Class ImageTranscoder

java.lang.Object

org.apache.batik.transcoder.TranscoderSupport

org.apache.batik.transcoder.AbstractTranscoder

org.apache.batik.transcoder.XMLAbstractTranscoder

org.apache.batik.transcoder.SVGAbstractTranscoder

org.apache.batik.transcoder.image.ImageTranscoder

All Implemented Interfaces:

Transcoder

Direct Known Subclasses:

JPEGTranscoder, PNGTranscoder, TIFFTranscoder

public abstract class ImageTranscoder
extends SVGAbstractTranscoder

This class enables to transcode an input to an image of any format.

Two transcoding hints (KEY_WIDTH and KEY_HEIGHT) can be used to respectively specify the image width and the image height. If only one of these keys is specified, the transcoder preserves the aspect ratio of the original image.

The KEY_BACKGROUND_COLOR defines the background color to use for opaque image formats, or the background color that may be used for image formats that support alpha channel.

The KEY_AOI represents the area of interest to paint in device space.

Three additional transcoding hints that act on the SVG processor can be specified:

KEY_LANGUAGE to set the default language to use (may be used by a <switch> SVG element for example), KEY_USER_STYLESHEET_URI to fix the URI of a user stylesheet, and KEY_MM_PER_PIXEL to specify the number of millimeters in each pixel .

Nested Class Summary

Nested classes/interfaces inherited from class SVGAbstractTranscoder

SVGAbstractTranscoder.SVGAbstractTranscoderUserAgent

Field Summary

Fields

Modifier and Type	Field	Description
static final TranscodingHints.Key	KEY_BACKGROUND_COLOR	The image background paint key.
static final TranscodingHints.Key	KEY_FORCE_TRANSPARENT_WHITE	The forceTransparentWhite key.

Fields inherited from class SVGAbstractTranscoder

builder, ctx, curAOI, curTxf, DEFAULT_ALLOWED_SCRIPT_TYPES, DEFAULT_DEFAULT_FONT_FAMILY, height, KEY_ALLOW_EXTERNAL_RESOURCES, KEY_ALLOWED_SCRIPT_TYPES, KEY_ALTERNATE_STYLESHEET, KEY_AOI, KEY_CONSTRAIN_SCRIPT_ORIGIN, KEY_DEFAULT_FONT_FAMILY, KEY_EXECUTE_ONLOAD, KEY_HEIGHT, KEY_LANGUAGE, KEY_MAX_HEIGHT, KEY_MAX_WIDTH, KEY_MEDIA, KEY_PIXEL_TO_MM, KEY_PIXEL_UNIT_TO_MILLIMETER, KEY_SNAPSHOT_TIME, KEY_USER_STYLESHEET_URI, KEY_WIDTH, root, userAgent, width

Fields inherited from class XMLAbstractTranscoder

KEY_DOCUMENT_ELEMENT, KEY_DOCUMENT_ELEMENT_NAMESPACE_URI, KEY_DOM_IMPLEMENTATION, KEY_XML_PARSER_CLASSNAME, KEY_XML_PARSER_VALIDATING

Fields inherited from class TranscoderSupport

handler, hints

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ImageTranscoder()	Constructs a new ImageTranscoder.

Method Summary

Modifier and Type	Method	Description
abstract BufferedImage	createImage(int width, int height)	Creates a new image with the specified dimension.
protected ImageRenderer	createRenderer()	Method so subclasses can modify the Renderer used to render document.
protected void	forceTransparentWhite(BufferedImage img, SinglePixelPackedSampleModel sppsm)	Converts an image so that viewers which do not support the alpha channel will see a white background (and not a black one).
protected void	transcode(Document document, String uri, TranscoderOutput output)	Transcodes the specified Document as an image in the specified output.
abstract void	writeImage(BufferedImage img, TranscoderOutput output)	Writes the specified image to the specified output.

Methods inherited from class SVGAbstractTranscoder

createBridgeContext, createBridgeContext, createBridgeContext, createDocumentFactory, createUserAgent, getCanvasGraphicsNode, setImageSize, transcode

Methods inherited from class TranscoderSupport

addTranscodingHint, getErrorHandler, getTranscodingHints, removeTranscodingHint, setErrorHandler, setTranscodingHints, setTranscodingHints

Methods inherited from class Object

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

Methods inherited from interface Transcoder

addTranscodingHint, getErrorHandler, getTranscodingHints, removeTranscodingHint, setErrorHandler, setTranscodingHints, setTranscodingHints

Field Details

KEY_BACKGROUND_COLOR

public static final TranscodingHints.Key KEY_BACKGROUND_COLOR

The image background paint key.

Key:	KEY_BACKGROUND_COLOR
Value:	Paint
Default:	null
Required:	No
Description:	Specify the background color to use. The color is required by opaque image formats and is used by image formats that support alpha channel.

KEY_FORCE_TRANSPARENT_WHITE

public static final TranscodingHints.Key KEY_FORCE_TRANSPARENT_WHITE

The forceTransparentWhite key.

Key:	KEY_FORCE_TRANSPARENT_WHITE
Value:	Boolean
Default:	false
Required:	No
Description:	It controls whether the encoder should force the image's fully transparent pixels to be fully transparent white instead of fully transparent black. This is useful when the encoded file is displayed in a browser which does not support transparency correctly and lets the image display with a white background instead of a black background. However, note that the modified image will display differently over a white background in a viewer that supports transparency. Not all Transcoders use this key (in particular some formats can't preserve the alpha channel at all in which case this is not used).

Constructor Details

ImageTranscoder

protected ImageTranscoder()

Constructs a new ImageTranscoder.

Method Details

transcode

protected void transcode(Document document,
 String uri,
 TranscoderOutput output)
                  throws TranscoderException

Transcodes the specified Document as an image in the specified output.

Overrides:

transcode in class SVGAbstractTranscoder

Parameters:

document - the document to transcode

uri - the uri of the document or null if any

output - the ouput where to transcode

Throws:

TranscoderException - if an error occured while transcoding

createRenderer

protected ImageRenderer createRenderer()

Method so subclasses can modify the Renderer used to render document.

forceTransparentWhite

protected void forceTransparentWhite(BufferedImage img,
 SinglePixelPackedSampleModel sppsm)

Converts an image so that viewers which do not support the alpha channel will see a white background (and not a black one).

Parameters:

img - the image to convert

sppsm -

createImage

public abstract BufferedImage createImage(int width,
 int height)

Creates a new image with the specified dimension.

Parameters:

width - the image width in pixels

height - the image height in pixels

writeImage

public abstract void writeImage(BufferedImage img,
 TranscoderOutput output)
                         throws TranscoderException

Writes the specified image to the specified output.

Parameters:

img - the image to write

output - the output where to store the image

Throws:

TranscoderException - if an error occured while storing the image