magoffin.matt.ma2.image
Class ImageMediaHelper

java.lang.Object
  magoffin.matt.ma2.image.ImageMediaHelper

public class ImageMediaHelper
extends java.lang.Object

Helper class for dealing with ImageIO-based images.

This class exists so the functionality can be shared between other MediaHandler implementations outside the .image package, which may need to render images from their media. Video handlers, for example, can use this class to render image previews for their video files.

Version:

$Revision: 43 $ $Date: 2007-10-21 11:10:01 +1300 (Sun, 21 Oct 2007) $

Author:

Matt Magoffin (spamsqr@msqr.us)

Constructor Summary

ImageMediaHelper()

Method Summary

java.awt.image.BufferedImage	getBufferedImage(java.awt.Image image) Get a BufferedImage from an Image.
javax.imageio.ImageReader	getReaderForFile(java.io.File file) Get an ImageReader for a File (based on file extension).
javax.imageio.ImageReader	getReaderForMIME(java.lang.String mime, java.io.InputStream in) Get an ImageReader for the given InputStream for the given MIME type.
javax.imageio.ImageWriter	getWriterForMIME(java.io.OutputStream out, java.lang.String mime) Get an ImageWriter for the given OutputStream for the given MIME type.
javax.imageio.ImageWriter	getWriterForMIME(java.lang.String mime) Get an image writer for a specific MIME type.
boolean	hasAlpha(java.awt.Image image) Returns true if the specified image has transparent pixels.
void	writeJpegStream(java.awt.image.BufferedImage image, java.lang.Long itemId, int quality, java.io.OutputStream out) Encode a JPEG image to an OutputStream with the specified quality.

Methods inherited from class java.lang.Object

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

Constructor Detail

ImageMediaHelper

public ImageMediaHelper()

Method Detail

getBufferedImage

public java.awt.image.BufferedImage getBufferedImage(java.awt.Image image)

Get a BufferedImage from an Image.

Parameters:

image - the image to get a BufferedImage for

Returns:

BufferedImage

hasAlpha

public boolean hasAlpha(java.awt.Image image)

Returns true if the specified image has transparent pixels.

Parameters:

image - the Image to test

Returns:

true if the image has transparent pixels

getWriterForMIME

public javax.imageio.ImageWriter getWriterForMIME(java.lang.String mime)

Get an image writer for a specific MIME type.

This method will be called by getWriterForMIME(OutputStream, String) and will return an ImageWriter registered for item's MIME type, as defined by MediaItem.getMime(). Media handler implementations that wish to generate an output type different than their native type can override this method.

Parameters:

mime - the MIME type to get a ImageWriter for

Returns:

an ImageWriter, or null if none available

getWriterForMIME

public javax.imageio.ImageWriter getWriterForMIME(java.io.OutputStream out,
                                                  java.lang.String mime)

Get an ImageWriter for the given OutputStream for the given MIME type.

This method will create an ImageOutputStream from the given OutputStream.

Parameters:

out - the OutputStream to encode the image to

mime - the MIME type to get an ImageWriter for

Returns:

an ImageWriter set to the OutputStream in

getReaderForFile

public javax.imageio.ImageReader getReaderForFile(java.io.File file)

Get an ImageReader for a File (based on file extension).

Parameters:

file - the file to get the reader for

Returns:

the ImageReader

getReaderForMIME

public javax.imageio.ImageReader getReaderForMIME(java.lang.String mime,
                                                  java.io.InputStream in)

Get an ImageReader for the given InputStream for the given MIME type.

This method will create an ImageInputStream from the given InputStream.

Parameters:

mime - the MIME to get an ImageReader for

in - the InputStream of the image to decode

Returns:

an ImageReader set to the InputStream in

writeJpegStream

public void writeJpegStream(java.awt.image.BufferedImage image,
                            java.lang.Long itemId,
                            int quality,
                            java.io.OutputStream out)

Encode a JPEG image to an OutputStream with the specified quality.

Parameters:

image - the image to encode as a JPEG stream

itemId - the media item ID being written (for logging only)

quality - integer between 0 and 100, with 100 being the higest quality

out - the output stream