageData().

The format of the image (and therefore the resource's extension) can be specified with setFormat(String). The default format is "PNG" because JPEG is lossy and makes generated images look bad and GIF has patent issues.

Author:

Jonathan Locke, Gili Tzabari, Johan Compagner

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.wicket.markup.html.DynamicWebResource

DynamicWebResource.ResourceState

Field Summary

Fields inherited from interface org.apache.wicket.IResourceListener

INTERFACE

Constructor Summary

DynamicImageResource()
Creates a dynamic image resource.

DynamicImageResource(java.util.Locale locale)
Creates a dynamic resource from for the given locale

DynamicImageResource(java.lang.String format)
Creates a dynamic resource from for the given locale

DynamicImageResource(java.lang.String format, java.util.Locale locale)
Creates a dynamic resource from for the given locale

Method Summary

java.lang.String	getFormat()
protected abstract byte[]	getImageData() Get image data for our dynamic image resource.
protected DynamicWebResource.ResourceState	getResourceState() Gets the byte array for our dynamic resource.
void	setFormat(java.lang.String format) Sets the format of this resource
protected void	setLastModifiedTime(Time time) set the last modified time for this resource.
protected byte[]	toImageData(java.awt.image.BufferedImage image)

Methods inherited from class org.apache.wicket.markup.html.DynamicWebResource

getLocale, getResourceStream, setHeaders

Methods inherited from class org.apache.wicket.markup.html.WebResource

configureResponse, getCacheDuration

Methods inherited from class org.apache.wicket.Resource

getParameters, invalidate, isCacheable, onResourceRequested, setCacheable, setParameters

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DynamicImageResource

public DynamicImageResource()

Creates a dynamic image resource.

DynamicImageResource

public DynamicImageResource(java.util.Locale locale)

Creates a dynamic resource from for the given locale

Parameters:

locale - The locale of this resource

DynamicImageResource

public DynamicImageResource(java.lang.String format)

Creates a dynamic resource from for the given locale

Parameters:

format - The image format ("png", "jpeg", etc)

DynamicImageResource

public DynamicImageResource(java.lang.String format,
                            java.util.Locale locale)

Creates a dynamic resource from for the given locale

Parameters:

format - The image format ("png", "jpeg", etc)

locale - The locale of this resource

Method Detail

getFormat

public final java.lang.String getFormat()

Returns:

Returns the image format.

setFormat

public final void setFormat(java.lang.String format)

Sets the format of this resource

Parameters:

format - The format (jpg, png or gif..)

setLastModifiedTime

protected void setLastModifiedTime(Time time)

set the last modified time for this resource.

Parameters:

time -

toImageData

protected byte[] toImageData(java.awt.image.BufferedImage image)

Parameters:

image - The image to turn into data

Returns:

The image data for this dynamic image

getResourceState

protected DynamicWebResource.ResourceState getResourceState()

Description copied from class: DynamicWebResource

Gets the byte array for our dynamic resource. If the subclass regenerates the data, it should set the lastModifiedTime too. This ensures that resource caching works correctly.

Specified by:

getResourceState in class DynamicWebResource

Returns:

The byte array for this dynamic resource.

See Also:

DynamicWebResource.getResourceState()

getImageData

protected abstract byte[] getImageData()

Get image data for our dynamic image resource. If the subclass regenerates the data, it should set the lastModifiedTime when it does so. This ensures that image caching works correctly.

Returns:

The image data for this dynamic image