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org.ydp.jai
Class PNGCodec  

java.lang.Object
  org.ydp.jai.ImageCodec
      org.ydp.jai.PNGCodec

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public final class PNGCodec

extends ImageCodec

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Field Summary

 

Fields inherited from class org.ydp.jai.ImageCodec

 

Constructor Summary

PNGCodec()

 

Method Summary
boolean	canEncodeImage(java.awt.image.RenderedImage im, ImageEncodeParam param)           Returns true if the given image and encoder param object are suitable for encoding by this ImageCodec.
protected  ImageDecoder	createImageDecoder(java.io.File src, ImageDecodeParam param)           Returns an implementation of the ImageDecoder interface appropriate for that codec.
protected  ImageDecoder	createImageDecoder(java.io.InputStream src, ImageDecodeParam param)           Returns an implementation of the ImageDecoder interface appropriate for that codec.
protected  ImageDecoder	createImageDecoder(SeekableStream src, ImageDecodeParam param)           In a concrete subclass of ImageCodec, returns an implementation of the ImageDecoder interface appropriate for that codec.
protected  ImageEncoder	createImageEncoder(java.io.OutputStream dst, ImageEncodeParam param)           In a concrete subclass of ImageCodec, returns an implementation of the ImageEncoder interface appropriate for that codec.
java.lang.Class	getDecodeParamClass()           Returns a Class object indicating the proper subclass of ImageDecodeParam to be used with this ImageCodec.
java.lang.Class	getEncodeParamClass()           Returns a Class object indicating the proper subclass of ImageEncodeParam to be used with this ImageCodec.
java.lang.String	getFormatName()           Returns the name of this image format.
int	getNumHeaderBytes()           Returns the number of bytes of header needed to recognize the format, or 0 if an arbitrary number of bytes may be needed.
boolean	isFormatRecognized(byte[] header)           Returns true if the format is recognized in the initial portion of a stream.

 

Methods inherited from class org.ydp.jai.ImageCodec

createComponentColorModel, createGrayIndexColorModel, createImageDecoder, createImageDecoder, createImageDecoder, createImageEncoder, getCodec, getCodecs, getDecoderNames, getEncoderNames, isFormatRecognized, registerCodec, unregisterCodec

 

Methods inherited from class java.lang.Object

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

 

Constructor Detail

PNGCodec

public PNGCodec()

Method Detail

getFormatName

public java.lang.String getFormatName()

Description copied from class: ImageCodec

Returns the name of this image format.

Specified by:

getFormatName in class ImageCodec

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getEncodeParamClass

public java.lang.Class getEncodeParamClass()

Description copied from class: ImageCodec

Returns a Class object indicating the proper subclass of ImageEncodeParam to be used with this ImageCodec. If encoding is not supported by this codec, null is returned. If encoding is supported, but a parameter object is not used during encoding, Object.class is returned to signal this fact.

Specified by:

getEncodeParamClass in class ImageCodec

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getDecodeParamClass

public java.lang.Class getDecodeParamClass()

Description copied from class: ImageCodec

Returns a Class object indicating the proper subclass of ImageDecodeParam to be used with this ImageCodec. If encoding is not supported by this codec, null is returned. If decoding is supported, but a parameter object is not used during decoding, Object.class is returned to signal this fact.

Specified by:

getDecodeParamClass in class ImageCodec

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canEncodeImage

public boolean canEncodeImage(java.awt.image.RenderedImage im,
                              ImageEncodeParam param)

Description copied from class: ImageCodec

Returns true if the given image and encoder param object are suitable for encoding by this ImageCodec. For example, some codecs may only deal with images with a certain number of bands; an attempt to encode an image with an unsupported number of bands will fail.

Specified by:

canEncodeImage in class ImageCodec

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createImageEncoder

protected ImageEncoder createImageEncoder(java.io.OutputStream dst,
                                          ImageEncodeParam param)

Description copied from class: ImageCodec

In a concrete subclass of ImageCodec, returns an implementation of the ImageEncoder interface appropriate for that codec.

Specified by:

createImageEncoder in class ImageCodec

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createImageDecoder

protected ImageDecoder createImageDecoder(java.io.InputStream src,
                                          ImageDecodeParam param)

Description copied from class: ImageCodec

Returns an implementation of the ImageDecoder interface appropriate for that codec. Subclasses of ImageCodec may override this method if they wish to accept data directly from an InputStream; otherwise, this method will convert the source into a backwards-seekable SeekableStream and call the appropriate version of createImageDecoder for that data type.

Instances of ImageCodec that do not require the ability to seek backwards in their source SeekableStream should override this method in order to avoid the default call to SeekableStream.wrapInputStream(src, true).

Overrides:

createImageDecoder in class ImageCodec

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createImageDecoder

protected ImageDecoder createImageDecoder(java.io.File src,
                                          ImageDecodeParam param)
                                   throws java.io.IOException

Description copied from class: ImageCodec

Returns an implementation of the ImageDecoder interface appropriate for that codec. Subclasses of ImageCodec may override this method if they wish to accept data directly from a File; otherwise, this method will convert the source into a SeekableStream and call the appropriate version of createImageDecoder for that data type.

Overrides:

createImageDecoder in class ImageCodec

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createImageDecoder

protected ImageDecoder createImageDecoder(SeekableStream src,
                                          ImageDecodeParam param)

Description copied from class: ImageCodec

In a concrete subclass of ImageCodec, returns an implementation of the ImageDecoder interface appropriate for that codec.

Specified by:

createImageDecoder in class ImageCodec

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getNumHeaderBytes

public int getNumHeaderBytes()

Description copied from class: ImageCodec

Returns the number of bytes of header needed to recognize the format, or 0 if an arbitrary number of bytes may be needed. The default implementation returns 0.

The return value must be a constant for all instances of each particular subclass of ImageCodec.

Although it is legal to always return 0, in some cases processing may be more efficient if the number of bytes needed is known in advance.

Overrides:

getNumHeaderBytes in class ImageCodec

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isFormatRecognized

public boolean isFormatRecognized(byte[] header)

Description copied from class: ImageCodec

Returns true if the format is recognized in the initial portion of a stream. The header will be passed in as a byte array of length getNumHeaderBytes(). This method should be called only if getNumHeaderBytes() returns a value greater than 0.

The default implementation throws an exception to indicate that it should never be called.

Overrides:

isFormatRecognized in class ImageCodec

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