Module org.apache.wicket.core

Package org.apache.wicket.markup.html.image.resource

Class RenderedDynamicImageResource

java.lang.Object

org.apache.wicket.request.resource.AbstractResource

org.apache.wicket.request.resource.DynamicImageResource

org.apache.wicket.markup.html.image.resource.RenderedDynamicImageResource

All Implemented Interfaces:

Serializable, IResource, IClusterable

Direct Known Subclasses:

DefaultButtonImageResource

public abstract class RenderedDynamicImageResource
extends DynamicImageResource

A DynamicImageResource subclass that allows easy rendering of regeneratable (unbuffered) dynamic images. A RenderedDynamicImageResource implements the abstract method render(Graphics2D) to create/re-create a given image on-the-fly. When a RenderedDynamicImageResource is serialized, the image state is transient, which means it will disappear when the resource is sent over the wire and then will be recreated when required.

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:

• DefaultButtonImageResource
• DefaultButtonImageResourceFactory
• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.wicket.request.resource.AbstractResource

AbstractResource.ContentRangeType, AbstractResource.ResourceResponse, AbstractResource.WriteCallback

Nested classes/interfaces inherited from interface org.apache.wicket.request.resource.IResource

IResource.Attributes

Field Summary

Fields inherited from class org.apache.wicket.request.resource.AbstractResource

CONTENT_DISPOSITION_HEADER_NAME, CONTENT_RANGE_ENDBYTE, CONTENT_RANGE_STARTBYTE, INTERNAL_HEADERS

Constructor Summary

Constructors

Constructor	Description
RenderedDynamicImageResource(int width, int height)	Constructor.
RenderedDynamicImageResource(int width, int height, String format)	Constructor.

Method Summary

Modifier and Type	Method	Description
int	getHeight()
protected byte[]	getImageData(IResource.Attributes attributes)	Get image data for our dynamic image resource.
int	getType()
int	getWidth()
void	invalidate()	Causes the image to be redrawn the next time its requested.
protected abstract boolean	render(Graphics2D graphics, IResource.Attributes attributes)	Override this method to provide your rendering code.
protected byte[]	render(IResource.Attributes attributes)	Renders this image
void	setHeight(int height)
void	setType(int type)
void	setWidth(int width)

Methods inherited from class org.apache.wicket.request.resource.DynamicImageResource

configureResponse, getFormat, newResourceResponse, setFormat, setLastModifiedTime, toImageData

Methods inherited from class org.apache.wicket.request.resource.AbstractResource

configureCache, getCachingStrategy, respond, setRequestMetaData, setRequestRangeMetaData, setResponseContentRangeHeaderFields, setResponseHeaders

Methods inherited from class java.lang.Object

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

Constructor Details

RenderedDynamicImageResource

public RenderedDynamicImageResource(int width,
 int height)

Constructor.

Parameters:

width - Width of image

height - Height of image

RenderedDynamicImageResource

public RenderedDynamicImageResource(int width,
 int height,
 String format)

Constructor.

Parameters:

width - Width of image

height - Height of image

format - The format of the image (jpg, png or gif)

Method Details

getHeight

public int getHeight()

Returns:

Returns the height.

getType

public int getType()

Returns:

Returns the type (one of BufferedImage.TYPE_*).

getWidth

public int getWidth()

Returns:

Returns the width.

invalidate

public void invalidate()

Causes the image to be redrawn the next time its requested.

setHeight

public void setHeight(int height)

Parameters:

height - The height to set.

setType

public void setType(int type)

Parameters:

type - The type to set (one of BufferedImage.TYPE_*).

setWidth

public void setWidth(int width)

Parameters:

width - The width to set.

getImageData

protected byte[] getImageData(IResource.Attributes attributes)

Description copied from class: DynamicImageResource

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

Specified by:

getImageData in class DynamicImageResource

Parameters:

attributes - the context bringing the request, response and the parameters

Returns:

The image data for this dynamic image. null means there is no image and 404 (Not found) response will be return.

render

protected byte[] render(IResource.Attributes attributes)

Renders this image

Parameters:

attributes - the current request attributes

Returns:

The image data

render

protected abstract boolean render(Graphics2D graphics,
 IResource.Attributes attributes)

Override this method to provide your rendering code.

Parameters:

graphics - The graphics context to render on.

attributes - the current request attributes

Returns:

true if the image was rendered. false if the image size was changed by the rendering implementation and the image should be re-rendered at the new size.